Human T-cell leukemia virus type 1 tax attenuates the ATM-mediated cellular DNA damage response.
Genomic instability, a hallmark of leukemic cells, is associated with malfunctioning cellular responses to DNA damage caused by defective cell cycle checkpoints and/or DNA repair. Adult T-cell leukemia, which can result from infection with human T-cell leukemia virus type 1 (HTLV-1), is associated with extensive genomic instability that has been attributed to the viral oncoprotein Tax. How Tax influences cellular responses to DNA damage to mediate genomic instability, however, remains unclear. Therefore, we investigated the effect of Tax on cellular pathways involved in recognition and repair of DNA double-strand breaks. Premature attenuation of ATM kinase activity and reduced association of MDC1 with repair foci were observed in Tax-expressing cells. Following ionizing radiation-induced S-phase checkpoint activation, Tax-expressing cells progressed more rapidly than non-Tax-expressing cells toward DNA replication. These results demonstrate that Tax expression may allow premature DNA replication in the presence of genomic lesions. Attempts to replicate in the presence of these lesions would result in gradual accumulation of mutations, leading to genome instability and cellular transformation.
Chandhasin
Chandtip
C
Department of Molecular Virology and Microbiology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
Ducu
Razvan I
RI
Berkovich
Elijahu
E
Kastan
Michael B
MB
Marriott
Susan J
SJ
D048868:Adaptor Proteins, Signal Transducing; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors*; D002460:Cell Line; D004260:DNA Repair / Q000502:physiology*; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors*; D016356:Gene Products, tax / Q000378:metabolism*; D015368:Human T-lymphotropic virus 1 / Q000502:physiology*; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors*; D013601:T-Lymphocytes / Q000528:radiation effects / Q000821:virology; D015534:Trans-Activators / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors*
D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D016356:Gene Products, tax; C413163:MDC1 protein, human; D009687:Nuclear Proteins; D015534:Trans-Activators; D025521:Tumor Suppressor Proteins; C514970:tax protein, Human T-lymphotrophic virus 1; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases