The human cytomegalovirus (HCMV) major immediate-early (MIE) promoter has strong transcriptional promoting capability. Its cis-acting regulatory elements form a special structure in this region that is repeated multiple times; the biological significance of these elements and their different compositions in the transcriptional promoting process remain unclear. Our results demonstrate that the HSV-I MIE protein ICP22 can generate strong repression of many viral and cellular promoters and enhancers. We further studied the transcriptional effects of ICP22 on structural elements and mutations in various HCMV MIE promoters by using a CAT assay. In spite of different transcriptional effects of all the ele- ments in the presence of ICP22, the transcriptional efficiencies exhibited by mutations generated by different compositions and an entire HCMV promoter, are not the simple sum of the functions of these elements. Furthermore, the transcriptional activities of specific sequences were not affected by the presence of ICP22. Therefore, it is assumed that the HCMV MIE promoter co-regulates expression of downstream genes by using viral and cellular specific factors via a specific pathway.
LUO Jie, CUN Wei, CHE YanChun, WANG LiChun, LI WeiZhong, LIU LongDing & LI QiHan Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming 650118, China
The herpes simplex virus type 1 (HSV-1) tegument proteins have important functions in the viral repli- cation process. In order to investigate the role of the HSV-1 tegument protein VP22 in viral replication, its transcriptional regulation of viral promoters was investigated using the chloramphenicol acetyl- transferase (CAT) assay. The results indicate that VP22 exerts a dose-dependent transcriptional in- hibitory effect on the HSV-1 α4, TK, and gC gene promoters. VP22 had the capacity to repress tran- scriptional activation of promoters via different viral transcription regulatory factors such as VP16 and ICP0, as evidenced by the specific repression of the TK and gC gene promoters by ICP0. In addition, VP22 was capable of inhibiting the promotion of ICP0 transcriptional activation in the presence of HAT PCAF, which is even more remarkable than the VP22 repression of ICP0 transcriptional activation. Fi- nally, the transcriptional inhibitory effect of VP22 on other viral promoters was demonstrated by the analysis of β-galactosidase activities in internal controls.
YU Xian1,2, LI WeiZhong1, LIU LongDing1, CHE YanChun1, CUN Wei1, WU WenJuan1, HE ChunYan1, SHAO CongWen1 & LI QiHan1 1 Department of Viral Immunology, Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming 650118, China
HSV-1 infection-mediated regulation of mRNA translation in host cells is a systematic and complicated process. Investigation of the details of this mechanism will facilitate understanding of biological variations in the viral replication process and host cells. In this study, a comparative proteomics technology platform was applied by two-dimension electrophoresis of HSV-1 infected normal human L-02 cell and control cell lysates. The observed protein spots were analyzed qualitatively and quantitatively by the PDQuest software package. A number of the different observed protein spots closely associated with cellular protein synthesis were identified by matrix-assisted laser-desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS). The expression levels of the RPLP1 protein, which is required for mRNA translation, and KHSRP protein, which is involved in rapid decay of mRNA, were up-regulated, whereas the expression level of RNP H2, which is involved in positive regulation on the mRNA splicing process, was down-regulated. All of these results suggest that HSV-1 infection can influence cellular protein synthesis via modulation of cellular regulatory proteins involved in RNA splicing, translation and decay, resulting in optimisation of viral protein synthesis when cellular protein synthesis is shut off. Although there is need for further investigations regarding the detailed mechanisms of cellular protein control, our studies provide new insight into the targeting of varied virus signaling pathways involved in host cellular protein synthesis.
Min HONG Yan-chun CHE Gui-zhen TANG Wei CUN Xue-mei ZHANG Long-ding LIU Qi-han LI
An interaction between the HSV-1 UL25 capsid protein and cellular microtubule-associated protein was found using a yeast two-hybrid screen and β-D-galactosidase activity assays. Immunofluorescence microscopy of the UL25 protein demonstrated its co-localization with cellular microtubule-associated protein in the plasma membrane. Further investigations with deletion mutants suggest that UL25 is likely to have a function in the nucleus.
Lei GUO Ying ZHANG Yan-chun CHE Wen-juan WU Wei-zhong LI Li-chun WANG Yun LIAO Long-ding LIU Qi-han LI
Herpes Simplex Virus 1 (HSV1) is capable of inducing two forms of infection in individuals, and the establishment of which type of infection occurs is linked to the transcriptional activation of viral α genes. One of the HSV1 α genes, ICP22, is known to have multiple functions during virus replication, but its distinct roles are still unclear. This study showed that ICP22 functions as a general repressor for certain viral and cellular promoters, and this transcriptional repression by ICP22 is independent of the specific upstream promoter element, as shown using the CAT enzyme assay system. Further work also found that VP16 interfered with ICP22 mediated transcriptional repression of the viral α4 gene, through interactions with specific elements upstream of the α4 gene promoter. These findings support the possibility that ICP22 and VP16 control transcription of HSV1α genes in a common pathway for the establishment of either viral lytic or latent infections.
CUN Wei, GUO Lei, ZHANG Ying, LIU LongDing, WANG LiChun, LI JianFeng, DONG ChengHong, WANG JinJin & LI QiHan Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming 650118, China
As a product of HSVI immediate-early gene, ICP22 is capable of interacting with various cellular tran-scriptive and regulatory molecules during viral infection so as to impact the normal cellular molecular mechanism. ICP22 expressed in transfected cells can push the cells’ entering into S phase with binding to mdm-1 promoter region and impact its trans-transcription activating effect by P53. Consequently, the MDM-2 binds to P53, and the degradation effects by the ubiquitous pathway are decreased, improving indirectly the P53 levels in cells and making the cells progress into the S phase.
GUO HongXiong, CUN Wei, LIU LongDing, WANG LiChun, ZHAO HongLing, DONG ChengHong & LI QiHan Department of Viral Immunology, Institute of Medical Biology, CAMS and PUMC, Kunming 650118, China These authors contributed equally to this work
