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Zonnefeld AG, Cui CY, Tsitsipatis D, Piao Y, Fan J, Mazan-Mamczarz K, Xue Y, Indig FE, De S, Gorospe M. Characterization of age-associated gene expression changes in mouse sweat glands. Aging (Albany NY) 2024; 16:6717-6730. [PMID: 38637019 PMCID: PMC11087089 DOI: 10.18632/aging.205776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 03/18/2024] [Indexed: 04/20/2024]
Abstract
Evaporation of sweat on the skin surface is the major mechanism for dissipating heat in humans. The secretory capacity of sweat glands (SWGs) declines during aging, leading to heat intolerance in the elderly, but the mechanisms responsible for this decline are poorly understood. We investigated the molecular changes accompanying SWG aging in mice, where sweat tests confirmed a significant reduction of active SWGs in old mice relative to young mice. We first identified SWG-enriched mRNAs by comparing the skin transcriptome of Eda mutant Tabby male mice, which lack SWGs, with that of wild-type control mice by RNA-sequencing analysis. This comparison revealed 171 mRNAs enriched in SWGs, including 47 mRNAs encoding 'core secretory' proteins such as transcription factors, ion channels, ion transporters, and trans-synaptic signaling proteins. Among these, 28 SWG-enriched mRNAs showed significantly altered abundance in the aged male footpad skin, and 11 of them, including Foxa1, Best2, Chrm3, and Foxc1 mRNAs, were found in the 'core secretory' category. Consistent with the changes in mRNA expression levels, immunohistology revealed that higher numbers of secretory cells from old SWGs express the transcription factor FOXC1, the protein product of Foxc1 mRNA. In sum, our study identified mRNAs enriched in SWGs, including those that encode core secretory proteins, and altered abundance of these mRNAs and proteins with aging in mouse SWGs.
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Affiliation(s)
- Alexandra G. Zonnefeld
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Chang-Yi Cui
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Dimitrios Tsitsipatis
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Yulan Piao
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Jinshui Fan
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Krystyna Mazan-Mamczarz
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Yutong Xue
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Fred E. Indig
- Confocal Imaging Core Facility, National Institute on Aging Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Supriyo De
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Myriam Gorospe
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
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Leung M, Steinman J, Li D, Lor A, Gruesen A, Sadah A, van Kuijk FJ, Montezuma SR, Kondkar AA, Radhakrishnan R, Lobo GP. The Logistical Backbone of Photoreceptor Cell Function: Complementary Mechanisms of Dietary Vitamin A Receptors and Rhodopsin Transporters. Int J Mol Sci 2024; 25:4278. [PMID: 38673863 PMCID: PMC11050646 DOI: 10.3390/ijms25084278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 04/02/2024] [Accepted: 04/04/2024] [Indexed: 04/28/2024] Open
Abstract
In this review, we outline our current understanding of the mechanisms involved in the absorption, storage, and transport of dietary vitamin A to the eye, and the trafficking of rhodopsin protein to the photoreceptor outer segments, which encompasses the logistical backbone required for photoreceptor cell function. Two key mechanisms of this process are emphasized in this manuscript: ocular and systemic vitamin A membrane transporters, and rhodopsin transporters. Understanding the complementary mechanisms responsible for the generation and proper transport of the retinylidene protein to the photoreceptor outer segment will eventually shed light on the importance of genes encoded by these proteins, and their relationship on normal visual function and in the pathophysiology of retinal degenerative diseases.
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Affiliation(s)
- Matthias Leung
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Jeremy Steinman
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Dorothy Li
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Anjelynt Lor
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Andrew Gruesen
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Ahmed Sadah
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Frederik J. van Kuijk
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Sandra R. Montezuma
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Altaf A. Kondkar
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh 12271, Saudi Arabia;
| | - Rakesh Radhakrishnan
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Glenn P. Lobo
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
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Chen S, Pan Z, Liu M, Guo L, Jiang X, He G. Recent Advances on Small-Molecule Inhibitors of Lipocalin-like Proteins. J Med Chem 2024; 67:5144-5167. [PMID: 38525852 DOI: 10.1021/acs.jmedchem.4c00086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2024]
Abstract
Lipid transfer proteins (LTPs) are crucial players in nonvesicular lipid trafficking. LTPs sharing a lipocalin lipid transfer domain (lipocalin-like proteins) have a wide range of biological functions, such as regulating immune responses and cell proliferation, differentiation, and death as well as participating in the pathogenesis of inflammatory, metabolic, and neurological disorders and cancer. Therefore, the development of small-molecule inhibitors targeting these LTPs is important and has potential clinical applications. Herein, we summarize the structure and function of lipocalin-like proteins, mainly including retinol-binding proteins, lipocalins, and fatty acid-binding proteins and discuss the recent advances on small-molecule inhibitors for these protein families and their applications in disease treatment. The findings of our Perspective can provide guidance for the development of inhibitors of these LTPs and highlight the challenges that might be faced during the procedures.
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Affiliation(s)
- Siliang Chen
- Department of Dermatology & Venerology, West China Hospital, Sichuan University, Chengdu 610041, China
- Laboratory of Dermatology, Clinical Institute of Inflammation and Immunology, Frontiers Science Center for Disease-related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Zhaoping Pan
- Department of Dermatology & Venerology, West China Hospital, Sichuan University, Chengdu 610041, China
- Laboratory of Dermatology, Clinical Institute of Inflammation and Immunology, Frontiers Science Center for Disease-related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Mingxia Liu
- Laboratory of Dermatology, Clinical Institute of Inflammation and Immunology, Frontiers Science Center for Disease-related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Linghong Guo
- Department of Dermatology & Venerology, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Xian Jiang
- Department of Dermatology & Venerology, West China Hospital, Sichuan University, Chengdu 610041, China
- Laboratory of Dermatology, Clinical Institute of Inflammation and Immunology, Frontiers Science Center for Disease-related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Gu He
- Department of Dermatology & Venerology, West China Hospital, Sichuan University, Chengdu 610041, China
- Laboratory of Dermatology, Clinical Institute of Inflammation and Immunology, Frontiers Science Center for Disease-related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
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4
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Fan C, Flood E, Sukomon N, Agarwal S, Allen TW, Nimigean CM. Calcium-gated potassium channel blockade via membrane-facing fenestrations. Nat Chem Biol 2024; 20:52-61. [PMID: 37653172 PMCID: PMC10847966 DOI: 10.1038/s41589-023-01406-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 07/18/2023] [Indexed: 09/02/2023]
Abstract
Quaternary ammonium blockers were previously shown to bind in the pore to block both open and closed conformations of large-conductance calcium-activated potassium (BK and MthK) channels. Because blocker entry was assumed through the intracellular entryway (bundle crossing), closed-pore access suggested that the gate was not at the bundle crossing. Structures of closed MthK, a Methanobacterium thermoautotrophicum homolog of BK channels, revealed a tightly constricted intracellular gate, leading us to investigate the membrane-facing fenestrations as alternative pathways for blocker access directly from the membrane. Atomistic free energy simulations showed that intracellular blockers indeed access the pore through the fenestrations, and a mutant channel with narrower fenestrations displayed no closed-state TPeA block at concentrations that blocked the wild-type channel. Apo BK channels display similar fenestrations, suggesting that blockers may use them as access paths into closed channels. Thus, membrane fenestrations represent a non-canonical pathway for selective targeting of specific channel conformations, opening novel ways to selectively drug BK channels.
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Affiliation(s)
- Chen Fan
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden
| | - Emelie Flood
- School of Science, RMIT University, Melbourne, Victoria, Australia
- Schrödinger, Inc., New York, NY, USA
| | - Nattakan Sukomon
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA
| | - Shubhangi Agarwal
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA
| | - Toby W Allen
- School of Science, RMIT University, Melbourne, Victoria, Australia.
| | - Crina M Nimigean
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA.
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA.
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5
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Est CB, Murphy RM. An in vitro model for vitamin A transport across the human blood-brain barrier. eLife 2023; 12:RP87863. [PMID: 37934575 PMCID: PMC10629827 DOI: 10.7554/elife.87863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023] Open
Abstract
Vitamin A, supplied by the diet, is critical for brain health, but little is known about its delivery across the blood-brain barrier (BBB). Brain microvascular endothelial-like cells (BMECs) differentiated from human-derived induced pluripotent stem cells (iPSCs) form a tight barrier that recapitulates many of the properties of the human BBB. We paired iPSC-derived BMECs with recombinant vitamin A serum transport proteins, retinol-binding protein (RBP), and transthyretin (TTR), to create an in vitro model for the study of vitamin A (retinol) delivery across the human BBB. iPSC-derived BMECs display a strong barrier phenotype, express key vitamin A metabolism markers, and can be used for quantitative modeling of retinol accumulation and permeation. Manipulation of retinol, RBP, and TTR concentrations, and the use of mutant RBP and TTR, yielded novel insights into the patterns of retinol accumulation in, and permeation across, the BBB. The results described herein provide a platform for deeper exploration of the regulatory mechanisms of retinol trafficking to the human brain.
