Steroid receptor coactivators – their role in immunity

Steroid Receptor Coactivators (SRCs) are essential regulators of transcription with a wide range of impact on human physiology and pathology. In immunology, SRCs play multiple roles; they are involved in the regulation of nuclear factor-κB (NF-κB), macrophage (MΦ) activity, lymphoid cells proliferation, development and function, to name just a few. The three SRC family members, SRC-1, SRC-2 and SRC-3, can exert their immunological function either in an independent manner or act in synergy with each other. In certain biological contexts, one SRC family member can compensate for lack of activity of another member, while in other cases one SRC can exert a biological function that competes against the function of another family counterpart. In this review we illustrate the diverse biological functionality of the SRCs with regard to their role in immunity. In the light of recent development of SRC small molecule inhibitors and stimulators, we discuss their potential relevance as modulators of the immunological activity of the SRCs for therapeutic purposes

A scoring system for the follow up study of nuclear receptor coactivator complexes

We have systematically isolated a variety of coactivator complexes from HeLa S3 cells using proteomic approaches. In the present report, we have evaluated twelve coactivator complexes involved in nuclear receptor-dependent gene transcription that have been purified by using an immunoprecipitation method. The twelve purified coactivator complexes are SRC-1, SRC-2, SRC-3, CBP, p300, CAPER, E6-AP, ASC-1, CoREST, CRSP3, CRSP2, and CDK7 containing complexes. We have identified 153 protein components associated with these coactivator complexes using mass spectrometry. In order to systematically characterize the functional roles for these components in nuclear receptor-dependent gene transcription and their investigative potential, we have developed a scoring system. This scoring system is comprised of biological and experimental parameters. The biological evaluation considers aspects such as intrinsic enzymatic activity of a protein component, cellular signaling processes in which protein components may be involved, associations with human disease, specific protein motifs, and the known biological roles of other interacting partners of the identified protein. In the experimental evaluation, we include parameters, such as the availability of research materials for the functional study of the identified protein component; such as full-length cDNA clones, antibodies, and commercially available knock-out embryonic stem (ES) cells. Each scoring parameter has been assigned an arbitrary number of points according to perceived relative importance. On the basis of this scoring system, we prioritized each of the protein components in terms of the likelihood of their importance for coactivator complex networking in nuclear receptor-dependent gene transcription

12-h clock regulation of genetic information flow by XBP1s

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Pan, Y., Ballance, H., Meng, H., Gonzalez, N., Kim, S., Abdurehman, L., York, B., Chen, X., Schnytzer, Y., Levy, O., Dacso, C. C., McClung, C. A., O'Malley, B. W., Liu, S., & Zhu, B. 12-h clock regulation of genetic information flow by XBP1s. Plos Biology, 18(1), (2020): e3000580, doi:10.1371/journal.pbio.3000580.Our group recently characterized a cell-autonomous mammalian 12-h clock independent from the circadian clock, but its function and mechanism of regulation remain poorly understood. Here, we show that in mouse liver, transcriptional regulation significantly contributes to the establishment of 12-h rhythms of mRNA expression in a manner dependent on Spliced Form of X-box Binding Protein 1 (XBP1s). Mechanistically, the motif stringency of XBP1s promoter binding sites dictates XBP1s’s ability to drive 12-h rhythms of nascent mRNA transcription at dawn and dusk, which are enriched for basal transcription regulation, mRNA processing and export, ribosome biogenesis, translation initiation, and protein processing/sorting in the Endoplasmic Reticulum (ER)-Golgi in a temporal order consistent with the progressive molecular processing sequence described by the central dogma information flow (CEDIF). We further identified GA-binding proteins (GABPs) as putative novel transcriptional regulators driving 12-h rhythms of gene expression with more diverse phases. These 12-h rhythms of gene expression are cell autonomous and evolutionarily conserved in marine animals possessing a circatidal clock. Our results demonstrate an evolutionarily conserved, intricate network of transcriptional control of the mammalian 12-h clock that mediates diverse biological pathways. We speculate that the 12-h clock is coopted to accommodate elevated gene expression and processing in mammals at the two rush hours, with the particular genes processed at each rush hour regulated by the circadian and/or tissue-specific pathways.This study was supported by the American Diabetes Association junior faculty development award 1-18-JDF-025 to B.Z., by funding from National Institute of Health HD07879 and 1P01DK113954 to B.W.O, by funding from National Science Foundation award 1703170 to C.C.D. and B.Z., and by funding from Brockman Foundation to C.C.D and B.W.O. This work was further supported by the UPMC Genome Center with funding from UPMC’s Immunotherapy and Transplant Center. This research was supported in part by the University of Pittsburgh Center for Research Computing through the resources provided. Research reported in this publication was further supported by the National Institute of Diabetes And Digestive And Kidney Diseases of the National Institutes of Health under award number P30DK120531 to Pittsburgh Liver Research Center, in which both S.L. and B.Z. are members. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Progesterone receptors: a key for neuroprotection in experimental stroke

