Ataxia-telangiectasia-mutated (ATM) is a T-antigen kinase that controls SV40 viral replication in vivo.
The structurally related ATM (ataxia-telangiectasia-mutated) and ATR (ATM-Rad3-related) protein kinases fulfill overlapping yet non-redundant functions as key regulators of cellular DNA damage responses. We recently showed that ATM phosphorylates the cyclic AMP response element-binding protein, CREB, following exposure to ionizing radiation (IR) and other DNA-damaging stimuli. Here, we show that a phospho-specific antibody recognizing the major ATM phosphorylation site in CREB cross-reacts with SV40 large tumor antigen (LTag), a multifunctional oncoprotein required for replication of the SV40 minichromosome. The relevant IR-induced phosphorylation site in LTag recognized by phospho-CREB antibody was mapped to Ser-120. IR strongly induced the phosphorylation of Ser-120 in an ATM-dependent manner in mouse embryo fibroblasts. Infection of African green monkey CV1 cells with SV40 resulted in the activation of ATM and phosphorylation of LTag and endogenous ATM substrates. Infection-induced LTag phosphorylation correlated with the onset of DNA replication, was ATM-dependent, and peaked when viral DNA levels reached their maximum. SV40 replication in CV1 cells required an intact LTag Ser-120 phosphorylation site and was inhibited following transfection with ATM small interfering RNA suggesting that ATM is required for optimal SV40 replication in primate cells. Our findings uncover a direct link between ATM and SV40 LTag that may have implications for understanding the replication cycle of oncogenic polyoma viruses.
Shi
Yuling
Y
Department of Pharmacology, University of Wisconsin Medical School, Madison, Wisconsin 53706, USA.
Dodson
Gerald E
GE
Shaikh
Sophie
S
Rundell
Kathleen
K
Tibbetts
Randal S
RS
D000595:Amino Acid Sequence; D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000737:chemistry; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism; D002460:Cell Line; D002522:Chlorocebus aethiops; D004247:DNA / Q000737:chemistry; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D004789:Enzyme Activation; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D011839:Radiation, Ionizing; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000737:chemistry; D013539:Simian virus 40 / Q000378:metabolism / Q000502:physiology*; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000737:chemistry* / Q000378:metabolism; D014779:Virus Replication
D000952:Antigens, Polyomavirus Transforming; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; D012694:Serine; D004247:DNA; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases