Runx3 interacts with DNA repair protein Ku70.
Recent studies have suggested that Runt-related transcription factor 3 (Runx3) is associated with genesis and progression of gastric carcinoma. A proteomic approach was used to search for Runx3-interacting proteins to elucidate the molecular mechanisms of gastric carcinogenesis. Runx3 bound with myc and flag tags (MEF tags) is expressed in HEK293T cells, and the protein complex formed with Runx3 was purified and identified by mass spectrometry. Ku70 and Ku80, members of the DNA repair protein complex, were identified as Runx3-interacting proteins. Runx3, Ku70, and Ku80 associate in vivo, and in vitro interaction between Runx3 and Ku70 was confirmed via His-tag pull-down assay. The amino acids 241-322 of Runx3, which correspond to the transcriptional activation domain, and the amino acids 1-116 of Ku70 were necessary for binding with each other, and immunocytochemistry under confocal laser microscopy demonstrated that Runx3 and Ku70 localized throughout the nucleus excluding the nucleoli. Furthermore, Runx3 highly activated the transcription of p21, the target gene of Runx3, in Ku70 knockdown cells. These results suggest a possible link between a tumor suppressor function and DNA repair.
Department of Gastroenterology, Graduate School of Medicine, University of Tokyo, and Department of Clinical Drug Evaluation, University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
Yasuo
Y
Tanaka
Jun
J
Imamura
Fumihiko
F
Kanai
Tohru
T
Ichimura
Toshiaki
T
Isobe
Manabu
M
Koike
Yotaro
Y
Kudo
Keisuke
K
Tateishi
Tsuneo
T
Ikenoue
Hideaki
H
Ijichi
Yutaka
Y
Yamaji
Haruhiko
H
Yoshida
Takao
T
Kawabe
Masao
M
Omata
D000818:Animals; D034961:Antigens, Nuclear / Q000235:genetics / Q000378:metabolism*; D019556:COS Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D002522:Chlorocebus aethiops; D050677:Core Binding Factor Alpha 3 Subunit / Q000235:genetics / Q000378:metabolism*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism*; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D000072200:Ku Autoantigen; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism
D034961:Antigens, Nuclear; D050677:Core Binding Factor Alpha 3 Subunit; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen