Ku protein as a potential human T-cell leukemia virus type 1 (HTLV-1) Tax target in clastogenic chromosomal instability of mammalian cells.
The HTLV-1 Tax oncoprotein rapidly induces cytogenetic damage which can be measured by a significant increase in the number of micronuclei (MN) in cells. Tax is thought to have both aneuploidogenic and clastogenic effects. To examine the cellular target for Tax which might mechanistically explain the clastogenic phenomenon, we tested the ability of Tax to induce MN in rodents cells genetically defective for either the Ku80 protein or the catalytic subunit of DNA protein kinase (DNAPKcs). We found that cells genetically mutated in Ku80 were refractory to Tax's induction of MN while cells knocked-out for DNAPKcs showed increased number of Tax-induced MN. Using a cytogenetic method termed FISHI (Fluorescent In Situ Hybridization and Incorporation) which measures the number of DNA-breaks in cells that contained unprotected 3'-OH ends, we observed that Tax increased the prevalence of unprotected DNA breaks in Ku80-intact cells, but not in Ku80-mutated cells. Taken together, our findings suggest Ku80 as a cellular factor targeted by Tax in engendering clastogenic DNA damage.
Majone
Franca
F
Department of Biology, University of Padua, Padua, Italy. majone@mail.bio.unipd.it
Luisetto
Roberto
R
Zamboni
Daniela
D
Iwanaga
Yoichi
Y
Jeang
Kuan-Teh
KT
D000818:Animals; D016466:CHO Cells; D002460:Cell Line; D002461:Cell Line, Transformed; D006224:Cricetinae; D004249:DNA Damage; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D003856:Deoxyuracil Nucleotides / Q000378:metabolism; D004077:Digoxin / Q000378:metabolism; D016356:Gene Products, tax / Q000235:genetics / Q000378:metabolism*; D015368:Human T-lymphotropic virus 1 / Q000378:metabolism / Q000472:pathogenicity*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D019169:Jurkat Cells; D000072200:Ku Autoantigen; D051379:Mice; D048629:Micronuclei, Chromosome-Defective; D015162:Micronucleus Tests
D003856:Deoxyuracil Nucleotides; D016356:Gene Products, tax; C027078:deoxyuridine triphosphate; D004077:Digoxin; D004265:DNA Helicases; C106893:XRCC5 protein, human; D000072200:Ku Autoantigen