title: HuR regulates alternative splicing of the TRA2β gene in human colon cancer cells under oxidative stress.
abstract: Hu antigen R (HuR) regulates stress responses through stabilizing and/or facilitating the translation of target mRNAs. The human TRA2β gene encodes splicing factor transformer 2β (Tra2β) and generates 5 mRNA isoforms (TRA2β1 to -5) through alternative splicing. Exposure of HCT116 colon cancer cells to sodium arsenite stimulated checkpoint kinase 2 (Chk2)- and mitogen-activated protein kinase p38 (p38(MAPK))-mediated phosphorylation of HuR at positions S88 and T118. This induced an association between HuR and the 39-nucleotide (nt) proximal region of TRA2β exon 2, generating a TRA2β4 mRNA that includes exon 2, which has multiple premature stop codons. HuR knockdown or Chk2/p38(MAPK) double knockdown inhibited the arsenite-stimulated production of TRA2β4 and increased Tra2β protein, facilitating Tra2β-dependent inclusion of exons in target pre-mRNAs. The effects of HuR knockdown or Chk2/p38(MAPK) double knockdown were also confirmed using a TRA2β minigene spanning exons 1 to 4, and the effects disappeared when the 39-nt region was deleted from the minigene. In endogenous HuR knockdown cells, the overexpression of a HuR mutant that could not be phosphorylated (with changes of serine to alanine at position 88 [S88A], S100A, and T118A) blocked the associated TRA2β4 interaction and TRA2β4 generation, while the overexpression of a phosphomimetic HuR (with mutations S88D, S100D, and T118D) restored the TRA2β4-related activities. Our findings revealed the potential role of nuclear HuR in the regulation of alternative splicing programs under oxidative stress.
authors.affiliation: Department of Stress Science, Institute of Health Biosciences, Tokushima University Graduate School, Tokushima, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Akaike
authors.affiliation: Department of Stress Science, Institute of Health Biosciences, Tokushima University Graduate School, Tokushima, Japan Department of Human Genetics and Public Health, Institute of Health Bioscience, Tokushima University Graduate School, Tokushima, Japan kiyoshim@tokushima-u.ac.jp.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Masuda
authors.affiliation: Department of Stress Science, Institute of Health Biosciences, Tokushima University Graduate School, Tokushima, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kuwano
authors.affiliation: Department of Stress Science, Institute of Health Biosciences, Tokushima University Graduate School, Tokushima, Japan.
authors.forename: Kensei
authors.initials: K
authors.lastname: Nishida
authors.affiliation: Department of Stress Science, Institute of Health Biosciences, Tokushima University Graduate School, Tokushima, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kajita
authors.affiliation: Department of Stress Science, Institute of Health Biosciences, Tokushima University Graduate School, Tokushima, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Kurokawa
authors.affiliation: Department of Stress Science, Institute of Health Biosciences, Tokushima University Graduate School, Tokushima, Japan.
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Satake
authors.affiliation: Department of Human Genetics and Public Health, Institute of Health Bioscience, Tokushima University Graduate School, Tokushima, Japan.
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Shoda
authors.affiliation: Department of Human Genetics and Public Health, Institute of Health Bioscience, Tokushima University Graduate School, Tokushima, Japan.
authors.forename: Issei
authors.initials: I
authors.lastname: Imoto
authors.affiliation: Department of Stress Science, Institute of Health Biosciences, Tokushima University Graduate School, Tokushima, Japan.
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Rokutan
mesh_terms: D017398:Alternative Splicing / Q000187:drug effects / Q000235:genetics*; D018053:Arsenites / Q000494:pharmacology; D045744:Cell Line, Tumor; D064447:Checkpoint Kinase 2 / Q000235:genetics / Q000378:metabolism; D003110:Colonic Neoplasms / Q000235:genetics* / Q000378:metabolism; D051959:ELAV Proteins / Q000235:genetics* / Q000378:metabolism; D005091:Exons / Q000187:drug effects / Q000235:genetics; D045325:HCT116 Cells; D006801:Humans; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics*; D010766:Phosphorylation / Q000187:drug effects / Q000235:genetics; D060066:Protein Interaction Maps / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D000068103:Serine-Arginine Splicing Factors; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D018053:Arsenites; D051959:ELAV Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C097083:TRA2B protein, human; D000068103:Serine-Arginine Splicing Factors; D064447:Checkpoint Kinase 2; C578634:CHEK2 protein, human; D048051:p38 Mitogen-Activated Protein Kinases; C015001:arsenite