The 2.0-A crystal structure of the ligand-binding domain (LBD) of the human retinoic acid receptor (RAR)-gamma bound to all-trans retinoic acid reveals the ligand-binding interactions and suggests an electrostatic guidance mechanism. The overall fold is similar to that of the human RXR-alpha apo-LBD, except for the carboxy-terminal part which folds back towards the LBD core, contributing to the hydrophobic ligand pocket and 'sealing' its entry site. We propose a 'mouse trap' mechanism whereby a ligand-induced conformational transition repositions the amphipathic alpha-helix of the AF-2 activating domain and forms a transcriptionally active receptor.
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http://dx.doi.org/10.1038/378681a0 | DOI Listing |
Curr Top Dev Biol
January 2025
Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, OH, United States.
Alterations in tissue expression levels of both retinol-binding protein 2 (RBP2) and retinol-binding protein 4 (RBP4) have been associated with metabolic disease, specifically with obesity, glucose intolerance and hepatic steatosis. Our laboratories have shown that this involves novel pathways not previously considered as possible linkages between impaired retinoid metabolism and metabolic disease development. We have established both biochemically and structurally that RBP2 binds with very high affinity to very long-chain unsaturated 2-monoacylglycerols like the canonical endocannabinoid 2-arachidonoyl glycerol (2-AG) and other endocannabinoid-like substances.
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January 2025
Université de Strasbourg, IGBMC UMR 7104, Illkirch, France; CNRS, UMR 7104, Illkirch, France; Inserm, UMR-S 1258, Illkirch, France; IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France. Electronic address:
In mammals, differentiation of germ cells is crucial for sexual reproduction, involving complex signaling pathways and environmental cues defined by the somatic cells of the gonads. This review examines the long-standing model positing that all-trans retinoic acid (ATRA) acts as a meiosis-inducing substance (MIS) in the fetal ovary by inducing expression of STRA8 in female germ cells, while CYP26B1 serves as a meiosis-preventing substance (MPS) in the fetal testis by degrading ATRA and preventing STRA8 expression in the male germ cells until postnatal development. Recent genetic studies in the mouse challenge this paradigm, revealing that meiosis initiation in female germ cells can occur independently of ATRA signaling, with key roles played by other intrinsic factors like DAZL and DMRT1, and extrinsic signals such as BMPs and vitamin C.
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January 2025
Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY, United States. Electronic address:
Retinoic acid (RA) signaling plays multiple essential roles in development of the head and face. Animal models with mutations in genes involved in RA signaling have enabled understanding of craniofacial morphogenic processes that are regulated by the retinoid pathway. During craniofacial morphogenesis RA signaling is active in spatially restricted domains defined by the expression of genes involved in RA production and RA breakdown.
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January 2025
Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, United States. Electronic address:
Animals perceiving light through visual pigments have evolved pathways for absorbing, transporting, and metabolizing the precursors essential for synthesis of their retinylidene chromophores. Over the past decades, our understanding of this metabolism has grown significantly. Through genetic manipulation, researchers gained insights into the metabolic complexity of the pathways mediating the flow of chromophore precursors throughout the body, and their enrichment within the eyes.
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January 2025
University of Michigan, Department of Pharmacology, Caswell Diabetes Institute, Ann Arbor, MI, United States. Electronic address:
All-trans retinoic acid (ATRA) signaling is essential in numerous different biological contexts. This review highlights the diverse roles of ATRA during development, function, and diseases of the pancreas. ATRA is essential to specify pancreatic progenitors from gut tube endoderm, endocrine and exocrine differentiation, and adult islet function.
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