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Find video protocols related to scientific articles indexed in Pubmed.
Combined inhibition of PI3K? and PI3K? reduces fat mass by enhancing ?-MSH-dependent sympathetic drive.
Sci Signal
PUBLISHED: 11-20-2014
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Obesity is defined as an abnormal increase in white adipose tissue and has become a major medical burden worldwide. Signals from the brain control not only appetite but also energy expenditure, both of which contribute to body weight. We showed that genetic or pharmacological inhibition of two phosphatidylinositol 3-kinases (PI3K? and PI3K?) in mice reduced fat mass by promoting increased energy expenditure. This effect was accompanied by stimulation of lipolysis and the acquisition of the energy-burning characteristics of brown adipocytes by white adipocytes, a process referred to as "browning." The browning of the white adipocytes involved increased norepinephrine release from the sympathetic nervous system. We found that PI3K? and PI3K? together promoted a negative feedback loop downstream of the melanocortin 4 receptor in the central nervous system, which controls appetite and energy expenditure in the periphery. Analysis of mice with drug-induced sympathetic denervation suggested that these kinases controlled the sympathetic drive in the brain. Administration of inhibitors of both PI3K? and PI3K? to mice by intracerebroventricular delivery induced a 10% reduction in fat mass as quickly as 10 days. These results suggest that combined inhibition of PI3K? and PI3K? might represent a promising treatment for obesity.
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Targeting PI3K? activity decreases vascular trauma-induced intimal hyperplasia through modulation of the Th1 response.
J. Exp. Med.
PUBLISHED: 07-29-2014
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Interventional strategies to treat atherosclerosis, such as transluminal angioplasty and stent implantation, often cause vascular injury. This leads to intimal hyperplasia (IH) formation that induces inflammatory and fibroproliferative processes and ultimately restenosis. We show that phosphoinositide 3-kinase ? (PI3K?) is a key player in IH formation and is a valid therapeutic target in its prevention/treatment. PI3K?-deficient mice and mice expressing catalytically inactive PI3K? (PI3K? KD) showed reduced arterial occlusion and accumulation of monocytes and T cells around sites of vascular lesion. The transfer of PI3K? KD CD4(+) T cells into Rag2-deficient mice greatly reduced vascular occlusion compared with WT cells, clearly demonstrating the involvement of PI3K? in CD4(+) T cells during IH formation. In addition we found that IH is associated with increased levels of Th1 and Th17 cytokines. A specific decrease in the Th1 response was observed in the absence of PI3K? activity, leading to decreased CXCL10 and RANTES production by smooth muscle cells. Finally, we show that treatment with the PI3K? inhibitor AS-605240 is sufficient to decrease IH in both mouse and rat models, reinforcing the therapeutic potential of PI3K? inhibition. Altogether, these findings demonstrate a new role for PI3K? activity in Th1-controlled IH development.
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Phosphoinositide 3-Kinase ? Affects LPS-Induced Disturbance of Blood-Brain Barrier Via Lipid Kinase-Independent Control of cAMP in Microglial Cells.
Neuromolecular Med.
PUBLISHED: 07-10-2014
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The breakdown of the blood-brain barrier (BBB) is a key event in the development of sepsis-induced brain damage. BBB opening allows blood-born immune cells to enter the CNS to provoke a neuroinflammatory response. Abnormal expression and activation of matrix metalloproteinases (MMP) was shown to contribute to BBB opening. Using different mouse genotypes in a model of LPS-induced systemic inflammation, our present report reveals phosphoinositide 3-kinase ? (PI3K?) as a mediator of BBB deterioration and concomitant generation of MMP by microglia. Unexpectedly, microglia expressing lipid kinase-deficient mutant PI3K? exhibited similar MMP regulation as wild-type cells. Our data suggest kinase-independent control of cAMP phosphodiesterase activity by PI3K? as a crucial mediator of microglial cell activation, MMP expression and subsequent BBB deterioration. The results identify the suppressive effect of PI3K? on cAMP as a critical mediator of immune cell functions.
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Methods to measure the enzymatic activity of PI3Ks.
Meth. Enzymol.
PUBLISHED: 06-14-2014
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Phosphoinositide-3-kinase (PI3K) signaling has been implicated in a panoply of cellular responses including survival, proliferation, protein synthesis, migration, and vesicular trafficking. In addition, alterations in the enzymatic activity of PI3Ks have been involved in the pathogenesis of multiple diseases, ranging from cancer to chronic inflammation. The emerging interest in PI3K as a pharmacological target has prompted the development of several molecules with inhibitory activity. In this context, the quantification of the second messenger generated by PI3Ks, phosphoinositide-3-phosphate, offers an opportunity to directly test variations in the lipid kinase activity of PI3K in physiological as well as pathological conditions. Here, we will describe common methods to measure the lipid kinase activity of PI3K in vitro and new techniques to follow the production of phosphoinositide-3-phosphate in vivo. These methods are relevant to study the alterations of the PI3K systems at the interface between signaling and oncometabolism.
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PI3K/AKT signaling pathway and cancer: an updated review.
Ann. Med.
PUBLISHED: 06-05-2014
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Despite development of novel agents targeting oncogenic pathways, matching targeted therapies to the genetic status of individual tumors is proving to be a daunting task for clinicians. To improve the clinical efficacy and to reduce the toxic side effects of treatments, a deep characterization of genetic alterations in different tumors is required. The mutational profile often evidences a gain of function or hyperactivity of phosphoinositide 3-kinases (PI3Ks) in tumors. These enzymes are activated downstream tyrosine kinase receptors (RTKs) and/or G proteins coupled receptors (GPCRs) and, via AKT, are able to induce mammalian target of rapamycin (mTOR) stimulation. Here, we elucidate the impact of class I (p110?, ?, ?, and ?) catalytic subunit mutations on AKT-mediated cellular processes that control crucial mechanisms in tumor development. Moreover, the interrelation of PI3K signaling with mTOR, ERK, and RAS pathways will be discussed, exploiting the potential benefits of PI3K signaling inhibitors in clinical use.
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Deficiency of cannabinoid receptor of type 2 worsens renal functional and structural abnormalities in streptozotocin-induced diabetic mice.
Kidney Int.
PUBLISHED: 03-25-2014
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A functionally active endocannabinoid system is present within the kidney. The cannabinoid receptor type 2 (CB2) is expressed by both inflammatory cells and podocytes, and its activation has beneficial effects in experimental diabetic nephropathy. To further explore the role of CB2 in diabetic nephropathy, we studied renal functional and structural abnormalities in streptozotocin-induced diabetic CB2 knockout mice. In diabetic mice, deletion of the CB2 receptor albuminuria, the downregulation of podocin and nephrin, mesangial expansion, overexpression of extracellular matrix components, monocyte infiltration, and reduced renal function were all exacerbated. To investigate the relative contributions of podocytes and monocytes to the phenotype of diabetic knockout mice, bone marrow transplantation experiments were performed. The lack of CB2 on bone marrow-derived cells was shown to be important in driving the enhanced glomerular monocyte accrual found in diabetic knockout mice. Absence of CB2 on resident glomerular cells had a major role in worsening diabetic nephropathy, both functional and structural abnormalities, likely by enhanced MCP-1 and CB1 signaling. Studies in cultured podocytes demonstrated that CB2 expression is not altered by a high glucose milieu but is downregulated by mechanical stretch, mimicking glomerular capillary hypertension. Thus, CB2 deletion worsens diabetic nephropathy, independent of bone marrow-derived cells.
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PI3K? integrates cAMP and Akt signalling of the ?-opioid receptor.
Br. J. Pharmacol.
PUBLISHED: 03-03-2014
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The ?-opioid receptor has been characterized as the main mediator of opioid signalling in neuronal cells. Opioid-induced pain suppression was originally proposed to be mediated by ?-opioid receptor-induced inhibitory effects on cAMP, which is known to mediate inflammatory hypernociception. Recent investigations revealed PI3K? and Akt (PKB) as additional elements of ?-opioid receptor signalling. Hence, we investigated the interaction between pronociceptive cAMP and antinociceptive PI3K/Akt signalling pathways.
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Role of phosphoinositide 3-kinase in the pathogenesis of acute pancreatitis.
World J. Gastroenterol.
PUBLISHED: 03-01-2014
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A large body of experimental and clinical data supports the notion that inflammation in acute pancreatitis has a crucial role in the pathogenesis of local and systemic damage and is a major determinant of clinical severity. Thus, research has recently focused on molecules that can regulate the inflammatory processes, such as phosphoinositide 3-kinases (PI3Ks), a family of lipid and protein kinases involved in intracellular signal transduction. Studies using genetic ablation or pharmacologic inhibitors of different PI3K isoforms, in particular the class I PI3K? and PI3K?, have contributed to a greater understanding of the roles of these kinases in the modulation of inflammatory and immune responses. Recent data suggest that PI3Ks are also involved in the pathogenesis of acute pancreatitis. Activation of the PI3K signaling pathway, and in particular of the class IB PI3K? isoform, has a significant role in those events which are necessary for the initiation of acute pancreatic injury, namely calcium signaling alteration, trypsinogen activation, and nuclear factor-?B transcription. Moreover, PI3K? is instrumental in modulating acinar cell apoptosis, and regulating local neutrophil infiltration and systemic inflammatory responses during the course of experimental acute pancreatitis. The availability of PI3K inhibitors selective for specific isoforms may provide new valuable therapeutic strategies to improve the clinical course of this disease. This article presents a brief summary of PI3K structure and function, and highlights recent advances that implicate PI3Ks in the pathogenesis of acute pancreatitis.