Progesterone receptors (PR) are expressed throughout the brain. However, their functional significance remains understudied. Here we report a novel role of PR as crucial mediators of neuroprotection using a model of transient middle cerebral artery occlusion and PR knockout mice. Six hours after ischemia, we observed a rapid increase in progesterone and 5-dihydroprogesterone, the endogenous PR ligands, a process that may be a part of the natural neuroprotective mechanisms. PR deficiency, and even haploinsufficiency, increases the susceptibility of the brain to stroke damage. Within a time window of 24 h, PR-dependent signaling of endogenous brain progesterone limits the extent of tissue damage and the impairment of motor functions. Longer-term improvement requires additional treatment with exogenous progesterone and is also PR dependent. The potent and selective PR agonist Nestorone is also effective. In contrast to progesterone, levels of the neurosteroid allopregnanolone, which modulates -aminobutyric acid type A receptors, did not increase after stroke, but its administration protected both wild-type and PR-deficient mice against ischemic damage. These results show that 1) PR are linked to signaling pathways that influence susceptibility to stroke, and 2) PR are direct key targets for both endogenous neuroprotection and for therapeutic strategies after stroke, and they suggest a novel indication for synthetic progestins already validated for contraception. Although allopregnanolone may not be an endogenous neuroprotective agent, its administration protects the brain against ischemicdamageby signaling mechanisms not involving PR. Collectively, our data clarify the relative roles of PR and allopregnanolone in neuroprotection after stroke.Fil: Liu, Ailing. Institut National de la Santé et de la Recherche Médicale; Francia. Université Paris Sud; FranciaFil: Margaill, Isabelle. Institut National de la Santé et de la Recherche Médicale; Francia. Universite de Paris V; Francia. University Paris Descartes; FranciaFil: Zhang, Shaodong. Institut National de la Santé et de la Recherche Médicale; Francia. Université Paris Sud; FranciaFil: Labombarda, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Bioquímica Humana; ArgentinaFil: Coqueran, Bérard. Institut National de la Santé et de la Recherche Médicale; Francia. Universite de Paris V; FranciaFil: Delespierre, Brigitte. Université Paris Sud; Francia. Institut National de la Santé et de la Recherche Médicale; FranciaFil: Liere, Philippe. Université Paris Sud; Francia. Institut National de la Santé et de la Recherche Médicale; FranciaFil: Marchand Leroux, Catherine. Institut National de la Santé et de la Recherche Médicale; Francia. Universite de Paris V; FranciaFil: O’Malley, Bert W.. Baylor College of Medicine;Fil: Lydon, John P.. Baylor College of Medicine;Fil: de Nicola, Alejandro Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Sitruk Ware, Regine. The Rockefeller University; Estados UnidosFil: Mattern, Claudia. MetP Pharma AG; SuizaFil: Plotkine, Michel. Universite de Paris V; FranciaFil: Schumacher, Michael. Institut National de la Santé et de la Recherche Médicale; Francia. Université Paris Sud; FranciaFil: Guennoun, Rachida. Université Paris Sud; Francia. Institut National de la Santé et de la Recherche Médicale; Franci

Interplay between estrogen receptor and AKT in estradiol-induced alternative splicing.