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Affiliation(s)
- Chandler B Est
- Department of Chemical and Biological Engineering, University of WisconsinMadisonUnited States
| | - Regina M Murphy
- Department of Chemical and Biological Engineering, University of WisconsinMadisonUnited States
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6
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DiKun KM, Gudas LJ. Vitamin A and retinoid signaling in the kidneys. Pharmacol Ther 2023; 248:108481. [PMID: 37331524 PMCID: PMC10528136 DOI: 10.1016/j.pharmthera.2023.108481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 05/18/2023] [Accepted: 06/14/2023] [Indexed: 06/20/2023]
Abstract
Vitamin A (VA, retinol) and its metabolites (commonly called retinoids) are required for the proper development of the kidney during embryogenesis, but retinoids also play key roles in the function and repair of the kidney in adults. Kidneys filter 180-200 liters of blood per day and each kidney contains approximately 1 million nephrons, which are often referred to as the 'functional units' of the kidney. Each nephron consists of a glomerulus and a series of tubules (proximal tubule, loop of Henle, distal tubule, and collecting duct) surrounded by a network of capillaries. VA is stored in the liver and converted to active metabolites, most notably retinoic acid (RA), which acts as an agonist for the retinoic acid receptors ((RARs α, β, and γ) to regulate gene transcription. In this review we discuss some of the actions of retinoids in the kidney after injury. For example, in an ischemia-reperfusion model in mice, injury-associated loss of proximal tubule (PT) differentiation markers occurs, followed by re-expression of these differentiation markers during PT repair. Notably, healthy proximal tubules express ALDH1a2, the enzyme that metabolizes retinaldehyde to RA, but transiently lose ALDH1a2 expression after injury, while nearby myofibroblasts transiently acquire RA-producing capabilities after injury. These results indicate that RA is important for renal tubular injury repair and that compensatory mechanisms exist for the generation of endogenous RA by other cell types upon proximal tubule injury. ALDH1a2 levels also increase in podocytes, epithelial cells of the glomeruli, after injury, and RA promotes podocyte differentiation. We also review the ability of exogenous, pharmacological doses of RA and receptor selective retinoids to treat numerous kidney diseases, including kidney cancer and diabetic kidney disease, and the emerging genetic evidence for the importance of retinoids and their receptors in maintaining or restoring kidney function after injury. In general, RA has a protective effect on the kidney after various types of injuries (eg. ischemia, cytotoxic actions of chemicals, hyperglycemia related to diabetes). As more research into the actions of each of the three RARs in the kidney is carried out, a greater understanding of the actions of vitamin A is likely to lead to new insights into the pathology of kidney disorders and the development of new therapies for kidney diseases.
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Affiliation(s)
- Krysta M DiKun
- Department of Pharmacology, Weill Cornell Medical College of Cornell University, New York, NY, USA; New York Presbyterian Hospital, New York, NY, USA; Weill Cornell Graduate School of Medical Sciences, New York, NY, USA
| | - Lorraine J Gudas
- Department of Pharmacology, Weill Cornell Medical College of Cornell University, New York, NY, USA; Department of Urology, Weill Cornell Medicine, New York, NY, USA; New York Presbyterian Hospital, New York, NY, USA; Weill Cornell Graduate School of Medical Sciences, New York, NY, USA.
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7
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Est CB, Murphy RM. An in vitro model for vitamin A transport across the human blood-brain barrier. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.11.536348. [PMID: 37090623 PMCID: PMC10120720 DOI: 10.1101/2023.04.11.536348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Vitamin A, supplied by the diet, is critical for brain health, but little is known about its delivery across the blood-brain barrier (BBB). Brain microvascular endothelial-like cells (BMECs) differentiated from human-derived induced pluripotent stem cells (iPSC) form a tight barrier that recapitulates many of the properties of the human BBB. We paired iPSC-derived BMECs with recombinant vitamin A serum transport proteins, retinol binding protein (RBP) and transthyretin (TTR), to create an in vitro model for the study of vitamin A (retinol) delivery across the human BBB. iPSC-derived BMECs display a strong barrier phenotype, express key vitamin A metabolism markers and can be used for quantitative modeling of retinol accumulation and permeation. Manipulation of retinol, RBP and TTR concentrations, and the use of mutant RBP and TTR, yielded novel insights into the patterns of retinol accumulation in, and permeation across, the BBB. The results described herein provide a platform for deeper exploration of the regulatory mechanisms of retinol trafficking to the human brain.
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Affiliation(s)
| | - Regina M. Murphy
- Department of Chemical and Biological Engineering, University of Wisconsin – Madison 1415 Engineering Dr., Madison, WI 53706
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He W, Cheng Z, Huo Z, Lin B, Wang X, Sun Y, Yu S, Cao S, Xue J, Liu R, Lv W, Li Y, Hong S, Xiao H. STRA6 Promotes Thyroid Carcinoma Progression via Activation of the ILK/AKT/mTOR Axis in Cells and Female Nude Mice. Endocrinology 2023; 164:6967061. [PMID: 36592123 DOI: 10.1210/endocr/bqac215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 12/24/2022] [Accepted: 12/28/2022] [Indexed: 01/03/2023]
Abstract
BACKGROUND Metastasis has emerged to be an important cause for poor prognosis of thyroid carcinoma (TC) and its molecular mechanisms are not fully understood. STRA6 is a multifunctional membrane protein widely expressed in embryonic and adult tissues. The function and mechanism of STRA6 in TC remain elusive. OBJECTIVE We aimed to explore the role of STRA6 in TC progression and provide a therapeutic target for TC. METHODS The expression and clinicopathological relevance of STRA6 were explored in TC. Stable STRA6-knockdown TC cells were established and used to determine the biological function of STRA6 in vitro and in vivo. RNA sequencing and co-immunoprecipitation were performed to unveil the molecular mechanism of STRA6 in TC progression. The potential of STRA6 as a therapeutic target was evaluated by lipid nanoparticles (LNPs) containing siRNA. RESULTS STRA6 was upregulated in TC and correlated with aggressive clinicopathological features, including extrathyroidal extension and lymph node metastasis, which contributed to the poor prognosis of TC. STRA6 facilitated TC progression by enhancing proliferation and metastasis in vitro and in vivo. Mechanistically, STRA6 could interact with integrin-linked kinase (ILK) and subsequently activate the protein kinase B/mechanistic target of rapamycin (AKT/mTOR) signaling pathway. We further unveiled that STRA6 reprogrammed lipid metabolism through SREBP1, which was crucial for the metastasis of TC. Moreover, STRA6 siRNA delivered by LNPs significantly inhibited cell growth in xenograft tumor models. CONCLUSIONS Our study demonstrates the critical roles of STRA6 contributing to TC progression via the ILK/AKT/mTOR axis, which may provide a novel prognostic marker as well as a promising therapeutic target for aggressive TC.
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Affiliation(s)
- Weiman He
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Zhen Cheng
- Department of Pulmonary Oncology, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524000, China
| | - Zijun Huo
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Bo Lin
- Department of Thyroid Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Xuejie Wang
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Yijia Sun
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Shuang Yu
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Siting Cao
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Junyu Xue
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Rengyun Liu
- Institute of Precision Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Weiming Lv
- Department of Thyroid Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Yanbing Li
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Shubin Hong
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Haipeng Xiao
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China
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9
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Radhakrishnan R, Leung M, Solanki AK, Lobo GP. Mapping of the extracellular RBP4 ligand binding domain on the RBPR2 receptor for Vitamin A transport. Front Cell Dev Biol 2023; 11:1105657. [PMID: 36910150 PMCID: PMC9992173 DOI: 10.3389/fcell.2023.1105657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 02/07/2023] [Indexed: 02/24/2023] Open
Abstract
The distribution of dietary vitamin A/all-trans retinol/ROL throughout the body is critical for maintaining retinoid function in peripheral tissues and for retinoid delivery to the eye in the support of visual function. In the circulation, all-trans-retinol bound to the RBP4 protein is transported and sequestered into target tissues for long-term storage. Two membrane receptors that facilitate all-trans retinol uptake from RBP4 have been proposed. While it is well established that the membrane receptor, STRA6, binds to circulatory RBP4 for ROL transport into the eye, the second vitamin A receptor, RBPR2, which is expressed in non-ocular tissues, is less characterized. Based on the structural homology between these two RBP4 receptors, published literature, and from our recent work in Rbpr2 -/- deficient mice, we hypothesized that RBPR2 might also have high-binding affinity for RBP4 and this mechanism facilitates ROL transport. Herein, we aimed to elucidate the membrane topology and putative RBP4 binding residues on RBPR2 to understand its physiological function for retinoid homeostasis. Using in silico analysis and site-directed mutagenesis, we identified a potential RBP4 binding domain on RBPR2. We employed an in vitro cell-based system and confirmed that mutations of these residues on RBPR2 affected its binding to exogenous RBP4 and subsequently vitamin A uptake. Using Surface Plasmon Resonance assays, we analyzed both the binding affinities and kinetic parameters of wild-type RBPR2 and individual mutants affecting the RBPR2-RBP4 binding domain with its physiological ligand RBP4. These studies not only revealed a putative RBP4 binding domain on RBPR2 but also provided new structural, biochemical, and critical information on its proposed role in RBP4 binding for ROL transport and retinoid homeostasis.