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Myocyte signalling in leucocyte recruitment to the heart.
Cardiovasc. Res.
PUBLISHED: 02-05-2014
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Myocardial damage, by different noxious causes, triggers an inflammatory reaction driving post-injury repair mechanisms and chronic remodelling processes that are largely detrimental to cardiac function. Cardiomyocytes have recently emerged as key players in orchestrating this inflammatory response. Injured cardiomyocytes release damage-associated molecular pattern molecules, such as high-mobility group box 1 (HMGB1), DNA fragments, heat shock proteins, and matricellular proteins, which instruct surrounding healthy cadiomyocytes to produce inflammatory mediators. These mediators, mainly interleukin (IL)-1?, IL-6, macrophage chemoattractant protein (MCP)-1, and tumour necrosis factor ? (TNF-?), in turn activate versatile signalling networks within surviving cardiomyocytes and trigger leucocyte activation and recruitment. In this review, we will focus on recently characterized signalling pathways activated in cardiomyocytes that mediate inflammatory responses during myocardial infarction, hypertensive heart disease, and myocarditis.
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PI3K class II ? controls spatially restricted endosomal PtdIns3P and Rab11 activation to promote primary cilium function.
Dev. Cell
PUBLISHED: 01-23-2014
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Multiple phosphatidylinositol (PtdIns) 3-kinases (PI3Ks) can produce PtdIns3P to control endocytic trafficking, but whether enzyme specialization occurs in defined subcellular locations is unclear. Here, we report that PI3K-C2? is enriched in the pericentriolar recycling endocytic compartment (PRE) at the base of the primary cilium, where it regulates production of a specific pool of PtdIns3P. Loss of PI3K-C2?-derived PtdIns3P leads to mislocalization of PRE markers such as TfR and Rab11, reduces Rab11 activation, and blocks accumulation of Rab8 at the primary cilium. These changes in turn cause defects in primary cilium elongation, Smo ciliary translocation, and Sonic Hedgehog (Shh) signaling and ultimately impair embryonic development. Selective reconstitution of PtdIns3P levels in cells lacking PI3K-C2? rescues Rab11 activation, primary cilium length, and Shh pathway induction. Thus, PI3K-C2? regulates the formation of a PtdIns3P pool at the PRE required for Rab11 and Shh pathway activation.
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ESC Working Group on Myocardial Function Position Paper: how to study the right ventricle in experimental models.
Eur. J. Heart Fail.
PUBLISHED: 01-17-2014
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The right ventricle has become an increasing focus in cardiovascular research. In this position paper, we give a brief overview of the specific pathophysiological features of the right ventricle, with particular emphasis on functional and molecular modifications as well as therapeutic strategies in chronic overload, highlighting the differences from the left ventricle. Importantly, we put together recommendations on promising topics of research in the field, experimental study design, and functional evaluation of the right ventricle in experimental models, from non-invasive methodologies to haemodynamic evaluation and ex vivo set-ups.
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Targeting myocardial remodelling to develop novel therapies for heart failure: a position paper from the Working Group on Myocardial Function of the European Society of Cardiology.
Eur. J. Heart Fail.
PUBLISHED: 01-02-2014
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The failing heart is characterized by complex tissue remodelling involving increased cardiomyocyte death, and impairment of sarcomere function, metabolic activity, endothelial and vascular function, together with increased inflammation and interstitial fibrosis. For years, therapeutic approaches for heart failure (HF) relied on vasodilators and diuretics which relieve cardiac workload and HF symptoms. The introduction in the clinic of drugs interfering with beta-adrenergic and angiotensin signalling have ameliorated survival by interfering with the intimate mechanism of cardiac compensation. Current therapy, though, still has a limited capacity to restore muscle function fully, and the development of novel therapeutic targets is still an important medical need. Recent progress in understanding the molecular basis of myocardial dysfunction in HF is paving the way for development of new treatments capable of restoring muscle function and targeting specific pathological subsets of LV dysfunction. These include potentiating cardiomyocyte contractility, increasing cardiomyocyte survival and adaptive hypertrophy, increasing oxygen and nutrition supply by sustaining vessel formation, and reducing ventricular stiffness by favourable extracellular matrix remodelling. Here, we consider drugs such as omecamtiv mecarbil, nitroxyl donors, cyclosporin A, SERCA2a (sarcoplasmic/endoplasmic Ca(2 +) ATPase 2a), neuregulin, and bromocriptine, all of which are currently in clinical trials as potential HF therapies, and discuss novel molecular targets with potential therapeutic impact that are in the pre-clinical phases of investigation. Finally, we consider conceptual changes in basic science approaches to improve their translation into successful clinical applications.
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Melusin protects from cardiac rupture and improves functional remodelling after myocardial infarction.
Cardiovasc. Res.
PUBLISHED: 10-15-2013
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Melusin is a muscle-specific chaperone protein whose expression is required for a compensatory hypertrophy response to pressure overload. Here, we evaluated the consequences of melusin overexpression in the setting of myocardial infarction (MI) using a comprehensive multicentre approach.
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Spatiotemporal control of endocytosis by phosphatidylinositol-3,4-bisphosphate.
Nature
PUBLISHED: 06-06-2013
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Phosphoinositides serve crucial roles in cell physiology, ranging from cell signalling to membrane traffic. Among the seven eukaryotic phosphoinositides the best studied species is phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2), which is concentrated at the plasma membrane where, among other functions, it is required for the nucleation of endocytic clathrin-coated pits. No phosphatidylinositol other than PI(4,5)P2 has been implicated in clathrin-mediated endocytosis, whereas the subsequent endosomal stages of the endocytic pathway are dominated by phosphatidylinositol-3-phosphates(PI(3)P). How phosphatidylinositol conversion from PI(4,5)P2-positive endocytic intermediates to PI(3)P-containing endosomes is achieved is unclear. Here we show that formation of phosphatidylinositol-3,4-bisphosphate (PI(3,4)P2) by class II phosphatidylinositol-3-kinase C2? (PI(3)K C2?) spatiotemporally controls clathrin-mediated endocytosis. Depletion of PI(3,4)P2 or PI(3)K C2? impairs the maturation of late-stage clathrin-coated pits before fission. Timed formation of PI(3,4)P2 by PI(3)K C2? is required for selective enrichment of the BAR domain protein SNX9 at late-stage endocytic intermediates. These findings provide a mechanistic framework for the role of PI(3,4)P2 in endocytosis and unravel a novel discrete function of PI(3,4)P2 in a central cell physiological process.
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PKC? phosphorylates PI3K? to activate it and release it from GPCR control.
PLoS Biol.
PUBLISHED: 06-01-2013
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All class I phosphoinositide 3-kinases (PI3Ks) associate tightly with regulatory subunits through interactions that have been thought to be constitutive. PI3K? is key to the regulation of immune cell responses activated by G protein-coupled receptors (GPCRs). Remarkably we find that PKC? phosphorylates Ser582 in the helical domain of the PI3K? catalytic subunit p110? in response to clustering of the high-affinity IgE receptor (Fc?RI) and/or store-operated Ca²?- influx in mast cells. Phosphorylation of p110? correlates with the release of the p84 PI3K? adapter subunit from the p84-p110? complex. Ser582 phospho-mimicking mutants show increased p110? activity and a reduced binding to the p84 adapter subunit. As functional p84-p110? is key to GPCR-mediated p110? signaling, this suggests that PKC?-mediated p110? phosphorylation disconnects PI3K? from its canonical inputs from trimeric G proteins, and enables p110? to operate downstream of Ca²? and PKC?. Hydrogen deuterium exchange mass spectrometry shows that the p84 adaptor subunit interacts with the p110? helical domain, and reveals an unexpected mechanism of PI3K? regulation. Our data show that the interaction of p110? with its adapter subunit is vulnerable to phosphorylation, and outline a novel level of PI3K control.
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Therapeutic applications of PI3K inhibitors in cardiovascular diseases.
Future Med Chem
PUBLISHED: 03-19-2013
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PI3Ks are signaling enzymes engaged by different types of membrane receptors and activated in cardiovascular diseases such as hypertension, atherosclerosis, thrombosis and heart failure. Studies performed on genetically modified animals have provided proof-of-concept that general or isoform-specific blockade of these enzymes can modify disease development and progression. Hence, therapeutic inhibition of PI3Ks with novel pharmacological compounds constitutes a promising area of drug development. In particular, inhibitors of PI3Ks have the potential to reduce blood pressure, restrain the development of atherosclerosis and/or stabilize atherosclerotic plaques, blunt platelet aggregation, prevent left ventricular remodeling and preserve myocardial contractility in heart failure. This review summarizes the rationale of PI3K inhibition in the most prevalent cardiovascular diseases, and the available data on the therapeutic effects of PI3K inhibitors in their preclinical models. Implications for future drug development and human therapy are also discussed.
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Class I phosphoinositide-3-kinases and SRC kinases play a nonredundant role in regulation of adhesion-independent and -dependent neutrophil reactive oxygen species generation.
