Recent studies on senescence marker protein-30 (SMP30) have shown that it has an important functional role in the aging process, but its precise participation in cellular works has not been fully determined. We hypothesize that SMP30 plays crucial roles in signaling processes by modulating the balance of protein tyrosine kinase (PTK)/protein tyrosine phosphatase (PTP) and in activating proinflammatory NF-?B. An experimental paradigm of gain and loss of SMP30 function was established using SMP30-overexpressed YPEN-1 cells (herein referred to as "SMP30(+) cells") and SMP30 (Y/-) knockout mouse kidneys. The resulting data show that SMP30 expression suppressed oxidative stress-induced PTK/PTP dysregulation and PP1/2A inactivation in SMP30(+) cells, leading to the suppression of NF-?B activation. In the kidneys of SMP30 (Y/-) mice, SMP30 deficiency was found to induce NF-?B activation via the upstream signaling of NIK/IKK and MAPKs and to upregulate downstream NF-?B-responsive gene expression. In this study, we also demonstrate for the first time that SMP30 deficiency induced PTK activity in SMP30 (Y/-) kidneys, thereby significantly increasing the tyrosine phosphorylation of a catalytic subunit of PP2A (PP2Ac-Tyr307). Based on these findings, we propose that SMP30 involves NF-?B regulation through the PTK/PTP balance and that the age-related decrease of SMP30 causes NF-?B activation, which contributes to an exacerbation of the inflammatory process during aging.
Potato chips (PC) contain abundant amounts of the free radical scavenger ascorbic acid (AA) due to the rapid dehydration of potato tubers (Solanum tuberosum) that occurs during frying. To evaluate the antioxidant activity of PC, this study examined reactive oxygen species (ROS) levels in tissues from SMP30/GNL knockout (KO) mice that cannot synthesize AA and determined AA and ROS levels after the animals were fed 20 and 10% PC diets for 7 weeks. Compared with AA-sufficient mice, AA-depleted SMP30/GNL KO mice showed high ROS levels in tissues. SMP30/GNL KO mice fed a PC diet showed high AA and low ROS levels in the brain, heart, lung, testis, soleus muscle, plantaris muscle, stomach, small intestine, large intestine, eyeball, and epididymal fat compared with AA-depleted mice. The data suggest that PC intake increases AA levels and enhances ROS scavenging activity in tissues of SMP30/GNL KO mice, which are a promising model for evaluating the antioxidant activity of foods.
Senescence marker protein-30 (SMP30)/gluconolactonase (GNL) is an age-associated protein in that its presence decreases with aging. Here, we used immunohistochemical analysis to investigate the changes of SMP30/GNL in individual cells of the liver from progressively aged mice.
Individuals born with a low birth weight (LBW) have a higher risk of developing kidney dysfunction during their lifetime and sometimes exhibit focal segmental glomerulosclerosis (FSGS) lesions in their glomeruli. We herein try to obtain other pathological characteristics of LBW-related nephropathy.
The actions of catecholamines on adrenergic receptors (ARs) induce sympathetic responses, and sustained activation of the sympathetic nervous system results in disrupted circulatory homeostasis. In cardiomyocytes, ?1-ARs localize to flask-shaped membrane microdomains known as "caveolae." Caveolae require both caveolin and cavin proteins for their biogenesis and function. However, the functional roles and molecular interactions of caveolar components in cardiomyocytes are poorly understood. Here, we showed that muscle-restricted coiled-coil protein (MURC)/Cavin-4 regulated ?1-AR-induced cardiomyocyte hypertrophy through enhancement of ERK1/2 activation in caveolae. MURC/Cavin-4 was expressed in the caveolae and T tubules of cardiomyocytes. MURC/Cavin-4 overexpression distended the caveolae, whereas MURC/Cavin-4 was not essential for their formation. MURC/Cavin-4 deficiency attenuated cardiac hypertrophy induced by ?1-AR stimulation in the presence of caveolae. Interestingly, MURC/Cavin-4 bound to ?1A- and ?1B-ARs as well as ERK1/2 in caveolae, and spatiotemporally modulated MEK/ERK signaling in response to ?1-AR stimulation. Thus, MURC/Cavin-4 facilitates ERK1/2 recruitment to caveolae and efficient ?1-AR signaling mediated by caveolae in cardiomyocytes, which provides a unique insight into the molecular mechanisms underlying caveola-mediated signaling in cardiac hypertrophy.
Superoxide dismutase 1 (SOD1) is an antioxidant enzyme that converts superoxide anion radicals into hydrogen peroxide and molecular oxygen. The senescence marker protein-30 (SMP30) is a gluconolactonase that functions as an antioxidant protein in mammals due to its involvement in ascorbic acid (AA) biosynthesis. SMP30 also participates in Ca(2+) efflux by activating the calmodulin-dependent Ca(2+)-pump. To reveal the role of oxidative stress in lipid metabolism defects occurring in non-alcoholic fatty liver disease pathogenesis, we generated SMP30/SOD1-double knockout (SMP30/SOD1-DKO) mice and investigated their survival curves, plasma and hepatic lipid profiles, amounts of hepatic oxidative stress, and hepatic protein levels expressed by genes related to lipid metabolism. While SMP30/SOD1-DKO pups had no growth retardation by 14 days of age, they did have low plasma and hepatic AA levels. Thereafter, 39% and 53% of male and female pups died by 15-24 and 89 days of age, respectively. Compared to wild type, SMP30-KO and SOD1-KO mice, by 14 days SMP30/SOD1-DKO mice exhibited: (1) higher plasma levels of triglyceride and aspartate aminotransferase; (2) severe accumulation of hepatic triglyceride and total cholesterol; (3) higher levels of superoxide anion radicals and thiobarbituric acid reactive substances in livers; and (4) decreased mRNA and protein levels of Apolipoprotein B (ApoB) in livers - ApoB is an essential component of VLDL secretion. These results suggest that high levels of oxidative stress due to concomitant deficiency of SMP30 and/or AA, and SOD1 cause abnormal plasma lipid metabolism, hepatic lipid accumulation and premature death resulting from impaired VLDL secretion.
Senescence marker protein-30 (SMP30) was first described as a physiologic entity that decreases in the rat liver and kidney with aging. Previously, we established that SMP30 is the lactone-hydrolyzing enzyme gluconolactonase (GNL), which is involved in ascorbic acid (AA) biosynthesis. In the present study, we found SMP30/GNL mRNA expressed in the mouse ovary. To ascertain the reason for ovarian SMP30/GNL expression, we examined mice during gestation. SMP30/GNL mRNA expression was evident at the start of gestation, increased for the next eight days then decreased rapidly. Moreover, L-gulono-?-lactone oxidase (Gulo) mRNA, which catalyzes the last step of AA, was found in the ovaries of these mice. The variations of these genes expression showed an inverse pattern to that of Cyp19a1 (aromatase) mRNA expression. Therefore, the SMP30/GNL and Gulo mRNA expression might be regulated by estrogen levels in the ovary. Since the presence of both SMP30/GNL and Gulo mRNAs could indicate that AA synthesis occurs in the ovary, we quantified AA levels in mouse ovaries during gestation. However, no correlation was found between changes of AA content and SMP30/GNL or Gulo mRNAs expression at this site. Moreover, we compared the changes of AA content during gestation between wild-type and SMP30/GNL knockout mice, which cannot synthesize AA, and found no significant differences between them. These results indicated that, although AA synthesis might occur in the ovaries, the amount of AA which is synthesized in ovaries must be quite low and insufficient to influence the AA content in ovary.
