Regulation Of Mitogen-Activated Protein Kinase On Cyclin-Dependent Kinase Inhibitor In Vascular Smooth Muscle Cell Proliferation

Regulation Of Mitogen-Activated Protein Kinase On Cyclin-Dependent Kinase Inhibitor In Vascular Smooth Muscle Cell Proliferafion ABSTRACT Proliferation of Vascular smooth muscle cells play a critical role in development of many vascular diseases. Progression of cell cycle depends on interaction between cyclin- cyclin dependent kinase complex (Cyclin-CDK) and cyclin dependent kinase inhibitor (CKI). Our previous study has showed that there were different changes of CKIs in vascular smooth muscle cells stimulated by PDGF and angiotensin II and suggested p27 is a key factor in transduction pathway of vascular smooth muscle cells proliferation. The purpose of this study was to elucidate the effects of MAPK and PKC pathway on regulation of vascular smooth muscle cells proliferation and p27 protein expresion. MAPK inhibitor(PD98059), PLC inhibitor (neomycin) and PKC receptor activator (PMA) were used. The role of MAPK on proliferation and hypertrophy of vascular smooth muscle cells stimulated by PDGF and angiotensin H and the regulation of MAPK on CM were evaluated by immunoprecipitation test, Western blot and DNA chip. The results have showed that 甅APK activity was 5.66 fold higher after PDGF stimulated in vascular smooth muscle cells compare with control group and 2.35 fold higher compare with angiotensin II group. The proliferation of vascular smooth muscle cells was significant by PDGF stimulated up to 24 hours (1.43 fold higher compare with control group) and expression of p11 protein was reduced to 71% compare with control group.Ilowever,p21 and p57 proteins were increased in VSMC after PDGF stimulation. After co-treatment of PD98059 plus PDGF or neomycin plus PDGF, the MAPK -6- activity was reduced 46% and 37%, respectively. The expression of p27 protein was 1.77 fold andl.49 fold higher compare with PDGF group, respectively. Proliferation of vascular smooth muscle cells was reduced to 68% and 65% compare with PDGF group, respectively. 甅APK activity was only enhanced 2.38 fold higher by angiotensin II, but the expression of p27 protein was not inhibited. Proliferation of vascular smooth muscle cells was not observed .甌he expression of p27 protein was slightly inhibited with co-treatment of PMA and angiotensin II, but the proliferation of vascular smooth muscle cells was not detected. Conclusions:MAPK pathway is a important signalling pathway of extracellular proliferation signal conducting to nucleus in VSMC. The increased range of p44/42 activity is a key factor regulating of CKI levels and regulating VSMC proliferation.