J. Immunol.
PUBLISHED: 02-27-2013
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Chemoattractant-induced reactive oxygen species (ROS) generation by adherent neutrophils occurs in two phases: the first is very rapid and transient, and the second one is delayed and lasts up to 30-40 min. We examined the role of phosphoinositide 3-kinases (PI3Ks) and Src-family kinases (SFKs) in these responses using human neutrophils treated with inhibitory compounds or murine neutrophils deficient of PI3K? or Hck, Fgr, and Lyn. Our studies show that PI3K? is indispensable for the early, fMLF-induced ROS generation and AKT and ERK phosphorylation, but is dispensable for the late response to fMLF. Additionally, the response to TNF, an agonist triggering only the delayed phase of ROS generation, was also unaffected in PI3K?-deficient neutrophils. In contrast, inhibition of SFKs by a selective inhibitor in human, or SFK deficiency in murine, neutrophils resulted in the inhibition of both the early and late phase of ROS generation, without affecting the early phase of AKT phosphorylation, but inhibiting the late one. Selective inhibitors of PI3K? and PI3K? markedly reduced both the early and late response to fMLF and TNF in human neutrophils. These findings suggest that class IA PI3Ks may be activated by PI3K? via Ras in the early phase of the response and by SFKs in the late phase. The evidence that inhibition of SFKs in human, or SFK deficiency in murine, neutrophils results in suppression of Vav phosphorylation at all time points of the response to fMLF or TNF suggests that SFKs are indispensable for Vav phosphorylation.
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Hemopexin therapy improves cardiovascular function by preventing heme-induced endothelial toxicity in mouse models of hemolytic diseases.
Circulation
PUBLISHED: 02-27-2013
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Hemolytic diseases are characterized by enhanced intravascular hemolysis resulting in heme-catalyzed reactive oxygen species generation, which leads to endothelial dysfunction and oxidative damage. Hemopexin (Hx) is a plasma heme scavenger able to prevent endothelial damage and tissue congestion in a model of heme overload. Here, we tested whether Hx could be used as a therapeutic tool to counteract heme toxic effects on the cardiovascular system in hemolytic diseases.
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PI3-kinase ? promotes Rap1a-mediated activation of myeloid cell integrin ?4?1, leading to tumor inflammation and growth.
PLoS ONE
PUBLISHED: 02-23-2013
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Tumor inflammation, the recruitment of myeloid lineage cells into the tumor microenvironment, promotes angiogenesis, immunosuppression and metastasis. CD11b+Gr1lo monocytic lineage cells and CD11b+Gr1hi granulocytic lineage cells are recruited from the circulation by tumor-derived chemoattractants, which stimulate PI3-kinase ? (PI3K?)-mediated integrin ?4 activation and extravasation. We show here that PI3K? activates PLC?, leading to RasGrp/CalDAG-GEF-I&II mediated, Rap1a-dependent activation of integrin ?4?1, extravasation of monocytes and granulocytes, and inflammation-associated tumor progression. Genetic depletion of PLC?, CalDAG-GEFI or II, Rap1a, or the Rap1 effector RIAM was sufficient to prevent integrin ?4 activation by chemoattractants or activated PI3K? (p110?CAAX), while activated Rap (RapV12) promoted constitutive integrin activation and cell adhesion that could only be blocked by inhibition of RIAM or integrin ?4?1. Similar to blockade of PI3K? or integrin ?4?1, blockade of Rap1a suppressed both the recruitment of monocytes and granulocytes to tumors and tumor progression. These results demonstrate critical roles for a PI3K?-Rap1a-dependent pathway in integrin activation during tumor inflammation and suggest novel avenues for cancer therapy.
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Rule out of acute aortic dissection with plasma matrix metalloproteinase 8 in the emergency department.
Crit Care
PUBLISHED: 02-20-2013
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INTRODUCTION: Matrix metalloproteinases (MMPs) are involved in aortic pathophysiology. Preliminary studies have detected increased plasma levels of MMP8 and MMP9 in patients with acute aortic dissection (AAD). However, the performance of plasma MMP8 and MMP9 for the diagnosis of AAD in the emergency department is at present unknown. METHODS: The levels of MMP8 and MMP9 were measured by ELISA on plasma samples obtained from 126 consecutive patients evaluated in the emergency department for suspected AAD. All patients were subjected to urgent computed tomography (CT) scan for final diagnosis. RESULTS: In the study cohort (N = 126), AAD was diagnosed in 52 patients and ruled out in 74 patients. Median plasma MMP8 levels were 36.4 (interquartile range 24.8 to 69.3) ng/ml in patients with AAD and 13.2 (8.1 to 31.8) ng/ml in patients receiving an alternative final diagnosis (P <0.0001). Median plasma MMP9 levels were 169.2 (93.0 to 261.8) ng/ml in patients with AAD and 80.5 (41.8 to 140.6) ng/ml in patients receiving an alternative final diagnosis (P = 0.001). The area under the curve (AUC) on receiver-operating characteristic (ROC) analysis of MMP8 and MMP9 for the diagnosis of AAD was respectively 0.75 and 0.70, as compared to 0.87 of D-dimer. At the cutoff of 3.6 ng/ml, plasma MMP8 had a sensitivity of 100.0% (95% CI, 93.2% to 100.0%) and a specificity of 9.5% (95% CI, 3.9% to 18.5%) and ruled out AAD in 5.6% of patients. Combination of plasma MMP8 with D-dimer increased the AUC on ROC analysis to 0.89. Presence of MMP8 <11.0 ng/ml and D-dimer <1.0 or <2.0 µg/ml provided a negative predictive value of 100% and ruled out AAD in 13.6% and 21.4% of patients respectively. CONCLUSIONS: Low levels of plasma MMP8 can rule out AAD in a minority of patients. Combination of plasma MMP8 and D-dimer at individually suboptimal cutoffs could safely rule out AAD in a substantial proportion of patients evaluated in the emergency department.
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Transient targeting of phosphoinositide 3-kinase acts as a roadblock in mast cells route to allergy.
J. Allergy Clin. Immunol.
PUBLISHED: 02-05-2013
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Tissue mast cell numbers are dynamically regulated by recruitment of progenitors from the vasculature. It is unclear whether progenitors are recruited during allergic sensitization and whether recruitment promotes allergic responses.
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PI3K p110? deletion attenuates murine atherosclerosis by reducing macrophage proliferation but not polarization or apoptosis in lesions.
PLoS ONE
PUBLISHED: 01-01-2013
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Atherosclerosis is an inflammatory disease regulated by infiltrating monocytes and T cells, among other cell types. Macrophage recruitment to atherosclerotic lesions is controlled by monocyte infiltration into plaques. Once in the lesion, macrophage proliferation in situ, apoptosis, and differentiation to an inflammatory (M1) or anti-inflammatory phenotype (M2) are involved in progression to advanced atherosclerotic lesions. We studied the role of phosphoinositol-3-kinase (PI3K) p110? in the regulation of in situ apoptosis, macrophage proliferation and polarization towards M1 or M2 phenotypes in atherosclerotic lesions. We analyzed atherosclerosis development in LDLR(-/-)p110?(+/-) and LDLR(-/-)p110?(-/-) mice, and performed expression and functional assays in tissues and primary cells from these and from p110?(+/-) and p110?(-/-) mice. Lack of p110? in LDLR(-/-) mice reduces the atherosclerosis burden. Atherosclerotic lesions in fat-fed LDLR(-/-)p110?(-/-) mice were smaller than in LDLR(-/-)p110?(+/-) controls, which coincided with decreased macrophage proliferation in LDLR(-/-)p110?(-/-) mouse lesions. This proliferation defect was also observed in p110?(-/-) bone marrow-derived macrophages (BMM) stimulated with macrophage colony-stimulating factor (M-CSF), and was associated with higher intracellular cyclic adenosine monophosphate (cAMP) levels. In contrast, T cell proliferation was unaffected in LDLR(-/-)p110?(-/-) mice. Moreover, p110? deficiency did not affect macrophage polarization towards the M1 or M2 phenotypes or apoptosis in atherosclerotic plaques, or polarization in cultured BMM. Our results suggest that higher cAMP levels and the ensuing inhibition of macrophage proliferation contribute to atheroprotection in LDLR(-/-) mice lacking p110?. Nonetheless, p110? deletion does not appear to be involved in apoptosis, in macrophage polarization or in T cell proliferation.
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Targeting PI3K in Cancer: Any Good News?
Front Oncol
PUBLISHED: 01-01-2013
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The phosphatidylinositol 3-kinase (PI3K) signaling pathway regulates several cellular processes and its one of the most frequently deregulated pathway in human tumors. Given its prominent role in cancer, there is great interest in the development of inhibitors able to target several members of PI3K signaling pathway in clinical trials. These drug candidates include PI3K inhibitors, both pan- and isoform-specific inhibitors, AKT, mTOR, and dual PI3K/mTOR inhibitors. As novel compounds progress into clinical trials, its becoming urgent to identify and select patient population that most likely benefit from PI3K inhibition. In this review we will discuss individual PIK3CA mutations as predictors of sensitivity and resistance to targeted therapies, leading to use of novel PI3K/mTOR/AKT inhibitors to a more "personalized" treatment.
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Role and regulation of phosphatidylinositol 3-kinase ? in platelet integrin ?2?1 signaling.
Blood
PUBLISHED: 11-21-2011
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Integrin ?2?1-mediated adhesion of human platelets to monomeric type I collagen or to the GFOGER peptide caused a time-dependent activation of PI3K and Akt phosphorylation. This process was abrogated by pharmacologic inhibition of PI3K?, but not of PI3K? or PI3K?. Moreover, Akt phosphorylation was undetectable in murine platelets expressing a kinase-dead mutant of PI3K? (PI3K?(KD)), but occurred normally in PI3K?(KD) platelets. Integrin ?2?1 failed to stimulate PI3K? in platelets from phospholipase C?2 (PLC?2)-knockout mice, and we found that intracellular Ca(2+) linked PLC?2 to PI3K? activation. Integrin ?2?1 also caused a time-dependent stimulation of the focal kinase Pyk2 downstream of PLC?2 and intracellular Ca(2+). Whereas activation of Pyk2 occurred normally in PI3K?(KD) platelets, stimulation of PI3K? was strongly reduced in Pyk2-knockout mice. Neither Pyk2 nor PI3K? was required for ?2?1-mediated adhesion and spreading. However, activation of Rap1b and inside-out stimulation of integrin ?IIb?3 were reduced after inhibition of PI3K? and were significantly impaired in Pyk2-deficient platelets. Finally, both PI3K? and Pyk2 significantly contributed to thrombus formation under flow. These results demonstrate that Pyk2 regulates PI3K? downstream of integrin ?2?1, and document a novel role for Pyk2 and PI3K? in integrin ?2?1 promoted inside-out activation of integrin ?IIb?3 and thrombus formation.
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PI3K? inhibition reduces blood pressure by a vasorelaxant Akt/L-type calcium channel mechanism.
Cardiovasc. Res.
PUBLISHED: 10-27-2011
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The lipid and protein kinase phosphoinositide 3-kinase ? (PI3K?) is abundantly expressed in inflammatory cells and in the cardiovascular tissue. In recent years, its role in inflammation and in cardiac function and remodelling has been unravelled, highlighting the beneficial effects of its pharmacological inhibition. Furthermore, a role for PI3K? in the regulation of vascular tone has been emphasized. However, the impact of this signalling in the control of blood pressure is still poorly understood. Our study investigated the effect of a selective inhibition of PI3K?, obtained by using two independent small molecules, on blood pressure. Moreover, we dissected the molecular mechanisms involved in control of contraction of resistance arteries by PI3K?.
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The RacGAP ArhGAP15 is a master negative regulator of neutrophil functions.
Blood
PUBLISHED: 05-06-2011
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In phagocytes, GTPases of the Rac family control crucial antimicrobial functions. The RacGAP ArhGAP15 negatively modulates Rac activity in leukocytes, but its in vivo role in innate immunity remains largely unknown. Here we show that neutrophils and macrophages derived from mice lacking ArhGAP15 presented higher Rac activity but distinct phenotypes. In macrophages, the loss of ArhGAP15 induced increased cellular elongation and membrane protrusions but did not modify chemotactic responses. Conversely, the lack of ArhGAP15 in neutrophils affected critical Rac-dependent antimicrobial functions, specifically causing enhanced chemotactic responses, straighter directional migration, amplified reactive oxygen species production, increased phagocytosis, and improved bacterial killing. In vivo, in a model of severe abdominal sepsis, these effects contributed to increase neutrophil recruitment to the site of infection, thereby limiting bacterial growth, controlling infection spread, reducing systemic inflammation, and ultimately improving survival in ArhGAP15-null mice. Altogether, these results demonstrate the relevance of ArhGAP15 in the selective regulation of multiple neutrophil functions, suggesting that ArhGAP15 targeting might be beneficial in specific pathologic settings like severe sepsis.
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Specific PI3K isoform modulation in heart failure: lessons from transgenic mice.
Curr Heart Fail Rep
PUBLISHED: 04-27-2011
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Cardiac pathophysiology heavily relies on receptor-mediated signal transduction, and pharmacologic control of such biological processes has proven successful in preventing and treating multiple heart diseases. Recent progress in the study of receptor-mediated signal transduction events in the heart highlighted the role of a family of lipid kinases known as phosphoinositide 3-kinases (PI3Ks). These enzymes are involved downstream different receptors in the production of a lipid second messenger molecule (namely phosphatidylinositol (3,4,5)-trisphosphate [PIP(3)]), which mediates a large number of biological responses critical for the heart, including cardiomyocyte growth, survival, and contractility as well as cardiovascular inflammation. This review focuses on the recent advances in the understanding of PI3K function in cardiac pathophysiology obtained by studying mouse mutants for different PI3K genes and by validating the effects of PI3K pharmacologic inhibition in preclinical models of critical cardiac diseases like heart failure.
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Phosphoinositide 3-kinase p110? in immunity.
IUBMB Life
PUBLISHED: 04-25-2011
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The rapid and accurate response of leukocytes to environmental cues is critical for a proper inflammatory reaction to foreign particles or invading microbes. In the last decade, the signal transduction enzyme phosphoinositide 3-kinase ? (PI3K?) has emerged as a critical modulator of leukocyte responses, with its effects spanning from recruitment to the site of inflammation to the production of reactive oxygen species. These findings initially obtained from genetically modified mice have led to the development of experimental anti-inflammatory inhibitors with reasonable selectivity and specificity. While such molecules have not yet reached clinical use, preclinical studies combining genetics and pharmacology continue to provide new therapeutic indications for targeting PI3K?. Thus, this review focuses on the latest discoveries regarding PI3K? function in leukocytes and on the most recent findings in disease models related to immunity.
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Groebke multicomponent reaction and subsequent nucleophilic aromatic substitution for a convenient synthesis of 3,8-diaminoimidazo[1,2-a]pyrazines as potential kinase inhibitors.
Org. Biomol. Chem.
PUBLISHED: 04-14-2011
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In a program aimed at discovering novel protein kinase inhibitors, a convenient synthesis of 3,8-diaminoimidazo[1,2-a]pyrazines has been developed exploiting the isocyanide-based multicomponent Blackburn reaction, followed by a nucleophilic aromatic substitution with ammonia or primary and secondary amines. The potential of the reported scaffold is strengthened by the inhibition of STAT5-dependent transcription displayed by four of the synthesized compounds.
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IQGAP1 regulates ERK1/2 and AKT signalling in the heart and sustains functional remodelling upon pressure overload.
Cardiovasc. Res.
PUBLISHED: 04-14-2011
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The Raf-MEK1/2-ERK1/2 (ERK1/2-extracellular signal-regulated kinases 1/2) signalling cascade is crucial in triggering cardiac responses to different stress stimuli. Scaffold proteins are key elements in coordinating signalling molecules for their appropriate spatiotemporal activation. Here, we investigated the role of IQ motif-containing GTPase-activating protein 1 (IQGAP1), a scaffold for the ERK1/2 cascade, in heart function and remodelling in response to pressure overload.
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Cardiovascular side effects of cancer therapies: a position statement from the Heart Failure Association of the European Society of Cardiology.
Eur. J. Heart Fail.
PUBLISHED: 04-06-2011
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The reductions in mortality and morbidity being achieved among cancer patients with current therapies represent a major achievement. However, given their mechanisms of action, many anti-cancer agents may have significant potential for cardiovascular side effects, including the induction of heart failure. The magnitude of this problem remains unclear and is not readily apparent from current clinical trials of emerging targeted agents, which generally under-represent older patients and those with significant co-morbidities. The risk of adverse events may also increase when novel agents, which frequently modulate survival pathways, are used in combination with each other or with other conventional cytotoxic chemotherapeutics. The extent to which survival and growth pathways in the tumour cell (which we seek to inhibit) coincide with those in cardiovascular cells (which we seek to preserve) is an open question but one that will become ever more important with the development of new cancer therapies that target intracellular signalling pathways. It remains unclear whether potential cardiovascular problems can be predicted from analyses of such basic signalling mechanisms and what pre-clinical evaluation should be undertaken. The screening of patients, optimization of therapeutic schemes, monitoring of cardiovascular function during treatment, and the management of cardiovascular side effects are likely to become increasingly important in cancer patients. This paper summarizes the deliberations of a cross-disciplinary workshop organized by the Heart Failure Association of the European Society of Cardiology (held in Brussels in May 2009), which brought together clinicians working in cardiology and oncology and those involved in basic, translational, and pharmaceutical science.
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PI3K? mediates kaposis sarcoma-associated herpesvirus vGPCR-induced sarcomagenesis.
Cancer Cell
PUBLISHED: 03-05-2011
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Angioproliferative tumors induced by the Kaposis sarcoma-associated herpesvirus (KSHV) have been successfully treated with rapamycin, which provided direct evidence of the clinical activity of mTOR inhibitors in human malignancies. However, prolonged mTOR inhibition may raise concerns in immunocompromised patients, including AIDS-Kaposis sarcoma (KS). Here, we explored whether KSHV oncogenes deploy cell type-specific signaling pathways activating mTOR, which could be exploited to halt KS development while minimizing immune suppressive effects. We found that PI3K?, a PI3K isoform exhibiting restricted tissue distribution, is strictly required for signaling from the KSHV-encoded vGPCR oncogene to Akt/mTOR. Indeed, by using an endothelial-specific gene delivery system modeling KS development, we provide genetic and pharmacological evidence that PI3K? may represent a suitable molecular target for therapeutic intervention in KS.
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Sustained release of PI3K inhibitor from PHA nanoparticles and in vitro growth inhibition of cancer cell lines.
Appl. Microbiol. Biotechnol.
PUBLISHED: 02-01-2011
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The phosphoinositide-3-kinases (PI3Ks) are a conserved family of lipid kinases that phosphorylate the 3-hydroxyl group of phosphatidylinositols in response to extracellular stimuli. PI3K pathway is enrolled in different kinds of human cancer and plays a prominent role in cancer cell growth and survival. Several PI3K inhibitors have been recently identified but some PI3K inhibitors with high potency in vitro do not show satisfactory effects in animal cancer models because of the poor pharmaceutical properties in vivo such as poor solubility, instability, and fast plasma clearance rate. In this study, we developed a sustained release system of PI3K inhibitor (TGX221) based on polyhydroxyalkanoate nanoparticles (NP) and used it to block proliferation of cancer cell lines. TGX221 was gradually released from PHA-based NP and growth of cancer cell lines was significantly slower in NP-TGX221-treated cells than in either negative controls or in cells receiving free TGX221. Since poor bioavailability and limited in vivo half-life are common features of hydrophobic PI3K inhibitors, our results open the way to similar formulation of other PI3K blockers and to new strategies in cancer treatment.
