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

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.

Human Papilloma Virus Type 16 E7 Genes Protect Astrocytes against Apoptotic and Necrotic Death Induced by Hydrogen Peroxide

Hydrogen peroxide is considered to be a dose- and time-dependent mediator in apoptotic and necrotic death. In this study, we examined the signaling of the E6 and E7 proteins with respect to apoptosis or necrosis after H2O2 injury using an in vitro model with overexpressed E6 or E7 genes. For this purpose, the E6 and E7 gene expressing astrocytes were exposed to 0.01 mM and 0.2 mM H2 O2 solutions. Twenty- four hours after treatment with the lower dosage(0.01 mM H2O2), control, E6-expressing cells suffered about 45% injury and LXSN-expressi ng cells decreased by 67% as assessed by LDH release. However, E7-expressing cells showed less injury, resulting in 20-30% of LDH release. Astrocytes expressing E6, E7, LXSN and mock-infected cells showed a typical apoptotic death patter n on the DNA gel after treatment with a low-dose of H2O2 (0.01 mM), however the y died from necrotic death after a high-dose (0.2 mM) H2O2. Overexpression of HPV-E7 genes protected the cells from apoptotic death after a low-dose of H2O2 and from necrotic death after a high-dose of H2O2, while the overexpression of E 6 genes from the necrotic death. E7 expressing astrocytes showed higher catalas e activity and the levels of E2F protein surged more than 100-folds compared with the control astrocytes. We believe that the activity of E7 protein to protect astrocytes from H2O2 injury was at least partly due to increased catalase, a scavenger protein.