Effect Of Smad Protein In Extracellular Signal Regulated Kinase (ERK) Signal Transduct Pathway And On The Proliferation Of Vascular Smooth Muscle Cell

The proliferation and hypertrophy of vascular smooth muscle cell(VSMC) is the common cell pathologic bases of many vascular proliferation disease such as hypertension and atherosclerosis.It has been demonstrated that G protein couple receptor pathway,receptor tyrosine protein kinase pathway,integrin pathway and TGF-? /Smad pathway are very important in the proliferation and hypertrophy process of VSMC.In addition,there are many other pathway which have been known or not,they have interactive regulation on many level and construct complex network of signal transducion in cell,to regulate many cell biological actions.We have known that ERK pathway and TGF-? /Smad pathway have cross-talking in many cells,they conduct some biological action of this cells. Both of the two pathway can stimulate the proliferation of VSMC.But we do not know whether the two pathway have cross-talking in VSMC and they would have interactive regulation on which links and its concrete molecular mechanism.In this experiment,human umbilical artery smooth muscle cells(hUASMC) were primary cultured in vitro and used between passages 3~15,the hUASMC were divided into four groups:(1)control group,(2)PDGF group,(3)ERK blocking agentgroup(PD98059),(4) PDGF+ERK blocking agent group.After cultured 24h,the proliferation of hUASMC were detected by MTT method;the expression of PCNA,phosphorylated ERK(p-ERK) and phosphorylated Smad2/3(p-Smad2/3) protein were detected by immunohistochemistry and the expression of Smad2/3 mRNA were detected by reverse transcription-polymerase chain reaction(RT-PCR).Results:(1)Compared with control group, the expression of PCNA and A value of MTT method in hUASMC of PDGF group increased obviously(P<0.01),and the expression of PCNA and A value of MTT method in hUASMC of ERK blocking agent group and PDGF +ERK blocking agent group was decreased than that of PDGF group,and was similar with control group.(2)Compared with control group, the expression of p-ERK in hUASMC of PDGF group increased obviously,and the expression of phosphorylated ERK protein in hUASMC of ERK blocking agent group and PDGF+ERK blocking agent group was decreased than that of PDGF group;(3)Compared with control group,the expression of phosphorylated Smad2/3 protein in hUASMC of PDGF group increased obviously(P<0.01),and the expression of phosphorylated Smad2/3 protein in hUASMC of ERK bolcking agent group and PDGF + ERK blocking agent group was decreased than that of...