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Affiliation(s)
- Rakesh Radhakrishnan
- Department of Ophthalmology, University of Minnesota, Minneapolis, MN, United States
| | - Matthias Leung
- Department of Ophthalmology, University of Minnesota, Minneapolis, MN, United States
| | - Ashish K Solanki
- Department of Medicine, Medical University of South Carolina, Charleston, SC, United States
| | - Glenn P Lobo
- Department of Ophthalmology, University of Minnesota, Minneapolis, MN, United States.,Department of Medicine, Medical University of South Carolina, Charleston, SC, United States.,Department of Ophthalmology, Medical University of South Carolina, Charleston, SC, United States
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10
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Young BD, Cook ME, Costabile BK, Samanta R, Zhuang X, Sevdalis SE, Varney KM, Mancia F, Matysiak S, Lattman E, Weber DJ. Binding and Functional Folding (BFF): A Physiological Framework for Studying Biomolecular Interactions and Allostery. J Mol Biol 2022; 434:167872. [PMID: 36354074 PMCID: PMC10871162 DOI: 10.1016/j.jmb.2022.167872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 09/20/2022] [Accepted: 10/24/2022] [Indexed: 11/06/2022]
Abstract
EF-hand Ca2+-binding proteins (CBPs), such as S100 proteins (S100s) and calmodulin (CaM), are signaling proteins that undergo conformational changes upon increasing intracellular Ca2+. Upon binding Ca2+, S100 proteins and CaM interact with protein targets and induce important biological responses. The Ca2+-binding affinity of CaM and most S100s in the absence of target is weak (CaKD > 1 μM). However, upon effector protein binding, the Ca2+ affinity of these proteins increases via heterotropic allostery (CaKD < 1 μM). Because of the high number and micromolar concentrations of EF-hand CBPs in a cell, at any given time, allostery is required physiologically, allowing for (i) proper Ca2+ homeostasis and (ii) strict maintenance of Ca2+-signaling within a narrow dynamic range of free Ca2+ ion concentrations, [Ca2+]free. In this review, mechanisms of allostery are coalesced into an empirical "binding and functional folding (BFF)" physiological framework. At the molecular level, folding (F), binding and folding (BF), and BFF events include all atoms in the biomolecular complex under study. The BFF framework is introduced with two straightforward BFF types for proteins (type 1, concerted; type 2, stepwise) and considers how homologous and nonhomologous amino acid residues of CBPs and their effector protein(s) evolved to provide allosteric tightening of Ca2+ and simultaneously determine how specific and relatively promiscuous CBP-target complexes form as both are needed for proper cellular function.
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Affiliation(s)
- Brianna D Young
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Mary E Cook
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Brianna K Costabile
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Riya Samanta
- Biophysics Graduate Program, University of Maryland, College Park, MD 20742, USA; Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
| | - Xinhao Zhuang
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Spiridon E Sevdalis
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Kristen M Varney
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Filippo Mancia
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Silvina Matysiak
- Biophysics Graduate Program, University of Maryland, College Park, MD 20742, USA; Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
| | - Eaton Lattman
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Physics, Arizona State University, Tempe, AZ 85287, USA
| | - David J Weber
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), Rockville, MD 20850, USA.
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11
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Ramchatesingh B, Martínez Villarreal A, Arcuri D, Lagacé F, Setah SA, Touma F, Al-Badarin F, Litvinov IV. The Use of Retinoids for the Prevention and Treatment of Skin Cancers: An Updated Review. Int J Mol Sci 2022; 23:ijms232012622. [PMID: 36293471 PMCID: PMC9603842 DOI: 10.3390/ijms232012622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 10/12/2022] [Accepted: 10/13/2022] [Indexed: 11/21/2022] Open
Abstract
Retinoids are natural and synthetic vitamin A derivatives that are effective for the prevention and the treatment of non-melanoma skin cancers (NMSC). NMSCs constitute a heterogenous group of non-melanocyte-derived skin cancers that impose substantial burdens on patients and healthcare systems. They include entities such as basal cell carcinoma and cutaneous squamous cell carcinoma (collectively called keratinocyte carcinomas), cutaneous lymphomas and Kaposi’s sarcoma among others. The retinoid signaling pathway plays influential roles in skin physiology and pathology. These compounds regulate diverse biological processes within the skin, including proliferation, differentiation, angiogenesis and immune regulation. Collectively, retinoids can suppress skin carcinogenesis. Both topical and systemic retinoids have been investigated in clinical trials as NMSC prophylactics and treatments. Desirable efficacy and tolerability in clinical trials have prompted health regulatory bodies to approve the use of retinoids for NMSC management. Acceptable off-label uses of these compounds as drugs for skin cancers are also described. This review is a comprehensive outline on the biochemistry of retinoids, their activities in the skin, their effects on cancer cells and their adoption in clinical practice.
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Affiliation(s)
| | | | - Domenico Arcuri
- Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H4A 3J1, Canada
| | - François Lagacé
- Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H4A 3J1, Canada
- Division of Dermatology, McGill University Health Center, Montreal, QC H4A 3J1, Canada
| | - Samy Abu Setah
- Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H4A 3J1, Canada
| | - Fadi Touma
- Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H4A 3J1, Canada
| | - Faris Al-Badarin
- Faculté de Médicine, Université Laval, Québec, QC G1V 0V6, Canada
| | - Ivan V. Litvinov
- Division of Experimental Medicine, McGill University, Montreal, QC H4A 3J1, Canada
- Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H4A 3J1, Canada
- Division of Dermatology, McGill University Health Center, Montreal, QC H4A 3J1, Canada
- Correspondence:
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12
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Das A, Imanishi Y. Drug Discovery Strategies for Inherited Retinal Degenerations. BIOLOGY 2022; 11:1338. [PMID: 36138817 PMCID: PMC9495580 DOI: 10.3390/biology11091338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 08/31/2022] [Accepted: 09/07/2022] [Indexed: 12/03/2022]
Abstract
Inherited retinal degeneration is a group of blinding disorders afflicting more than 1 in 4000 worldwide. These disorders frequently cause the death of photoreceptor cells or retinal ganglion cells. In a subset of these disorders, photoreceptor cell death is a secondary consequence of retinal pigment epithelial cell dysfunction or degeneration. This manuscript reviews current efforts in identifying targets and developing small molecule-based therapies for these devastating neuronal degenerations, for which no cures exist. Photoreceptors and retinal ganglion cells are metabolically demanding owing to their unique structures and functional properties. Modulations of metabolic pathways, which are disrupted in most inherited retinal degenerations, serve as promising therapeutic strategies. In monogenic disorders, great insights were previously obtained regarding targets associated with the defective pathways, including phototransduction, visual cycle, and mitophagy. In addition to these target-based drug discoveries, we will discuss how phenotypic screening can be harnessed to discover beneficial molecules without prior knowledge of their mechanisms of action. Because of major anatomical and biological differences, it has frequently been challenging to model human inherited retinal degeneration conditions using small animals such as rodents. Recent advances in stem cell-based techniques are opening new avenues to obtain pure populations of human retinal ganglion cells and retinal organoids with photoreceptor cells. We will discuss concurrent ideas of utilizing stem-cell-based disease models for drug discovery and preclinical development.
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Affiliation(s)
- Arupratan Das
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Yoshikazu Imanishi
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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13
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Reconnoitring the Usage of Agroindustrial Waste in Carotenoid Production for Food Fortification: a Sustainable Approach to Tackle Vitamin A Deficiency. FOOD BIOPROCESS TECH 2022. [DOI: 10.1007/s11947-022-02888-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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14
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Piper SJ, Johnson RM, Wootten D, Sexton PM. Membranes under the Magnetic Lens: A Dive into the Diverse World of Membrane Protein Structures Using Cryo-EM. Chem Rev 2022; 122:13989-14017. [PMID: 35849490 DOI: 10.1021/acs.chemrev.1c00837] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Membrane proteins are highly diverse in both structure and function and can, therefore, present different challenges for structure determination. They are biologically important for cells and organisms as gatekeepers for information and molecule transfer across membranes, but each class of membrane proteins can present unique obstacles to structure determination. Historically, many membrane protein structures have been investigated using highly engineered constructs or using larger fusion proteins to improve solubility and/or increase particle size. Other strategies included the deconstruction of the full-length protein to target smaller soluble domains. These manipulations were often required for crystal formation to support X-ray crystallography or to circumvent lower resolution due to high noise and dynamic motions of protein subdomains. However, recent revolutions in membrane protein biochemistry and cryo-electron microscopy now provide an opportunity to solve high resolution structures of both large, >1 megadalton (MDa), and small, <100 kDa (kDa), drug targets in near-native conditions, routinely reaching resolutions around or below 3 Å. This review provides insights into how the recent advances in membrane biology and biochemistry, as well as technical advances in cryo-electron microscopy, help us to solve structures of a large variety of membrane protein groups, from small receptors to large transporters and more complex machineries.