The orbital floor is one of the most frequently broken bones in maxillofacial fracture, and orbital reconstruction is needed in many cases. Various materials are used for orbital floor reconstruction. We report here orbital reconstruction using autologous orbital bone with cyanoacrylate. Entrapped soft tissues were freed and repositioned intraorbitally and bone fragments were gathered with a microscope simultaneously. The bone fragments were fixed to a board of bone with ethyl-2-cyanoacrylate and returned to the orbital fracture site. Of 96 fresh orbital floor fractures, this method was used for 31 (32.3%) patients. Simple reduction was performed in 48 patients. Bone graft with iliac crest was performed in the other 12 patients. Reconstruction with alloplastic materials was performed in 5 patients. Diplopia was corrected in 26 patients on whom this method was performed. The reconstructed bone collapsed into the maxillary sinus in 1 patient who underwent iliac bone graft on reoperation. Another 4 patients did not show diplopia preoperatively. None of the patients showed enophthalmos, foreign body reaction, or infection postoperatively. We were able to perform orbital bone reconstruction with autologous orbital bone without another donor site in 30 (62.5%) of 48 cases that required grafting. The indications for this method are that a sufficient quantity of bone fragments can be obtained and returned on a board of bone which can be stabilized in the orbit without collapsing into the maxillary sinus. Good results were obtained, and we consider this to be a safe and useful method.
Senescence marker protein-30 (SMP30)/gluconolactonase (GNL) knockout (KO) mice are incapable of synthesizing L-ascorbic acid (AA) in?vivo. As AA is known to be a water-soluble anti-oxidant, we assessed protein oxidation levels in livers from SMP30/GNL KO mice maintained in an AA-insufficient condition.
Senescence-accelerated mice (SAM) are a series of mouse strains originally derived from unexpected crosses between AKR/J and unknown mice, from which phenotypically distinct senescence-prone (SAMP) and -resistant (SAMR) inbred strains were subsequently established. Although SAMP strains have been widely used for aging research focusing on their short life spans and various age-related phenotypes, such as immune dysfunction, osteoporosis, and brain atrophy, the responsible gene mutations have not yet been fully elucidated.
PURPOSE: The effect of an AA deficiency on catecholamine biosynthesis in adult mice in vivo is unknown. Therefore, we quantified catecholamine and the expression of catecholamine synthetic enzymes in the adrenal glands of senescence marker protein-30 (SMP30)/gluconolactonase (GNL) knockout (KO) mice placed in an AA-deficient state. METHODS: At 30 days of age, mice were divided into the following 4 groups: AA (-) SMP30/GNL KO, AA (+) SMP30/GNL KO, AA (-) wild type (WT), and AA (+) WT. The AA (+) groups were given water containing 1.5 g/L AA, whereas the AA (-) groups received water without AA until the experiment ended. In addition, all mice were fed an AA-depleted diet. Catecholamine levels were measured by a liquid chromatographic method. Tyrosine hydroxylase, dopa decarboxylase, dopamine ?-hydroxylase, and phenylethanolamine N-methyltransferase mRNA expression levels were measured with the quantitative real-time polymerase chain reaction (qPCR). Tyrosine hydroxylase and dopamine ?-hydroxylase protein levels were quantified by Western blot analysis. RESULTS: In the adrenals of AA (-) SMP30/GNL KO mice, noradrenaline and adrenaline levels decreased significantly compared to other three groups of mice, although there were no significant differences in dopamine ?-hydroxylase or phenylethanolamine N-methyltransferase mRNA content. Moreover, there was no significant difference in their dopamine ?-hydroxylase protein levels. On the other hand, AA depletion did not affect dopamine levels in adrenal glands of mice. CONCLUSION: An AA deficiency decreases the noradrenaline and adrenaline levels in adrenal glands of mice in vivo.
A 69-year-old postmenopausal woman who was prescribed anastrozole for 10 months after surgical removal of her breast cancer, was referred to our hospital for acute renal failure. Because it was possible that her renal failure was related to her treatment with anastrozole, the treatment was immediately discontinued. After renal biopsy was performed to examine her renal failure, she was diagnosed as crescentic glomerulonephritis, probably related with the treatment of anastrozole. Twenty mg of oral prednisolone was administered daily after methylprednisolone pulse therapy(500 mg/day intravenous administration for three days). Her renal dysfunction was gradually improved. Renal dysfunction was considered to be a rare complication of anastrozole. Patients who are prescribed anastrozole should be watched carefully for the development of renal dysfunction.
Despite the acknowledged importance of ascorbic acid (AA) in maintaining pregnancy and normal fetal development, its precise actions remain obscure. Therefore, we investigated the impact of maternal AA content on the growth of fetal mice during the gestation period using senescence marker protein-30/gluconolactonase (SMP30/GNL) knockout (KO) mice, which cannot synthesize AA in vivo.
The senescence marker protein-30 (SMP30), which is also called regucalcin, exhibits gluconolactonase (GNL) activity. Biochemical and biological analyses revealed that SMP30/GNL catalyzes formation of the ?-lactone-ring of L-gulonate in the ascorbic acid biosynthesis pathway. The molecular basis of the ?-lactone formation, however, remains elusive due to the lack of structural information on SMP30/GNL in complex with its substrate. Here, we report the crystal structures of mouse SMP30/GNL and its complex with xylitol, a substrate analogue, and those with 1,5-anhydro-D-glucitol and D-glucose, product analogues. Comparison of the crystal structure of mouse SMP30/GNL with other related enzymes has revealed unique characteristics of mouse SMP30/GNL. First, the substrate-binding pocket of mouse SMP30/GNL is designed to specifically recognize monosaccharide molecules. The divalent metal ion in the active site and polar residues lining the substrate-binding cavity interact with hydroxyl groups of substrate/product analogues. Second, in mouse SMP30/GNL, a lid loop covering the substrate-binding cavity seems to hamper the binding of L-gulonate in an extended (or all-trans) conformation; L-gulonate seems to bind to the active site in a folded conformation. In contrast, the substrate-binding cavities of the other related enzymes are open to the solvent and do not have a cover. This structural feature of mouse SMP30/GNL seems to facilitate the ?-lactone-ring formation.
