Effects Of ROCK On The Expression Of MMP-2, MMP-9and MEF2A In Vascular Smooth Muscle Cells Induced By PDGF

Objectives Atherosclerosis (AS) is a serious threat to human health of commonand frequently-occurring diseases. The phenotype transformation, proliferation andmigration of vascular smooth muscle cells (VSMCs) are key factors in thepathogenesis of atherosclerosis. Platelet-derived growth factor (PDGF) is a strongmitotic agent and chemical chemotactic agent, which is no expression in normalarteries. When blood vessels were damaged to the depth of membrane, PDGF issecreted and released into the blood, and binds its receptors to promote smooth musclecells migration. Rho kinase (ROCK) belongs to serine/threonine protein kinase family,involved in regulating some cell behaviors and functions, such as cell migration, cellproliferation, cell adhesion, cytoskeleton restructuring and other inflammatory reaction.There are two subtypes ROCKⅠ and ROCKⅡ. It is confirmed that ROCKⅠplays aleading role in VSMC migration, but the effect of ROCKⅡis not obvious. Withvascular smooth muscle cell proliferation and migration, a large number of cell factorsexpress. Among them, the matrix metalloproteinases (MMPs) are groups of zinc iondependment peptide enzymes, which produce by VSMC and macrophages and someother cells. The function of MMPs is to biodegrade the extracellular matrix to promotevascular smooth muscle cell migration. MEF2A is a kind of DNA binding protein tocontrol VSMCs phenotype transform, and promote VSMC proliferation. This paperaims to study the effects of ROCKⅠ/ROCKⅡon the expression of MMP-9and Mef2ain vascular smooth muscle cells induced by PDGF.Methods (1) The activity of MMP-2and MMP-9in different vascular smoothmuscle cell lines such as A7r5, Aos, Gba and SM3induced by PDGF was assessed bygelatin zymography.(2)The expression levels of MMP-2, MMP-9and MEF2Ainduced by PDGF were detected by RT-PCR.(3)The expression levels of MMP-2,MMP-9and MEF2A were detected by RT-RCR and Western blot after ROCKⅠ or ROCKⅡ was down-regulated by siRNA transfection or inhibitor Y-27632;(4)Theexpression levels of MMP-2, MMP-9and MEF2A were detected by RT-PCR after theover-expression of ROCK Ⅰ/ROCKⅡusing stable transfection.Results (1)Gelatin zymography shows that PDGF promotes the activity ofMMP-2in A7r5, Aos, Gba cell lines, but it is no obvious change in SM3cell lines.(2)PDGF promotes the expression of MMP-2, MMP-9and MEF2A in vascular smoothmuscle cells(A7r5), and it presents time-effect relationship,which12hours is the top ofexpression.(3)The expression levels of ROCK Ⅰ/ROCK Ⅱ were down-regulatedobviously by siRNA transfection, and ROCKⅠ was down-regulated by77.3%, whileROCKⅡwas down-regulated by91.7%. The expressions of MMP-9were inhibited bythe down-regulated ROCKⅠand ROCKⅡby siRNA transfection or inhibitor Y-27632.On the other side, the expression of MEF2A was also inhibited, whereas ROCKⅡinhibitory effect was relatively remarkable. The expressions of MMP-2, MMP-9andMEF2A were significantly increased with over-expression of ROCKⅠand ROCKⅡbystable transfection.Conclusion (1)ROCKⅠand ROCKⅡhave regulation effects on the expressionMMP-2, MMP-9in vascular smooth muscle cells induced by PDGF, while twosubtypes have no obvious difference, MMP-2and MMP-9were the downstreameffects molecules of Rho/ROCK signal pathway in VSMC migration.(2)ROCKⅠandROCKⅡhave an regulation impact upon the expression of MEF2A in vascular smoothmuscle cells induced by PDGF, while ROCKⅡwas obviously. MEF2A was thedownstream molecules of Rho/ROCK signal pathway during the proliferation inVSMC.