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Affiliation(s)
- Sarah J Piper
- Drug Discovery Biology theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Rachel M Johnson
- Drug Discovery Biology theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Denise Wootten
- Drug Discovery Biology theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Patrick M Sexton
- Drug Discovery Biology theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
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15
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Thirunavukarasu AJ, Ross AC, Gilbert RM. Vitamin A, systemic T-cells, and the eye: Focus on degenerative retinal disease. Front Nutr 2022; 9:914457. [PMID: 35923205 PMCID: PMC9339908 DOI: 10.3389/fnut.2022.914457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/29/2022] [Indexed: 11/13/2022] Open
Abstract
The first discovered vitamin, vitamin A, exists in a range of forms, primarily retinoids and provitamin carotenoids. The bioactive forms of vitamin A, retinol and retinoic acid, have many critical functions in body systems including the eye and immune system. Vitamin A deficiency is associated with dysfunctional immunity, and presents clinically as a characteristic ocular syndrome, xerophthalmia. The immune functions of vitamin A extend to the gut, where microbiome interactions and nutritional retinoids and carotenoids contribute to the balance of T cell differentiation, thereby determining immune status and contributing to inflammatory disease around the whole body. In the eye, degenerative conditions affecting the retina and uvea are influenced by vitamin A. Stargardt’s disease (STGD1; MIM 248200) is characterised by bisretinoid deposits such as lipofuscin, produced by retinal photoreceptors as they use and recycle a vitamin A-derived chromophore. Age-related macular degeneration features comparable retinal deposits, such as drusen featuring lipofuscin accumulation; and is characterised by parainflammatory processes. We hypothesise that local parainflammatory processes secondary to lipofuscin deposition in the retina are mediated by T cells interacting with dietary vitamin A derivatives and the gut microbiome, and outline the current evidence for this. No cures exist for Stargardt’s or age-related macular degeneration, but many vitamin A-based therapeutic approaches have been or are being trialled. The relationship between vitamin A’s functions in systemic immunology and the eye could be further exploited, and further research may seek to leverage the interactions of the gut-eye immunological axis.
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Affiliation(s)
- Arun J. Thirunavukarasu
- Corpus Christi College, University of Cambridge, Cambridge, United Kingdom
- University of Cambridge School of Clinical Medicine, Cambridge, United Kingdom
| | - A. Catharine Ross
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA, United States
| | - Rose M. Gilbert
- Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom
- NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, United Kingdom
- *Correspondence: Rose M. Gilbert,
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16
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Baker NC, Pierro JD, Taylor LW, Knudsen TB. Identifying candidate reference chemicals for in vitro testing of the retinoid pathway for predictive developmental toxicity. ALTEX 2022; 40:217–236. [PMID: 35796328 PMCID: PMC10765368 DOI: 10.14573/altex.2202231] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 06/21/2022] [Indexed: 11/23/2022]
Abstract
Evaluating chemicals for potential in vivo toxicity based on their in vitro bioactivity profile is an important step toward animal- free testing. A compendium of reference chemicals and data describing their bioactivity on specific molecular targets, cellular pathways, and biological processes is needed to bolster confidence in the predictive value of in vitro hazard detection. Endogenous signaling by all-trans retinoic acid (ATRA) is an important pathway in developmental processes and toxicities. Employing data extraction methods and advanced literature extraction tools, we assembled a set of candidate reference chemicals with demonstrated activity on ten protein family targets in the retinoid system. The compendium was culled from Protein Data Bank, ChEMBL, ToxCast/Tox21, and the biomedical literature in PubMed. Finally, we performed a case study on one chemical in our collection, citral, an inhibitor of endogenous ATRA production, to determine whether the literature supports an adverse outcome pathway explaining the compound’s developmental toxicity initiated by disruption of the retinoid pathway. We also deliver an updated Abstract Sifter tool populated with these reference compounds and complex search terms designed to query the literature for the downstream consequences to support concordance with targeted retinoid pathway disruption.
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Affiliation(s)
| | - Jocylin D. Pierro
- Center for Computational Toxicology and Exposure, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Laura W. Taylor
- Center for Computational Toxicology and Exposure, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Thomas B. Knudsen
- Center for Computational Toxicology and Exposure, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
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17
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Mice Lacking the Systemic Vitamin A Receptor RBPR2 Show Decreased Ocular Retinoids and Loss of Visual Function. Nutrients 2022; 14:nu14122371. [PMID: 35745101 PMCID: PMC9231411 DOI: 10.3390/nu14122371] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/31/2022] [Accepted: 06/03/2022] [Indexed: 02/05/2023] Open
Abstract
Simple Summary This work represents an initial evaluation of the second RBP4-vitamin A receptor RBPR2 in a mammalian model. We provide evidence that the membrane localized RBPR2 protein, under variable conditions of dietary vitamin A intake, plays an important role for dietary vitamin A transport to the eye for ocular retinoid homeostasis and visual function. These findings are of general interest, as disturbances in blood and ocular vitamin A homeostasis are linked to retinal degenerative diseases, which are blinding diseases. The animal model described here could also serve as an in vivo tool to study mechanisms related to retinal cell degeneration that are associated with vitamin A deficiency. Abstract The systemic transport of dietary vitamin A/all-trans retinol bound to RBP4 into peripheral tissues for storage is an essential physiological process that continuously provides visual chromophore precursors to the retina under fasting conditions. This mechanism is critical for phototransduction, photoreceptor cell maintenance and survival, and in the support of visual function. While the membrane receptor STRA6 facilitates the blood transport of lipophilic vitamin A into the eye, it is not expressed in most peripheral organs, which are proposed to express a second membrane receptor for the uptake of vitamin A from circulating RBP4. The discovery of a novel vitamin A receptor, RBPR2, which is expressed in the liver and intestine, but not in the eye, alluded to this long-sort non-ocular membrane receptor for systemic RBP4-ROL uptake and transport. We have previously shown in zebrafish that the retinol-binding protein receptor 2 (Rbpr2) plays an important role in the transport of yolk vitamin A to the eye. Mutant rbpr2 zebrafish lines manifested in decreased ocular retinoid concentrations and retinal phenotypes. To investigate a physiological role for the second vitamin A receptor, RBPR2, in mammals and to analyze the metabolic basis of systemic vitamin A transport for retinoid homeostasis, we established a whole-body Rbpr2 knockout mouse (Rbpr2−/−) model. These mice were viable on both vitamin A-sufficient and -deficient diets. Rbpr2−/− mice that were fed a vitamin A-sufficient diet displayed lower ocular retinoid levels, decreased opsins, and manifested in decrease visual function, as measured by electroretinography. Interestingly, when Rbpr2−/− mice were fed a vitamin A-deficient diet, they additionally showed shorter photoreceptor outer segment phenotypes, altogether manifesting in a significant loss of visual function. Thus, under conditions replicating vitamin A sufficiency and deficiency, our analyses revealed that RBPR2-mediated systemic vitamin A transport is a regulated process that is important for vitamin A delivery to the eye when RBP4-bound ROL is the only transport pathway in the fasting condition or under vitamin A deficiency conditions.
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18
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Antagonizing RARγ Drives Necroptosis of Cancer Stem Cells. Int J Mol Sci 2022; 23:ijms23094814. [PMID: 35563205 PMCID: PMC9105400 DOI: 10.3390/ijms23094814] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 04/25/2022] [Accepted: 04/25/2022] [Indexed: 12/23/2022] Open
Abstract
There is a need for agents that eliminate cancer stem cells, which sustain cancer and are also largely responsible for disease relapse and metastasis. Conventional chemotherapeutics and radiotherapy are often highly effective against the bulk of cancer cells, which are proliferating, but spare cancer stem cells. Therapeutics that target cancer stem cells may also provide a bona fide cure for cancer. There are two rationales for targeting the retinoic acid receptor (RAR)γ. First, RARγ is expressed selectively within primitive cells. Second, RARγ is a putative oncogene for a number of human cancers, including cases of acute myeloid leukemia, cholangiocarcinoma, and colorectal, renal and hepatocellular carcinomas. Prostate cancer cells depend on active RARγ for their survival. Antagonizing all RARs caused necroptosis of prostate and breast cancer stem cell-like cells, and the cancer stem cells that gave rise to neurospheres from pediatric patients’ primitive neuroectodermal tumors and an astrocytoma. As tested for prostate cancer, antagonizing RARγ was sufficient to drive necroptosis. Achieving cancer-selectively is a longstanding paradigm for developing new treatments. The normal prostate epithelium was less sensitive to the RARγ antagonist and pan-RAR antagonist than prostate cancer cells, and fibroblasts and blood mononuclear cells were insensitive. The RARγ antagonist and pan-RAR antagonist are promising new cancer therapeutics.
