BID Binds to Replication Protein A and Stimulates ATR Function following Replicative Stress ▿

Proapoptotic BH3-interacting death domain agonist (BID) regulates apoptosis and the DNA damage response. Following replicative stress, BID associates with proteins of the DNA damage sensor complex, including replication protein A (RPA), ataxia telangiectasia and Rad3 related (ATR), and ATR-interacting protein (ATRIP), and facilitates an efficient DNA damage response. We have found that BID stimulates the association of RPA with components of the DNA damage sensor complex through interaction with the basic cleft of the N-terminal domain of the RPA70 subunit. Disruption of the BID-RPA interaction impairs the association of ATR-ATRIP with chromatin as well as ATR function, as measured by CHK1 activation and recovery of DNA replication following hydroxyurea (HU). We further demonstrate that the association of BID with RPA stimulates the association of ATR-ATRIP to the DNA damage sensor complex. We propose a model in which BID associates with RPA and stimulates the recruitment and/or stabilization of ATR-ATRIP to the DNA damage sensor complex

Functional genomic screens identify CINP as a genome maintenance protein

The DNA damage response (DDR) has a critical role in maintaining genome integrity and serves as a barrier to tumorigenesis by promoting cell-cycle arrest, DNA repair, and apoptosis. The DDR is activated not only by genotoxic agents that induce DNA damage, but also during aberrant cell-division cycles caused by activated oncogenes and inactivated tumor suppressors. Here we use RNAi and cDNA overexpression screens in human cells to identify genes that, when deregulated, lead to activation of the DDR. The RNAi screen identified 73 genes that, when silenced in at least two cell types, cause DDR activation. Silencing several of these genes also caused an increased frequency of micronuclei, a marker of genetically unstable cells. The cDNA screen identified 97 genes that when overexpressed induce DDR activation in the absence of any exogenous genotoxic agent, with an overrepresentation of genes linked to cancer. Secondary RNAi screens identified CDK2-interacting protein (CINP) as a cell-cycle checkpoint protein. CINP interacts with ATR-interacting protein and regulates ATR-dependent signaling, resistance to replication stress, and G2 checkpoint integrity