title: Coactivators for the orphan nuclear receptor RORalpha.
abstract: A mutation in the nuclear orphan receptor RORalpha results in a severe impairment of cerebellar development by unknown mechanisms. We have shown previously that RORalpha contains a strong constitutive activation domain in its C terminus. We therefore searched for mammalian RORalpha coactivators using the minimal activation domain as bait in a two-hybrid screen. Several known and putative coactivators were isolated, including glucocorticoid receptor-interacting protein-1 (GRIP-1) and peroxisome proliferator-activated receptor (PPAR)-binding protein (PBP/TRAP220/DRIP205). These interactions were confirmed in vitro and require the intact activation domain of RORalpha although different requirements for interaction with GRIP-1 and PBP were detected. Even in the absence of exogenous ligand, RORalpha interacts with a complex or complexes of endogenous proteins, similar to those that bind to ligand-occupied thyroid hormone and vitamin D receptors. Both PBP and GRIP-1 were shown to be present in these complexes. Thus we have identified several potential RORalpha coactivators that, in contrast to the interactions with hormone receptors, interact with RORalpha in yeast, in bacterial extracts, and in mammalian cells in vivo and in vitro in the absence of exogenous ligand. GRIP-1 functioned as a coactivator for the RORalpha both in yeast and in mammalian cells. Thus, GRIP-1 is the first proven coactivator for RORalpha.
authors.affiliation: Department of Medicine, The Penn Diabetes Center, University of Pennsylvania School of Medicine, Philadelphia 19104-6149, USA.
authors.forename: G B
authors.initials: GB
authors.lastname: Atkins
authors.forename: X
authors.initials: X
authors.lastname: Hu
authors.forename: M G
authors.initials: MG
authors.lastname: Guenther
authors.forename: C
authors.initials: C
authors.lastname: Rachez
authors.forename: L P
authors.initials: LP
authors.lastname: Freedman
authors.forename: M A
authors.initials: MA
authors.lastname: Lazar
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002457:Cell Extracts; D002460:Cell Line; D002474:Cell-Free System / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D060588:LIM Domain Proteins; D056913:Mediator Complex Subunit 1; D051379:Mice; D009154:Mutation; D051958:Nuclear Receptor Coactivator 2; D057094:Nuclear Receptor Subfamily 1, Group F, Member 1; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D002457:Cell Extracts; D060588:LIM Domain Proteins; C538855:MED1 protein, human; C538856:Med1 protein, mouse; D056913:Mediator Complex Subunit 1; C498001:NCOA2 protein, human; C498002:Ncoa2 protein, mouse; D051958:Nuclear Receptor Coactivator 2; D057094:Nuclear Receptor Subfamily 1, Group F, Member 1; C092282:PSMC5 protein, human; C539738:RORA protein, human; D018160:Receptors, Cytoplasmic and Nuclear; D015534:Trans-Activators; D014157:Transcription Factors; D046988:Proteasome Endopeptidase Complex; D000074183:ATPases Associated with Diverse Cellular Activities