The senescence marker protein-30 (SMP30) is a 34 kDa protein originally identified in rat liver that shows decreased levels with age. Several functional studies using SMP30 knockout (Smp30(Y/-) ) mice established that SMP30 functions as an antioxidant and protects against apoptosis. To address the potential role of SMP30 in nonalcoholic fatty liver disease (NAFLD) pathogenesis, we established Smp30(Y/-) mice on a Lepr(db/db) background (Lepr(db/db)Smp30(Y/-) mice). RESEARCH DESIGN/PRINCIPAL FINDINGS: Male Lepr(db/db)Smp30(Y/-) mice were fed a standard diet (340 kcal/100 g, fat 5.6%) for 16 weeks whereupon the lipid/lipoprotein profiles, hepatic expression of genes related to lipid metabolism and endoplasmic reticulum stress markers were analyzed by HPLC, quantitative RT-PCR and western blotting, respectively. Changes in the liver at a histological level were also investigated. The amount of SMP30 mRNA and protein in livers was decreased in Lepr(db/db)Smp30(Y/+) mice compared with Lepr(db/+)Smp30(Y/+) mice. Compared with Lepr(db/db)Smp30(Y/+) mice, 24 week old Lepr(db/db)Smp30(Y/-) mice showed: i) increased small dense LDL-cho and decreased HDL-cho levels; ii) fatty liver accompanied by numerous inflammatory cells and increased oxidative stress; iii) decreased mRNA expression of genes involved in fatty acid oxidation (PPAR?) and lipoprotein uptake (LDLR and VLDLR) but increased CD36 levels; and iv) increased endoplasmic reticulum stress.
It has been suggested that some food components, such as bioflavonoids, affect the bioavailability of ascorbic acid in humans. Since little is known in Japan about the effective intake of this dietary requirement, we tested young Japanese males after the ingestion of commercial ascorbic acid or acerola (Malpighia emarginata DC.) juice to compare the quantities absorbed and excreted. Healthy Japanese subjects received a single oral dose of ascorbic acid solution (50, 100, 200 or 500 mg) and received distilled water as a reference at intervals of 14 d or longer. All subjects were collected blood and urine until 6 h after ingestion and evaluated for time-dependent changes in plasma and urinary ascorbic acid levels. Predictably, the area under the curve (AUC) values in plasma and urine after ingestion increased dose-dependently. Next, each subject received diluted acerola juice containing 50 mg ascorbic acid. Likewise, their plasma and urinary ascorbic acid concentrations were measured. In plasma, the AUC value of ascorbic acid after ingestion of acerola juice tended to be higher than that from ascorbic acid alone. In contrast, the urinary excretion of ascorbic acid at 1, 2 and 5 h after ingestion of acerola juice were significantly less than that of ascorbic acid. These results indicate that some component of acerola juice favorably affected the absorption and excretion of ascorbic acid.
"Heart Risk View" is the software to evaluate the cardiac event probability, and it is based on the results of the prospective cohort study (J-ACCESS). We examined the usefulness of this software. Study population consisted of 83 patients, who were diagnosed that cardiac event probability was over 20% by "Heart Risk View." During the follow-up period (596 +/- 356 days), cardiac event occurred in 23 patients (27.7%), including 7 patients death. No significant differences were observed in the ejection fraction by Quantitative Gated SPECT, total defect score calculated from SPECT, and the percentage of stress perfusion abnormality detected by SPECT between event and non-event groups. However, the percentage of cardiac revascularization therapy based on the SPECT was significantly lower in the event group (9 vs. 38%, p = 0.03). In conclusion, cardiac event probability calculated by "Heart Risk View" was reliable in our study cohort. Cardiac event strongly depended on the cardiac ischemia, for which the therapy was difficult because of lesion complexity or combined diseases.
Senescence marker protein-30 (SMP30) plays an important role in intracellular Ca(2+) homeostasis. The aim of the present study was to investigate the effects of estrogens on liver apoptotic damage and changes in SMP30 expression induced by a high saturated fatty acid diet (HSFD). Ovariectomized mice (OVX) and sham-operated mice (SHAM) were randomly divided into five groups: SHAM fed a normal diet (SHAM/ND), SHAM fed HSFD (SHAM/HSFD), OVX fed ND (OVX/ND), OVX fed HSFD (OVX/HSFD) and OVX fed HSFD with 17?-estradiol (E2) supplementation using an implanted slow-release pellet (OVX/HSFD+E2). After 8 weeks, markers of endoplasmic reticulum (ER) stress and apoptosis, and levels of tumor necrosis factor-? (TNF? and SMP30 expression were investigated. Compared with SHAM/ND, OVX/HSFD mice showed significantly increased spliced X-box protein-1 (s-XBP1), phosphorylated eukaryotic initiation factor-2? (p-eIF2?), glucose-regulated protein 78 (GPR78), C/EBP homologous protein (CHOP), cytosolic cytochrome c, caspase-3 activity, and TNF?, and significantly decreased SMP30. These differences in OVX/HSFD mice were restored to the levels of SHAM/ND mice by E2 supplementation. These results suggest that E2 supplementation attenuates HSFD-induced liver apoptotic death in ovariectomized mice by up-regulating SMP30.
Maintenance of physical performance could improve the quality of life in old age. Recent studies suggested a beneficial relationship between antioxidant vitamin (eg, vitamin C) intake and physical performance in elderly people. The purpose of this study was to examine the relationship between plasma vitamin C concentration and physical performance among Japanese community-dwelling elderly women.
Potato (Solanum tuberosum) tubers contain vitamin C (VC) and commercial potato chips have more VC content per wet weight by dehydration during frying. However, intestinal absorption of VC from orally ingested potatoes and its transfer to the blood remains questionable. The present study was designed to determine whether the dietary consumption of potatoes affects VC concentration in plasma and urinary excretion of VC in human subjects. After overnight fasting, five healthy Japanese men between 22 and 27 years of age consumed 87 g mashed potatoes and 282 g potato chips. Each portion contained 50 mg of VC, 50 mg VC in mineral water and mineral water. Before and after a single episode of ingestion, blood and urine samples were collected every 30 min or 1 h for 8 h. When measured by subtraction of the initial baseline value before administration of potatoes from the values measured throughout the 8 h test period, plasma VC concentrations increased almost linearly up to 3 h. Subsequently, the values of potato-fed subjects were higher than those of water, but did not differ significantly from those of VC in water (P = 0·14 and P = 0·5). Less VC tended to be excreted in urine during the 8 h test than VC in water alone (17·0 (sem 7·5) and 25·9 (sem 8·8) v. 47·9 (sem 17·9) ?mol/mmol creatinine). Upon human consumption, mashed potatoes and potato chips provide VC content that is effectively absorbed in the intestine and transferred to the blood. Clearly, potatoes are a readily available source of dietary VC.
Senescence marker protein-30 (SMP30) has been identified as the lactone-hydrolysing enzyme gluconolactonase (GNL), which is involved in vitamin C (L-ascorbic acid, AA) biosynthesis. We previously reported the development of SMP30/GNL knockout (KO) mice unable to synthesize AA in vivo. For more efficient study of the livers AA uptake and as yet uncharacterized efflux system, we established an immortal hepatocyte line derived from a hybrid of SMP30/GNL KO mice and Immortomice. Immortomice express the thermolabile simian virus 40 (SV40) large T antigen tsA58. These SMP30/GNL KO immortal hepatocytes proliferate at the permissive temperature of 33°C but degrade rapidly at the non-permissive temperature of 39°C. Additionally, they are SMP30-/GNL-deficient, express SV40 large T antigen and proliferate steadily at 33°C. However, the cells proliferation is arrested at 39°C. A phase contrast micrograph revealed that the cells are binucleated with an enlarged cytoplasm similar to that of primary cultured hepatocytes from wild-type mice. Dose-response and time-dependent study of AA uptake revealed that the cells, although unable to synthesize AA, took up AA from the culture medium. This property of our SMP30/GNL immortal hepatocytes makes them extremely useful for studying AA uptake and efflux systems in the liver.
