The Progesterone Receptor Hinge Region Regulates the Kinetics of Transcriptional Responses Through Acetylation, Phosphorylation, and Nuclear Retention

Abstract

Progesterone receptors (PRs) are critical regulators of mammary gland development and contributors to breast cancer progression. Posttranslational modifications of PR have been shown to alter hormone responsiveness. Site-directed mutagenesis demonstrated that upon hormone binding, PR is acetylated at the consensus sequence, KXKK (amino acids 638-641), located within the hinge region. We created an acetylation-deficient (K-A) mutant as well as acetylation mimics (K-Q or K-T). Interestingly, similar to K-A PR, PR acetylation mimics (K-Q or K-T) displayed delayed phosphorylation and nuclear entry relative to wild-type (wt) PR-B, indicative of disruption of PR nuclear-cytoplasmic shuttling. Wt PR-B, but not K-mutant PRs, induced c-myc at 1 h of progestin treatment. However, at 6 h of treatment, c-myc induction was comparable with levels induced by wt PR-B, suggesting that the precise timing of PR phosphorylation and nuclear retention are critical for cells to rapidly initiate robust transcriptional programs. In contrast to c-myc, progestin-induced serum- and glucocorticoid-regulated kinase (SGK) expression displayed sensitivity to PR acetylation but not nuclear entry. Namely, in the presence of progestin, acetylation-deficient (K-A) mutant PR-B up-regulated SGK mRNA relative to wt PR; progesterone response element-luciferase assays confirmed this result. However, K-Q and K-T acetylation mimics only weakly induced SGK expression independently of nuclear retention. These data reveal the ability of PR acetylation to alter the magnitude of transcriptional response at selected (slow response) promoters (SGK), whereas the hinge region dictates the kinetics of the transcriptional response to hormone at other (rapid response) promoters (c-myc). In sum, the PR hinge region is multifunctional. Understanding the ability of this region to couple acetylation, phosphorylation, and nuclear entry may provide clues to mechanisms of altered hormone responsiveness.

Histone Deacetylase Inhibition Attenuates Transcriptional Activity of Mineralocorticoid Receptor Through Its Acetylation and Prevents Development of Hypertension

“…32,33 Progesterone receptor hinge region regulates the kinetics of nuclear translocation and transcriptional responses of progesterone receptor through acetylation and phosphorylation. 34 Acetylation by circadian locomotor output cycles kaput/BMAL1 in the hinge region of GR results in reduced transcriptional activity. 24 However, acetylation of MR and its effect on physiology are unknown.…”

Hic-5 is a transcription coregulator that acts before and/or after glucocorticoid receptor genome occupancy in a gene-selective manner

“…GR has a transcriptional activation function called "tau2," mapped by deletion analysis to 29 amino acids (527-556 in human GR) that span the junction between the hinge and LBD (14). Hinge regions of other nuclear receptors are also important for transcriptional activation (15)(16)(17). Only a few coregulators that interact with the hinge region of nuclear receptors have been identified, including HEXIM1, JDP2, TAFII30, SNURF, ASC-1, BAF57, and hydrogen peroxide-inducible clone-5 (Hic-5, TGFB1I1) (18)(19)(20)(21)(22)(23)(24).…”

Modifications to glucocorticoid and progesterone receptors alter cell fate in breast cancer

“…Like GR (discussed earlier), PR is heavily modified (Clemm et al 2000), and PTMs to PR greatly alter its transcriptional activity at selected target genes or gene subsets (Daniel et al 2010, Knutson et al 2012, Hagan et al 2013, enacting expression of highly contextdependent transcriptomes by complex mechanisms. Notably, the concentration of steroid hormone required for half-maximal induction or repression by a given receptor-steroid complex (i.e.…”

“…Additionally, progestin-induced breast cancer cell proliferation and spreading/focal adhesion were impaired upon loss of PR monomethylation (Chung et al 2014). Similarly, ligand-induced PR acetylation at Lys138 and at residues 638-641 in the hinge region of PR has been studied (Daniel et al 2010, Chung et al 2014. Notably, acetylation of PR at Lys138 by p300 resulted in increased Ser294 phosphorylation.…”