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Integrating cardiac PIP3 and cAMP signaling through a PKA anchoring function of p110?.
Mol. Cell
PUBLISHED: 01-24-2011
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Adrenergic stimulation of the heart engages cAMP and phosphoinositide second messenger signaling cascades. Cardiac phosphoinositide 3-kinase p110? participates in these processes by sustaining ?-adrenergic receptor internalization through its catalytic function and by controlling phosphodiesterase 3B (PDE3B) activity via an unknown kinase-independent mechanism. We have discovered that p110? anchors protein kinase A (PKA) through a site in its N-terminal region. Anchored PKA activates PDE3B to enhance cAMP degradation and phosphorylates p110? to inhibit PIP(3) production. This provides local feedback control of PIP(3) and cAMP signaling events. In congestive heart failure, p110? is upregulated and escapes PKA-mediated inhibition, contributing to a reduction in ?-adrenergic receptor density. Pharmacological inhibition of p110? normalizes ?-adrenergic receptor density and improves contractility in failing hearts.
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Distinct effects of leukocyte and cardiac phosphoinositide 3-kinase ? activity in pressure overload-induced cardiac failure.
Circulation
PUBLISHED: 01-17-2011
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Signaling from phosphoinositide 3-kinase ? (PI3K?) is crucial for leukocyte recruitment and inflammation but also contributes to cardiac maladaptive remodeling. To better understand the translational potential of these findings, this study investigates the role of PI3K? activity in pressure overload-induced heart failure, addressing the distinct contributions of bone marrow-derived and cardiac cells.
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High frequency of development of B cell lymphoproliferation and diffuse large B cell lymphoma in Dbl knock-in mice.
J. Mol. Med.
PUBLISHED: 01-11-2011
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Dbl is the prototype of a large family of GDP-GTP exchange factors for small GTPases of the Rho family. In vitro, Dbl is known to activate Rho, Rac, and Cdc42 and to induce a transformed phenotype in murine fibroblasts. We previously reported that Dbl-null mice are viable and fertile but display defective dendrite elongation of distinct subpopulations of cortical neurons, suggesting a role of Dbl in controlling dendritic growth. To gain deeper insights into the role of Dbl in development and disease, we attempted a knock-in approach to create an endogenous allele that encodes a missense-mutation-mediated loss of function in the DH domain. We generated, by gene targeting technology, a mutant mouse strain by inserting a mutagenized human proto-Dbl cDNA clone expressing only the Dbl N terminus regulatory sequence at the starting codon of murine exon 1. Animals were monitored over a 21-month period, and necropsy specimens were collected for histological examination and immunohistochemistry analysis. Dbl knock-in mice are viable and did not manifest either decreased reproductive performances or gross developmental phenotype but revealed a reduced lifespan compared to wild-type (w.t.) mice and showed, with aging, a B cell lymphoproliferation that often has features of a frank diffuse large B cell lymphoma. Moreover, Dbl knock-in male mice displayed an increased incidence of lung adenoma compared to w.t. mice. These data indicate that Dbl is a tumor susceptibility gene in mice and that loss of function of Dbl DH domain by genetic missense mutations is responsible for induction of diffuse large B cell lymphoma.
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Regulating neutrophil apoptosis: new players enter the game.
Trends Immunol.
PUBLISHED: 01-04-2011
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Recently, unexpected biological features of polymorphonuclear neutrophils have been revealed. In addition to their pivotal role in the defence against pathogens, neutrophils display a high degree of plasticity and contribute to control of adaptive immune responses. An emerging aspect of neutrophils is their ability to modulate their survival in response to both intrinsic and extrinsic factors. This review focuses on recent advances that have uncovered proliferating cell nuclear antigen (PCNA) and other cell cycle regulatory proteins as novel players regulating neutrophil survival. A better understanding of the mechanisms involved in neutrophil fate might pave the way for the identification of new anti-inflammatory molecules.
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Receptor tyrosine kinases and TLR/IL1Rs unexpectedly activate myeloid cell PI3k?, a single convergent point promoting tumor inflammation and progression.
Cancer Cell
PUBLISHED: 01-03-2011
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Tumor inflammation promotes angiogenesis, immunosuppression, and tumor growth, but the mechanisms controlling inflammatory cell recruitment to tumors are not well understood. We found that a range of chemoattractants activating G protein-coupled receptors (GPCRs), receptor tyrosine kinases (RTKs) and Toll-like/IL-1 receptors (TLR/IL1Rs) unexpectedly initiate tumor inflammation by activating the PI3-kinase isoform p110? in Gr1+CD11b+ myeloid cells. Whereas GPCRs activate p110? in a Ras/p101-dependent manner, RTKs and TLR/IL1Rs directly activate p110? in a Ras/p87-dependent manner. Once activated, p110? promotes inside-out activation of a single integrin, ?4?1, causing myeloid cell invasion into tumors. Pharmacological or genetic blockade of p110? suppressed inflammation, growth, and metastasis of implanted and spontaneous tumors, revealing an important therapeutic target in oncology.
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Leukocyte and cardiac phosphoinositide 3-kinase ? activity in pressure overload-induced cardiac failure.
Trends Cardiovasc. Med.
PUBLISHED: 11-01-2010
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Class IB phosphoinositide 3-kinase p110? is a master regulator of both leukocyte and cardiomyocyte function. Whereas in the immune system p110? is principally involved in the control of leukocyte chemotaxis and inflammatory reactions, in cardiomyocytes p110? affects multiple aspects of ?-adrenergic receptor signaling and cardiac function. Because inflammatory cell recruitment/activation and cardiac dysfunction are strictly connected, p110? has recently been revealed as a promising target for drug design in the treatment of heart failure. This review discusses recent works that dissect the relative contribution of leukocyte p110? and its cardiac counterpart in the onset and progression of pressure overload-induced cardiac remodeling and the ensuing therapeutic implications.
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Pharmacologic inhibition of phosphoinositide 3-kinase gamma (PI3K?) promotes infarct resorption and prevents adverse cardiac remodeling after myocardial infarction in mice.
J. Cardiovasc. Pharmacol.
PUBLISHED: 10-01-2010
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Phosphoinositide 3-kinase gamma is upregulated in the heart during acute myocardial infarction (AMI) potentially contributing to the development and maintenance of heart failure.
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Dissection of the interplay between class I PI3Ks and Rac signaling in phagocytic functions.
ScientificWorldJournal
PUBLISHED: 09-21-2010
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Phagocytes, like neutrophils and macrophages, are specialized cells evolved to clear infectious pathogens. This function resides at the core of innate immunity and requires a series of concerted events that lead first to migration to the infected tissue and then to the killing of the invading pathogens. Molecular mechanisms underlying these processes are starting to emerge and point to the interplay between two families of crucial proteins: the PI3K lipid kinases and the Rac GTPases. This review focuses on how these two protein families contribute to migration, phagocytosis, and reactive oxygen species production, as well as their epistatic and feedback relations that finely tune these crucial aspects of the immune response.
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Loss of PI3K? enhances cAMP-dependent MMP remodeling of the myocardial N-cadherin adhesion complexes and extracellular matrix in response to early biomechanical stress.
Circ. Res.
PUBLISHED: 09-16-2010
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Mechanotransduction and the response to biomechanical stress is a fundamental response in heart disease. Loss of phosphoinositide 3-kinase (PI3K)?, the isoform linked to G protein-coupled receptor signaling, results in increased myocardial contractility, but the response to pressure overload is controversial.
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Pulmonary-derived phosphoinositide 3-kinase gamma (PI3K?) contributes to ventilator-induced lung injury and edema.
Intensive Care Med
PUBLISHED: 07-13-2010
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Ventilator-induced lung injury (VILI) occurs in part by increased vascular permeability and impaired alveolar fluid clearance. Phosphoinositide 3-kinase gamma (PI3K?) is activated by mechanical stress, induces nitric oxide (NO) production, and participates in cyclic adenosine monophosphate (cAMP) hydrolysis, each of which contributes to alveolar edema. We hypothesized that lungs lacking PI3K? or treated with PI3K? inhibitors would be protected from ventilation-induced alveolar edema and lung injury.
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Nonredundant role of CCRL2 in lung dendritic cell trafficking.
Blood
PUBLISHED: 07-06-2010
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Chemokine CC motif receptor-like 2 (CCRL2) is a heptahelic transmembrane receptor that shows the highest degree of homology with CCR1, an inflammatory chemokine receptor. CCRL2 mRNA was rapidly (30 minutes) and transiently (2-4 hours) regulated during dendritic cell (DC) maturation. Protein expression paralleled RNA regulation. In vivo, CCRL2 was expressed by activated DC and macrophages, but not by eosinophils and T cells. CCRL2(-/-) mice showed normal recruitment of circulating DC into the lung, but a defective trafficking of antigen-loaded lung DC to mediastinal lymph nodes. This defect was associated to a reduction in lymph node cellularity and reduced priming of T helper cell 2 response. CCRL2(-/-) mice were protected in a model of ovalbumin-induced airway inflammation, with reduced leukocyte recruitment in the BAL (eosinophils and mononuclear cells) and reduced production of the T helper cell 2 cytokines, interleukin-4 and -5, and chemokines CCL11 and CCL17. The central role of CCRL2 deficiency in DC was supported by the fact that adoptive transfer of CCRL2(-/-) antigen-loaded DC in wild-type animals recapitulated the phenotype observed in knockout mice. These data show a nonredundant role of CCRL2 in lung DC trafficking and propose a role for this receptor in the control of excessive airway inflammatory responses.