We investigated whether decreased vitamin C (VC) in a mouse model increases lens opacity (cataract) induced by in vivo exposure to ultraviolet radiation type B (UVR-B). Senescence marker protein-30 (SMP30) knockout (KO) mice, which cannot synthesize VC due to genetic disruption of the gluconolactonase (GNL) gene, were divided into 2 groups: VC sufficient (VC (+)) and VC deficient (VC (-)). Starting at 1 month of age, these groups had free access to water containing 0.0375 and 1.5 g/L of VC, respectively. SMP30 KO VC (-), SMP30 KO VC (+), and wild-type (WT) mice, all 14 weeks of age, were unilaterally exposed in vivo to UVR-B (200 mW/cm(2)) for 100 s twice a week for 3 weeks (total: 1200 mJ/cm(2)). At 48 h after the last UVR-B exposure, cataract morphology was documented, and the ratio of cataract induction was quantified as the cataract area ratio (opacity area/anterior capsule). UVR-B exposure induced cataract mainly at anterior sub-capsular in SMP30 KO VC (-), SMP30 KO VC (+), and WT mice. In SMP30 KO VC (-) lenses the opacities were more extensive than in SMP30 KO VC (+) or WT lenses (cataract area ratios: 59.3% ± 10% vs. 32.2% ± 11.7% or 29.0% ± 9.0%; P < 0.01). In conclusion, VC depletion may increase the susceptibility to develop UVR-B induced cataracts in mice unable to endogenously produce VC.
We recently identified senescence marker protein-30 as the lactone-hydrolyzing enzyme gluconolactonase, which is involved in vitamin C biosynthesis. In this study, we investigated the effects of vitamin C on insulin secretion from pancreatic ?-cells using senescence marker protein-30/gluconolactonase knockout mice. In intraperitoneal glucose tolerance tests, vitamin C-deficient senescence marker protein-30/gluconolactonase knockout mice demonstrated impaired glucose tolerance with significantly lower blood insulin levels at 30 and 120 min post-challenge than in wild type mice (p<0.01-0.05). In contrast, vitamin C-sufficient senescence marker protein-30/gluconolactonase knockout mice demonstrated significantly higher blood glucose and lower insulin only at the 30 min post-challenge time point (p<0.05). Senescence marker protein-30/gluconolactonase knockout mice showed enhanced insulin sensitivity regardless of vitamin C status. Static incubation of islets revealed that 20 mM glucose-stimulated insulin secretion and islet ATP production were significantly decreased at 60 min only in vitamin C-deficient SMP30/GNL knockout mice relative to wild type mice (p<0.05). These results indicate that the site of vitamin C action lies between glycolysis and mitochondrial oxidative phosphorylation, while SMP30 deficiency itself impairs the distal portion of insulin secretion pathway.
Antibodies against acetylcholine receptors (AChRs) cause pathogenicity in myasthenia gravis (MG) patients through complement pathway-mediated destruction of postsynaptic membranes at neuromuscular junctions (NMJs). However, antibodies against muscle-specific kinase (MuSK), which constitute a major subclass of antibodies found in MG patients, do not activate the complement pathway. To investigate the pathophysiology of MuSK-MG and establish an experimental autoimmune MG (EAMG) model, we injected MuSK protein into mice deficient in complement component five (C5). MuSK-injected mice simultaneously developed severe muscle weakness, accompanied by an electromyographic pattern such as is typically observed in MG patients. In addition, we observed morphological and functional defects in the NMJs of EAMG mice, demonstrating that complement activation is not necessary for the onset of MuSK-MG. Furthermore, MuSK-injected mice exhibited acetylcholinesterase (AChE) inhibitor-evoked cholinergic hypersensitivity, as is observed in MuSK-MG patients, and a decrease in both AChE and the AChE-anchoring protein collagen Q at postsynaptic membranes. These findings suggest that MuSK is indispensable for the maintenance of NMJ structure and function, and that disruption of MuSK activity by autoantibodies causes MG. This mouse model of EAMG could be used to develop appropriate medications for the treatment of MuSK-MG in humans.
Angiography is not always an accurate indicator of physiologically significant stenosis. We examined the usefulness of functional evaluation of coronary stenosis severity by determining the fractional flow reserve (FFR) using a pressure wire in patients who received hemodialysis with angiographically intermediate lesions. We recruited 44 patients with intermediate lesions; of these, 22 were undergoing hemodialysis while 22 were not. Quantitative coronary angiography (QCA) was performed to measure the minimal lumen diameter (MLD) and calculate the percent diameter stenosis (%DS). The FFR was calculated as the ratio of the coronary pressure at the distal stenotic site to the mean aortic pressure during maximum hyperemia. In each group, we investigated the relationship between the FFR and %DS and FFR and MLD. The patients in the hemodialysis group were significantly younger and had more calcified and type B2/C lesions than those in the non-dialysis group. Although the FFR was correlated with both %DS (r = 0.71, p < 0.01) and MLD (r = 0.58, p < 0.01) in the non-dialysis group, the FFR was not correlated with either MLD or %DS in the hemodialysis group. In the hemodialysis group, there was a discordance between the QCA- and FFR-based assessments of the severity of coronary stenosis. In patients receiving hemodialysis, both anatomical and functional assessments should be conducted to determine the physiological significance of the stenosis accurately.
We examined whether activity of the nucleus basalis of Meynert (NBM) regulates regional cerebral cortical blood flow (rCBF) in mice, using laser speckle and laser Doppler flowmetry. In anesthetized mice, unilateral focal stimulation, either electrical or chemical, of the NBM increased rCBF of the ipsilateral cerebral cortex in the frontal, parietal and occipital lobes, independent of changes in systemic blood pressure. Most of vasodilative responses to low intensity stimuli (2 times threshold intensity: 2T) were abolished by atropine (a muscarinic cholinergic blocker), whereas responses to higher intensity stimuli (3T) were abolished by atropine and mecamylamine (a nicotinic cholinergic blocker). Blood flow changes were largest when the tip of the electrode was located within the area containing cholinergic neurons shown by choline acetyltransferase-immunocytochemistry. These results suggest that cholinergic projections from basal forebrain neurons in mice cause vasodilation in the ipsilateral cerebral cortex by a combination of muscarinic and nicotinic mechanisms, as previously found in rats and cats.
