Endothelin-1 Induced Phosphorylation of Caveolin-1 and Smad2C inHuman Vascular Smooth Muscle Cells: Role of NADPH Oxidases, c-Abl,and Caveolae Integrity in TGF-β Receptor Transactivation

Caveolin-1(cav-1) is one of the most important components of caveolae in the cell membrane,which plays an important role in cell signaling transduction, such as egfr and tgf-β receptortransactivation. the purpose of this study was to evaluate the effect of c-abl and nad(p)hoxidases (nox) on phosphorylation of cav-1 and consequently their effect on phosphorylationof smad2c induced by endothelin-1 in human vascular smooth muscle cells (vsmcs). in thisstudy, all experiments were performed using human vsmcs. the phosphorylation level of thecaveolin-1 and smad2c proteins were assessed by western blotting using phospho-caveolin-1(tyr14) antibody and phospho-smad2 (ser465/467) antibody. the data were reported as mean ±sem. the vsmcs treated with endothelin-1(et-1) (100 nanomolar (nmol)) demonstrated a timedependent increase in the pcav-1 level (p<0.05). the inhibitors of nox (diphenyleneiodonium)(p<0.05), cholesterol depleting agent (beta-cyclodextrin) (p<0.05) and c-abl inhibitor (pp1)(p<0.01) were able to reduce the level of the phospho-cav-1 and phospho-smad2c induced byet-1 (p<0.05). our results proposed that caveolae structure, nox, c-abl played an important rolein the phosphorylation of cav-1 induced by et-1 in the human vsmcs. furthermore, ourfindings showed that phosphocav-1 involved in tgfr transactivation. thus, et-1 via atransactivation-dependent mechanism can cause phosphorylation of smad2c.