title: Ubiquitination-dependent cofactor exchange on LIM homeodomain transcription factors.
abstract: The interactions of distinct cofactor complexes with transcription factors are decisive determinants for the regulation of gene expression. Depending on the bound cofactor, transcription factors can have either repressing or transactivating activities. To allow a switch between these different states, regulated cofactor exchange has been proposed; however, little is known about the molecular mechanisms that are involved in this process. LIM homeodomain (LIM-HD) transcription factors associate with RLIM (RING finger LIM domain-binding protein) and with CLIM (cofactor of LIM-HD proteins; also known as NLI, Ldb and Chip) cofactors. The co-repressor RLIM inhibits the function of LIM-HD transcription factors, whereas interaction with CLIM proteins is important for the exertion of the biological activity conferred by LIM-HD transcription-factors. Here we identify RLIM as a ubiquitin protein ligase that is able to target CLIM cofactors for degradation through the 26S proteasome pathway. Furthermore, we demonstrate a ubiquitination-dependent association of RLIM with LIM-HD proteins in the presence of CLIM cofactors. Our data provide a mechanistic basis for cofactor exchange on DNA-bound transcription factors, and probably represent a general mechanism of transcriptional regulation.
authors.affiliation: Zentrum für Molekulare Neurobiologie Hamburg (ZMNH), Universität Hamburg, Martinistrasse 85, 20251 Hamburg, Germany.
authors.forename: Heather P
authors.initials: HP
authors.lastname: Ostendorff
authors.forename: Reto I
authors.initials: RI
authors.lastname: Peirano
authors.forename: Marvin A
authors.initials: MA
authors.lastname: Peters
authors.forename: Anne
authors.initials: A
authors.lastname: Schlüter
authors.forename: Michael
authors.initials: M
authors.lastname: Bossenz
authors.forename: Martin
authors.initials: M
authors.lastname: Scheffner
authors.forename: Ingolf
authors.initials: I
authors.lastname: Bach
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D004268:DNA-Binding Proteins / Q000378:metabolism; D006367:HeLa Cells; D018398:Homeodomain Proteins / Q000378:metabolism*; D006801:Humans; D060588:LIM Domain Proteins; D008025:Ligases / Q000378:metabolism; D008667:Metalloproteins / Q000378:metabolism; D051379:Mice; D010447:Peptide Hydrolases / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; C486312:LDB1 protein, human; C484572:LDB2 protein, human; D060588:LIM Domain Proteins; C085117:LMO2 protein, human; C102084:Ldb1 protein, mouse; C106649:Ldb2 protein, mouse; C513188:Lmo2 protein, mouse; D008667:Metalloproteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D025801:Ubiquitin; C492370:RLIM protein, human; C120758:Rlim protein, mouse; D044767:Ubiquitin-Protein Ligases; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D008025:Ligases