Peptidylarginine deiminase (PAD) and citrullinated proteins have emerged as key molecules in various human diseases, but detailed subcellular localizations of PAD2 and citrullinated proteins are poorly mapped in brain under normal and pathologic conditions. We performed subcellular fractionation and electron microscopic analysis using brains of normal and scrapie-infected mice. Peptidylarginine deiminase 2 was abundantly present in cytosol and weakly in microsomal and mitochondrial fractions and expression in these fractions was higher in brains of scrapie-infected mice. Despite relatively low PAD2 expression, in microsomal and mitochondrial fractions, citrullinated proteins were present at high levels in these fractions in scrapie-infected brains. Surprisingly, increased PAD2 expression and accumulated citrullinated proteins were also found in nuclear fractions in scrapie-infected brains. By electron microscopy, PAD2 and citrullinated proteins in scrapie-infected brains were widely distributed in most cellular compartments including mitochondria, endoplasmic reticulum, glial filaments, nuclei, and Golgi apparatus in astrocytes and hippocampal neurons. Taken together, we report for the first time the nuclear localization of PAD2 and the detailed subcellular localization of PAD2 and of citrullinated proteins in scrapie-infected brains. Our findings suggest that different subcellular compartmentalization of PAD2 and citrullinated proteins may have different physiological roles in normal and neurodegenerative conditions.
A novel rat liver protein of 30 kDa, SMP30 decreases with aging. This protein is expressed most prominently in the liver and kidneys among the various organs. Its gene is located on the X chromosome. No functional domain was recognized in the entire amino acid sequence. Recently, we found a homology between rat SMP30 and two species of bacterial gluconolactonase (EC 184.108.40.206). The lactonase reaction with L-gulono-gamma-lactone is the penultimate step in vitamin C (L-ascorbic acid) biosynthesis. SMP30-knockout (KO) mice fed a vitamin C-deficient diet displayed symptoms of scurvy. In SMP30-KO mice, hepatocytes were more susceptible to apoptosis induced by TNF-alpha plus actinomycin D than hepatocytes from wild-type mice. Two morphological features considered to be a hallmark of senescence are apparent in SMP30-KO mice. At 12 months of age, SMP30-knockout mice had clearly visible deposits of lipofuscin and senescence-associated beta-galactosidase (SA-beta-GAL) in their renal tubular epithelia. These features are compatible with high electron dense deposits in lysosomes. This observation suggests that the SMP30-knockout mouse is a useful model of ordinal senescence.
Peptidylarginine deiminases (PAD) are a group of post-translational modification enzymes that citrullinate (deiminate) protein arginine residues in a calcium ion-dependent manner. Enzymatic citrullination abolishes positive charges of native protein molecules, inevitably causing significant alterations in their structure and functions. Citrullinated protein has an important physiological purpose; the formation of a cornified layer of skin that covers the human body. Despite this beneficial function, citrullinated protein also has a negative side, because this proteins accumulation in the brain is a possible cause of Alzheimers disease. In the present review, we introduce PAD and their protein citrullination function, now considered critical for advancing research on aging and disease.
Because vitamin C (VC) has multiple metabolic and antioxidant functions, we investigated the movement of VC throughout the tissues of senescence marker protein-30 (SMP30)/gluconolactonase (GNL) knockout (KO) mice.
Vitamin C (VC) is a potent antioxidant and plays an essential role in collagen synthesis. As we previously reported, senescence marker protein-30 (SMP30) knockout (KO) mice cannot synthesize VC due to the genetic disruption of gluconolactonase (i.e., SMP30). Here, we utilized SMP30 KO mice deprived of VC and found that VC depletion caused pulmonary emphysema due to oxidative stress and a decrease of collagen synthesis by the third month of age. We grew SMP30 KO mice and wild-type (WT) mice on VC-free chow and either VC water [VC(+)] or plain water [VC(-)] after weaning at 4 wk of age. Morphometric findings and reactive oxygen species (ROS) in the lungs were evaluated at 3 mo of age. No VC was detected in the lungs of SMP30 KO VC(-) mice, but their ROS increased 50.9% over that of the VC(+) group. Moreover, their collagen content in the lungs markedly decreased, and their collagen I mRNA decreased 82.2% compared with that of the WT VC(-) group. In the SMP30 KO VC(-) mice, emphysema developed [21.6% increase of mean linear intercepts (MLI) and 42.7% increase of destructive index compared with VC(+) groups], and the levels of sirtuin 1 (Sirt1) decreased 16.8%. However, VC intake increased the MLI 16.2% and thiobarbituric acid reactive substances 22.2% in WT mice, suggesting that an excess of VC can generate oxidative stress and may be harmful during this period of lung development. These results suggest that VC plays an important role in lung development through affecting oxidant-antioxidant balance and collagen synthesis.
We have previously demonstrated that excessive mitochondrial reactive oxygen species caused by mutations in the SDHC subunit of Complex II resulted in premature death in C. elegans and Drosophila, tumors in mouse cells and infertility in transgenic mice. We now report the generation and initial characterization of conditional transgenic mice (Tet-mev-1) using our uniquely developed Tet-On/Off system, which equilibrates transgene expression to endogenous levels. The mice experienced mitochondrial respiratory chain dysfunction that induced reactive oxygen species overproduction. The mitochondrial oxidative stress resulted in excessive apoptosis leading to low birth weight and growth retardation in the neonatal developmental phase in Tet-mev-1 mice.
In this study, we examined whether ascorbic acid (AA) and dehydroascorbic acid (DHA), the oxidized form of AA, levels in tissues regulate the AA transporters, sodium-dependent vitamin C transporters (SVCT) 1 and SVCT2 and DHA transporters, glucose transporter (GLUT) 1, GLUT3, GLUT4 mRNA by using senescence marker protein-30 (SMP30)/gluconolactonase (GNL) knockout (KO) mice. These mice are incapable of synthesizing AA in vivo. AA depletion enhanced SVCT1 and SVCT2 mRNA expression in the liver and SVCT1 and GLUT4 mRNA expression in the small intestine, but not in the cerebrum or kidney. Next, we examined the actual impact of AA uptake by using primary cultured hepatocytes from SMP30/GNL KO mice. In the AA-depleted hepatocytes from SMP30/GNL KO mice, AA uptake was significantly greater than in matched cultures from wild-type mice. These results strongly affirm that intracellular AA is an important regulator of SVCT1 and SVCT2 expression in the liver.
Hypoglycemia is reported to be one of the manifestations of a patient with hypothalamic sarcoid infiltrates due to impaired counter-regulation of glucose. But, without hypothalamic lesion, patients with sarcoidosis would not be expected to have hypoglycemia. We recently identified a patient with an isolated sarcoidosis of the spleen who had experienced frequent fasting hypoglycemia which completely disappeared after splenectomy. During hypoglycemia, serum insulin was undetectable. Endocrinological examination revealed no abnormality. The objective was to investigate whether the patients hypoglycemia was due to ectopic secretion of an insulin-mimetic factor by the splenic sarcoidosis. Serum insulin-like growth factor-I (IGF-I) and IGF-II were measured by RIA. Serum visfatin and free IGF-I were by ELISA. A high molecular weight form of IGF-II, termed "big" IGF-II, was identified by Western blotting. Tissue IGF-I was quantified by real time RT-PCR after RNA extraction. Before operation, total and free serum IGF-I, serum IGF-II and serum visfatin were within reference range. Big IGF-II was not detected in patients serum extract. After operation, hypoglycemia did not recur and serum insulin returned to normal, while serum IGF-I decreased by half the preoperative level. RT-PCR revealed that mRNA level of IGF-I in the sarcoidosis tissue was about 1.8-fold greater than that in the normal spleen tissue. These data suggest that ectopic secretion of IGF-I by the splenic sarcoidosis and its direct access to the liver via the portal vein might cause fasting hypoglycemia mainly by suppressing hepatic gluconeogenesis.
