Lysine Methylation of Progesterone Receptor at Activation Function 1 Regulates both Ligand-independent Activity and Ligand Sensitivity of the Receptor

作者：Chung Hwa Hwa; Sze Siu Kwan; Woo Amanda Rui En; Sun Yang; Sim Kae Hwan; Dong Xue Ming; Lin Valerie C L^*

来源：JOURNAL OF BIOLOGICAL CHEMISTRY, 2014, 289(9): 5704-5722.

DOI：10.1074/jbc.M113.522839

• Post-translational Modification
• Protein Methylation
• Steroid Hormone
• Steroid Hormone Receptor
• Transcription

Background: Activation function 1 (AF-1) is important for the activity of progesterone receptor (PR), but its functional motif is not known. Results: AF-1 of progesterone receptor (PR) is monomethylated at Lys-464. Lys-464 mutation markedly alters PR properties and ligand sensitivity. Conclusion: Lys-464 is critical for AF-1 function. Significance: Lys-464 is a potential target for modulating AF-1 activity of PR.
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.

• 出版日期2014-2-28
• 单位南阳理工学院