Role of multifunctional transcription factor TFII-I and putative tumour suppressor DBC1 in cell cycle and DNA double strand damage repair.
BACKGROUND
In multicellular organisms, precise control of cell cycle and the maintenance of genomic stability are crucial to prevent chromosomal alterations. The accurate function of the DNA damage pathway is maintained by DNA repair mechanisms including homologous recombination (HR). Herein, we show that both TFII-I and DBC1 mediate cellular mechanisms of cell-cycle regulation and DNA double strand damage repair.


METHODS
Regulation of cell cycle by TFII-I and DBC1 was investigated using Trypan blue dye exclusion test, luciferase assay, and flow cytometry analysis. We also analysed the role of TFII-I and DBC1 in DNA double strand damage repair after irradiation by immunofluorescence study, clonogenicity assay, and HR assay.


RESULTS
Flow cytometry analysis revealed a novel function that siRNA-mediated knockdown of endogenous DBC1 resulted in G2/M phase arrest. We also have shown that both endogenous TFII-I and DBC1 activate DNA repair mechanisms after irradiation because irradiation-induced foci formation of TFII-I-γH2AX was observed, and the depletion of endogenous TFII-I or DBC1 resulted in the inhibition of normal HR efficiency.


CONCLUSIONS
These results reveal novel mechanisms by which TFII-I and DBC1 can modulate cellular fate by affecting cell-cycle control as well as HR pathway.
Department of Obstetrics and Gynecology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
M
M
Tanikawa
O
O
Wada-Hiraike
N
N
Yoshizawa-Sugata
A
A
Shirane
M
M
Hirano
H
H
Hiraike
Y
Y
Miyamoto
K
K
Sone
Y
Y
Ikeda
T
T
Kashiyama
K
K
Oda
K
K
Kawana
Y
Y
Katakura
T
T
Yano
H
H
Masai
A L
AL
Roy
Y
Y
Osuga
T
T
Fujii
D048868:Adaptor Proteins, Signal Transducing / Q000502:physiology*; D059447:Cell Cycle Checkpoints / Q000235:genetics / Q000502:physiology*; D002455:Cell Division / Q000235:genetics / Q000502:physiology; D002460:Cell Line; D045744:Cell Line, Tumor; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D005434:Flow Cytometry; D059565:G2 Phase Cell Cycle Checkpoints / Q000235:genetics / Q000502:physiology; D006801:Humans; D019473:Transcription Factors, TFII / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D048868:Adaptor Proteins, Signal Transducing; C527450:CCAR2 protein, human; C104259:GTF2I protein, human; D019473:Transcription Factors, TFII; D004247:DNA