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More than just kinases: the scaffolding function of PI3K.
Curr. Top. Microbiol. Immunol.
PUBLISHED: 06-22-2010
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Recently, it has been reported that some members of the PI3K family might have a "double identity"; in other words, PI3K have been found to act not only as classical kinases, but also as scaffolding proteins. Until now, the use of knockout mice has been considered sufficient to model the effects of PI3K inhibition and to predict the outcome of anti-PI3K pharmacological treatments by observing the resulting phenotypes. These studies supported the view that PI3K may represent promising pharmacological targets for cancer and inflammation. However, in selected cases, different experimental strategies of gene targeting of the same locus have resulted in distinct phenotypes. This demonstrates that "knocking-out" a gene is not necessarily equivalent to "knocking-in" an inactivating point mutation (Vanhaesebroeck et al. in Cell 118:274-276, 2004). Specifically, knockout and kinase-dead models have led to the discovery that PI3K? and ? may act independently of their kinase activity, likely as adaptor proteins.
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Phosphoinositide-3 kinase gamma activity contributes to sepsis and organ damage by altering neutrophil recruitment.
Am. J. Respir. Crit. Care Med.
PUBLISHED: 05-27-2010
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Sepsis is a leading cause of death in the intensive care unit, characterized by a systemic inflammatory response (SIRS) and bacterial infection, which can often induce multiorgan damage and failure. Leukocyte recruitment, required to limit bacterial spread, depends on phosphoinositide-3 kinase ? (PI3K?) signaling in vitro; however, the role of this enzyme in polymicrobial sepsis has remained unclear.
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Morgana/chp-1, a ROCK inhibitor involved in centrosome duplication and tumorigenesis.
Dev. Cell
PUBLISHED: 03-17-2010
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Centrosome abnormalities lead to genomic instability and are a common feature of many cancer cells. Here we show that mutations in morgana/chp-1 result in centrosome amplification and lethality in both Drosophila and mouse, and that the fly centrosome phenotype is fully rescued by the human ortholog of morgana. In mouse cells, morgana forms a complex with Hsp90 and ROCK I and II, and directly binds ROCK II. Morgana downregulation promotes the interaction between ROCK II and nucleophosmin (NPM), leading to an increased ROCK II kinase activity, which results in centrosome amplification. Morgana(+/-) primary cells and mice display an increased susceptibility to neoplastic transformation. In addition, tumor tissue array histochemical analysis revealed that morgana is underexpressed in a large fraction of breast and lung human cancers. Thus, morgana/chp-1 appears to prevent both centrosome amplification and tumorigenesis.
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PI3K kinase and scaffold functions in heart.
Ann. N. Y. Acad. Sci.
PUBLISHED: 03-06-2010
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Signal transduction events are key modulators of cellular function and, in the cardiovascular system, an emerging role is played by phosphoinositide 3-kinases (PI3Ks), a family of enzymes containing a 3-phosphorylated phosphoinositide that produce lipid second messengers. In the heart, multiple PI3K isoforms are expressed, but play potentially distinct roles. Among cardiac PI3Ks, PI3Kalpha is triggered by tyrosine kinase receptors and plays a role in adaptive hypertrophy, while PI3Kgamma is triggered by G protein-coupled receptors and is involved in maladaptive heart remodeling. This view has been recently complicated by the finding that PI3Ks can also be involved in protein-protein interactions and affect signaling independently of their kinase activity. This review will thus focus on the effects of these multiple signaling events, with particular emphasis on their involvement in cardiac hypertrophy and failure.
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The catalytic PI3K isoforms p110gamma and p110delta contribute to B cell development and maintenance, transformation, and proliferation.
J. Leukoc. Biol.
PUBLISHED: 03-03-2010
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Class I PI3K-dependent signaling regulates cell proliferation, differentiation, and survival. Analysis of gene-deficient mice revealed specific roles for the hematopoietically expressed PI3K catalytic subunits, p110gamma and p110delta, in development and function of T and B lymphocytes. However, the functional redundancy between these two PI3K isoforms in the B cell lineage remains unclear. Here, we demonstrate that p110delta and p110gamma are expressed in B cells at early developmental stages. Normal B cell differentiation requires both isoforms, as p110gamma/p110delta double deficiency causes an increased percentage of CD43(hi)/B220(+)/CD19(-) cells as compared with single deficiency. Interestingly, initial transformation efficiency of B cell precursors was strongly reduced in double-deficient cells following transformation by p185 bcr-abl or v-abl oncogenes as compared with single-deficient cells. The requirement of p110gamma and p110delta in B cell development is underlined by reduced splenic B cell numbers of p110gamma/p110delta double-deficient mice and of lethally irradiated wild-type mice reconstituted with double-deficient BM. Moreover, the peripheral maintenance of p110gamma/p110delta double-deficient T and B cells was highly impaired following adoptive transfer of double-deficient splenocytes into wild-type mice. Functionally, LPS stimulation of splenocytes revealed proliferation defects resulting in decreased survival of p110gamma/p110delta double-deficient B cells, which correlated with impaired induction of D-type cyclins and Bcl-X(L). Surprisingly, this was not observed when purified B cells were analyzed, indicating a contribution of likely cell-extrinsic factor(s) to the impaired proliferation of double-deficient B cells. Thus, we provide novel evidence that p110gamma and p110delta have overlapping and cell-extrinsic roles in the development, peripheral maintenance, and function of B cells.
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Comparison of 3 Tfr2-deficient murine models suggests distinct functions for Tfr2-alpha and Tfr2-beta isoforms in different tissues.
Blood
PUBLISHED: 02-23-2010
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Transferrin receptor 2 (TFR2) is a transmembrane protein that is mutated in hemochromatosis type 3. The TFR2 gene is transcribed in 2 main isoforms: the full-length (alpha) and a shorter form (beta). alpha-Tfr2 is the sensor of diferric transferrin, implicated in the modulation of hepcidin, the main regulator of iron homeostasis. The function of the putative beta-Tfr2 protein is unknown. We have developed a new mouse model (KI) lacking beta-Tfr2 compared with Tfr2 knockout mice (KO). Adult Tfr2 KO mice show liver iron overload and inadequate hepcidin levels relative to body iron stores, even though they increase Bmp6 production. KI mice have normal transferrin saturation, liver iron concentration, hepcidin and Bmp6 levels but show a transient anemia at young age and severe spleen iron accumulation in adult animals. Fpn1 is strikingly decreased in the spleen of these animals. These findings and the expression of beta-Tfr2 in wild-type mice spleen suggest a role for beta-Tfr2 in Fpn1 transcriptional control. Selective inactivation of liver alpha-Tfr2 in KI mice (LCKO-KI) returned the phenotype to liver iron overload. Our results strengthen the function of hepatic alpha-Tfr2 in hepcidin activation, suggest a role for extrahepatic Tfr2 and indicate that beta-Tfr2 may specifically control spleen iron efflux.
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Tyrosine kinase Btk regulates E-selectin-mediated integrin activation and neutrophil recruitment by controlling phospholipase C (PLC) gamma2 and PI3Kgamma pathways.
Blood
PUBLISHED: 02-18-2010
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Selectins mediate leukocyte rolling, trigger beta(2)-integrin activation, and promote leukocyte recruitment into inflamed tissue. E-selectin binding to P-selectin glycoprotein ligand 1 (PSGL-1) leads to activation of an immunoreceptor tyrosine-based activation motif (ITAM)-dependent pathway, which in turn activates the spleen tyrosine kinase (Syk). However, the signaling pathway linking Syk to integrin activation after E-selectin engagement is unknown. To identify the pathway, we used different gene-deficient mice in autoperfused flow chamber, intravital microscopy, peritonitis, and biochemical studies. We report here that the signaling pathway downstream of Syk divides into a phospholipase C (PLC) gamma2- and phosphoinositide 3-kinase (PI3K) gamma-dependent pathway. The Tec family kinase Bruton tyrosine kinase (Btk) is required for activating both pathways, generating inositol-3,4,5-trisphosphate (IP(3)), and inducing E-selectin-mediated slow rolling. Inhibition of this signal-transduction pathway diminished Galpha(i)-independent leukocyte adhesion to and transmigration through endothelial cells in inflamed postcapillary venules of the cremaster. Galpha(i)-independent neutrophil recruitment into the inflamed peritoneal cavity was reduced in Btk(-/-) and Plcg2(-/-) mice. Our data demonstrate the functional importance of this newly identified signaling pathway mediated by E-selectin engagement.
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PI3K inhibition in inflammation: Toward tailored therapies for specific diseases.
Bioessays
PUBLISHED: 02-18-2010
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In the past decade, the availability of genetically modified animals has enabled the discovery of interesting roles for phosphatidylinositol 3-kinase-gamma (PI3Kgamma) and -delta (PI3Kdelta) in different cell types orchestrating innate and adaptive immune responses. Therefore, these PI3K isoforms appear to be attractive drug targets for the treatment of diseases caused by unrestrained immune reactions. Currently, pharmacological targeting of PI3Kgamma and/or PI3Kdelta represents one of the most promising challenges for companies interested in the development of novel safe treatments for inflammatory diseases. In this review we provide a general outline of PI3Kgamma- and PI3Kdelta-specific functions in distinct subsets of inflammatory cells. We also discuss the therapeutic impact of novel compounds targeting PI3Kgamma, PI3Kdelta or both, in mouse models of autoimmune disorders (systemic lupus erythematosus (SLE) and rheumatoid arthritis), respiratory diseases (allergic asthma and chronic obstructive pulmonary disease) and cardiovascular dysfunctions (atherosclerosis and myocardial infarction).
