title: Esterase 1 is a novel transcriptional repressor of growth hormone receptor gene expression: a unique noncatalytic role for a carboxyesterase protein.
abstract: The pleiotropic actions of GH result from its engagement with the GH receptor (GHR). GHR expression is regulated by free fatty acids (FFA). A cDNA phage expression library was screened to identify a phage clone expressing esterase 1 (ES1) binding to the FFA-response element (FARE), L2-D1, in the murine GHR promoter. Ectopically expressed ES1 inhibited GHR promoter activity via effects at two FARE, L2-D1 and L2-A2. Chromatin immunoprecipitation experiments demonstrated specific association of ES1 with the FARE. Catalytically inactive ES1 retained inhibitory activity on the GHR promoter and excluded the possibility that the effect on the GHR promoter was an indirect effect secondary to ES1's actions on the intracellular metabolism of FFA. Ectopically expressed ES1 inhibited the endogenous GHR mRNA and protein expression in 3T3-F442A preadipocytes. Subcellular fractionation and confocal microscopy established that ES1 localizes both to the cytoplasm and the nucleus. Experiments demonstrated chromosome region maintenance 1-dependent nuclear export and the presence of a functional nuclear export signal in ES1. The domain of ES1 responsible for the effect on the GHR promoter was localized to the C-terminal portion of the protein. The in vivo significance of ES1's effect on GHR expression was suggested by decreased liver GHR mRNA expression in mice on a high-fat diet correlating with increased steady-state abundance of liver ES1 mRNA. Our results identify and characterize ES1 as a novel transcriptional regulator of GHR gene expression, thereby establishing a unique nonenzymatic role for a carboxyesterase and expanding the potential biological roles of this protein superfamily.
authors.affiliation: Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan 48109-5718, USA.
authors.forename: Jinhong
authors.initials: J
authors.lastname: Sun
authors.forename: P Anil
authors.initials: PA
authors.lastname: Kumar
authors.forename: Jamuna
authors.initials: J
authors.lastname: Thimmarayappa
authors.forename: Natinder
authors.initials: N
authors.lastname: Saini
authors.forename: Pooja
authors.initials: P
authors.lastname: Goel
authors.forename: Travis
authors.initials: T
authors.lastname: Maures
authors.forename: Chunxia
authors.initials: C
authors.lastname: Lu
authors.forename: Ram K
authors.initials: RK
authors.lastname: Menon
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D055162:Biocatalysis / Q000187:drug effects; D043182:Carboxylesterase / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D004041:Dietary Fats / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D050505:Mutant Proteins / Q000378:metabolism; D049790:Nuclear Export Signals; D011485:Protein Binding / Q000187:drug effects; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011986:Receptors, Somatotropin / Q000235:genetics*; D012097:Repressor Proteins / Q000378:metabolism*; D020218:Response Elements / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D018076:DNA, Complementary; D004041:Dietary Fats; D050505:Mutant Proteins; D049790:Nuclear Export Signals; D020033:Protein Isoforms; D012333:RNA, Messenger; D011986:Receptors, Somatotropin; D012097:Repressor Proteins; D043182:Carboxylesterase; C469486:Ces1c protein, mouse