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19
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O’Connor C, Varshosaz P, Moise AR. Mechanisms of Feedback Regulation of Vitamin A Metabolism. Nutrients 2022; 14:nu14061312. [PMID: 35334970 PMCID: PMC8950952 DOI: 10.3390/nu14061312] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/15/2022] [Accepted: 03/17/2022] [Indexed: 02/06/2023] Open
Abstract
Vitamin A is an essential nutrient required throughout life. Through its various metabolites, vitamin A sustains fetal development, immunity, vision, and the maintenance, regulation, and repair of adult tissues. Abnormal tissue levels of the vitamin A metabolite, retinoic acid, can result in detrimental effects which can include congenital defects, immune deficiencies, proliferative defects, and toxicity. For this reason, intricate feedback mechanisms have evolved to allow tissues to generate appropriate levels of active retinoid metabolites despite variations in the level and format, or in the absorption and conversion efficiency of dietary vitamin A precursors. Here, we review basic mechanisms that govern vitamin A signaling and metabolism, and we focus on retinoic acid-controlled feedback mechanisms that contribute to vitamin A homeostasis. Several approaches to investigate mechanistic details of the vitamin A homeostatic regulation using genomic, gene editing, and chromatin capture technologies are also discussed.
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Affiliation(s)
- Catherine O’Connor
- MD Program, Northern Ontario School of Medicine, 317-MSE Bldg., 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada;
| | - Parisa Varshosaz
- Biology and Biomolecular Sciences Ph.D. Program, Northern Ontario School of Medicine, Laurentian University, Sudbury, ON P3E 2C6, Canada;
| | - Alexander R. Moise
- Medical Sciences Division, Northern Ontario School of Medicine, 317-MSE Bldg., 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada
- Department of Chemistry and Biochemistry, Biology and Biomolecular Sciences Program, Laurentian University, Sudbury, ON P3E 2C6, Canada
- Correspondence: ; Tel.: +1-705-662-7253
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20
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Steinhoff JS, Lass A, Schupp M. Retinoid Homeostasis and Beyond: How Retinol Binding Protein 4 Contributes to Health and Disease. Nutrients 2022; 14:nu14061236. [PMID: 35334893 PMCID: PMC8951293 DOI: 10.3390/nu14061236] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 03/09/2022] [Accepted: 03/11/2022] [Indexed: 02/06/2023] Open
Abstract
Retinol binding protein 4 (RBP4) is the specific transport protein of the lipophilic vitamin A, retinol, in blood. Circulating RBP4 originates from the liver. It is secreted by hepatocytes after it has been loaded with retinol and binding to transthyretin (TTR). TTR association prevents renal filtration due to the formation of a higher molecular weight complex. In the circulation, RBP4 binds to specific membrane receptors, thereby delivering retinol to target cells, rendering liver-secreted RBP4 the major mechanism to distribute hepatic vitamin A stores to extrahepatic tissues. In particular, binding of RBP4 to 'stimulated by retinoic acid 6' (STRA6) is required to balance tissue retinoid responses in a highly homeostatic manner. Consequently, defects/mutations in RBP4 can cause a variety of conditions and diseases due to dysregulated retinoid homeostasis and cover embryonic development, vision, metabolism, and cardiovascular diseases. Aside from the effects related to retinol transport, non-canonical functions of RBP4 have also been reported. In this review, we summarize the current knowledge on the regulation and function of RBP4 in health and disease derived from murine models and human mutations.
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Affiliation(s)
- Julia S. Steinhoff
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular Metabolic Renal (CMR)-Research Center, 10115 Berlin, Germany;
| | - Achim Lass
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Heinrichstraße 31/II, A-8010 Graz, Austria;
- Field of Excellence BioHealth, University of Graz, Heinrichstraße 31/II, A-8010 Graz, Austria
| | - Michael Schupp
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular Metabolic Renal (CMR)-Research Center, 10115 Berlin, Germany;
- Correspondence:
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21
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Marko HL, Hornig NC, Betz RC, Holterhus PM, Altmüller J, Thiele H, Fabiano M, Schweikert HU, Braun D, Schweizer U. Genomic variants reducing expression of two endocytic receptors in 46,XY differences of sex development. Hum Mutat 2022; 43:420-433. [PMID: 34979047 DOI: 10.1002/humu.24325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 10/12/2021] [Accepted: 12/30/2021] [Indexed: 11/07/2022]
Abstract
Transporter-dependent steroid hormone uptake into target cells was demonstrated in genetically engineered mice and fruit flies. We hypothesized that mutations in such transporters may cause differences in sex development (DSD) in humans. Exome sequencing was performed in 16 genetically unsolved cases of 46,XY DSD selected from an anonymized collection of 708 lines of genital fibroblasts (GF) that were taken from individuals with incomplete virilization. Selection criteria were based on available biochemical characterization of GF compatible with reduced androgen uptake. Two unrelated individuals were identified with mutations in LDL receptor-related protein 2 (LRP2), a gene previously associated with partial sex steroid insensitivity in mice. Like Lrp2-/- mice, affected individuals had non-descended testes. Western blots on GF confirmed reduced LRP2 expression, and endocytosis of sex hormone-binding globulin was reduced. In three unrelated individuals, two with undescended testes, mutations in another endocytic receptor gene, limb development membrane protein 1 like (LMBR1L), were detected. Two of these individuals had mutations affecting the same codon. In a transfected cell model, mutated LMBR1L showed reduced cell surface expression. Our findings suggest that endocytic androgen uptake in complex with sex hormone-binding globulin is relevant in human. LMBR1L may play a similar role in androgen uptake.
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Affiliation(s)
- Hannah L Marko
- Institut für Biochemie und Molekularbiologie, Medizinische Fakultät, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Nadine C Hornig
- Klinik für Kinder und Jugendmedizin I, Bereich Pädiatrische Endokrinologie und Diabetologie, Universitätsklinikum Schleswig-Holstein, UKSH, Campus Kiel,, Kiel, Germany
| | - Regina C Betz
- Institute of Human Genetics, Medizinische Fakultät, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Paul-Martin Holterhus
- Klinik für Kinder und Jugendmedizin I, Bereich Pädiatrische Endokrinologie und Diabetologie, Universitätsklinikum Schleswig-Holstein, UKSH, Campus Kiel,, Kiel, Germany
| | - Janine Altmüller
- Cologne Center for Genomics, University of Cologne, Cologne, Germany
| | - Holger Thiele
- Cologne Center for Genomics, University of Cologne, Cologne, Germany
| | - Marietta Fabiano
- Department of Neurology, Medizinische Fakultät, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Hans-Udo Schweikert
- Institut für Biochemie und Molekularbiologie, Medizinische Fakultät, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Doreen Braun
- Institut für Biochemie und Molekularbiologie, Medizinische Fakultät, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Ulrich Schweizer
- Institut für Biochemie und Molekularbiologie, Medizinische Fakultät, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
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22
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Shimokawa N, Takahashi I, Iizuka H. Spinal malformation - A biochemical analysis using congenital kyphosis rats. J Cell Biochem 2022; 123:501-505. [PMID: 34978108 DOI: 10.1002/jcb.30206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 11/25/2021] [Accepted: 12/17/2021] [Indexed: 11/06/2022]
Abstract
Spinal kyphosis involves the vertebrae curving excessively backward, beyond their physiological curvature. Although the normal structure of the spinal vertebrae is extremely important for maintaining posture, the normal function of the thoracic and abdominal organs, and cosmetics, our knowledge concerning the pathogenesis of this disease is lacking. Furthermore, the responsible gene has not yet been identified. In this short review, we summarize the current state of kyphosis research and introduce the molecular and cellular mechanisms associated with the pathogenesis of this disease, based on findings obtained using rats that develop kyphosis.
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Affiliation(s)
- Noriaki Shimokawa
- Department of Nutrition, Takasaki University of Health and Welfare, Takasaki, Gunma, Japan.,Department of Integrative Physiology, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Itsuki Takahashi
- Department of Nutrition, Takasaki University of Health and Welfare, Takasaki, Gunma, Japan
| | - Haku Iizuka
- Division of Orthopedic Surgery, Isesaki Municipal Hospital, Isesaki, Gunma, Japan
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23
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Mahling R, Hovey L, Isbell HM, Marx DC, Miller MS, Kilpatrick AM, Weaver LD, Yoder JB, Kim EH, Andresen CNJ, Li S, Shea MA. Na V1.2 EFL domain allosterically enhances Ca 2+ binding to sites I and II of WT and pathogenic calmodulin mutants bound to the channel CTD. Structure 2021; 29:1339-1356.e7. [PMID: 33770503 PMCID: PMC8458505 DOI: 10.1016/j.str.2021.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 12/23/2020] [Accepted: 03/03/2021] [Indexed: 11/23/2022]
Abstract
Neuronal voltage-gated sodium channel NaV1.2 C-terminal domain (CTD) binds calmodulin (CaM) constitutively at its IQ motif. A solution structure (6BUT) and other NMR evidence showed that the CaM N domain (CaMN) is structurally independent of the C-domain (CaMC) whether CaM is bound to the NaV1.2IQp (1,901-1,927) or NaV1.2CTD (1,777-1,937) with or without calcium. However, in the CaM + NaV1.2CTD complex, the Ca2+ affinity of CaMN was more favorable than in free CaM, while Ca2+ affinity for CaMC was weaker than in the CaM + NaV1.2IQp complex. The CTD EF-like (EFL) domain allosterically widened the energetic gap between CaM domains. Cardiomyopathy-associated CaM mutants (N53I(N54I), D95V(D96V), A102V(A103V), E104A(E105A), D129G(D130G), and F141L(F142L)) all bound the NaV1.2 IQ motif favorably under resting (apo) conditions and bound calcium normally at CaMN sites. However, only N53I and A102V bound calcium at CaMC sites at [Ca2+] < 100 μM. Thus, they are expected to respond like wild-type CaM to Ca2+ spikes in excitable cells.
