title: The transcriptional coactivator PGC-1 regulates the expression and activity of the orphan nuclear receptor estrogen-related receptor alpha (ERRalpha).
abstract: The estrogen-related receptor alpha (ERRalpha) is one of the first orphan nuclear receptors identified. Still, we know little about the mechanisms that regulate its expression and its activity. In this study, we show that the transcriptional coactivator PGC-1, which is implicated in the control of energy metabolism, regulates ERRalpha at two levels. First, PGC-1 induces the expression of ERRalpha. Consistent with this induction, levels of ERRalpha mRNA in vivo are highest in PGC-1 expressing tissues, such as heart, kidney, and muscle, and up-regulated in response to signals that induce PGC-1, such as exposure to cold. Second, PGC-1 interacts physically with ERRalpha and enables it to activate transcription. Strikingly, we find that PGC-1 converts ERRalpha from a factor with little or no transcriptional activity to a potent regulator of gene expression, suggesting that ERRalpha is not a constitutively active nuclear receptor but rather one that is regulated by protein ligands, such as PGC-1. Our findings suggest that the two proteins act in a common pathway to regulate processes relating to energy metabolism. In support of this hypothesis, adenovirus-mediated delivery of small interfering RNA for ERRalpha, or of PGC-1 mutants that interact selectively with different types of nuclear receptors, shows that PGC-1 can induce the fatty acid oxidation enzyme MCAD (medium-chain acyl-coenzyme A dehydrogenase) in an ERRalpha-dependent manner.
authors.affiliation: Division of Biochemistry, Biozentrum of the University of Basel, Klingelbergstrasse 70, CH 4056 Basel, Switzerland.
authors.forename: Sylvia N
authors.initials: SN
authors.lastname: Schreiber
authors.forename: Darko
authors.initials: D
authors.lastname: Knutti
authors.forename: Kathrin
authors.initials: K
authors.lastname: Brogli
authors.forename: Thomas
authors.initials: T
authors.lastname: Uhlmann
authors.forename: Anastasia
authors.initials: A
authors.lastname: Kralli
mesh_terms: D042964:Acyl-CoA Dehydrogenase; D000256:Adenoviridae / Q000235:genetics; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D044943:Fatty Acid Desaturases / Q000378:metabolism; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D009154:Mutation; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014018:Tissue Distribution; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D020798:Two-Hybrid System Techniques; D015854:Up-Regulation; D000097983:ERRalpha Estrogen-Related Receptor
chemical_list: D042964:Acyl-CoA Dehydrogenase; D044943:Fatty Acid Desaturases; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D012313:RNA; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D011960:Receptors, Estrogen; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D000097983:ERRalpha Estrogen-Related Receptor; C111264:peroxisome-proliferator-activated receptor-gamma coactivator-1