Song B, Yeh K C, Liu J, Knipe D M
Department of Microbiology & Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
Virology. 2001 Nov 25;290(2):320-8. doi: 10.1006/viro.2001.1175.
HSV infection blocks G1 events in the cell cycle and arrests host cell growth in the G1 phase. To further define the mechanism of the effect and determine the viral gene product(s) responsible, we examined various mutant viruses for their effects on cell cycle regulatory proteins (pRb, cyclin D1, and cdk4) and on cell cycle progression into S phase. Unlike the wild-type virus, the ICP27 mutant virus was defective for blocking the phosphorylation of pRb proteins, and the normal pRb pattern was restored in cells infected with a rescued virus. The virion host shutoff (vhs) function, DNA replication, and late gene functions were not required for the virus-induced effects on pRb protein. BrdU incorporation in synchronized HSV-infected cells showed that ICP27 was required for blocking the cell cycle in the G1 phase. Furthermore, ICP27, ICP4, ICP0, and vhs were required for blocking the induction of the G1 cell cycle regulators cyclin D1 and cdk4 in HSV-infected cells. Both ICP27 and the vhs function contributed to the reduction of cyclin D1 mRNA levels in HSV-infected cells: These results provide evidence that HSV-1 ICP27 protein is essential for viral inhibition of G1-phase functions and that certain other HSV proteins are required for some of the viral effects on the cell cycle. Finally, these results show that HSV-1 ICP27 and vhs act jointly to reduce host mRNA levels in infected cells.
单纯疱疹病毒（HSV）感染会阻断细胞周期中的G1期事件，并使宿主细胞生长停滞在G1期。为了进一步明确这种作用的机制并确定相关的病毒基因产物，我们检测了多种突变病毒对细胞周期调节蛋白（pRb、细胞周期蛋白D1和细胞周期蛋白依赖性激酶4）以及细胞周期进入S期进程的影响。与野生型病毒不同，ICP27突变病毒在阻断pRb蛋白磷酸化方面存在缺陷，而在感染了拯救病毒的细胞中，正常的pRb模式得以恢复。病毒诱导对pRb蛋白产生影响并不需要病毒体宿主关闭（vhs）功能、DNA复制和晚期基因功能。在同步化的HSV感染细胞中掺入5-溴脱氧尿嘧啶核苷（BrdU）表明，ICP27是在G1期阻断细胞周期所必需的。此外，在HSV感染的细胞中，阻断G1期细胞周期调节因子细胞周期蛋白D1和细胞周期蛋白依赖性激酶4的诱导需要ICP27、ICP4、ICP0和vhs。ICP27和vhs功能均有助于降低HSV感染细胞中细胞周期蛋白D1的mRNA水平：这些结果证明，HSV-1 ICP27蛋白对于病毒抑制G1期功能至关重要，并且某些其他HSV蛋白对于病毒对细胞周期的某些影响也是必需的。最后，这些结果表明HSV-1 ICP27和vhs共同作用以降低感染细胞中的宿主mRNA水平。
