Sumoylation and proteasomal activity determine the transactivation properties of the mineralocorticoid receptor

Abstract

S0303-7207 (07) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.A c c e p t e d M a n u s c r i p t A c c e p t e d M a n u s c r i p t A c c e p t e d M a n u s c r i p t A c c e p t e d M a n u s c r i p t HA-MR AbstractMR is a hormone-activated transcription factor that carries a strong synergy inhibitory function at its N-terminus. Using this region as bait in a yeast twohybrid screening, we isolated major components of the sumoylation pathway, including the SUMO-1-conjugating enzyme Ubc9, and SUMO-1 itself. We found that MR interacts with both, Ubc9 and SUMO-1 in mammalian cells, and that the receptor is sumoylated at four acceptor sites which are clustered within its AF-1 domain. We observed that MR can be poly-ubiquitinated and that proteasome activity is essential for MR-activated transcription. Disruption of the SUMO-1 attachment sites abolished MR sumoylation but interfered with neither the polyubiquitination of the receptor nor its transactivation potential on MMTV. However, the hormone-activated mutant displayed enhanced synergistic potential on a compound promoter and delayed mobility in the nucleus. FRAP analysis further showed that proteasome inhibition immobilizes a subpopulation of unliganded MR receptors in the nucleus, a phenomenon that is significantly attenuated in the presence of aldosterone. Interestingly, the ability of the hormone to counteract the immobilizing effect of MG132 requires the sumoylation-competent form of MR. Moreover, increasing exogenously SUMO-1 cellular levels, resulted in a selective, dose-dependent inhibition of the activity of the sumoylation-deficient MR. This effect was observed only on a synergy-competent promoter, revealing a mode for negative regulation of synergy that might involve sumoylation of factors different from MR. The data suggest that the overall transcriptional activity of MR can be modulated by its sumoylation potential as well as the sumoylation

Finerenone Impedes Aldosterone-dependent Nuclear Import of the Mineralocorticoid Receptor and Prevents Genomic Recruitment of Steroid Receptor Coactivator-1

“…Interestingly we also showed that this aldosterone-induced MR phosphorylation is associated with a reduction in the MR protein level, as was previously described (53). Interestingly, Tirard et al (54) reported that a robust proteasome activity is required for optimal MR transactivation. Interestingly, finerenone likewise spironolactone totally blocked the aldosterone-induced MR phosphorylation, as well as its degradation, indicating that the antagonist compounds not only regulate receptor subcellular trafficking but also inhibit its turnover.…”

Bag‐1M inhibits the transactivation of the glucocorticoid receptor via recruitment of corepressors

“…However, our finding is consistent with the observation that several nuclear receptors including GR are ubiquitinated and degraded in the course of their nuclear activities [21][22][23][24][25][26]. In addition to receptors, studies have revealed that coactivators, including steroid receptor coactivator 1 (SRC1), SRC2, SRC3, CBP and E6-associated protein (E6-AP), could also be ubiquitinated and degraded, through the proteosome, in order to disassemble and reassemble coactivator complexes, thereby promoting enhanced transcription [27].…”

Mechanisms Underlying the Control of Progesterone Receptor Transcriptional Activity by SUMOylation

“…Mineralocorticoid receptors are SUMOylated at four acceptor sites clustered around AF-1. Their mutation allows mineralocorticoid receptors to synergistically activate a compound promoter but not the single palindromic PRE of the mouse mammary tumor virus promoter (38). GR are modified by SUMO-1 in vivo (39) and contain three consensus SUMO attachment sites, two in the N terminus at Lys-277 and Lys-293 in AF-1 and one in the LBD at Lys-703 (40).…”