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Affiliation(s)
- Ryan Mahling
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Liam Hovey
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Holly M Isbell
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Dagan C Marx
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Mark S Miller
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Adina M Kilpatrick
- Department of Physics and Astronomy, Drake University, Des Moines, IA 50311-4516, USA
| | - Lisa D Weaver
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Jesse B Yoder
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Elaine H Kim
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Corinne N J Andresen
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Shuxiang Li
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Madeline A Shea
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA.
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Martin Ask N, Leung M, Radhakrishnan R, Lobo GP. Vitamin A Transporters in Visual Function: A Mini Review on Membrane Receptors for Dietary Vitamin A Uptake, Storage, and Transport to the Eye. Nutrients 2021; 13:nu13113987. [PMID: 34836244 PMCID: PMC8620617 DOI: 10.3390/nu13113987] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/04/2021] [Accepted: 11/07/2021] [Indexed: 11/23/2022] Open
Abstract
Vitamins are essential compounds obtained through diet that are necessary for normal development and function in an organism. One of the most important vitamins for human physiology is vitamin A, a group of retinoid compounds and carotenoids, which generally function as a mediator for cell growth, differentiation, immunity, and embryonic development, as well as serving as a key component in the phototransduction cycle in the vertebrate retina. For humans, vitamin A is obtained through the diet, where provitamin A carotenoids such as β-carotene from plants or preformed vitamin A such as retinyl esters from animal sources are absorbed into the body via the small intestine and converted into all-trans retinol within the intestinal enterocytes. Specifically, once absorbed, carotenoids are cleaved by carotenoid cleavage oxygenases (CCOs), such as Beta-carotene 15,15’-monooxygenase (BCO1), to produce all-trans retinal that subsequently gets converted into all-trans retinol. CRBP2 bound retinol is then converted into retinyl esters (REs) by the enzyme lecithin retinol acyltransferase (LRAT) in the endoplasmic reticulum, which is then packaged into chylomicrons and sent into the bloodstream for storage in hepatic stellate cells in the liver or for functional use in peripheral tissues such as the retina. All-trans retinol also travels through the bloodstream bound to retinol binding protein 4 (RBP4), where it enters cells with the assistance of the transmembrane transporters, stimulated by retinoic acid 6 (STRA6) in peripheral tissues or retinol binding protein 4 receptor 2 (RBPR2) in systemic tissues (e.g., in the retina and the liver, respectively). Much is known about the intake, metabolism, storage, and function of vitamin A compounds, especially with regard to its impact on eye development and visual function in the retinoid cycle. However, there is much to learn about the role of vitamin A as a transcription factor in development and cell growth, as well as how peripheral cells signal hepatocytes to secrete all-trans retinol into the blood for peripheral cell use. This article aims to review literature regarding the major known pathways of vitamin A intake from dietary sources into hepatocytes, vitamin A excretion by hepatocytes, as well as vitamin A usage within the retinoid cycle in the RPE and retina to provide insight on future directions of novel membrane transporters for vitamin A in retinal cell physiology and visual function.
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Young BD, Varney KM, Wilder PT, Costabile BK, Pozharski E, Cook ME, Godoy-Ruiz R, Clarke OB, Mancia F, Weber DJ. Physiologically Relevant Free Ca 2+ Ion Concentrations Regulate STRA6-Calmodulin Complex Formation via the BP2 Region of STRA6. J Mol Biol 2021; 433:167272. [PMID: 34592217 PMCID: PMC8568335 DOI: 10.1016/j.jmb.2021.167272] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/13/2021] [Accepted: 09/21/2021] [Indexed: 11/28/2022]
Abstract
The interaction of calmodulin (CaM) with the receptor for retinol uptake, STRA6, involves an α-helix termed BP2 that is located on the intracellular side of this homodimeric transporter (Chen et al., 2016 [1]). In the absence of Ca2+, NMR data showed that a peptide derived from BP2 bound to the C-terminal lobe (C-lobe) of Mg2+-bound CaM (MgCaM). Upon titration of Ca2+ into MgCaM-BP2, NMR chemical shift perturbations (CSPs) were observed for residues in the C-lobe, including those in the EF-hand Ca2+-binding domains, EF3 and EF4 (CaKD = 60 ± 7 nM). As higher concentrations of free Ca2+ were achieved, CSPs occurred for residues in the N-terminal lobe (N-lobe) including those in EF1 and EF2 (CaKD = 1000 ± 160 nM). Thermodynamic and kinetic Ca2+ binding studies showed that BP2 addition increased the Ca2+-binding affinity of CaM and slowed its Ca2+ dissociation rates (koff) in both the C- and N-lobe EF-hand domains, respectively. These data are consistent with BP2 binding to the C-lobe of CaM at low free Ca2+ concentrations (<100 nM) like those found at resting intracellular levels. As free Ca2+ levels approach 1000 nM, which is typical inside a cell upon an intracellular Ca2+-signaling event, BP2 is shown here to interact with both the N- and C-lobes of Ca2+-loaded CaM (CaCaM-BP2). Because this structural rearrangement observed for the CaCaM-BP2 complex occurs as intracellular free Ca2+ concentrations approach those typical of a Ca2+-signaling event (CaKD = 1000 ± 160 nM), this conformational change could be relevant to vitamin A transport by full-length CaCaM-STRA6.
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Affiliation(s)
- Brianna D Young
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA
| | - Kristen M Varney
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), 9600 Gudelsky Dr., Rockville, MD 20850, USA
| | - Paul T Wilder
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), 9600 Gudelsky Dr., Rockville, MD 20850, USA
| | - Brianna K Costabile
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Edwin Pozharski
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), 9600 Gudelsky Dr., Rockville, MD 20850, USA
| | - Mary E Cook
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA
| | - Raquel Godoy-Ruiz
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), 9600 Gudelsky Dr., Rockville, MD 20850, USA
| | - Oliver B Clarke
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Filippo Mancia
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - David J Weber
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), 9600 Gudelsky Dr., Rockville, MD 20850, USA.
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26
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The diversity of lipocalin receptors. Biochimie 2021; 192:22-29. [PMID: 34534611 DOI: 10.1016/j.biochi.2021.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 09/10/2021] [Accepted: 09/11/2021] [Indexed: 11/23/2022]
Abstract
Lipocalins are important carriers of preferentially hydrophobic molecules, but they can also bind other ligands, like highly polar siderophores or intact proteins. Consequently, they are involved in a variety of physiological processes in many species. Since lipocalins are mainly extracellular proteins, they have to interact with cell receptors to exert their biological effects. In contrast to the large number of lipocalins identified in the last years, the number of receptors known is still limited. Nevertheless, some novel findings concerning the molecules involved in cellular uptake or signaling effects of lipocalins have been made recently. This review presents a detailed overview of the receptors identified so far. The methods used for isolation or identification are described and structural as well as functional information on these proteins is presented essentially in chronological order of their initial discovery.
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Ramkumar S, Parmar VM, Samuels I, Berger NA, Jastrzebska B, von Lintig J. The vitamin a transporter STRA6 adjusts the stoichiometry of chromophore and opsins in visual pigment synthesis and recycling. Hum Mol Genet 2021; 31:548-560. [PMID: 34508587 DOI: 10.1093/hmg/ddab267] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 09/02/2021] [Accepted: 09/03/2021] [Indexed: 12/21/2022] Open
Abstract
The retinal pigment epithelium of the vertebrate eyes acquires vitamin A from circulating retinol binding protein for chromophore biosynthesis. The chromophore covalently links with an opsin protein in the adjacent photoreceptors of the retina to form the bipartite visual pigment complexes. We here analyzed visual pigment biosynthesis in mice deficient for the retinol binding protein receptor STRA6. We observed that chromophore content was decreased throughout the life cycle of these animals, indicating that lipoprotein-dependent delivery pathways for the vitamin cannot substitute for STRA6. Changes in the expression of photoreceptor marker genes, including a down-regulation of the genes encoding rod and cone opsins, paralleled the decrease in ocular retinoid concentration in STRA6-deficient mice. Despite this adaptation, cone photoreceptors displayed absent or mislocalized opsins at all ages examined. Rod photoreceptors entrapped the available chromophore but exhibited significant amounts of chromophore-free opsins in the dark-adapted stage. Treatment of mice with pharmacological doses of vitamin A ameliorated the rod phenotype but did not restore visual pigment synthesis in cone photoreceptors of STRA6-deficient mice. The imbalance between chromophore and opsin concentrations of rod and cone photoreceptors was associated with an unfavorable retinal physiology, including diminished electrical responses of photoreceptors to light, and retinal degeneration during aging. Together, our study demonstrates that STRA6 is critical to adjust the stoichiometry of chromophore and opsins in rod cone photoreceptors and to prevent pathologies associated with ocular vitamin A deprivation.
