Yalamanchili P, Datta U, Dasgupta A
Department of Microbiology and Immunology, Jonsson Comprehensive Cancer Center, UCLA School of Medicine, Los Angeles, California 90095-1747, USA.
J Virol. 1997 Feb;71(2):1220-6. doi: 10.1128/JVI.71.2.1220-1226.1997.
Host cell RNA polymerase II-mediated transcription is inhibited by poliovirus infection. Previous studies from our laboratory showed that activated transcription from a cyclic AMP-responsive element (CRE)-containing promoter was severely inhibited in extracts prepared from poliovirus-infected HeLa cells compared to those from mock-infected cells. Here we demonstrate that the CRE-binding protein, CREB, is specifically cleaved by the poliovirus-encoded protease 3Cpro both in vitro and in virus-infected cells. The proteolytic cleavage of CREB leads to a significant loss of its DNA binding as well as transcriptional activity. Additionally, we demonstrate that the phosphorylated, transcriptionally active form of CREB is cleaved by the viral protease in vitro. The results presented here suggest that a direct cleavage of CREB by the viral protease 3Cpro leads to inhibition of CREB-activated transcription in poliovirus-infected HeLa cells.
脊髓灰质炎病毒感染会抑制宿主细胞RNA聚合酶II介导的转录。我们实验室之前的研究表明，与 mock 感染细胞制备的提取物相比，从脊髓灰质炎病毒感染的HeLa细胞制备的提取物中，含环磷酸腺苷反应元件（CRE）的启动子的激活转录受到严重抑制。在这里，我们证明CRE结合蛋白CREB在体外和病毒感染的细胞中都被脊髓灰质炎病毒编码的蛋白酶3Cpro特异性切割。CREB的蛋白水解切割导致其DNA结合以及转录活性的显著丧失。此外，我们证明磷酸化的、具有转录活性的CREB形式在体外被病毒蛋白酶切割。这里呈现的结果表明，病毒蛋白酶3Cpro对CREB的直接切割导致脊髓灰质炎病毒感染的HeLa细胞中CREB激活转录的抑制。