Senescence marker protein-30 (SMP30) is an androgen-independent factor that decreases with age. We recently identified SMP30 as the lactone-hydrolyzing enzyme gluconolactonase (GNL), which is involved in vitamin C biosynthesis in animal species. To examine whether the age-related decrease in SMP30/GNL has effects on glucose homeostasis, we used SMP30/GNL knockout (KO) mice treated with L-ascorbic acid. In an ip glucose tolerance test at 15 wk of age, blood glucose levels in SMP30/GNL KO mice were significantly increased by 25% at 30 min after glucose administration compared with wild-type (WT) mice. Insulin levels in SMP30/GNL KO mice were significantly decreased by 37% at 30 min after glucose compared with WT mice. Interestingly, an insulin tolerance test showed a greater glucose-lowering effect in SMP30/GNL KO mice. High-fat diet feeding severely worsened glucose tolerance in both WT and SMP30/GNL KO mice. Morphometric analysis revealed no differences in the degree of high-fat diet-induced compensatory increase in beta-cell mass and proliferation. In the static incubation study of islets, insulin secretion in response to 20 mm glucose or KCl was significantly decreased in SMP30/GNL KO mice. On the other hand, islet ATP content at 20 mm in SMP30/GNL KO mice was similar to that in WT mice. Collectively, these data indicate that impairment of the early phase of insulin secretion due to dysfunction of the distal portion of the secretion pathway underlies glucose intolerance in SMP30/GNL KO mice. Decreased SMP30/GNL may contribute to the worsening of glucose tolerance that occurs in normal aging.
Senescence Marker Protein-30 (SMP30) is an androgen-independent factor that decreases with aging. We recently characterized SMP30 as a gluconolactonase (GNL) involved in the biosynthetic pathway of vitamin C and established that SMP30 knockout mice could not synthesize vitamin C in vivo. Although mice normally synthesize vitamin C, humans are prevented from doing so by mutations that have altered the gluconolactone oxidase gene during evolution. Even the SMP30/GNL present abundantly in the human liver does not synthesize vitamin C in vivo. To clarify the functions of this SMP30/GNL, we transfected the human SMP30/GNL gene into the human liver carcinoma cell line, Hep G2. The resulting Hep G2/SMP30 cells expressed approximately 10.9-fold more SMP30/GNL than Hep G2/pcDNA3 mock-transfected control cells. Examination of SMP30/GNLs impact on the state of oxidative stress in these cells revealed that formation of the reactive oxygen species (ROS) of mitochondrial and post-mitochondrial fractions from Hep G2/SMP30 cells decreased by a significant 24.0% and 18.1%, respectively, compared to those from Hep G2/pcDNA3 cells. Lipid peroxidation levels in Hep G2/SMP30 cells similarly decreased. Moreover, levels of the antioxidants superoxide dismutase (SOD) and glutathione (GSH) in Hep G2/SMP30 cells were a significant 42.6% and 62.4% lower than those in Hep G2/pcDNA3 cells, respectively. Thus, over-expression of SMP30/GNL in Hep G2 cells contributed to a decrease of ROS formation accompanied by decreases of lipid peroxidation, SOD activity and GSH levels.
Mice lacking manganese-superoxide dismutase (Mn-SOD) activity exhibit the typical pathology of dilated cardiomyopathy (DCM). In the present study, presymptomatic and symptomatic mutant mice were treated with the SOD/catalase mimetic, EUK-8.
Alzheimers disease (AD) is among the most common causes of progressive cognitive impairment in humans and is characterized by neurodegeneration in the brain. Lipid peroxidation is thought to play a role in the pathogenesis of AD. 4-hydroxynonenal (HNE) results from peroxidation of polyunsaturated fatty acids and it in turn gives evidence of lipid peroxidation in vivo. HNE reacts with protein histidine residue to form a stable HNE-histidine Michael adduct. To clarify the influence of lipid peroxidation on the pathogenesis of AD, we measured HNE-histidine Michael adduct in hippocampi from four AD patients and four age-matched controls by means of semiquantitative immunohistochemistry using a specific antibody to cyclic hemiacetal type of HNE-histidine Michael adduct. This antibody does not react with the ring-opened form of HNE-histidine Michael adduct and the pyrrole form of HNE-lysine Michael adduct. The HNE adduct was detected in the hippocampi of both AD and control donors, especially in the CA2, CA3 and CA4 sectors. Immunoreactive intensity of HNE adduct in these sectors were significantly higher in AD patients than in the controls. The HNE adduct was found in the perikarya of pyramidal cells in the hippocampus. These results show that the hippocampi of patients with AD undergo lipid peroxidation and imply that this activity underlies the production of cytotoxic products such as HNE that are responsible for the pathogenesis of AD.
We report the case of a 25-year-old woman with systemic lupus erythematosus. She complained of headache and left hemiparesis and was admitted to our hospital. She was in a coma after admission. Brain MRI showed no abnormalities, but brain single photon emission computed tomography showed diffuse hyperperfusion in the right frontal and temporal lobes. The calculated measured regional cerebral blood flow in the right hemisphere was increased to 40 to 55 mL/100 g/min, and that in the left was within the normal range of 25 to 35 mL/100 g/min. Two months later, the hyperperfusion was disappeared. The hyperperfusion could be explained by inflammatory changes.
Peptidylarginine deiminases (PADs)-mediated post-translational citrullination processes play key roles in protein functions and structural stability through the conversion of arginine to citrulline in the presence of excessive calcium concentrations. In brain, PAD2 is abundantly expressed and can be involved in citrullination in disease. Recently, we have reported pathological characterization of PAD2 and citrullinated proteins in scrapie-infected mice, but the implication of protein citrullination in the pathophysiology in human prion disease is not clear. In the present study, we explored the molecular and biological involvement of PAD2 and the pathogenesis of citrullinated proteins in frontal cortex of patients with sporadic Creutzfeldt-Jakob disease (sCJD). We found increased expression of PAD2 in reactive astrocytes that also contained increased levels of citrullinated proteins. In addition, PAD activity was significantly elevated in patients with sCJD compared to controls. From two-dimensional gel electrophoresis and MALDI-TOF mass analysis, we found various citrullinated candidates, including cytoskeletal and energy metabolism-associated proteins such as vimentin, glial fibrillary acidic protein, enolase, and phosphoglycerate kinase. Based on these findings, our investigations suggest that PAD2 activation and aberrant citrullinated proteins could play a role in pathogenesis and have value as a marker for the postmortem classification of neurodegenerative diseases.
Both insulin resistance and increased oxidative stress in the liver are associated with the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Senescence marker protein-30 (SMP30) was initially identified as a novel protein in the rat liver, and acts as an antioxidant and antiapoptotic protein. Our aim was to determine whether hepatic SMP30 levels are associated with the development and progression of NAFLD.