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Affiliation(s)
- Srinivasagan Ramkumar
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, 44106, OH, USA
| | - Vipul M Parmar
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, 44106, OH, USA
| | - Ivy Samuels
- Northeast Ohio VA Healthcare System, Cleveland, 44106, OH, USA
| | - Nathan A Berger
- Center for Science, Health and Society, School of Medicine, Case Western Reserve University, Cleveland, 44106, OH, USA.,Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, 44106, OH, USA
| | - Beata Jastrzebska
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, 44106, OH, USA.,Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, 44106, OH, USA
| | - Johannes von Lintig
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, 44106, OH, USA
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Cooke LDF, Tumbarello DA, Harvey NC, Sethi JK, Lewis RM, Cleal JK. Endocytosis in the placenta: An undervalued mediator of placental transfer. Placenta 2021; 113:67-73. [PMID: 33994009 DOI: 10.1016/j.placenta.2021.04.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 04/21/2021] [Accepted: 04/27/2021] [Indexed: 12/16/2022]
Abstract
Endocytosis is an essential mechanism for cellular uptake in many human tissues. A range of endocytic mechanisms occur including clathrin-dependent and -independent mechanisms. However, the role of endocytosis in the placenta and the spatial localisation of individual mechanisms is not well understood. The two principal cell layers that comprise the placental barrier to maternal-fetal transfer are the syncytiotrophoblast and fetal capillary endothelium. Endocytic uptake into the syncytiotrophoblast has been demonstrated for physiological maternal molecules such as transferrin-bound iron and low density lipoprotein (LDL) and may play an important role in the uptake of several other micronutrients, serum proteins, and therapeutics at both major placental cell barriers. These mechanisms may also mediate placental uptake of some viruses and nanoparticles. This review introduces the mechanisms of cargo-specific endocytosis and what is known about their localisation in the placenta, focussing predominantly on the syncytiotrophoblast. A fuller understanding of placental endocytosis is necessary to explain both fetal nutrition and the properties of the placental barrier. Characterising placental endocytic mechanisms and their regulation may allow us to identify their role in pregnancy pathologies and provide new avenues for therapeutic intervention.
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Affiliation(s)
- Laura D F Cooke
- The Institute of Developmental Sciences, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK.
| | - David A Tumbarello
- Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Highfield Campus, Life Sciences Building 85, Southampton, SO17 1BJ, UK
| | - Nicholas C Harvey
- MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK; NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
| | - Jaswinder K Sethi
- The Institute of Developmental Sciences, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK; NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK; Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Rohan M Lewis
- The Institute of Developmental Sciences, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK; Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Jane K Cleal
- The Institute of Developmental Sciences, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK; Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
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29
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Egbert M, Porter KA, Ghani U, Kotelnikov S, Nguyen T, Ashizawa R, Kozakov D, Vajda S. Conservation of binding properties in protein models. Comput Struct Biotechnol J 2021; 19:2549-2566. [PMID: 34025942 PMCID: PMC8114079 DOI: 10.1016/j.csbj.2021.04.048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 04/19/2021] [Accepted: 04/22/2021] [Indexed: 01/09/2023] Open
Abstract
We study the models submitted to round 12 of the Critical Assessment of protein Structure Prediction (CASP) experiment to assess how well the binding properties are conserved when the X-ray structures of the target proteins are replaced by their models. To explore small molecule binding we generate distributions of molecular probes - which are fragment-sized organic molecules of varying size, shape, and polarity - around the protein, and count the number of interactions between each residue and the probes, resulting in a vector of interactions we call a binding fingerprint. The similarity between two fingerprints, one for the X-ray structure and the other for a model of the protein, is determined by calculating the correlation coefficient between the two vectors. The resulting correlation coefficients are shown to correlate with global measures of accuracy established in CASP, and the relationship yields an accuracy threshold that has to be reached for meaningful binding surface conservation. The clusters formed by the probe molecules reliably predict binding hot spots and ligand binding sites in both X-ray structures and reasonably accurate models of the target, but ensembles of models may be needed for assessing the availability of proper binding pockets. We explored ligand docking to the few targets that had bound ligands in the X-ray structure. More targets were available to assess the ability of the models to reproduce protein-protein interactions by docking both the X-ray structures and models to their interaction partners in complexes. It was shown that this application is more difficult than finding small ligand binding sites, and the success rates heavily depend on the local structure in the potential interface. In particular, predicted conformations of flexible loops are frequently incorrect in otherwise highly accurate models, and may prevent predicting correct protein-protein interactions.
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Affiliation(s)
- Megan Egbert
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States
| | - Kathryn A. Porter
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States
| | - Usman Ghani
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States
| | - Sergei Kotelnikov
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794, United States
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, United States
| | - Thu Nguyen
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, United States
| | - Ryota Ashizawa
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794, United States
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, United States
| | - Dima Kozakov
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794, United States
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, United States
| | - Sandor Vajda
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States
- Department of Chemistry, Boston University, Boston, MA 02215, United States
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30
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Matos-Filipe P, Preto AJ, Koukos PI, Mourão J, Bonvin AMJJ, Moreira IS. MENSAdb: a thorough structural analysis of membrane protein dimers. Database (Oxford) 2021; 2021:baab013. [PMID: 33822911 PMCID: PMC8023553 DOI: 10.1093/database/baab013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 01/19/2021] [Accepted: 03/01/2021] [Indexed: 11/14/2022]
Abstract
Membrane proteins (MPs) are key players in a variety of different cellular processes and constitute the target of around 60% of all Food and Drug Administration-approved drugs. Despite their importance, there is still a massive lack of relevant structural, biochemical and mechanistic information mainly due to their localization within the lipid bilayer. To help fulfil this gap, we developed the MEmbrane protein dimer Novel Structure Analyser database (MENSAdb). This interactive web application summarizes the evolutionary and physicochemical properties of dimeric MPs to expand the available knowledge on the fundamental principles underlying their formation. Currently, MENSAdb contains features of 167 unique MPs (63% homo- and 37% heterodimers) and brings insights into the conservation of residues, accessible solvent area descriptors, average B-factors, intermolecular contacts at 2.5 Å and 4.0 Å distance cut-offs, hydrophobic contacts, hydrogen bonds, salt bridges, π-π stacking, T-stacking and cation-π interactions. The regular update and organization of all these data into a unique platform will allow a broad community of researchers to collect and analyse a large number of features efficiently, thus facilitating their use in the development of prediction models associated with MPs. Database URL: http://www.moreiralab.com/resources/mensadb.
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Affiliation(s)
- Pedro Matos-Filipe
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra 3005-504, Portugal
| | - António J Preto
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra 3005-504, Portugal
- PhD Programme in Experimental Biology and Biomedicine, Institute for Interdisciplinary Research, University of Coimbra, Coimbra, 3030-789, Portugal
| | - Panagiotis I Koukos
- Bijvoet Centre for Biomolecular Research, Faculty of Science—Chemistry, Utrecht University, Utrecht, 3584, CH, Netherlands
| | - Joana Mourão
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra 3005-504, Portugal
| | - Alexandre M J J Bonvin
- Bijvoet Centre for Biomolecular Research, Faculty of Science—Chemistry, Utrecht University, Utrecht, 3584, CH, Netherlands
| | - Irina S Moreira
- Department of Life Sciences, University of Coimbra, Coimbra, 3000-456, Portugal
- Center for Neuroscience and Cell Biology, Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal
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Steinhoff JS, Lass A, Schupp M. Biological Functions of RBP4 and Its Relevance for Human Diseases. Front Physiol 2021; 12:659977. [PMID: 33790810 PMCID: PMC8006376 DOI: 10.3389/fphys.2021.659977] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 02/22/2021] [Indexed: 12/13/2022] Open
Abstract
Retinol binding protein 4 (RBP4) is a member of the lipocalin family and the major transport protein of the hydrophobic molecule retinol, also known as vitamin A, in the circulation. Expression of RBP4 is highest in the liver, where most of the body’s vitamin A reserves are stored as retinyl esters. For the mobilization of vitamin A from the liver, retinyl esters are hydrolyzed to retinol, which then binds to RBP4 in the hepatocyte. After associating with transthyretin (TTR), the retinol/RBP4/TTR complex is released into the bloodstream and delivers retinol to tissues via binding to specific membrane receptors. So far, two distinct RBP4 receptors have been identified that mediate the uptake of retinol across the cell membrane and, under specific conditions, bi-directional retinol transport. Although most of RBP4’s actions depend on its role in retinoid homeostasis, functions independent of retinol transport have been described. In this review, we summarize and discuss the recent findings on the structure, regulation, and functions of RBP4 and lay out the biological relevance of this lipocalin for human diseases.
