The Involvement Of P38 Mitogen-activated Protein Kinase In Vascular Smooth Muscle Cells Proliferation In SHR

Objective: To investigate the role of P38 mitogen-activated protein kinase(P38MAPK) pathway in the proliferation of SHR vascular smooth muscle cellsinduced by angiotensin II(AngII) and platelet-derived growth factor-BB(PDGF-BB).Methods: VSMC were obtained from SHR thoracic aorta. DNA synthesis wasquatified through measuring [³H]-thymidine incorporation. WST-1 was used toestimate the proliferation activity of VSMC. The P38MAPK activity was evaluated byimmunobloting technique with phospho-P38MAPK antibody and the translocation ofphospho-P38MAPK from cytoplasm to nuclear was confirmed byimmunocytochemistry with the specific antibody.Results:1.AngII increased the phosphorylation of P38MAPK in VSMC. The phosphorylationof P38MAPK stimulated by AngII peaked at 5 min .Within a certain concentrationcoverage, AngII(10^-8-10^-6mol/L) increased P38MAPK activity of VSMC in adose-dependent manner. Compared with control, the phosphorylation of P38MAPKinduced by 10^-8 , 10^-7 , 10^-6mol/L AngII increased by 80% , 193.4% ,261.2%(P<0.01),respectively.AngII(10^-8-10^-6mol/L) increased the proliferationactivity ([³H]-TdR incorporation and WST-1) of VSMC with markedly statisticsdifference(P<0.05 or P<0.01) compared with control.2. PDGF increased the phosphorylation of P38MAPK in VSMC. The phosphorylationof P38MAPK stimulated by PDGF reached maximum level at 15 min. Within acertain concentration range, PDGF(3-30ng/ml) increased P38MAPK activity ofVSMC in a dose-dependent manner. Compared with control, the phosphorylation ofP38MAPK induced by 3,10,30ng/ml PDGF increased by 27.3%,205.82%,323.29%(P<0.05),respectively.PDGF(3-30ng/ml) increased the proliferation activity([3H]-TdRincorporation and WST-1)of VSMC with dramatically statistics difference(P<0.05 orP<0.01) compared with control. 3.SB202190(10-9-10-7mol/L), a selective antagonist of P38MAPK, blocked theP38MAPK activity and decreased the proliferation of VSMC stimulated byAngII(10-7mol/L) or PDGF(10ng/ml) in a dose-dependent manner, compared withAngII group or PDGF group, respectively (P<0.05 or P<0.01). 4.The Phospho-P38MAPK increased dramaticlly in cytoplasm at 2 min, thentranslocated to nucleus at 5 min and finally disappeared from the nucleus at 1h afterthe stimulation of AngII. The translocation process of Phospho-P38MAPK wasblocked distinctly by SB202190. 5.The Phospho-P38MAPK increased greatly in cytoplasm at 5 min, thentranslocated to nucleus at 15 min and finally disappeared from the nucleus at 1h afterthe stimulation of PDGF. The translocation process of Phospho-P38MAPK wasblocked distinctly by SB202190.Conclusion: 1.AngII and PDGF stimulated cell proliferation of VSMC in SHR. 2. AngII and PDGF induced the phosphorylation of P38MAPK and translocation tonucleus in SHR VSMC. 3. P38MAPK phosphorylation and translocation to nucleus might cause VSMCproliferation. 4. P38MAPK might be involved in cell proliferation of VSMC induced by AngIIand PDGF.