Chau David H W, Yuan Ji, Zhang Huifang, Cheung Paul, Lim Travis, Liu Zhen, Sall Alhousseynou, Yang Decheng
Department of Pathology and Laboratory Medicine, The James Hogg iCAPTURE Centre, University of British Columbia, St. Paul's Hospital, Room 166, 1081 Burrard Street, Vancouver, BC, Canada.
Apoptosis. 2007 Mar;12(3):513-24. doi: 10.1007/s10495-006-0013-0. Epub 2006 Dec 29.
By transfection of Coxsackievirus B3 (CVB3) individual protease gene into HeLa cells, we demonstrated that 2A(pro) and 3C(pro) induced apoptosis through multiple converging pathways. Firstly, both 2A(pro) and 3C(pro) induced caspase-8-mediated activation of caspase-3 and dramatically reduced cell viability. Secondly, they both activated the intrinsic mitochondria-mediated apoptosis pathway leading to cytochrome c release from mitochondria and activation of caspase-9. However, 3C(pro) induced these events via both up-regulation of Bax and cleavage of Bid, and 2A(pro) induced these events via cleavage of Bid only. Nevertheless, neither altered Bcl-2 expression. Thirdly, both proteases induced cell death through cleavage or down regulation of cellular factors for translation and transcription: both 2A(pro) and 3C(pro) cleaved eukaryotic translation initiation factor 4GI but their cleavage products are different, indicating different cleavage sites; further, both 2A(pro) and 3C(pro) down-regulated cyclic AMP responsive element binding protein, a transcription factor, with 2A(pro) exhibiting a stronger effect than 3C(pro). Surprisingly, neither could cleave DAP5/p97/NAT1, a translation regulator, although this cleavage was observed during CVB3 infection and could not be blocked by caspase inhibitor z-VAD-fmk. Taken together, these data suggest that 2A(pro) and 3C(pro) induce apoptosis through both activation of proapoptotic mediators and suppression of translation and transcription.
通过将柯萨奇病毒B3（CVB3）的单个蛋白酶基因转染到HeLa细胞中，我们证明2A（pro）和3C（pro）通过多种汇聚途径诱导细胞凋亡。首先，2A（pro）和3C（pro）均诱导半胱天冬酶-8介导的半胱天冬酶-3激活，并显著降低细胞活力。其次，它们都激活了内在的线粒体介导的细胞凋亡途径，导致细胞色素c从线粒体释放并激活半胱天冬酶-9。然而，3C（pro）通过上调Bax和切割Bid来诱导这些事件，而2A（pro）仅通过切割Bid来诱导这些事件。尽管如此，两者均未改变Bcl-2的表达。第三，两种蛋白酶均通过切割或下调细胞翻译和转录因子诱导细胞死亡：2A（pro）和3C（pro）均切割真核翻译起始因子4GI，但它们的切割产物不同，表明切割位点不同；此外，2A（pro）和3C（pro）均下调环磷酸腺苷反应元件结合蛋白（一种转录因子），2A（pro）的作用比3C（pro）更强。令人惊讶的是，两者均不能切割翻译调节因子DAP5/p97/NAT1，尽管在CVB3感染期间观察到了这种切割，并且不能被半胱天冬酶抑制剂z-VAD-fmk阻断。综上所述，这些数据表明2A（pro）和3C（pro）通过激活促凋亡介质以及抑制翻译和转录来诱导细胞凋亡。