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PI3Kgamma protects from myocardial ischemia and reperfusion injury through a kinase-independent pathway.
PLoS ONE
PUBLISHED: 02-01-2010
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PI3Kgamma functions in the immune compartment to promote inflammation in response to G-protein-coupled receptor (GPCR) agonists and PI3Kgamma also acts within the heart itself both as a negative regulator of cardiac contractility and as a pro-survival factor. Thus, PI3Kgamma has the potential to both promote and limit M I/R injury.
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The absence of functional PI3Kgamma prevents leukocyte recruitment and ameliorates DSS-induced colitis in mice.
Immunol. Lett.
PUBLISHED: 01-27-2010
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Phosphatidylinositol-3-kinase gamma (PI3Kgamma) is the major PI3K that is activated in response to chemoattractants. It is responsible for the migration of leukocytes from the bloodstream to sites of injury or infection. Constant migration of new leukocytes to the intestinal mucosa may be an important factor in maintenance of inflammation and tissue damage in inflammatory bowel disease (IBD). Reducing this influx, for example by inhibition of PI3Kgamma, might therefore be a potential goal for therapy. Here we investigated the role of PI3Kgamma in the migration of leukocytes to sites of intestinal inflammation. We induced colitis in mice with a point mutation that inactivates PI3Kgamma enzymatic activity (kinase-dead) by oral administration of dextran sodium sulphate (DSS). Mice were treated with 1.5% DSS for 1 week and effects on cytokine production, leukocyte recruitment and disease severity were examined. Both clinical and histological parameters showed that the severity of colitis was significantly reduced in PI3Kgamma-kinase-dead mice compared to controls. Although mutant mice had a less severe colitis than controls they produced significantly more pro-inflammatory Th1 cytokines such as Il-12, Tnfalpha and Ifngamma and more Il-10. PI3Kgamma mutant mice showed increased numbers of resident macrophages and T cells in the colonic lamina propria in an unstressed condition but failed to recruit new leukocytes to the mucosa upon treatment with DSS despite the increased cytokine levels. These results suggest that PI3Kgamma plays a critical role in lamina propria leukocyte trafficking and that loss of PI3Kgamma-activity ameliorates DSS-induced colitis in mice.
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Involvement of phosphoinositide 3-kinase gamma in angiogenesis and healing of experimental myocardial infarction in mice.
Circ. Res.
PUBLISHED: 01-07-2010
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Phosphoinositide 3-kinase (PI3K)gamma is expressed in hematopoietic cells, endothelial cells (ECs), and cardiomyocytes and regulates different cellular functions relevant to inflammation, tissue remodeling and cicatrization. Recently, PI3Kgamma inhibitors have been indicated for the treatment of chronic inflammatory/autoimmune diseases and atherosclerosis.
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Essential role of the p110beta subunit of phosphoinositide 3-OH kinase in male fertility.
Mol. Biol. Cell
PUBLISHED: 01-06-2010
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Phosphoinositide 3-kinases (PI3K) are key molecular players in male fertility. However, the specific roles of different p110 PI3K catalytic subunits within the spermatogenic lineage have not been characterized so far. Herein, we report that male mice expressing a catalytically inactive p110beta develop testicular hypotrophy and impaired spermatogenesis, leading to a phenotype of oligo-azoospermia and defective fertility. The examination of testes from p110beta-defective tubules demonstrates a widespread loss in spermatogenic cells, due to defective proliferation and survival of pre- and postmeiotic cells. In particular, p110beta is crucially needed in c-Kit-mediated spermatogonial expansion, as c-Kit-positive cells are lost in the adult testis and activation of Akt by SCF is blocked by a p110beta inhibitor. These data establish that activation of the p110beta PI3K isoform by c-Kit is required during spermatogenesis, thus opening the way to new treatments for c-Kit positive testicular cancers.
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Phosphoinositide 3-kinase signalling in the vascular system.
Cardiovasc. Res.
PUBLISHED: 07-09-2009
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Phosphoinositide 3-kinases (PI3Ks) are protein and lipid kinases activated by different classes of membrane receptors, including G-protein coupled and tyrosine kinase receptors. Several lines of evidence have uncovered specific roles for distinct PI3K isoforms in the vascular system in both physiology and disease. The present review will summarize and discuss the most recent advances regarding PI3K-Akt signalling in endothelial cells, vascular smooth muscle cells, platelets, and inflammatory cells involved in the atherosclerotic process. Of interest, the development of novel isoform-selective PI3K inhibitor drugs offers a unique opportunity to selectively and differentially target PI3K-driven pathways in the vascular system and may give rise to new strategies for the treatment of cardiovascular diseases.
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A pro-inflammatory signature mediates FGF2-induced angiogenesis.
J. Cell. Mol. Med.
PUBLISHED: 06-28-2009
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Fibroblast growth factor-2 (FGF2) is a potent angiogenic growth factor. Here, gene expression profiling of FGF2-stimulated microvascular endothelial cells revealed, together with a prominent pro-angiogenic profile, a pro-inflammatory signature characterized by the upregulation of pro-inflammatory cytokine/chemokines and their receptors, endothelial cell adhesion molecules and members of the eicosanoid pathway. Real-time quantitative PCR demonstrated early induction of most of the FGF2-induced, inflammation-related genes. Accordingly, chick embryo chorioallantoic membrane (CAM) and murine Matrigel plug angiogenesis assays demonstrated a significant monocyte/macrophage infiltrate in the areas of FGF2-driven neovascularization. Similar results were obtained when the conditioned medium (CM) of FGF2-stimulated endothelial cells was delivered onto the CAM, suggesting that FGF2-upregulated chemoattractants mediate the inflammatory response. Importantly, FGF2-triggered new blood vessel formation was significantly reduced in phosphatidylinositol 3-kinase-gamma null mice exhibiting defective leucocyte migration or in clodronate liposome-treated, macrophage-depleted mice. Furthermore, the viral pan-chemokine antagonist M3 inhibited the angiogenic and inflammatory responses induced by the CM of FGF2-stimulated endothelial cells and impaired FGF2-driven neovascularization in the CAM assay. These findings point to inflammatory chemokines as early mediators of FGF2-driven angiogenesis and indicate a non-redundant role for inflammatory cells in the neovascularization process elicited by the growth factor.
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Essential role of phosphoinositide 3-kinase gamma in eosinophil chemotaxis within acute pulmonary inflammation.
Immunology
PUBLISHED: 06-17-2009
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We and others have established an important role for phosphoinositide-3 kinase gamma (PI3Kgamma) in the chemotactic responses of macrophages and neutrophils. The involvement of this lipid kinase in allergic inflammatory responses is, however, yet to be fully determined. Here we compare wild-type (WT) and PI3Kgamma(-/-) (KO) mice within a model of ovalbumin (OVA) -specific pulmonary inflammation. Upon OVA aerosol challenge, cell influx into the bronchoalveolar lavage (BAL) fluid consisted of neutrophils, macrophages and, more significantly, eosinophils - which are key effector cells in allergic inflammation. Each population was reduced by up to 80% in KO mice, demonstrating a role for PI3Kgamma in cell infiltration into the airways. The mechanism of reduced eosinophilia was analysed within both development and effector stages of the immune response. Comparable levels of OVA-specific T-cell proliferation and immunoglobulin production were established in both strains. Furthermore, no significant differences between WT and KO chemokine production were observed. Having identified the critical point of PI3Kgamma involvement, KO eosinophil chemotactic dysfunction was confirmed in vitro. These data are the first to demonstrate the vital role of PI3Kgamma in acute allergic inflammation. The profound dependency of eosinophils on PI3Kgamma for pulmonary influx identifies this lipid kinase as an attractive target for the pharmacological intervention of asthma.
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PI3Kgamma adaptor subunits define coupling to degranulation and cell motility by distinct PtdIns(3,4,5)P3 pools in mast cells.
Sci Signal
PUBLISHED: 06-11-2009
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Phosphoinositide 3-kinase gamma (PI3Kgamma) plays a major role in chronic inflammation and allergy. It is a heterodimer of a catalytic p110gamma subunit and an adaptor protein, either p101 or the p101 homolog p84 (p87(PIKAP)). It is unclear whether both PI3Kgamma complexes specifically modulate responses such as chemotaxis and degranulation. In mast cells, the p84:p110gamma complex synergizes with immunoglobulin E (IgE)- and antigen-clustered FcepsilonRI receptor signaling and is required to achieve maximal degranulation. During this process, PI3Kgamma is activated by ligands of heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs), in particular adenosine receptors, through autocrine and paracrine pathways. Here, we show that p110gamma needs p84 to relay signals from GPCRs to formation of phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P(3)], phosphorylation of Akt, migration of cells, and synergistic adenosine-enforced degranulation. Furthermore, the absence of adaptor subunits could not be compensated for by increased p110gamma abundance. Differentiated, p110gamma null cells also lost adaptor proteins. Complementation of p110gamma null mast cells with p101 and p110gamma restored the activation of Akt and cell migration, but failed to support degranulation. Lack of degranulation was attributed to a change in the spatiotemporal localization of PI3Kgamma-derived PtdIns(3,4,5)P(3); although both p84:p110gamma and p101:p110gamma complexes initially deposited PtdIns(3,4,5)P(3) at the plasma membrane, p101:p110gamma-derived PtdIns(3,4,5)P(3) was rapidly endocytosed to motile, microtubule-associated vesicles. In addition, p84:p110gamma, but not p101:p110gamma signaling was sensitive to disruption of lipid rafts. Our results demonstrate a nonredundant function for the p101 and p84 PI3Kgamma adaptor proteins and show that distinct pools of PtdIns(3,4,5)P(3) at the plasma membrane can elicit specific cell responses.
