维持真核细胞DNA复制叉的稳定直接关联到基因组的稳定。Checkpoint ATR-Chk2介导的通路已被证明是维持停顿的DNA复制叉稳定及推动正常复制叉跨过染色体内在的复制障碍物所必需的。在ATR或Chk2缺失时，停顿的复制叉倒转形成病理的鸡脚爪结构，进而引起复制不能完成、或DNA断裂、重组，最终导致基因组不稳定。ATR及Chk2介导的通路维持复制叉稳定的机理仍是一个待解决的重大问题。我们已发现ATR-Chk2通路通过磷酸化募集Dna2蛋白至染色体上以防止复制叉倒转。进一步的研究将阐明Dna2及其相互作用蛋白Rqh1和Cdc24在防止复制叉倒转及推进复制叉跨过染色体内在的复制障碍物的分子机理。我们最近通过大规模筛选发现蛋白激酶ppk19 在维持DNA复制叉及基因组稳定中起极重要作用。ppk19是Chk2调控的又一个蛋白,我们将对其生物功能及作用机理将作深入细致研究。

To stabilize DNA replication forks is directly related to genomic stability. The checkpoint ATR-Chk2 pathway has been proved essential to stabilize stalled replication forks and overcome replication barriers. In the absence of ATR or Chk2, stalled replication forks reverse to form pathological chicken-foot structure that results in incomplete DNA replication, dsDNA breaks, unscheduled DNA recombination, all of which cause genomic instability. How ATR- or Chk2-mediated checkpoint stabilizes DNA replication forks is still an open question. We discover that ATR-Chk2 phosphorylates Dna2 and stabilizes Dna2 associating with stalled replication forks for preventing stalled fork from reversing. The further studies will examine what are roles of the Dna2 interacting protein Rqh1 and Cdc24 in preventing fork reversal and facilitating crossing of replication over replication barriers. We recently found, through large-scale screening,that the protein kinase ppk19 is a protein targeted by Chk2 and plays an critical role in stabilizing stalled replication forks and maintaining genomic integrity. In this program, we will study the mechanism how ppk19 maintains genomic stability.