Senescence maker protein 30 (SMP30) is decreased in an androgen-independent manner in kidney and liver with age. However, regulation of SMP30 expression in the brain has not been examined in aging and neurodegenerative diseases. To investigate SMP30 expression in the brain, we utilized aging and kainate (KA)-induced neurodegenerative disease models. Interestingly, expression of SMP30 was unlikely to decrease in the aged brain, but total levels of SMP30 protein were increased at 4 weeks after KA injury. Increased glial fibrillary acidic protein (GFAP) with elevated SMP30 expression was observed at the same time post-KA, indicating that regulation of SMP30 expression in the brain may be associated with astrocytosis. We confirmed that KA induced GFAP expression with increased SMP30 in rat astrocyte cells. Moreover, we found that ERK1/2 activation was involved in the up-regulation of SMP30 in astrocytes. Our results suggest that elevated SMP30 in activated astrocytes plays an important supportive role after brain damage.
Ascorbic acid (AA) is essential for collagen biosynthesis as a cofactor for prolyl and lysyl hydroxylase and as a stimulus for collagen gene expression. Many studies have evaluated the relationship between AA and collagen expression in short- and long-term effects on cells after a single administration of AA into the culture medium. However, no such study has monitored in detail the stability of AA in medium or the alterations of intracellular AA levels during a protracted interval. Therefore, we examined here intracellular AA levels and stability throughout its exposure to human skin fibroblasts in vitro. Moreover, we determined the effects on type 1 and type 4 collagen and sodium-dependent vitamin C transporter (SVCT) gene expression when medium containing 100 ?M AA was replaced every 24h for 5 days to avoid depletion of AA. Throughout this long-term culture, intracellular AA levels remained constant; the expression of type 1 and type 4 collagens and SVCT2 mRNA was enhanced, and type 1 procollagen synthesis increased. Thus, these results indicate that human skin fibroblasts exposed to AA over time had rising levels of type 1/type 4 collagens and SVCT2 mRNA expression and type 1 procollagen synthesis.
The post-translational citrullination (deimination) process is mediated by peptidylarginine deiminases (PADs), which convert peptidylarginine into peptidylcitrulline in the presence of high calcium concentrations. Over the past decade, PADs and protein citrullination have been commonly implicated as abnormal pathological features in neurodegeneration and inflammatory responses associated with diseases such as multiple sclerosis, Alzheimer disease and rheumatoid arthritis. Based on this evidence, we investigated the roles of PADs and citrullination in the pathogenesis of prion diseases. Prion diseases (also known as transmissible spongiform encephalopathies) are fatal neurodegenerative diseases that are pathologically well characterized as the accumulation of disease-associated misfolded prion proteins, spongiform changes, glial cell activation and neuronal loss. We previously demonstrated that the upregulation of PAD2, mainly found in reactive astrocytes of infected brains, leads to excessive citrullination, which is correlated with disease progression. Further, we demonstrated that various cytoskeletal and energy metabolism-associated proteins are particularly vulnerable to citrullination. Our recent in vivo and in vitro studies elicited altered functions of enolase as the result of citrullination; these altered functions included reduced enzyme activity, increased protease sensitivity and enhanced plasminogen-binding affinity. These findings suggest that PAD2 and citrullinated proteins may play a key role in the brain pathology of prion diseases. By extension, we believe that abnormal increases in protein citrullination may be strong evidence of neurodegeneration.
The peptidylarginine deiminase 4 (PAD4) gene and PAD4 autoantibodies have been associated with rheumatoid arthritis (RA) and its pathogenesis. Therefore, methods for accurately determining their levels in the peripheral blood of these patients would be a diagnostic asset. The objective of our study was to adapt the enzyme-linked immunosorbent assay (ELISA) method for evaluating PAD4 levels in human blood.
Myositis ossificans traumatica (MOT) is a disease in which muscular ossification develops following trauma. Almost all cases of MOT are found in skeletal muscle. The authors report in a 39-year-old man MOT involving several muscles in the head and neck, namely, bilateral masseter muscles, the left temporal muscle, the left lateral pterygoid muscle, and the left frontal muscle. Involvement of the lateral pterygoid muscle is especially rare.
Several new amyloid-? (A?) aggregation inhibitors were synthesized according to our theory that a hydrophilic moiety could be attached to the A?-recognition unit for the purpose of preventing amyloid plaque formation. A distyrylbenzene-derivative, DSB(EEX)(3), which consider the A? recognition unit (DSB, 1,4-distyrylbenzene) and expected to bind to amyloid fibrils (?-sheet structure), was combined with the hydrophilic aggregation disrupting element (EEX) (E, Glu; X, 2-(2-(2-aminoethoxy)ethoxy)acetic acid). This DSB(EEX)(3) compound, compared to several others synthesized similarly, was found to be the most active for reducing A? toxicity toward IMR-32 human neuroblastoma cells. Moreover, its inhibition of A?-aggregation or fibril formation was directly confirmed by transmission electron microscopy and atomic force microscopy. These results suggest that the A? aggregation inhibitor DSB(EEX)(3) disrupts clumps of A? protein and is a likely candidate for drug development to treat Alzheimers disease.
Catecholamines, which are physiologically important neurotransmitters and hormones, apparently decrease in the brain and plasma as some species age. Because this observation has engendered controversy, we used mice to investigate whether age-related changes occur in adrenal catecholamine levels and in the expression of catecholamine synthetic enzymes.
Adrenomedullin (AM) is a hypotension-causing peptide that was originally isolated from human pheochromocytoma cells, and it has been found to be expressed in various organs, including the liver. As the individual physiological and pathophysiological properties of AM peptide in the liver during endotoxemia in vivo has not yet been examined, we investigated this in experimental endotoxemia using heterozygote AM-deficient (AM(+/-)) mice. The AM concentration of AM(+/-) mice was significantly lesser than that of wild-type (WT) mice in lipopolysaccharide (LPS)-induced endotoxemia. After administering LPS, the survival rate for AM(+/-) mice was significantly lower than that for WT mice. Also, expressions of IL-1? mRNA, and TNF-? mRNA, and NF-?B p65 in the liver were markedly increased and serum ALT greatly elevated in comparison with WT mice. However, supplementation of exogenous AM reversed the deteriorations in mortality and inflammatory responses. Therefore, we conclude that AM plays an important role in regulating systemic inflammation and may be an important intrinsic factor for protecting against liver damage in LPS-induced endotoxemia.
Here we quantified ascorbic acid (AA) levels in 14 tissues, plasma and urine of C57BL/6 male mice to track its turnover during 3 to 30 mo of aging. The AA content of adrenal glands and testes decreased somewhat with age, and eventually rose, but increased in the spleen, lungs, eyes and heart. AA levels rose in the liver, skin and skeletal muscles from 6 to 12 mo of age, but declined from 12 to 24 mo. In the cerebellum, cerebrum, small intestine, kidney and plasma, amounts of AA remained almost constant as the animals aged. Most notably, urinary AA decreased markedly until becoming almost undetectable at 24 and 30 mo of age. Collectively, these results, which compare changes in AA levels in specific physiologic targets throughout the aging process, strongly suggest that the AA synthesizing capacity declines over time to become a major factor in senescence-related diseases.
