Genome instability via RNA:DNA hybrid-mediated R loops has been observed in mutants involved in various aspects of transcription and RNA processing. The prevalence of this mechanism among essential chromosome instability (CIN) genes remains unclear. In a secondary screen for increased Rad52 foci in CIN mutants, representing approximately 25% of essential genes, we identified seven essential subunits of the mRNA cleavage and polyadenylation (mCP) machinery. Genome-wide analysis of fragile sites by chromatin immunoprecipitation (ChIP) and microarray (ChIP-chip) of phosphorylated H2A in these mutants supported a transcription-dependent mechanism of DNA damage characteristic of R loops. In parallel, we directly detected increased RNA:DNA hybrid formation in mCP mutants and demonstrated that CIN is suppressed by expression of the R-loop-degrading enzyme RNaseH. To investigate the conservation of CIN in mCP mutants, we focused on FIP1L1, the human ortholog of yeast FIP1, a conserved mCP component that is part of an oncogenic fusion in eosinophilic leukemia. We found that truncation fusions of yeast FIP1 analogous to those in cancer cause loss of function and that siRNA knockdown of FIP1L1 in human cells increases DNA damage and chromosome breakage. Our findings illuminate how mCP maintains genome integrity by suppressing R-loop formation and suggest that this function may be relevant to certain human cancers.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Annotation Extension||Reference|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Assay||Construct||Conditions||Strain Background||Reference|