Sae2/CtIP prevents R-loop accumulation in eukaryotic cells
Nodar Makharashvili,
Sucheta Arora,
Yizhi Yin,
Qiong Fu,
Xuemei Wen,
Ji-Hoon Lee,
Chung-Hsuan Kao,
Justin WC Leung,
Kyle M Miller,
Tanya T Paull
Affiliations
Nodar Makharashvili
Howard Hughes Medical Institute, The University of Texas at Austin, Austin, United states; Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States
Sucheta Arora
Howard Hughes Medical Institute, The University of Texas at Austin, Austin, United states; Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States
Yizhi Yin
Howard Hughes Medical Institute, The University of Texas at Austin, Austin, United states; Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States
Qiong Fu
Gastrointestinal Malignancy Section, Thoracic and Gastrointestinal Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, United States
Xuemei Wen
Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States
Howard Hughes Medical Institute, The University of Texas at Austin, Austin, United states; Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States
The Sae2/CtIP protein is required for efficient processing of DNA double-strand breaks that initiate homologous recombination in eukaryotic cells. Sae2/CtIP is also important for survival of single-stranded Top1-induced lesions and CtIP is known to associate directly with transcription-associated complexes in mammalian cells. Here we investigate the role of Sae2/CtIP at single-strand lesions in budding yeast and in human cells and find that depletion of Sae2/CtIP promotes the accumulation of stalled RNA polymerase and RNA-DNA hybrids at sites of highly expressed genes. Overexpression of the RNA-DNA helicase Senataxin suppresses DNA damage sensitivity and R-loop accumulation in Sae2/CtIP-deficient cells, and a catalytic mutant of CtIP fails to complement this sensitivity, indicating a role for CtIP nuclease activity in the repair process. Based on this evidence, we propose that R-loop processing by 5’ flap endonucleases is a necessary step in the stabilization and removal of nascent R-loop initiating structures in eukaryotic cells.
