Serine/arginine-rich splicing factor 3 (SRSF3) regulates homologous recombination-mediated DNA repair.
BACKGROUND
Our previous work found that serine/arginine-rich splicing factor 3 (SRSF3) was overexpressed in human ovarian cancer and the overexpression of SRSF3 was required for ovarian cancer cell growth and survival. The mechanism underlying the role of SRSF3 in ovarian cancer remains to be addressed.


METHODS
We conducted microarray analysis to profile the gene expression and splicing in SRSF3-knockdown cells and employed quantitative PCR and western blotting to validate the profiling results. We used chromatin immunoprecipitation to study transcription and the direct repeat green fluorescent protein reporter assay to study homologous recombination-mediated DNA repair (HRR).


RESULTS
We identified 687 genes with altered expression and 807 genes with altered splicing in SRSF3-knockdown cells. Among expression-altered genes, those involved in HRR, including BRCA1, BRIP1 and RAD51, were enriched and were all downregulated. We demonstrated that the downregulation of BRCA1, BRIP1 and RAD51 expression was caused by decreased transcription and not due to increased nonsense-mediated mRNA decay. Further, we found that SRSF3 knockdown impaired HRR activity in the cell and increased the level of γ-H2AX, a biomarker for double-strand DNA breaks. Finally, we observed that SRSF3 knockdown changed splicing pattern of KMT2C, a H3K4-specific histone methyltransferase, and reduced the levels of mono- and trimethylated H3K4.


CONCLUSIONS
These results suggest that SRSF3 is a new regulator of HRR process, which possibly regulates the expression of HRR-related genes indirectly through an epigenetic pathway. This new function of SRSF3 not only explains why overexpression of SRSF3 is required for ovarian cancer cell growth and survival but also offers a new insight into the mechanism of the neoplastic transformation.
Department of Biopharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago-Rockford Campus, 1601 Parkview Avenue, Room N308, Rockford, IL, 61107, USA. xiaohe@uic.edu.|University of Illinois Cancer Center, University of Illinois at Chicago, Chicago, IL, USA. xiaohe@uic.edu.
Xiaolong
X
He
Department of Biopharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago-Rockford Campus, 1601 Parkview Avenue, Room N308, Rockford, IL, 61107, USA. pezhang@uic.edu.
Pei
P
Zhang
D017398:Alternative Splicing / Q000235:genetics; D063646:Carcinogenesis / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000235:genetics; D053903:DNA Breaks, Double-Stranded; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006801:Humans; D009363:Neoplasm Proteins / Q000096:biosynthesis*; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000473:pathology; D016601:RNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D059767:Recombinational DNA Repair / Q000235:genetics*; D000068103:Serine-Arginine Splicing Factors
D009363:Neoplasm Proteins; D016601:RNA-Binding Proteins; C491388:SRSF3 protein, human; D000068103:Serine-Arginine Splicing Factors