Interaction of hepatitis B virus X protein with damaged DNA-binding protein p127: Structural analysis and identification of antagonists

2002 ◽  
Vol 9 (6) ◽  
pp. 706-715 ◽  
Author(s):  
Françoise Bergametti ◽  
Julie Bianchi ◽  
Catherine Transy
Virology ◽  
2001 ◽  
Vol 287 (2) ◽  
pp. 266-274 ◽  
Author(s):  
Nathalie Lin-Marq ◽  
Séverine Bontron ◽  
Olivier Leupin ◽  
Michel Strubin

Hepatology ◽  
2008 ◽  
Vol 48 (5) ◽  
pp. 1467-1476 ◽  
Author(s):  
Silvia Martin-Lluesma ◽  
Céline Schaeffer ◽  
Eva Isabelle Robert ◽  
Pieter Cornelis van Breugel ◽  
Olivier Leupin ◽  
...  

1998 ◽  
Vol 18 (12) ◽  
pp. 7546-7555 ◽  
Author(s):  
Dorjbal Dorjsuren ◽  
Yong Lin ◽  
Wenxiang Wei ◽  
Tatsuya Yamashita ◽  
Takahiro Nomura ◽  
...  

ABSTRACT To modulate transcription, regulatory factors communicate with basal transcription factors and/or RNA polymerases in a variety of ways. Previously, it has been reported that RNA polymerase II subunit 5 (RPB5) is one of the targets of hepatitis B virus X protein (HBx) and that both HBx and RPB5 specifically interact with general transcription factor IIB (TFIIB), implying that RPB5 is one of the communicating subunits of RNA polymerase II involved in transcriptional regulation. In this context, we screened for a host protein(s) that interacts with RPB5. By far-Western blot screening, we cloned a novel gene encoding a 508-amino-acid-residue RPB5-binding protein from a HepG2 cDNA library and designated it RPB5-mediating protein (RMP). Expression of RMP mRNA was detected ubiquitously in various tissues. Bacterially expressed recombinant RMP strongly bound RPB5 but neither HBx nor TATA-binding protein in vitro. Endogenous RMP was immunologically detected interacting with assembled RPB5 in RNA polymerase in mammalian cells. The central part of RMP is responsible for RPB5 binding, and the RMP-binding region covers both the TFIIB- and HBx-binding sites of RPB5. Overexpression of RMP, but not mutant RMP lacking the RPB5-binding region, inhibited HBx transactivation of reporters with different HBx-responsive cis elements in transiently transfected cells. The repression by RMP was counteracted by HBx in a dose-dependent manner. Furthermore, RMP has an inhibitory effect on transcriptional activation by VP16 in the absence of HBx. These results suggest that RMP negatively modulates RNA polymerase II function by binding to RPB5 and that HBx counteracts the negative role of RMP on transcription indirectly by interacting with RPB5.


2020 ◽  
Vol 295 (9) ◽  
pp. 2888-2888
Author(s):  
Delphine Cougot ◽  
Yuanfei Wu ◽  
Stefano Cairo ◽  
Julie Caramel ◽  
Claire-Angélique Renard ◽  
...  

2006 ◽  
Vol 282 (7) ◽  
pp. 4277-4287 ◽  
Author(s):  
Delphine Cougot ◽  
Yuanfei Wu ◽  
Stefano Cairo ◽  
Julie Caramel ◽  
Claire-Angélique Renard ◽  
...  

The hepatitis B virus infects more than 350 million people worldwide and is a leading cause of liver cancer. The virus encodes a multifunctional regulator, the hepatitis B virus X protein (HBx), that is essential for virus replication. HBx is involved in modulating signal transduction pathways and transcription mediated by various factors, notably CREB that requires the recruitment of the co-activators CREB-binding protein (CBP)/p300. Here we investigated the role of HBx and its potential interaction with CBP/p300 in regulating CREB transcriptional activity. We show that HBx and CBP/p300 synergistically enhanced CREB activity and that CREB phosphorylation by protein kinase A was a prerequisite for the cooperative action of HBx and CBP/p300. We further show that HBx interacted directly with CBP/p300 in vitro and in vivo. Using chromatin immunoprecipitation, we provide evidence that HBx physically occupied the CREB-binding domain of CREB-responsive promoters of endogenous cellular genes such as interleukin 8 and proliferating cell nuclear antigen. Moreover expression of HBx increased the recruitment of p300 to the interleukin 8 and proliferating cell nuclear antigen promoters in cells, and this is associated with increased gene expression. As recruitment of CBP/p300 is known to represent the limiting event for activating CREB target genes, HBx may disrupt this cellular regulation, thus predisposing cells to transformation.


1998 ◽  
Vol 72 (1) ◽  
pp. 266-272 ◽  
Author(s):  
Sherry A. Becker ◽  
Teh-Hsiu Lee ◽  
Janet S. Butel ◽  
Betty L. Slagle

ABSTRACT The hepatitis B virus X protein (HBx) is a broadly acting transactivator implicated in the development of liver cancer. Recently, HBx has been reported to interact with several different cellular proteins, including our report of its binding to XAP-1, the human homolog of the simian repair protein UVDDB. In the present study, several HBx mutants were used to localize the minimal domain of HBx required for binding to XAP-1/UVDDB to amino acids 55 to 101. The normal function of XAP-1/UVDDB is thought to involve binding to damaged DNA, the first step in nucleotide excision repair (NER); therefore, we hypothesized that this interaction may affect the cell’s capacity to correct lesions in the genome. When tested in two independent assays that measure NER (unscheduled DNA synthesis and host cell reactivation), the expression of HBx significantly inhibited the ability of cells to repair damaged DNA. Under the assay conditions, HBx was expressed at a level similar to that previously observed during natural viral infection and was able to transactivate several target reporter genes. These results are consistent with a model in which HBx acts as a cofactor in hepatocarcinogenesis by preventing the cell from efficiently repairing damaged DNA, thus leading to an accumulation of DNA mutations and, eventually, cancer. An adverse effect on cellular DNA repair processes suggests a new mechanism by which a tumor-associated virus might contribute to carcinogenesis.


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