PUL21a-Cyclin A2 Interaction is Required to Protect Human Cytomegalovirus-Infected Cells from the Deleterious Consequences of Mitotic Entry

PLoS Pathogens

Stipan Jonjic¹  Tihana Lenac-Rovis¹  Heidemarie Neitzel²  Christian Hagemeier³  Ralf Uecker³  Barbara Vetter³  Boris Bogdanow³  Ellen Richter³  Henry Weisbach³  Martin Eifler³  Lydia König³  Lüder Wiebusch³ 

[1] Center for Proteomics, Faculty of Medicine, University of Rijeka, Rijeka, Croatia;Institut für Medizinische Genetik und Humangenetik, Charité Universitätsmedizin Berlin, Berlin, Germany;Labor für Pädiatrische Molekularbiologie, Charité Universitätsmedizin Berlin, Berlin, Germany

关键词: Cyclins;    Cell cycle;    cell division;    Viral replication;    Mitosis;    Cloning;    DNA replication;    Metaphase;    DNA synthesis;   

DOI  :  10.1371/journal.ppat.1004514

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Entry into mitosis is accompanied by dramatic changes in cellular architecture, metabolism and gene expression. Many viruses have evolved cell cycle arrest strategies to prevent mitotic entry, presumably to ensure sustained, uninterrupted viral replication. Here we show for human cytomegalovirus (HCMV) what happens if the viral cell cycle arrest mechanism is disabled and cells engaged in viral replication enter into unscheduled mitosis. We made use of an HCMV mutant that, due to a defective Cyclin A2 binding motif in its UL21a gene product (pUL21a), has lost its ability to down-regulate Cyclin A2 and, therefore, to arrest cells at the G1/S transition. Cyclin A2 up-regulation in infected cells not only triggered the onset of cellular DNA synthesis, but also promoted the accumulation and nuclear translocation of Cyclin B1-CDK1, premature chromatin condensation and mitotic entry. The infected cells were able to enter metaphase as shown by nuclear lamina disassembly and, often irregular, metaphase spindle formation. However, anaphase onset was blocked by the still intact anaphase promoting complex/cyclosome (APC/C) inhibitory function of pUL21a. Remarkably, the essential viral IE2, but not the related chromosome-associated IE1 protein, disappeared upon mitotic entry, suggesting an inherent instability of IE2 under mitotic conditions. Viral DNA synthesis was impaired in mitosis, as demonstrated by the abnormal morphology and strongly reduced BrdU incorporation rates of viral replication compartments. The prolonged metaphase arrest in infected cells coincided with precocious sister chromatid separation and progressive fragmentation of the chromosomal material. We conclude that the Cyclin A2-binding function of pUL21a contributes to the maintenance of a cell cycle state conducive for the completion of the HCMV replication cycle. Unscheduled mitotic entry during the course of the HCMV replication has fatal consequences, leading to abortive infection and cell death.

【 授权许可】

CC BY