Identification of Genome Maintenance Proteins with Functional Genomic Screens

Abstract

The precise replication of the genome and the continuous surveillance of its integrity are essential for cell survival and the avoidance of various diseases, including cancer. The genome is constantly exposed to environmental and endogenous genotoxic insults. To cope with this challenge, the DNA damage response coordinates DNA repair, replication, and the cell cycle. We have completed several RNAi screens to identify genes that function to maintain genome integrity during DNA replication. SMARCAL1 and CINP are two of the genes identified. SMARCAL1 acts as an annealing helicase to maintain genome integrity at stalled replication forks. Loss of SMARCAL1 activity increases the single‐stranded DNA at stalled replication forks and causes double‐strand breaks to accumulate. SMARCAL1 is regulated by an interaction with replication protein A and phosphorylation by the ATM/ATR family of kinases. CINP also is required to prevent double‐strand break accumulation. It interacts with ATR and regulates ATR checkpoint signaling. Both SMARCAL1‐ and CINP‐deficient cells are hypersensitive to replication stress agents. Thus, our functional genomic screens have identified new genome maintenance proteins inlcuding SMARCAL1 and CINP that maintain genome integrity within DNA damage response pathways. This research is funded by the National Cancer Institute and Susan G. Komen for the Cure.