title: Ataxia telangiectasia-mutated damage-signaling kinase- and proteasome-dependent destruction of Mre11-Rad50-Nbs1 subunits in Simian virus 40-infected primate cells.
abstract: Although the mechanism of simian virus 40 (SV40) DNA replication has been extensively investigated with cell extracts, viral DNA replication in productively infected cells utilizes additional viral and host functions whose interplay remains poorly understood. We show here that in SV40-infected primate cells, the activated ataxia telangiectasia-mutated (ATM) damage-signaling kinase, gamma-H2AX, and Mre11-Rad50-Nbs1 (MRN) assemble with T antigen and other viral DNA replication proteins in large nuclear foci. During infection, steady-state levels of MRN subunits decline, although the corresponding mRNA levels remain unchanged. A proteasome inhibitor stabilizes the MRN complex, suggesting that MRN may undergo proteasome-dependent degradation. Analysis of mutant T antigens with disrupted binding to the ubiquitin ligase CUL7 revealed that MRN subunits are stable in cells infected with mutant virus or transfected with mutant viral DNA, implicating CUL7 association with T antigen in MRN proteolysis. The mutant genomes produce fewer virus progeny than the wild type, suggesting that T antigen-CUL7-directed proteolysis facilitates virus propagation. Use of a specific ATM kinase inhibitor showed that ATM kinase signaling is a prerequisite for proteasome-dependent degradation of MRN subunits as well as for the localization of T antigen and damage-signaling proteins to viral replication foci and optimal viral DNA replication. Taken together, the results indicate that SV40 infection manipulates host DNA damage-signaling to reprogram the cell for viral replication, perhaps through mechanisms related to host recovery from DNA damage.
authors: Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235-1634, USA.
authors: Xiaorong
authors: X
authors: Zhao
authors: Ramiro J
authors: RJ
authors: Madden-Fuentes
authors: Becky X
authors: BX
authors: Lou
authors: James M
authors: JM
authors: Pipas
authors: Jeannine
authors: J
authors: Gerhardt
authors: Christopher J
authors: CJ
authors: Rigell
authors: Ellen
authors: E
authors: Fanning
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D004249:DNA Damage / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*; D021122:Protein Subunits / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction; D013539:Simian virus 40 / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D021122:Protein Subunits; D011494:Protein Kinases; D046988:Proteasome Endopeptidase Complex