Human neutrophils isolated from peripheral blood contain Ku protein but not DNA-dependent protein kinase.
Ku protein, a heterodimer of 70kDa (Ku70) and 86kDa (Ku86) polypeptides, is involved in non-homologous DNA end-joining (NHEJ) of DNA double-strand break repair and V(D)J recombination in combination with the catalytic component of DNA-dependent protein kinase (p470). Although Ku protein is known to be ubiquitously present in eukaryotic cells, it was previously reported to be absent in mature neutrophils. Using a mixture of protease inhibitors in the isolation procedure of neutrophils from human peripheral blood, we were able to detect Ku in the neutrophils by immunoblot and flow-cytometric analyses. Transcripts of Ku70 and Ku86 genes were also detected by the reverse transcriptase-polymerase chain reaction (RT-PCR), and Ku protein was shown to be localized in the nucleus of neutrophils as a heterodimer. Like poly(ADP-ribose) polymerase-1, neither mRNA nor protein of p470 was detected in the neutrophils. These results suggest that Ku is involved independently of p470 in DNA metabolism and signal transduction.
Kurosawa
Aya
A
Medical Research Institute, Tokyo Medical and Dental University, 2-3-10 Kandasurugadai, Chiyoda-ku, 101-0062, Tokyo, Japan.
Shinohara
Ken-ichi
K
Watanabe
Fumiaki
F
Shimizu-Saito
Keiko
K
Koiwai
Osamu
O
Yamamoto
Kohtaro
K
Teraoka
Hirobumi
H
D034961:Antigens, Nuclear / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D004265:DNA Helicases; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D005434:Flow Cytometry / Q000379:methods; D015870:Gene Expression; D006801:Humans; D000072200:Ku Autoantigen; D009504:Neutrophils / Q000378:metabolism*; D009687:Nuclear Proteins; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics; D011480:Protease Inhibitors / Q000737:chemistry / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*
D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D011480:Protease Inhibitors; D011065:Poly(ADP-ribose) Polymerases; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen