title: Lysine methylation of progesterone receptor at activation function 1 regulates both ligand-independent activity and ligand sensitivity of the receptor.
abstract: Progesterone receptor (PR) exists in two isoforms, PRA and PRB, and both contain activation functions AF-1 and AF-2. It is believed that AF-1 is primarily responsible for the ligand-independent activity, whereas AF-2 mediates ligand-dependent PR activation. Although more than a dozen post-translational modifications of PR have been reported, no post-translational modification on AF-1 or AF-2 has been reported. Using LC-MS/MS-based proteomic analysis, this study revealed AF-1 monomethylation at Lys-464. Mutational analysis revealed the remarkable importance of Lys-464 in regulating PR activity. Single point mutation K464Q or K464A led to ligand-independent PR gel upshift similar to the ligand-induced gel upshift. This upshift was associated with increases in both ligand-dependent and ligand-independent PR phosphorylation and PR activity due to the hyperactivation of AF-1. In contrast, mutation of Lys-464 to the bulkier phenylalanine to mimic the effect of methylation caused a drastic decrease in PR activity. Importantly, PR-K464Q also showed heightened ligand sensitivity, and this was associated with increases in its functional interaction with transcription co-regulators NCoR1 and SRC-1. These results suggest that monomethylation of PR at Lys-464 probably has a repressive effect on AF-1 activity and ligand sensitivity.
authors.affiliation: From the School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.
authors.forename: Hwa Hwa
authors.initials: HH
authors.lastname: Chung
authors.forename: Siu Kwan
authors.initials: SK
authors.lastname: Sze
authors.forename: Amanda Rui En
authors.initials: AR
authors.lastname: Woo
authors.forename: Yang
authors.initials: Y
authors.lastname: Sun
authors.forename: Kae Hwan
authors.initials: KH
authors.lastname: Sim
authors.forename: Xue Ming
authors.initials: XM
authors.lastname: Dong
authors.forename: Valerie C-L
authors.initials: VC
authors.lastname: Lin
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D006801:Humans; D008024:Ligands; D008239:Lysine; D008745:Methylation; D020125:Mutation, Missense; D056971:Nuclear Receptor Co-Repressor 1 / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000502:physiology; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011980:Receptors, Progesterone / Q000235:genetics / Q000378:metabolism*
chemical_list: D008024:Ligands; C539127:NCOR1 protein, human; D056971:Nuclear Receptor Co-Repressor 1; D020033:Protein Isoforms; D011980:Receptors, Progesterone; D008239:Lysine
keywords: Post-translational Modification; Protein Methylation; Steroid Hormone; Steroid Hormone Receptor; Transcription