title: SUMO-1 modification of PIASy, an E3 ligase, is necessary for PIASy-dependent activation of Tcf-4.
abstract: We have previously shown that modification of Tcf-4, a transcription factor in the Wnt pathway, with SUMO by PIASy, a SUMO E3 ligase, enhances its transcriptional activity. Since PIASy itself was also modified with SUMO-1, we studied the role of sumoylation of PIASy in the regulation of Tcf-4. Lys(35) was found to be a sumoylation site of PIASy. PIASy(K35R), in which Lys(35) was mutated to Arg, did not enhance sumoylation of Tcf-4, although this PIASy mutant did not lose the ligase activity of sumoylation for other proteins. Wild-type PIASy and PIASy(K35R) showed a distinct distribution in the nucleus, although both were colocalized with Tcf-4. Promyelocytic leukemia protein, which is involved in transcriptional regulation, was associated with PIASy(K35R) more frequently than wild-type PIASy in the nucleus. PIASy(K35R) could not stimulate the transcriptional activity of Tcf-4 under the conditions in which wild-type PIASy enhanced it. Conjugation of SUMO-1 to the amino terminus of PIASy(K35R) neither enhanced sumoylation of Tcf-4 nor stimulated the transcriptional activity of Tcf-4. These results suggest that sumoylation of Lys(35) in PIASy determines the nuclear localization of PIASy and that it is necessary for PIASy-dependent sumoylation and transcriptional activation of Tcf-4.
authors.affiliation: Department of Biochemistry, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
authors.forename: Motomasa
authors.initials: M
authors.lastname: Ihara
authors.forename: Hideki
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Akira
authors.initials: A
authors.lastname: Kikuchi
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D001120:Arginine / Q000378:metabolism; D002460:Cell Line; D002467:Cell Nucleus / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009363:Neoplasm Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D000075223:Poly-ADP-Ribose Binding Proteins; D000071156:Promyelocytic Leukemia Protein; D050828:Protein Inhibitors of Activated STAT; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D025842:SUMO-1 Protein / Q000502:physiology*; D051820:TCF Transcription Factors; D058118:Transcription Factor 7-Like 2 Protein; D014157:Transcription Factors / Q000032:analysis / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics / Q000502:physiology; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; C485891:PIAS4 protein, human; D000075223:Poly-ADP-Ribose Binding Proteins; D000071156:Promyelocytic Leukemia Protein; D050828:Protein Inhibitors of Activated STAT; D011993:Recombinant Fusion Proteins; D025842:SUMO-1 Protein; D051820:TCF Transcription Factors; C544894:TCF7L2 protein, human; D058118:Transcription Factor 7-Like 2 Protein; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C070576:PML protein, human; D001120:Arginine; D044767:Ubiquitin-Protein Ligases; D008239:Lysine