title: Fast skeletal muscle troponin I is a co-activator of estrogen receptor-related receptor alpha.
abstract: ERRalpha (estrogen receptor-related receptor alpha) is a member of the nuclear receptor superfamily. To further our understanding of the detailed molecular mechanism of transcriptional regulation by ERRalpha, we searched for ERRalpha-interacting proteins using a yeast two-hybrid system by screening a human mammary gland cDNA expression library with the ligand-binding domain (LBD) of ERRalpha as the "bait". Fast skeletal muscle troponin I (TNNI2), along with several known nuclear receptor co-activators, were isolated. We demonstrated that TNNI2 localizes to the cell nucleus and interacts with ERRalpha in co-immunoprecipitation experiments. GST pull-down assays also revealed that TNNI2 interacts directly with ERRalpha. Through luciferase reporter gene assays, TNNI2 was found to enhance the transactivity of ERRalpha. Combining mutagenesis and yeast two-hybrid assays, we mapped the ERRalpha-interacting domain on TNNI2 to a region encompassing amino acids 1-128. These findings reveal a new function for TNNI2 as a co-activator of ERRalpha.
authors.affiliation: Department of Biochemistry and Molecular Biology, Third Military Medical University, No. 30 Gaotanyan Street, Chongqing 400038, China.
authors.forename: Yuping
authors.initials: Y
authors.lastname: Li
authors.forename: Bin
authors.initials: B
authors.lastname: Chen
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
authors.forename: Guiyu
authors.initials: G
authors.lastname: Lou
authors.forename: Shiuan
authors.initials: S
authors.lastname: Chen
authors.forename: Dujin
authors.initials: D
authors.lastname: Zhou
mesh_terms: D001665:Binding Sites; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism; D004252:DNA Mutational Analysis; D005453:Fluorescence; D017930:Genes, Reporter; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D008156:Luciferases / Q000235:genetics; D017434:Protein Structure, Tertiary; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D014158:Transcription, Genetic; D019210:Troponin I / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D000097983:ERRalpha Estrogen-Related Receptor
chemical_list: D008156:Luciferases; D011960:Receptors, Estrogen; D019210:Troponin I; D000097983:ERRalpha Estrogen-Related Receptor; C518658:TNNI2 protein, human