Activation of Tumor Suppressor Protein p53 Is Required for Theiler's Murine Encephalomyelitis Virus-Induced Apoptosis in M1-D Macrophages
Activation of Tumor Suppressor Protein p53 Is Required for Theiler's Murine Encephalomyelitis Virus-Induced Apoptosis in M1-D Macrophages
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DOI：
10.1128/jvi.01030-09
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发表时间：
2009-10-15
影响因子：
5.4
通讯作者：
Lipton, Howard L.
中科院分区：
文献类型：
--
作者：
Son, Kyung-No;Pugazhenthi, Subbiah;Lipton, Howard L.
Theiler小鼠脑脊髓炎病毒（TMEV）是一种高度溶细胞的小核糖核酸病毒，主要存在于小鼠中枢神经系统（CNS）的巨噬细胞中，通过巨噬细胞间传播维持感染。CNS中受感染的巨噬细胞经历细胞凋亡。我们最近发现，M1-D巨噬细胞感染低神经毒力TMEV BeAn病毒成为凋亡通过线粒体途径，是Bax介导的。我们目前对导致线粒体外膜透化的分子事件和信号通路的分析表明，在感染后2至3小时（p.i.），p38丝裂原活化蛋白激酶活化，随后在感染后3至6小时磷酸化肿瘤抑制蛋白p53 Ser 15，稳定p53水平直至6 h p.i.在感染后2 - 4 h，激活的p53上调促凋亡puma和noxa基因的转录。和它们的仅BH 3蛋白表达，随后在感染后4至10小时失去可检测的促存活Mcl-1和A1蛋白。已知促存活蛋白的降解释放Bax，其形成同源寡聚体并易位到线粒体外膜中并使线粒体外膜透化。两种特异性抑制剂SB 203580和BIRB 796对磷酸化p38的抑制导致感染后10小时细胞凋亡的显著减少，对病毒滴度无影响（仅检测SB 203580）。总之，这些数据表明，p53激活是需要在感染的M1-D细胞的细胞凋亡的诱导。
Theiler's murine encephalomyelitis virus (TMEV) is a highly cytolytic picornavirus that persists in the mouse central nervous system (CNS) largely in macrophages with infection maintained by macrophage-to-macrophage spread. Infected macrophages in the CNS undergo apoptosis. We recently showed that M1-D macrophages infected with the low-neurovirulence TMEV BeAn virus became apoptotic through the mitochondrial pathway that is Bax mediated. Our present analyses of the molecular events and signaling pathway(s) culminating in the mitochondrial outer membrane permeabilization that initiates the caspase cascade and apoptosis of BeAn virus-infected M1-D macrophages revealed activation of p38 mitogen-activated protein kinase by 2 to 3 h postinfection (p.i.), followed by phosphorylation of tumor suppressor protein p53 Ser 15 at 3 to 6 h p.i., stabilizing p53 levels until 6 h p.i. Activated p53 upregulated the transcription of proapoptotic puma and noxa genes at 2 to 4 h p.i. and their BH3-only protein expression, followed by the loss of detectable prosurvival Mcl-1 and A1 proteins at 4 to 10 h p.i. Degradation of the prosurvival proteins is known to release Bax, which forms homo-oligomers and translocates into and permeabilizes the mitochondrial outer membrane. Inhibition of phospho-p38 by two specific inhibitors, SB203580 and BIRB796, led to a significant decrease in apoptosis at 10 h p.i., with no effect on virus titers (only SB203580 tested). Together, these data indicate that p53 activation is required for the induction of apoptosis in infected M1-D cells.