Xu Yanjuan, Lei Zhiyong, Huang Hai, Dui Wen, Liang Xuehong, Ma Jun, Jiao Renjie
State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, the Chinese Academy of Sciences, Beijing, China.
PLoS One. 2009 Jul 2;4(7):e6107. doi: 10.1371/journal.pone.0006107.
The family of RecQ DNA helicases plays an important role in the maintenance of genomic integrity. Mutations in three of the five known RecQ family members in humans, BLM, WRN and RecQ4, lead to disorders that are characterized by predisposition to cancer and premature aging.
METHODOLOGY/PRINCIPAL FINDINGS: To address the in vivo functions of Drosophila RecQ4 (dRecQ4), we generated mutant alleles of dRecQ4 using the targeted gene knock-out technique. Our data show that dRecQ4 mutants are homozygous lethal with defects in DNA replication, cell cycle progression and cell proliferation. Two sets of experiments suggest that dRecQ4 also plays a role in DNA double strand break repair. First, mutant animals exhibit sensitivity to gamma irradiation. Second, the efficiency of DsRed reconstitution via single strand annealing repair is significantly reduced in the dRecQ4 mutant animals. Rescue experiments further show that both the N-terminal domain and the helicase domain are essential to dRecQ4 function in vivo. The N-terminal domain is sufficient for the DNA repair function of dRecQ4.
CONCLUSIONS/SIGNIFICANCE: Together, our results show that dRecQ4 is an essential gene that plays an important role in not only DNA replication but also DNA repair and cell cycle progression in vivo.
RecQ DNA解旋酶家族在维持基因组完整性方面发挥着重要作用。人类已知的五个RecQ家族成员中的三个，即BLM、WRN和RecQ4发生突变，会导致以易患癌症和早衰为特征的疾病。
方法/主要发现：为了研究果蝇RecQ4（dRecQ4）的体内功能，我们使用靶向基因敲除技术生成了dRecQ4的突变等位基因。我们的数据表明，dRecQ4突变体是纯合致死的，在DNA复制、细胞周期进程和细胞增殖方面存在缺陷。两组实验表明，dRecQ4在DNA双链断裂修复中也发挥作用。第一，突变动物对γ射线照射敏感。第二，在dRecQ4突变动物中，通过单链退火修复进行DsRed重组的效率显著降低。拯救实验进一步表明，N端结构域和解旋酶结构域对dRecQ4在体内的功能都是必不可少的。N端结构域足以实现dRecQ4的DNA修复功能。
结论/意义：总之，我们的结果表明，dRecQ4是一个必需基因，不仅在体内DNA复制中，而且在DNA修复和细胞周期进程中都发挥着重要作用。