BACKGROUND: Alternative splicing is critical for generating complex proteomes in response to extracellular signals. Nuclear receptors including estrogen receptor alpha (ERα) and their ligands promote alternative splicing. The endogenous targets of ERα:estradiol (E2)-mediated alternative splicing and the influence of extracellular kinases that phosphorylate ERα on E2-induced splicing are unknown. METHODS: MCF-7 and its anti-estrogen derivatives were used for the majority of the assays. CD44 mini gene was used to measure the effect of E2 and AKT on alternative splicing. ExonHit array analysis was performed to identify E2 and AKT-regulated endogenous alternatively spliced apoptosis-related genes. Quantitative reverse transcription polymerase chain reaction was performed to verify alternative splicing. ERα binding to alternatively spliced genes was verified by chromatin immunoprecipitation assay. Bromodeoxyuridine incorporation-ELISA and Annexin V labeling assays were done to measure cell proliferation and apoptosis, respectively. RESULTS: We identified the targets of E2-induced alternative splicing and deconstructed some of the mechanisms surrounding E2-induced splicing by combining splice array with ERα cistrome and gene expression array. E2-induced alternatively spliced genes fall into at least two subgroups: coupled to E2-regulated transcription and ERα binding to the gene without an effect on rate of transcription. Further, AKT, which phosphorylates both ERα and splicing factors, influenced ERα:E2 dependent splicing in a gene-specific manner. Genes that are alternatively spliced include FAS/CD95, FGFR2, and AXIN-1. E2 increased the expression of FGFR2 C1 isoform but reduced C3 isoform at mRNA level. E2-induced alternative splicing of FAS and FGFR2 in MCF-7 cells correlated with resistance to FAS activation-induced apoptosis and response to keratinocyte growth factor (KGF), respectively. Resistance of MCF-7 breast cancer cells to the anti-estrogen tamoxifen was associated with ERα-dependent overexpression of FGFR2, whereas resistance to fulvestrant was associated with ERα-dependent isoform switching, which correlated with altered response to KGF. CONCLUSION: E2 may partly alter cellular proteome through alternative splicing uncoupled to its effects on transcription initiation and aberration in E2-induced alternative splicing events may influence response to anti-estrogens.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Urban Renewal in the Nucleus: Is Protein Turnover by Proteasomes Absolutely Required for Nuclear Receptor-Regulated Transcription?

Abstract The importance of the ubiquitin proteasome pathway in higher eukaryotes has been well established in cell cycle regulation, signal transduction, and cell differentiation, but has only recently been linked to nuclear hormone receptor-regulated gene transcription. Characterization of a number of ubiquitin proteasome pathway enzymes as coactivators and observations that several nuclear receptors are ubiquitinated and degraded in the course of their nuclear activities provide evidence that ubiquitin proteasome-mediated protein degradation plays an integral role in eukaryotic transcription. In addition to receptors, studies have revealed that coactivators are ubiquitinated and degraded via the proteasome. The notion that the ubiquitin proteasome pathway is involved in gene transcription is further strengthened by the fact that ubiquitin proteasome pathway enzymes are recruited to the promoters of target genes and that proteasome-dependent degradation of nuclear receptors is required for efficient transcriptional activity. These findings suggest that protein degradation is coupled with nuclear receptor coactivation activity. It is possible that the ubiquitin proteasome pathway modulates transcription by promoting remodeling and turnover of the nuclear receptor-transcription complex. In this review, we discus the possible role of the ubiquitin proteasome pathway in nuclear hormone receptor-regulated gene transcription