title: Distinct functional modes of SUMOylation for retinoid X receptor alpha.
abstract: The present study investigated human retinoid X receptor alpha (hRXRα) as a substrate for modification with small ubiquitin like modifier (SUMO) and how members of the protein inhibitor of activated STAT (PIAS) family may impact upon this process. In agreement with a previous study, we validate Ubc9 to facilitate SUMOylation of hRXRα at lysine 108 but note this modification to occur for all isoforms rather than specifically with SUMO1 and to preferentially occur with the unliganded form of hRXRα. SUMOylation of hRXRα is significantly enhanced through PIAS4-mediated activity with lysine 245 identified as a specific SUMO2 acceptor site modified in a PIAS4-dependent fashion. While individual mutations at lysine 108 or 245 modestly increase receptor activity, the combined loss of SUMOylation at both sites significantly potentiates the transcriptional responsiveness of hRXRα suggesting both sites may cooperate in a DNA element-dependent context. Our findings highlight combinatorial effects of SUMOylation may regulate RXRα-directed signalling in a gene-specific fashion.
authors.affiliation: School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, Northern Ireland, UK.
authors.forename: Wai-Ping
authors.initials: WP
authors.lastname: Lee
authors.affiliation: School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, Northern Ireland, UK.
authors.forename: Sarita
authors.initials: S
authors.lastname: Jena
authors.affiliation: School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, Northern Ireland, UK.
authors.forename: E Patricia
authors.initials: EP
authors.lastname: Rodriguez
authors.affiliation: School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, Northern Ireland, UK.
authors.forename: Sinead P
authors.initials: SP
authors.lastname: O'Donovan
authors.affiliation: School of Mathematical and Natural Sciences, Arizona State University, Glendale, AZ, 85306, USA.
authors.forename: Carl
authors.initials: C
authors.lastname: Wagner
authors.affiliation: School of Mathematical and Natural Sciences, Arizona State University, Glendale, AZ, 85306, USA.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Jurutka
authors.affiliation: School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, Northern Ireland, UK. Electronic address: p.thompson@ulster.ac.uk.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Thompson
mesh_terms: D057809:HEK293 Cells; D006801:Humans; D008239:Lysine / Q000378:metabolism; D009154:Mutation; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D000075223:Poly-ADP-Ribose Binding Proteins; D050828:Protein Inhibitors of Activated STAT / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D047490:Retinoid X Receptor alpha / Q000235:genetics / Q000378:metabolism*; D025842:SUMO-1 Protein / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D058207:Sumoylation; D014162:Transfection; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics / Q000378:metabolism*; D000098843:Ubiquitin-Conjugating Enzyme UBC9
chemical_list: C485891:PIAS4 protein, human; D000075223:Poly-ADP-Ribose Binding Proteins; D050828:Protein Inhibitors of Activated STAT; D020033:Protein Isoforms; D047490:Retinoid X Receptor alpha; D025842:SUMO-1 Protein; C495501:SUMO1 protein, human; D044763:Ubiquitin-Conjugating Enzymes; D000098843:Ubiquitin-Conjugating Enzyme UBC9; D008239:Lysine
keywords: PIAS; Retinoid X receptor; SUMO; Transcription