Heat Treatment Suppressed the Expression and Activity of Matrix Metalloproteinases in the Primary Cultured Astrocytes

Kim, Jong Youl; Kim, Yeun Jung; Kim, Ji Hee; Lee, Won Tack; Park, Kyung Ah; Lee, Jong Eun

Abstract

Matrix metalloproteinases (MMPs), which is a kind of Zn-dependent enzyme, are a family of proteolytic enzymes that can degrade the extracellular matrix and then play important roles in the pathophysiology of ischemia/reperfusion, especially MMP-2 and MMP-9. This study was aimed to demonstrate how heat treatment and Hsp70 regulate expression of MMP-2 and MMP-9. The expression and regulation of MMPs after ischemic-like injury with and without heat treatment were investigated in the astrocytes expressing Hsp70 or LacZ and mock infected cells. Primary astrocyte cultures were prepared from ICR mice and infected with retroviral vectors overexpressed Hsp70 or LacZ. After heat treatment, expression of MMP-2 mRNAs was not remarkably changed in heat moc cells. Otherwise, expression of MMP-9 mRNAs was significantly reduced by heat treatment. Expression of MMP-2 and MMP-9 in astrocytes, which were treated with ischemic injury after heat treatment, was obviously decreased than in untreated Moc cells. Moreover, Hsp70s were significantly synthesized in response to heat treatment. Compared to amount of protein expression of MMP-2 and MMP-9, the expression of MMP-2 in astrocytes expressing Hsp70, LacZ and mock infected were decreased after heat treatment, especially pro-form of protein expression of MMP-2. However, the expression of MMP-9 were decreased only in the astrocytes expressing Hsp70 by heat treatment and OGD injury after heat treatment, not shown a big change in the LacZ cells and mock infected cells. The results of activity study with MMPs protein were that MMP-2 protein activity was reduced but not in condition of ischemic injury after heat treatment. On the other hand, the activity of MMP-9 after heat treatment was similar to the results of activity of MMP-9 adding ischemic injury. In this study, we shown that Hsp70 overexpression following heat treatment reduced the expression of proMMP-2, proMMP-9 and processed MMP-2, especially. This findings can suggest a possible role of Hsp70 induced by heat treatment for regulation of MMPs and neuroprotection in ischemic injury.