RhoA activation in mesangial cells by mechanical strain depends on caveolae and caveolin-1 interaction.

@article{citeulike:1136644, abstract = {Increased intraglomerular pressure is an important hemodynamic determinant of glomerulosclerosis and can be modeled in vitro by exposing mesangial cells to cyclic mechanical strain. A previous study showed that RhoA mediates strain-induced production of fibronectin; herein is investigated the role of caveolae in RhoA activation. Cyclodextrin and filipin, agents that disrupt caveolae, abrogated strain-induced RhoA activation in mesangial cells. Caveolin-1 (cav-1), the defining protein of caveolae, was Y14 phosphorylated by strain, and this was inhibited by PP1, showing Src dependence. Strain also induced c-SrcY416 phosphorylation and hence activation. Strain increased RhoA association with cav-1, which was blocked by PP1. Cyclodextrin and filipin inhibited the strain-induced RhoA/cav-1 association, indicating dependence on caveolar structural integrity. Restoration of caveolae by coincubation of cyclodextrin with cholesterol rescued both RhoA activation and RhoA/cav-1 association in response to strain. Sucrose gradient detected a significant portion of RhoA in caveolae, with Src located exclusively in these domains. Finally, in cells that were infected with retrovirus that encodes the nonphosphorylatable cav-1 Y14A, RhoA/cav-1 association, RhoA activation, and fibronectin secretion in response to strain were abrogated. It is concluded that strain-induced RhoA activation depends on the integrity of caveolae and on physical association of cav-1 and RhoA. The phosphorylation of cav-1 at Y14 by Src kinases is required for this to occur. These studies define a novel function for cav-1 and caveolae as positive effectors of RhoA activation. Targeting caveolae thus may provide a new therapeutic option for glomerular sclerosis that is associated with elevated intraglomerular pressure.}, address = {Division of Nephrology, McMaster University, Ontario, Canada.}, author = {Peng, F. and Wu, D. and Ingram, A. J. and Zhang, B. and Gao, B. and Krepinsky, J. C. }, citeulike-article-id = {1136644}, doi = {http://dx.doi.org/10.1681/ASN.2006050498}, issn = {1046-6673}, journal = {J Am Soc Nephrol}, month = {January}, number = {1}, pages = {189--198}, posted-at = {2007-10-23 10:15:14}, priority = {2}, title = {RhoA activation in mesangial cells by mechanical strain depends on caveolae and caveolin-1 interaction.}, url = {http://dx.doi.org/10.1681/ASN.2006050498}, volume = {18}, year = {2007} }

TY - JOUR ID - citeulike:1136644 L3 - citeulike-article-id:1136644 TI - RhoA activation in mesangial cells by mechanical strain depends on caveolae and caveolin-1 interaction. JF - J Am Soc Nephrol VL - 18 IS - 1 SP - 189 EP - 198 AD - Division of Nephrology, McMaster University, Ontario, Canada. SN - 1046-6673 N2 - Increased intraglomerular pressure is an important hemodynamic determinant of glomerulosclerosis and can be modeled in vitro by exposing mesangial cells to cyclic mechanical strain. A previous study showed that RhoA mediates strain-induced production of fibronectin; herein is investigated the role of caveolae in RhoA activation. Cyclodextrin and filipin, agents that disrupt caveolae, abrogated strain-induced RhoA activation in mesangial cells. Caveolin-1 (cav-1), the defining protein of caveolae, was Y14 phosphorylated by strain, and this was inhibited by PP1, showing Src dependence. Strain also induced c-SrcY416 phosphorylation and hence activation. Strain increased RhoA association with cav-1, which was blocked by PP1. Cyclodextrin and filipin inhibited the strain-induced RhoA/cav-1 association, indicating dependence on caveolar structural integrity. Restoration of caveolae by coincubation of cyclodextrin with cholesterol rescued both RhoA activation and RhoA/cav-1 association in response to strain. Sucrose gradient detected a significant portion of RhoA in caveolae, with Src located exclusively in these domains. Finally, in cells that were infected with retrovirus that encodes the nonphosphorylatable cav-1 Y14A, RhoA/cav-1 association, RhoA activation, and fibronectin secretion in response to strain were abrogated. It is concluded that strain-induced RhoA activation depends on the integrity of caveolae and on physical association of cav-1 and RhoA. The phosphorylation of cav-1 at Y14 by Src kinases is required for this to occur. These studies define a novel function for cav-1 and caveolae as positive effectors of RhoA activation. Targeting caveolae thus may provide a new therapeutic option for glomerular sclerosis that is associated with elevated intraglomerular pressure. AU - Peng, F AU - Wu, D AU - Ingram, AJ AU - Zhang, B AU - Gao, B AU - Krepinsky, JC PY - 2007/01// UR - http://dx.doi.org/10.1681/ASN.2006050498 ER -