title: PIASy, a nuclear matrix-associated SUMO E3 ligase, represses LEF1 activity by sequestration into nuclear bodies.
abstract: The Wnt-responsive transcription factor LEF1 can activate transcription in association with beta-catenin and repress transcription in association with Groucho. In search of additional regulatory mechanisms of LEF1 function, we identified the protein inhibitor of activated STAT, PIASy, as a novel interaction partner of LEF1. Coexpression of PIASy with LEF1 results in potent repression of LEF1 activity and in covalent modification of LEF1 with SUMO. PIASy markedly stimulates the sumoylation of LEF1 and multiple other proteins in vivo and functions as a SUMO E3 ligase for LEF1 in a reconstituted system in vitro. Moreover, PIASy binds to nuclear matrix-associated DNA sequences and targets LEF1 to nuclear bodies, suggesting that PIASy-mediated subnuclear sequestration accounts for the repression of LEF1 activity.
authors.affiliation: Gene Center and Institute of Biochemistry, University of Munich, 81377 Munich, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Sachdev
authors.forename: L
authors.initials: L
authors.lastname: Bruhn
authors.forename: H
authors.initials: H
authors.lastname: Sieber
authors.forename: A
authors.initials: A
authors.lastname: Pichler
authors.forename: F
authors.initials: F
authors.lastname: Melchior
authors.forename: R
authors.initials: R
authors.lastname: Grosschedl
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D002875:Chromosomes / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008025:Ligases / Q000378:metabolism*; D051821:Lymphoid Enhancer-Binding Factor 1; D051379:Mice; D018613:Microscopy, Confocal; D016297:Mutagenesis, Site-Directed; D015530:Nuclear Matrix / Q000235:genetics / Q000378:metabolism*; D015388:Organelles / Q000378:metabolism*; D000075223:Poly-ADP-Ribose Binding Proteins; D011485:Protein Binding; D050828:Protein Inhibitors of Activated STAT; D021381:Protein Transport; D015398:Signal Transduction; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C497573:LEF1 protein, human; C497574:Lef1 protein, mouse; D051821:Lymphoid Enhancer-Binding Factor 1; C485891:PIAS4 protein, human; D000075223:Poly-ADP-Ribose Binding Proteins; D050828:Protein Inhibitors of Activated STAT; D025841:Small Ubiquitin-Related Modifier Proteins; D014157:Transcription Factors; D004247:DNA; D044767:Ubiquitin-Protein Ligases; D008025:Ligases