Here we quantified the uric acid (UA) levels in 11 tissues and plasma of C57BL/6 male mice to track its turnover during 3 to 30 months of aging. UA levels in the adrenal glands, heart, and spleen increased with aging until 30 months of age. Similarly, UA levels in the liver, kidneys, pancreas, and testes increased until the mice were 24 months old. UA levels also rose in the lungs and skeletal muscles from 3 to 6 months and 6 to 12 months, respectively, and then remained at almost the same levels until 30 months of age. In the skin, UA decreased from 3 to 6 months and then stayed nearly constant until 30 months of age. Moreover, the small intestines and plasma had quite stable UA levels during aging. Thus, our assessment of 11 tissue types from mice showed that the UA levels increased in most tissues during aging.
The citrullination of enolase by PAD (peptidylarginine deiminase) has emerged as an important post-translational modification in human disorders; however, the physiological function of citrullination remains unknown. In the present study, we report that citrullination diversely regulates the biological functions of ENO1 (?-enolase) and NSE (neuron-specific enolase). We developed three mouse IgG1 monoclonal antibodies with specificity to the following: (i) citrullination of Arg9 of ENO1 [ENO1Cit9; anti-CE1 (citrullinated enolase 1) antibody]; (ii) citrullination of Arg9 in ENO1 and NSE (ENO1Cit9/NSECit9; anti-CE1/2 antibody); and (iii) citrullination of Arg429 of NSE (NSECit429; anti-CE2 antibody). Regardless of the total protein expression level, the levels of ENO1Cit9 and NSECit429 were elevated, and their immunoreactivities were also increased in cortical neuronal cells or around blood vessels in the frontal cortex of patients with sporadic Creutzfeldt-Jakob disease and Alzheimers disease compared with controls. In a time- and dose-dependent manner, PAD negatively regulated enolase activity via citrullination, and enolase in diseased patients was more inactive than in controls. Interestingly, the citrullination of enolase effectively promoted its proteolytic degradation by Ca2+-dependent calpain-1, and leupeptin (calpain inhibitor I) abrogated this degradation. Surprisingly, using an affinity assay, the citrullination of enolase enhanced its plasminogen-binding affinity, which was blocked by the lysine analogue ?-aminocaproic acid. These findings suggest that PAD-mediated citrullination regulates the diverse physiological activities of enolase and that CE may be a candidate diagnostic/prognostic factor for degenerative diseases.
This study investigated the effect of 3,4-diaminopyridine (3,4-DAP), a potent potentiator of transmitter release, on neuromuscular transmission in vivo in a mouse model of myasthenia gravis (MG) caused by antibodies against muscle-specific kinase (MuSK; MuSK-MG) and ex vivo in diaphragm muscle from these mice. 3,4-DAP significantly improved neuromuscular transmission, predominantly by increasing acetylcholine (ACh) release, supporting presynaptic potentiation as an effective treatment strategy for MuSK-MG patients who have defective transmitter release. In MuSK-MG, we suggest that only low-dose acetylcholinesterase (AChE) inhibitors be used to avoid side effects, and we propose that 3,4-DAP may be effective as a symptomatic therapy.
Muscle-specific kinase (MuSK), a receptor tyrosine kinase, is required for the formation and maintenance of neuromuscular junctions (NMJs). Although autoantibodies against MuSK have been demonstrated to cause myasthenia gravis (MG), the underlying pathogenic mechanism remains unclear because a major subclass of these antibodies is functionally monovalent. We investigated the pathogenic role of MuSK antibodies in the onset of MG in vivo and in vitro. Ultrastructural visualization of NMJs in paretic rabbits with MuSK antibodies indicated that postsynaptic membranes were preserved, despite a significant loss of complexity in the convoluted synaptic folds. In addition, an in vitro assay indicated that both divalent and monovalent antibodies from paretic rabbits could interfere with agrin-induced acetylcholine receptor (AChR) clustering in cultured myotubes. Furthermore, in the absence of agrin, divalent antibodies induced MuSK phosphorylation and accelerated downregulation of Dok-7, an essential intracellular MuSK binding protein, while monovalent antibodies inhibited agrin-induced phosphorylation of MuSK, thus demonstrating distinct molecular mechanisms underlying the MuSK dysfunction induced by these two types of antibodies. Taken together, these findings suggest that complement activation is not necessary for the MG onset and that both divalent and monovalent antibodies may cause MG in vivo by inducing MuSK dysfunction.
Although cisplatin is indispensable for the chemotherapy treatment of many malignancies, cisplatin-associated thrombosis is attracting increasing attention. However, experience of primary percutaneous coronary intervention (PCI) and intravascular ultrasound imaging (IVUS) for coronary thrombosis, possibly due to cisplatin-based chemotherapy, has been limited. Case 1 with postoperative gastric cancer developed acute myocardial infarction (AMI) on the sixth day of the second chemotherapy course with conventional doses of cisplatin and tegafur gimeracil oteracil potassium. Emergency coronary angiography (CAG) showed a filling defect in the proximal left anterior descending coronary artery (LAD) concomitant with no reflow in the distal LAD. Case 2 with advanced lung cancer and brain metastasis suffered AMI on the fifth day of the first chemotherapy course with conventional doses of cisplatin and gemcitabine. Emergency CAG delineated a total occlusion in the proximal right coronary artery. In both cases, thrombectomy using aspiration catheter alone obtained optimal angiographic results and subsequent IVUS revealed no definite atherosclerotic plaque, while slow flow still remained even after selective intra-coronary infusion of vasodilator in the case 1. These cases suggest that primary PCI using thrombus-aspiration catheter might be safe and effective for coronary thrombosis due to cisplatin-based chemotherapy.
Rationale: Vitamin C (VC) is a potent antioxidant and essential for collagen synthesis. Objectives: We investigated whether VC-treatment prevents and cures smoke-induced emphysema in senescence marker protein-30 knockout (SMP30-KO) mice, which cannot synthesize VC. Methods: Two smoke-exposure experiments using SMP30-KO were conducted. In the first one (a preventive study), four-month-old mice were received minimal VC (0.0375 g/L) [VC(L)] or physiologically sufficient VC (1.5 g/L) [VC(S)], then were exposed to cigarette smoke or smoke-free air for 2 months. Pulmonary evaluations followed when the mice were 6-months of age. The second, study began after the establishment of smoke-induced emphysema (a treatment study). These mice no longer underwent smoke exposure but received VC(S) or VC(L) treatment for 2 months. Morphometric analysis and measurements of oxidative stress, collagen synthesis, and vascular endothelial growth factor (VEGF) in the lungs were evaluated. Measurements and Main Results: Chronic smoke exposure caused emphysema [29.6% increases of mean linear intercepts (MLI) and 106.5% increases of destructive index (DI) compared with the air-only group] in 6-month-old SMP30-KO mice and this emphysema closely resembled human COPD. Furthermore, smoke-induced emphysema persisted in the VC(L) group after smoking cessation, whereas VC-treatment provided pulmonary restoration [18.5% decrease of MLI and 41.3% decrease of DI compared with VC(L) group]. VC-treatment diminished oxidative stress, increased collagen synthesis, and improved VEGF levels in the lungs. Conclusions: Our results suggest that VC not only prevents smoke-induced emphysema in SMP30-KO mice but also restores emphysematous lungs. Therefore, VC may provide a new therapeutic strategy for treating COPD in humans.
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