ET-1-induced growth promoting responses involving ERK1/2 and PKB signaling and Egr-1 expression are mediated by Ca2+/CaM-dependent protein kinase-II in vascular smooth muscle cells.
Endothelin-1 (ET-1), a potent vasoactive peptide with a pathogenic role in vascular diseases, has been shown to induce the activation of ERK1/2, PKB and the expression of a transcriptional regulator, the early growth response 1 (Egr-1), key mediators of hypertrophic and proliferative responses in vascular smooth muscle cells (VSMC). We have demonstrated earlier that ET-1 requires H2O2 generation to activate these signaling pathways and Ca2+, calmodulin (CaM) and Ca2+/CaM-dependent protein kinase II (CaMKII), play a critical role to trigger H2O2-induced effects in VSMC. However, an involvement of CaMKII in mediating ET-1-induced responses in VSMC remains unknown. Therefore, by utilizing pharmacological inhibitors of CaM, CaMKII, a CaMKII inhibitor peptide and CaMKII knockdown techniques, we have investigated the contribution of CaM and CaMKII in ET-1-induced ERK1/2 and PKB signaling, Egr-1 expression and hypertrophic and proliferative responses in VSMC. W-7 and calmidazolium, antagonists of CaM, as well as KN-93, an inhibitor of CaMKII activity, attenuated ET-1-induced ERK1/2 and PKB phosphorylation. In addition, transfection of VSMC with a CaMKII inhibitory peptide suppressed ET-1-evoked ERK1/2 and PKB phosphorylation. Similarly, siRNA-mediated CaMKII silencing reduced ET-1-produced ERK1/2 and PKB phosphorylation. CaM and CaMKII blockade also significantly lowered the ET-1-induced protein and DNA synthesis as well as Egr-1 expression. These findings demonstrate that CaMKII plays a critical role in ET-1-induced growth promoting signaling pathways as well as hypertrophic and proliferative responses in VSMC.
Laboratory of Cell Signaling, Montreal Diabetes Research Centre, Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM) - Technôpole Angus, Montréal, Québec, Canada; Department of Physiology, University of Montreal, Montreal, Quebec, Canada.
Ali
A
Bouallegue
Estelle R
ER
Simo Cheyou
Madhu B
MB
Anand-Srivastava
Ashok K
AK
Srivastava
D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D051766:Early Growth Response Protein 1 / Q000378:metabolism; D019332:Endothelin-1 / Q000494:pharmacology*; D051418:Focal Adhesion Kinase 2 / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects
D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D019332:Endothelin-1; D034741:RNA, Small Interfering; D051418:Focal Adhesion Kinase 2; D051057:Proto-Oncogene Proteins c-akt; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3
CaMKII; ERK1/2; Egr-1; Endothelin; PKB; VSMC