Translate this page to:
Hindi
In JoVE (1)
Other Publications (6)
Automatic Translation
This translation into Hindi was automatically generated.
English Version | Other Languages
Articles by Marcin P. Iwanicki in JoVE
JoVE Clinical and Translational Medicine
इन विट्रो mesothelial क्लीयरेंस परख कि डिम्बग्रंथि के कैंसर मेटास्टेसिस के प्रारंभिक चरण मॉडल
Department of Cell Biology, Harvard Medical School
mesothelial निकासी परख यहाँ वर्णित fluorescently लेबल कोशिकाओं और समय चूक वीडियो माइक्रोस्कोपी के लिए कल्पना और मात्रात्मक डिम्बग्रंथि के कैंसर के multicellular spheroids और mesothelial सेल monolayers की बातचीत को मापने का लाभ लेता है. इस परख डिम्बग्रंथि के कैंसर मेटास्टेसिस के प्रारंभिक चरणों मॉडल.
Other articles by Marcin P. Iwanicki on PubMed
RACK1 Targets the Extracellular Signal-regulated Kinase/mitogen-activated Protein Kinase Pathway to Link Integrin Engagement with Focal Adhesion Disassembly and Cell Motility
The extracellular signal-regulated kinase (ERK) cascade is activated in response to a multitude of extracellular signals and converts these signals into a variety of specific biological responses, including cell differentiation, cell movement, cell division, and apoptosis. The specificity of the biological response is likely to be controlled in large measure by the localization of signaling, thus enabling ERK activity to be directed towards specific targets. Here we show that the RACK1 scaffold protein functions specifically in integrin-mediated activation of the mitogen-activated protein kinase/ERK cascade and targets active ERK to focal adhesions. We found that RACK1 associated with the core kinases of the ERK pathway, Raf, MEK, and ERK, and that attenuation of RACK1 expression resulted in a decrease in ERK activity in response to adhesion but not in response to growth factors. RACK1 silencing also caused a reduction of active ERK in focal adhesions, an increase in focal adhesion length, a decreased rate of focal adhesion disassembly, and decreased motility. Our data further suggest that focal adhesion kinase is an upstream activator of the RACK1/ERK pathway. We suggest that RACK1 tethers the ERK pathway core kinases and channels signals from upstream activation by integrins to downstream targets at focal adhesions.
FAK, PDZ-RhoGEF and ROCKII Cooperate to Regulate Adhesion Movement and Trailing-edge Retraction in Fibroblasts
A key step in cell migration is the dynamic formation and disassembly of adhesions at the front and the concomitant movement and release of adhesions in the rear of the cell. Fibroblasts maintained in the absence of serum have stable adhesions within the rear of the cell and exhibit reduced trailing-edge retraction resulting in an elongated cell phenotype. Addition of lysophosphatidic acid (LPA) induced the movement of adhesions and retraction of the trailing edge, thus mimicking tail retraction in a migrating cell. Focal adhesion kinase (FAK), guanine nucleotide exchange factors (GEF) for Rho and the Rho effector Rho kinase II (ROCKII) are crucial for the regulation of adhesion movement and trailing-edge retraction. Downregulation of FAK by small interfering RNAs or small hairpin RNAs blocked LPA-induced adhesion movement and restoration of cell shape. This phenotype was rescued by the ectopic expression of PDZ-RhoGEF or a RhoA-effector-domain mutant that activates ROCK. Knockdown of PDZ-RhoGEF or ROCKII inhibited LPA-induced trailing-edge retraction and adhesion movement. Moreover, overexpressed PDZ-RhoGEF co-immunoprecipitated with FAK and localized to FAK-containing adhesions. These studies support a model in which FAK and PDZ-RhoGEF cooperate to induce Rho/ROCKII-dependent focal adhesion movement and trailing-edge retraction in response to LPA.
Extracellular Signal-regulated Kinase 2 (ERK2) Phosphorylation Sites and Docking Domain on the Nuclear Pore Complex Protein Tpr Cooperatively Regulate ERK2-Tpr Interaction
Identifying direct substrates of mitogen-activated protein kinases (MAPKs) and understanding how those substrates are selected is central to understanding how these ubiquitously activated enzymes generate diverse biological responses. In previous work, we identified several new candidate substrates for the MAPK ERK2 (extracellular signal-regulated kinase 2), including the nuclear pore complex protein Tpr (translocated promoter region). In this report, we identify sites on Tpr for ERK2 phosphorylation and binding and demonstrate their functional interaction. ERK2 phosphorylation and dimerization are necessary for ERK2-Tpr binding, and this occurs through a DEF (docking site for ERK2, FXF) domain on Tpr. Surprisingly, the DEF domain and the phosphorylation sites displayed positive cooperativity to promote ERK2 binding to Tpr, in contrast to substrates where phosphorylation reduces binding. Ectopic expression or depletion of Tpr resulted in decreased movement of activated ERK2 from the cytoplasm to the nucleus, implying a role for Tpr in ERK2 translocation. Collectively, the data provide direct evidence that a component of the nuclear pore complex is a bona fide substrate of ERK2 in vivo and that activated ERK2 stably associates with this substrate after phosphorylation, where it could play a continuing role in nuclear pore function. We propose that Tpr is both a substrate and a scaffold for activated ERKs.
Transcriptional Regulation of Metastatic [Id]entity by KLF17
A novel in vivo screening approach has identified KLF17 as a key metastasis suppressor gene that acts through regulation of Id1 transcription factor-dependent induction of the epithelial-to-mesenchymal transition.
Mutant P53 Drives Invasion by Promoting Integrin Recycling
p53 is a tumor suppressor protein whose function is frequently lost in cancers through missense mutations within the Tp53 gene. This results in the expression of point-mutated p53 proteins that have both lost wild-type tumor suppressor activity and show gain of functions that contribute to transformation and metastasis. Here, we show that mutant p53 expression can promote invasion, loss of directionality of migration, and metastatic behavior. These activities of p53 reflect enhanced integrin and epidermal growth factor receptor (EGFR) trafficking, which depends on Rab-coupling protein (RCP) and results in constitutive activation of EGFR/integrin signaling. We provide evidence that mutant p53 promotes cell invasion via the inhibition of TAp63, and simultaneous loss of p53 and TAp63 recapitulates the phenotype of mutant p53 in cells. These findings open the possibility that blocking alpha5/beta1-integrin and/or the EGF receptor will have therapeutic benefit in mutant p53-expressing cancers.
Ovarian Cancer Spheroids Use Myosin-generated Force to Clear the Mesothelium
Dissemination of ovarian tumors involves the implantation of cancer spheroids into the mesothelial monolayer on the walls of peritoneal and pleural cavity organs. Biopsies of tumors attached to peritoneal organs show that mesothelial cells are not present under tumor masses. We have developed a live, image-based in vitro model in which interactions between tumor spheroids and mesothelial cells can be monitored in real time to provide spatial and temporal understanding of mesothelial clearance. Here we provide evidence that ovarian cancer spheroids utilize integrin - and talin - dependent activation of myosin and traction force to promote mesothelial cells displacement from underneath a tumor cell spheroid. These results suggest that ovarian tumor cell clusters gain access to the sub-mesothelial environment by exerting force on the mesothelial cells lining target organs, driving migration and clearance of the mesothelial cells.