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Genetic evidence for a predominant role of PI3Kbeta catalytic activity in ITAM- and integrin-mediated signaling in platelets.
Blood
PUBLISHED: 06-10-2009
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Phosphatidylinositol 3-kinase (PI3K) isoforms PI3Kbeta and PI3Kgamma are implicated in platelet adhesion, activation, and aggregation, but their relative contribution is still unclear or controversial. Here, we report the first comparative functional analysis of platelets from mice expressing a catalytically inactive form of PI3Kbeta or PI3Kgamma. We demonstrate that both isoforms were similarly required for maximal activation of the small GTPase Rap1b and for complete platelet aggregation upon stimulation of G protein-coupled receptors for adenosine 5-diphosphate (ADP) or U46619. Their contribution to these events, however, was largely redundant and dispensable. However, PI3Kbeta, but not PI3Kgamma, enzymatic activity was absolutely required for Akt phosphorylation, Rap1 activation, and platelet aggregation downstream of the immunoreceptor tyrosine-based activation motif (ITAM)-bearing receptor glycoprotein VI (GPVI). Moreover, PI3Kbeta was a major essential regulator of platelet adhesion to fibrinogen and of integrin alpha(IIb)beta(3)-mediated spreading. These results provide genetic evidence for a crucial and selective role of PI3Kbeta in signaling through GPVI and integrin alpha(IIb)beta(3).
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Leukocyte transmigration is modulated by chemokine-mediated PI3Kgamma-dependent phosphorylation of vimentin.
Eur. J. Immunol.
PUBLISHED: 03-18-2009
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Phosphoinositide 3-kinase gamma (PI3Kgamma) plays a fundamental role in mediating leukocyte migration to inflammation sites. However, the downstream cytoplasmic events triggered by its signaling activity are still largely obscure. To address this issue, tyrosine and serine/threonine phosphorylated proteins of chemokine-stimulated WT or PI3Kgamma-null macrophages were investigated. Among the proteins analyzed, the intermediate filament vimentin was found as a downstream effector of the PI3Kgamma signaling pathway. Specific analysis of the phosphorylation state of vimentin in macrophages showed that this protein becomes rapidly phosphorylated in both tyrosine and serine residues upon chemokine stimulation. In the absence of PI3Kgamma or the kinase activity of PI3Kgamma (PI3Kgamma(KD/KD)), phosphorylation of vimentin was reduced. PI3Kgamma-null macrophages displayed impaired chemokine-driven vimentin fiber disassembly as well as reduced ability to transmigrate across endothelial cells. While WT macrophages infected with a vimentin mutant resistant to N-terminal serine phosphorylation showed a reduction in transendothelial migration, infection of PI3Kgamma-null macrophages with a vimentin mutant mimicking serine phosphorylation of N-terminal residues rescued the transendothelial migration defect. These results define vimentin N-terminal phosphorylation and fiber reorganization as a target of chemokine-dependent PI3Kgamma signaling in leukocytes.
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Tissue-specific KO of ECM proteins.
Methods Mol. Biol.
PUBLISHED: 02-28-2009
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Nearly 20 years after its first description, gene targeting and generation of transgenic mice by homologous recombination in embryonic stem cells still are cutting edge tools for the postgenomic era. Understanding the function of the large number of genes encoding extracellular matrix proteins and their cellular receptors appears a daunting task that can very much profit from a genetic approach. The generation of new mutant alleles remains essential to define the different biochemical properties of such proteins. While in the past, gene targeting represented a complex procedure, restricted to few laboratories, recent breakthroughs, such as the publication of the mouse genome sequence and the perfection of recombineering techniques in bacteria, made generation of transgenic mice faster and easier. This chapter will thus focus on the recent advances in gene-targeting technology with a special eye on the study of genes involved in cell adhesion and migration.
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Twice upon a time: PI3Ks secret double life exposed.
Trends Biochem. Sci.
PUBLISHED: 02-05-2009
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Class I phosphoinositide 3-kinases (PI3Ks) are heterodimeric enzymes involved in signal transduction triggered by growth factors and G-protein-coupled receptors. The catalytic function of PI3Ks is well known to promote a wide variety of biological processes, including proliferation, survival and migration, but a new layer of complexity in the function of PI3Ks has recently emerged, indicating that these proteins function not only as kinases but also as scaffold proteins. Knockout mice that lack PI3K protein expression show a different phenotype from knock-in mice expressing PI3K mutants that have lost their kinase activity, providing evidence for this novel role of PI3Ks. We will discuss such findings, highlighting the crucial scaffold function of PI3Kgamma in cAMP homeostasis and PI3Kbeta in receptor recycling.
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Inflammation as a therapeutic target in heart failure? A scientific statement from the Translational Research Committee of the Heart Failure Association of the European Society of Cardiology.
Eur. J. Heart Fail.
PUBLISHED: 01-27-2009
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The increasing prevalence of heart failure poses enormous challenges for health care systems worldwide. Despite effective medical interventions that target neurohumoral activation, mortality and morbidity remain substantial. Evidence for inflammatory activation as an important pathway in disease progression in chronic heart failure has emerged in the last two decades. However, clinical trials of anti-inflammatory therapies (such as anti-tumor necrosis factor-alpha approaches) have to date failed to show benefit in heart failure patients. The Heart Failure Association of the European Society of Cardiology recently organized an expert workshop to address the issue of inflammation in heart failure from a basic science, translational and clinical perspective, and to assess whether specific inflammatory pathways may yet serve as novel therapeutic targets for this condition. This consensus document represents the outcome of the workshop and defines key research questions that still need to be addressed as well as considering the requirements for future clinical trials in this area.
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Ablation of calcineurin A? reveals hyperlipidemia and signaling cross-talks with phosphodiesterases.
J. Biol. Chem.
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Insulin resistance, hyperlipidemia, and cardiovascular complications are common dysregulations of metabolic syndrome. Transplant patients treated with immunosuppressant drugs such as cyclosporine A (CsA), an inhibitor of calcineurin phosphatase, frequently develop similar metabolic complications. Although calcineurin is known to mediate insulin sensitivity by regulating ?-cell growth and adipokine gene transcription, its role in lipid homeostasis is poorly understood. Here, we examined lipid homeostasis in mice lacking calcineurin A? (CnA?(-/-)). We show that mice lacking calcineurin A? are hyperlipidemic and develop age-dependent insulin resistance. Hyperlipidemia found in CnA?(-/-) mice is, in part, due to increased lipolysis in adipose tissues, a process mediated by ?-adrenergic G-protein-coupled receptor signaling pathways. CnA?(-/-) mice also exhibit additional pathophysiological phenotypes caused by the potentiated GPCR signaling pathways. A cell autonomous mechanism with sustained cAMP/PKA activation is found in CnA?(-/-) mice or upon CsA treatment to inhibit calcineurin. Increased PKA activation and cAMP accumulation in CnA?(-/-) mice, however, are sensitive to phosphodiesterase inhibitor. Indeed, we show that calcineurin regulates degradation of phosphodiesterase 3B, in addition to phosphodiesterase 4D. These results establish a role for calcineurin in lipid homeostasis. These data also indicate that potentiated cAMP signaling pathway may provide an alternative molecular pathogenesis for the metabolic complications elicited by CsA in transplant patients.
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Construction of a global pain systems network highlights phospholipid signaling as a regulator of heat nociception.
PLoS Genet.
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The ability to perceive noxious stimuli is critical for an animals survival in the face of environmental danger, and thus pain perception is likely to be under stringent evolutionary pressure. Using a neuronal-specific RNAi knock-down strategy in adult Drosophila, we recently completed a genome-wide functional annotation of heat nociception that allowed us to identify ?2?3 as a novel pain gene. Here we report construction of an evolutionary-conserved, system-level, global molecular pain network map. Our systems map is markedly enriched for multiple genes associated with human pain and predicts a plethora of novel candidate pain pathways. One central node of this pain network is phospholipid signaling, which has been implicated before in pain processing. To further investigate the role of phospholipid signaling in mammalian heat pain perception, we analysed the phenotype of PIP5K? and PI3K? mutant mice. Intriguingly, both of these mice exhibit pronounced hypersensitivity to noxious heat and capsaicin-induced pain, which directly mapped through PI3K? kinase-dead knock-in mice to PI3K? lipid kinase activity. Using single primary sensory neuron recording, PI3K? function was mechanistically linked to a negative regulation of TRPV1 channel transduction. Our data provide a systems map for heat nociception and reinforces the extraordinary conservation of molecular mechanisms of nociception across different species.
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PI3Ks and small GTPases in neutrophil migration: two sides of the same coin.
Mol. Immunol.
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Cell migration is a key event in physiological processes such as embryonic development, tissue repair, angiogenesis and immune responses. Alteration of the migration program is an important component in multiple pathologies, including chronic inflammation, autoimmunity and tumor metastasis. Understanding of the precise mechanisms at the basis of cellular migration may lead to the identification of novel therapeutic approach for these diseases. Recent evidences show that the interplay between the lipid kinases phosphatidylinositol 3-kinase (PI3Ks) and small GTPases play a critical role in driving cell migration. In this review we will describe the role of these molecules and the interaction between their signal cascades in leukocyte polarization and amoeboid migration.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.