Analyses of functional interaction between RECQL1, RECQL5, and BLM which physically interact with DNA topoisomerase IIIalpha.
RECQL1 and RECQL5 as well as BLM reportedly interact with TOP3alpha whose defect is lethal for the cell. Therefore in this study, we characterized recql5/recql1/blm triple mutants from DT40 cells to determine whether the triple mutants show a top3alpha disrupted cell-like phenotype. The triple mutants are viable. Moreover, both blm/recql1 and recql5/blm cells, and recql5/recql1/blm cells grew slightly slower than blm cells, that is, triple mutant cells grew almost the same rate as either of the double mutant cells. The blm cells showed sensitivity to methyl methanesulfonate (MMS) and ultraviolet light (UV), about a 10-fold increase in sister chromatid exchange (SCE), and about a 3-fold increase in damage-induced mitotic chiasma compared to wild-type cells. The triple mutants showed the same sensitivity to MMS or UV and the same frequency of damage-induced mitotic chiasma compared to those of blm cells, indicating that unlike BLM, RECQL1 and RECQL5 play a little role in the repair of or tolerance to DNA damages. However, recql5/blm cells showed higher frequency of SCE than blm cells, whereas the RECQL1 gene disruption had no effect on SCE in blm cells and even in recql5/blm cells.
Otsuki
Makoto
M
Molecular Cell Biology Laboratory, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai, Japan.
Seki
Masayuki
M
Inoue
Eri
E
Abe
Takuya
T
Narita
Yoshiyasu
Y
Yoshimura
Akari
A
Tada
Shusuke
S
Ishii
Yutaka
Y
Enomoto
Takemi
T
D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D002478:Cells, Cultured; D002645:Chickens; D004249:DNA Damage / Q000502:physiology; D004265:DNA Helicases / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D004264:DNA Topoisomerases, Type I / Q000378:metabolism* / Q000502:physiology*; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D008954:Models, Biological; D050505:Mutant Proteins / Q000378:metabolism / Q000502:physiology; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs / Q000235:genetics / Q000502:physiology; D053484:RecQ Helicases / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D012854:Sister Chromatid Exchange / Q000528:radiation effects; D014466:Ultraviolet Rays
D050505:Mutant Proteins; D008741:Methyl Methanesulfonate; D000251:Adenosine Triphosphatases; C097151:Bloom syndrome protein; D004265:DNA Helicases; D053484:RecQ Helicases; D004264:DNA Topoisomerases, Type I