Oxidative stress-inducible truncated serine/arginine-rich splicing factor 3 regulates interleukin-8 production in human colon cancer cells

Shizuka Kano, Kensei Nishida, Hiroyuki Kurebe, Chihiro Nishiyama, Kentaro Kita, Yoko Akaike, Keisuke Kajita, Ken Kurokawa, Kiyoshi Masuda, Yuki Kuwano, Toshihito Tanahashi, Kazuhito Rokutan


Serine/arginine-rich splicing factor 3 (SRSF3) is a member of the SR protein family and plays wide-ranging roles in gene expression. The human SRSF3 gene generates two alternative splice transcripts, a major mRNA isoform (SRSF3-FL) encoding functional full-length protein and a premature termination codon (PTC)-containing isoform (SRSF3-PTC). The latter is degraded through nonsense-mediated mRNA decay (NMD). Treatment of a human colon cancer cell line (HCT116) with 100 μM sodium arsenite increased SRSF3-PTC mRNA levels without changing SRSF3-FL mRNA levels. A chemiluminescence-based NMD reporter assay system demonstrated that arsenite treatment inhibited NMD activity and increased SRSF3-PTC mRNA levels in the cytoplasm, facilitating translation of a truncated SRSF3 protein (SRSF3-TR) from SRSF3-PTC mRNA. SRSF3-TR lacked two-thirds of the Arg/Ser-rich (RS) domain whose phosphorylation state is known to be crucial for subcellular distribution. SRSF3-FL was localized in the nucleus, while overexpressed SRSF3-TR was diffusely distributed in the cytoplasm and the nucleus. A part of SRSF3-TR was also associated with stress granules in the cytoplasm. Interestingly, treatment of HCT116 cells with a small interference RNA specifically targeting SRSF3-PTC mRNA significantly attenuated arsenite-stimulated induction of c-JUN protein, its binding activity to the AP-1 binding site (−126 to 120 bp) in the interleukin (IL)-8 gene promoter, and AP-1 promoter activity, resulting in significant reduction of arsenite-stimulated IL-8 production. Our results suggest that SRSF3-TR may function as a positive regulator of oxidative stress-initiated inflammatory responses in colon cancer cells.

  • SRSF3 gene
  • oxidative stress
  • alternative splicing
  • nonsense-mediated mRNA decay
  • IL-8
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