Biology subjects

Chang, M. R.

Publications and source records attributed to Chang, M. R..

4 recordsLinked to original sources

bioRxiv2024

Acetylation of RORβ by lysine acetyltransferase p300 and deacetylation by SIRT1 modulates receptor stability, turnover and transcriptional activity.

Retinoic acid receptor-related orphan receptor beta (ROR{beta}) is a transcription factor expressed in the central nervous system, retina, and bone that regulates circadian rhythms, retinal neurogenesis, and inflammatory signaling. Despite these critical functions, the mechanisms governing ROR{beta} stability remain poorly understood. Here, we identify a post-translational regulatory axis in which the lysine acetyltransferase p300 and the NAD-dependent deacetylase SIRT1 control ROR{beta} stability and transcriptional activity. p300-mediated acetylation increases ROR{beta} abundance, while SIRT1 modulates turnover through both catalytic and non-catalytic scaffolding mechanisms. K176 acetylation in the hinge primes UBC9/PIAS1-mediated SUMOylation at nearby K179, marking ROR{beta} for proteasomal degradation and reducing transcriptional output, providing a mechanistic framework for targeting ROR{beta} in neurological and retinal disorders, and bone homeostasis. HighlightsO_LIp300 acetylates ROR{beta} at eight lysines; SIRT1 reverses this via catalytic activity C_LIO_LIK176 acetylation primes UBC9/PIAS1-mediated SUMOylation at nearby K179 C_LIO_LISUMOylated ROR{beta} undergoes proteasomal degradation leading to reduced ROR{beta}-mediated transcriptional output C_LIO_LIp300 displaces ubiquitin E3 ligases from ROR{beta}; SIRT1 activation reduces PIAS1 association C_LI In BriefOLeary et al. define a post-translational circuit in which p300 acetylates K176 within the ROR{beta} hinge domain, priming SUMOylation at nearby K179 preferentially by UBC9/PIAS1. SUMOylated ROR{beta} is targeted for proteasomal degradation with diminished transcriptional activity, while SIRT1 deacetylase activity antagonizes this pathway via both catalytic activity and protein-protein interactions to stabilize active ROR{beta}. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=103 SRC="FIGDIR/small/621067v3_ufig1.gif" ALT="Figure 1"> View larger version (18K): org.highwire.dtl.DTLVardef@16f18fforg.highwire.dtl.DTLVardef@d2208corg.highwire.dtl.DTLVardef@156d829org.highwire.dtl.DTLVardef@898e48_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2022

RORβ modulates a gene program that is protective against articular cartilage damage

Osteoarthritis (OA) is the most prevalent chronic joint disease which increases in frequency with age eventually impacting most people over the age of 65. OA is the leading cause of disability and impaired mobility, yet the pathogenesis of OA remains unclear. Treatments have focused mainly on pain relief and reducing joint swelling. Currently there are no effective treatments to slow the progression of the disease and to prevent irreversible loss of cartilage. Here we demonstrate that stable expression of ROR{beta} in cultured cells results in alteration of a gene program that is supportive of chondrogenesis and is protective against development of OA. Specifically, we determined that ROR{beta} regulates the balance of FGFRs signaling on FGFR1/FGFR3 that ERK1/2-MAPK signaling was suppressed by FGFR1(cartilage destruction) and AKT signaling was enhanced by FGFR3 (cartilage protection). These results suggest a critical role for ROR{beta} in chondrogenesis and suggest that identification of mechanisms that control the expression of ROR{beta} in chondrocytes could lead to the development of disease modifying therapies for the treatment of OA.

cell biology↗

bioRxiv2021

Conformational Changes of RORγ During Response Element Recognition and Coregulator Engagement.

The retinoic acid receptor-related orphan receptor {gamma} (ROR{gamma}) is a ligand-dependent transcription factor of the nuclear receptor super family that underpins metabolic activity, immune function, and cancer progression. Despite being a valuable drug target in health and disease, our understanding of the ligand-dependent activities of ROR{gamma} is far from complete. Like most nuclear receptors, ROR{gamma} must recruit coregulatory protein to enact the ROR{gamma} target gene program. To date, a majority of structural studies have been focused exclusively on the ROR{gamma} ligand-binding domain and the ligand-dependent recruitment of small peptide segments of coregulators. Herein, we examine the ligand-dependent assembly of full length ROR{gamma}:coregulator complexes on cognate DNA response elements using structural proteomics and small angle x-ray scattering. The results from our studies suggest that ROR{gamma} becomes elongated upon DNA recognition, preventing long range interdomain crosstalk. We also determined that the DNA binding domain adopts a sequence-specific conformation, and that coregulatory proteins may be able to sense the ligand- and DNA-bound status of ROR{gamma}. We propose a model where ligand-dependent coregulator recruitment may be influenced by the sequence of the DNA to which ROR{gamma} is bound. Overall, the efforts described herein will illuminate important aspects of full length ROR{gamma} and monomeric orphan nuclear receptor target gene regulation through DNA-dependent conformational changes. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=81 SRC="FIGDIR/small/445650v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@1f0a067org.highwire.dtl.DTLVardef@b2e9f6org.highwire.dtl.DTLVardef@1e15d5org.highwire.dtl.DTLVardef@12b8546_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

bioRxiv2019

HDX-MS reveals structural determinants for RORγ hyperactivation by synthetic agonists

Members of the nuclear receptor (NR) superfamily regulate both physiological and pathophysiological processes ranging from development and metabolism1 to inflammation2 and cancer3. As ligand-gated transcription factors, synthetic small molecules targeting NRs are often deployed as therapeutics to correct aberrant NR signaling or as chemical probes to explore the role of the receptor in physiology4. However, nearly half of NRs do not have specific cognate ligands or its unclear if they possess ligand dependent activities and these receptors are called orphans. Here we demonstrate that ligand-dependent action of the orphan nuclear receptor ROR{gamma} can be defined by selectively disrupting putative endogenous--but not synthetic--ligand binding. Furthermore, the characterization of a library of ROR{gamma} modulators reveals that structural dynamics of the receptor assessed by HDX-MS correlate with activity in biochemical and cell-based assays. These findings are corroborated with X-ray co-crystallography and site-directed mutagenesis to collectively reveal the structural determinants of ROR{gamma} ligand-dependent activation, critical for designing full agonists for application in cancer immunotherapy. Combined these observations support a model of receptor activation to more accurately describe ROR{gamma} pharmacology. Likewise, this bump-and-hole inspired approach could be extended to other orphan NRs to explore the ligand-dependent activities that are important for defining pharmacology.

biophysics↗