| [Background and Objective]Vascular remodeling represents the pathophysiological basis of many diseases, including atherosclerosis, hypertension and restenosis after PICA. It is characteristic of proliferation, migration of vascular smooth muscle cells (VSMCs) from the tunica media to intima and the remodeling of extracellular matrix (ECM). Matrixmetalloproteinases( MMPs) are important proteolysis that may play roles on proliferation and migration of VSMCs. MMPs are zinc, calcium dependant endopeptidases consisting of at least 20 different members. They are classified into five groups according to their structures and substrate specificity-es:interstitial collagenaeses,IV collagenaeses (gelatinases), stromely-sins, MT-MMPs and other MMPs. IV collagenaeses have more closely relation with cardiovascular diseases than others. MMP-2,one of IV collagenaeses,can degrades type IV and V collagens, elastin , and gelatin (a breakdown product of collagen) and the proteinase inhibitor TIMP-2 may selectively inhibit activated MMP-2 by binding (1:1) to the catalytic domain of MMP-2. MMP-2, secreted by VSMCs in vivo or vitro, participates in the pathogenesis of many vascular diseases for instance hypertension,atherosclerosis and restenosis after PICA.The generation of reactive oxygen species (ROS) including HA is considered toxic to cells. Recently, however,it has become apparent that moderate rise of H20z concentration in cell or tissue can results in cell proliferation, differentiation, and activation of transcription of some genes by the several ways of signal transduction. Otherwise H20z can induce some redox sensitive transcriptional factors such as NF- kB, YB~1. In the pathologic course such as atherosclerosis,PICA, a variety of ROS can be produced and result in oxygen stress of VSMCs. Rao et. al observed firstly H2O2 may act as stimulant of proliferation for VSMCs by induction of c-myc and c-fos mRNA. Belkhiri et. al found that H202 can stimulate MMP-2 expression and transcription in endothial cell.All above suggest H202 can play an important role in vascular remodeling by affectting proliferation and migration of VSMCs. To our knowledge, there isn' t any report about effect of H202 on mRNA of MMP-2 and TIMP-2 in VSMCs, so we postulate H202 may act as stimulator for proliferation of VSMCs and transcription of MMP-2> TIMP-2 in VSMCs and play an important role in the vascular remodeling. [Materials and Methods]VSMCs were isolated from the thoracic aortas of 200-250g male Sprague-Dawley rats by enzymatic dissociation. We used MTT method to determine the proliferation activities of VSMCs and the toxic concetration of H202 and used RT-PCR to reveal effect of H202 on the mRNA of MMP-2 and TIMP-2 in VSMCs.[Results]1, H202 of 0. 01-200 nM is no lethal to VSMCs and >300uM H202 is lethal to VSMCs. H202 can promote proliferation of VSMCs in dose-effect and time-effect dependant manners, presented by significantly increase of OD level. OD reaches a peak with 24h incubation of serum-free medium containing 10 uM HA and maintains similar level with 48h incubation.2, 10 uM H202 can induce transcription of mRNA of MMP-2 in dose-effect and time-effect dependant manners, presented by significantly increase of MMP-2/Beta actin mRNA ratio. The ratio reaches a peak with 24h incubation of serum-free medium containing 10 uM H202 and descends with 48h incubation.3, TIMP-2/beta-actin mRNA ratio was not significantly affected with 12h, 24h , 36h > 48h incubation of serum-free medium containing 1 u M> 10 uM, 50 uM H202 [Conclutions]H2Oz may stimulate proliferation of VSMCs and induce transcriptionof MMP-2 gene in VSMCs. There is no effect of H202 on transcription ofTIMP-2 gene in VSMCs... |
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