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.
Mesh Terms:
Amino Acid Sequence, Animals, Antigens, Polyomavirus Transforming, Ataxia Telangiectasia Mutated Proteins, Cell Cycle Proteins, Cell Line, Chlorocebus aethiops, DNA, DNA Damage, DNA-Binding Proteins, Enzyme Activation, Fibroblasts, Humans, Mice, Molecular Sequence Data, Phosphorylation, Plasmids, Protein Binding, Protein Serine-Threonine Kinases, RNA, Small Interfering, Radiation, Ionizing, Sequence Homology, Amino Acid, Serine, Simian virus 40, Transfection, Tumor Suppressor Proteins, Virus Replication
Amino Acid Sequence, Animals, Antigens, Polyomavirus Transforming, Ataxia Telangiectasia Mutated Proteins, Cell Cycle Proteins, Cell Line, Chlorocebus aethiops, DNA, DNA Damage, DNA-Binding Proteins, Enzyme Activation, Fibroblasts, Humans, Mice, Molecular Sequence Data, Phosphorylation, Plasmids, Protein Binding, Protein Serine-Threonine Kinases, RNA, Small Interfering, Radiation, Ionizing, Sequence Homology, Amino Acid, Serine, Simian virus 40, Transfection, Tumor Suppressor Proteins, Virus Replication
J Biol Chem
Date: Dec. 02, 2005
PubMed ID: 16221684
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