Molecular mechanism of transcriptional regulation forDNA repair genes: Identification of partner proteins for CXXC5, a novel MLH1 transcriptional factor

在本研究中，识别MLH1启动子FP3CAT位点的dna结合蛋白CXXC5被鉴定为MLH1转录的激活因子。共免疫沉淀和LC/MS/MS分析显示，CXXC5和SYF2具有共同的相互作用蛋白HNRNPH1，并可能协同反式激活MLH1。缺氧时，这三种蛋白水平均下调，内源性过表达部分挽救了MLH1的下调。缺氧下MLH1的下调可能是由CXXC5、SYF2和HNRNPH1介导的。

In this study, CXXC5, DNA-binding protein recognizing the FP3CAT site of MLH1 promoter, was identified as an activator of MLH1 transcription. Co-immunoprecipitation and LC/MS/MS analysis revealed that CXXC5 and SYF2, previously screened as an FP3 site-binding protein, share common interacting protein HNRNPH1 and may co-operatively trans-activate MLH1. In hypoxia, all three protein levels were down-regulated and endogenous over-expression of them partially rescued MLH1 down-regulation. Hypoxic down-regulationof MLH1 may be mediated by CXXC5, SYF2, and HNRNPH1.