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Affiliation(s)
- Julia S Steinhoff
- Institute of Pharmacology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Achim Lass
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria.,BioTechMed-Graz, Graz, Austria
| | - Michael Schupp
- Institute of Pharmacology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
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Mahling R, Rahlf CR, Hansen SC, Hayden MR, Shea MA. Ca 2+-saturated calmodulin binds tightly to the N-terminal domain of A-type fibroblast growth factor homologous factors. J Biol Chem 2021; 296:100458. [PMID: 33639159 PMCID: PMC8059062 DOI: 10.1016/j.jbc.2021.100458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/15/2021] [Accepted: 02/23/2021] [Indexed: 01/12/2023] Open
Abstract
Voltage-gated sodium channels (Navs) are tightly regulated by multiple conserved auxiliary proteins, including the four fibroblast growth factor homologous factors (FGFs), which bind the Nav EF-hand like domain (EFL), and calmodulin (CaM), a multifunctional messenger protein that binds the NaV IQ motif. The EFL domain and IQ motif are contiguous regions of NaV cytosolic C-terminal domains (CTD), placing CaM and FGF in close proximity. However, whether the FGFs and CaM act independently, directly associate, or operate through allosteric interactions to regulate channel function is unknown. Titrations monitored by steady-state fluorescence spectroscopy, structural studies with solution NMR, and computational modeling demonstrated for the first time that both domains of (Ca2+)4-CaM (but not apo CaM) directly bind two sites in the N-terminal domain (NTD) of A-type FGF splice variants (FGF11A, FGF12A, FGF13A, and FGF14A) with high affinity. The weaker of the (Ca2+)4-CaM-binding sites was known via electrophysiology to have a role in long-term inactivation of the channel but not known to bind CaM. FGF12A binding to a complex of CaM associated with a fragment of the NaV1.2 CTD increased the Ca2+-binding affinity of both CaM domains, consistent with (Ca2+)4-CaM interacting preferentially with its higher-affinity site in the FGF12A NTD. Thus, A-type FGFs can compete with NaV IQ motifs for (Ca2+)4-CaM. During spikes in the cytosolic Ca2+ concentration that accompany an action potential, CaM may translocate from the NaV IQ motif to the FGF NTD, or the A-type FGF NTD may recruit a second molecule of CaM to the channel.
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Affiliation(s)
- Ryan Mahling
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Cade R Rahlf
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Samuel C Hansen
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Matthew R Hayden
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Madeline A Shea
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
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Honarbakhsh M, Ericsson A, Zhong G, Isoherranen N, Zhu C, Bromberg Y, Van Buiten C, Malta K, Joseph L, Sampath H, Lackey AI, Storch J, Vetriani C, Chikindas ML, Breslin P, Quadro L. Impact of vitamin A transport and storage on intestinal retinoid homeostasis and functions. J Lipid Res 2021; 62:100046. [PMID: 33587919 PMCID: PMC8020483 DOI: 10.1016/j.jlr.2021.100046] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/15/2021] [Accepted: 01/29/2021] [Indexed: 12/15/2022] Open
Abstract
Lecithin:retinol acyltransferase and retinol-binding protein enable vitamin A (VA) storage and transport, respectively, maintaining tissue homeostasis of retinoids (VA derivatives). The precarious VA status of the lecithin:retinol acyltransferase-deficient (Lrat-/-) retinol-binding protein-deficient (Rbp-/-) mice rapidly deteriorates upon dietary VA restriction, leading to signs of severe vitamin A deficiency (VAD). As retinoids impact gut morphology and functions, VAD is often linked to intestinal pathological conditions and microbial dysbiosis. Thus, we investigated the contribution of VA storage and transport to intestinal retinoid homeostasis and functionalities. We showed the occurrence of intestinal VAD in Lrat-/-Rbp-/- mice, demonstrating the critical role of both pathways in preserving gut retinoid homeostasis. Moreover, in the mutant colon, VAD resulted in a compromised intestinal barrier as manifested by reduced mucins and antimicrobial defense, leaky gut, increased inflammation and oxidative stress, and altered mucosal immunocytokine profiles. These perturbations were accompanied by fecal dysbiosis, revealing that the VA status (sufficient vs. deficient), rather than the amount of dietary VA per se, is likely a major initial discriminant of the intestinal microbiome. Our data also pointed to a specific fecal taxonomic profile and distinct microbial functionalities associated with VAD. Overall, our findings revealed the suitability of the Lrat-/-Rbp-/- mice as a model to study intestinal dysfunctions and dysbiosis promoted by changes in tissue retinoid homeostasis induced by the host VA status and/or intake.
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Affiliation(s)
| | - Aaron Ericsson
- Department of Veterinary Pathobiology, University of Missouri Metagenomics Center, University of Missouri, Columbia, MO, USA
| | - Guo Zhong
- Department of Pharmaceutics Health Sciences, University of Washington, Seattle, WA, USA
| | - Nina Isoherranen
- Department of Pharmaceutics Health Sciences, University of Washington, Seattle, WA, USA
| | - Chengsheng Zhu
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ, USA
| | - Yana Bromberg
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ, USA
| | - Charlene Van Buiten
- Department of Food Science and Human Nutrition, Colorado State University, Fort Collins, CO, USA
| | - Kiana Malta
- Department of Food Science, Rutgers University, New Brunswick, NJ, USA
| | - Laurie Joseph
- Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ, USA
| | - Harini Sampath
- Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ, USA; Rutgers Center for Lipid Research and Institute of Food Nutrition and Health, Rutgers University, New Brunswick, NJ, USA
| | - Atreju I Lackey
- Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ, USA
| | - Judith Storch
- Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ, USA; Rutgers Center for Lipid Research and Institute of Food Nutrition and Health, Rutgers University, New Brunswick, NJ, USA
| | - Costantino Vetriani
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ, USA
| | | | - Paul Breslin
- Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ, USA
| | - Loredana Quadro
- Department of Food Science, Rutgers University, New Brunswick, NJ, USA; Rutgers Center for Lipid Research and Institute of Food Nutrition and Health, Rutgers University, New Brunswick, NJ, USA.
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Choi EH, Daruwalla A, Suh S, Leinonen H, Palczewski K. Retinoids in the visual cycle: role of the retinal G protein-coupled receptor. J Lipid Res 2021; 62:100040. [PMID: 32493732 PMCID: PMC7910522 DOI: 10.1194/jlr.tr120000850] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/20/2020] [Indexed: 12/13/2022] Open
Abstract
Driven by the energy of a photon, the visual pigments in rod and cone photoreceptor cells isomerize 11-cis-retinal to the all-trans configuration. This photochemical reaction initiates the signal transduction pathway that eventually leads to the transmission of a visual signal to the brain and leaves the opsins insensitive to further light stimulation. For the eye to restore light sensitivity, opsins require recharging with 11-cis-retinal. This trans-cis back conversion is achieved through a series of enzymatic reactions composing the retinoid (visual) cycle. Although it is evident that the classical retinoid cycle is critical for vision, the existence of an adjunct pathway for 11-cis-retinal regeneration has been debated for many years. Retinal pigment epithelium (RPE)-retinal G protein-coupled receptor (RGR) has been identified previously as a mammalian retinaldehyde photoisomerase homologous to retinochrome found in invertebrates. Using pharmacological, genetic, and biochemical approaches, researchers have now established the physiological relevance of the RGR in 11-cis-retinal regeneration. The photoisomerase activity of RGR in the RPE and Müller glia explains how the eye can remain responsive in daylight. In this review, we will focus on retinoid metabolism in the eye and visual chromophore regeneration mediated by RGR.
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Affiliation(s)
- Elliot H Choi
- Department of Ophthalmology, Gavin Herbert Eye Institute, Center for Translational Vision Research, University of California, Irvine, CA, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA.
| | - Anahita Daruwalla
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA; Departments of Physiology and Biophysics, and Chemistry, University of California, Irvine, CA, USA
| | - Susie Suh
- Department of Ophthalmology, Gavin Herbert Eye Institute, Center for Translational Vision Research, University of California, Irvine, CA, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
| | - Henri Leinonen
- Department of Ophthalmology, Gavin Herbert Eye Institute, Center for Translational Vision Research, University of California, Irvine, CA, USA
| | - Krzysztof Palczewski
- Department of Ophthalmology, Gavin Herbert Eye Institute, Center for Translational Vision Research, University of California, Irvine, CA, USA; Departments of Physiology and Biophysics, and Chemistry, University of California, Irvine, CA, USA.
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Huang R, Bai X, Li X, Wang X, Zhao L. Retinol-Binding Protein 4 Activates STRA6, Provoking Pancreatic β-Cell Dysfunction in Type 2 Diabetes. Diabetes 2021; 70:449-463. [PMID: 33199363 DOI: 10.2337/db19-1241] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 11/05/2020] [Indexed: 11/13/2022]
Abstract
Pancreatic β-cell dysfunction plays a decisive role in the progression of type 2 diabetes. Retinol-binding protein 4 (RBP4) is a prominent adipokine in type 2 diabetes, although its effect on β-cell function remains elusive, and the underlying mechanisms are unknown. Here, we found that elevated circulating RBP4 levels were inversely correlated with pancreatic β-cell function in db/db mice across different glycemic stages. RBP4 directly suppressed glucose-stimulated insulin secretion (GSIS) in primary isolated islets and INS-1E cells in a dose- and time-dependent manner. RBP4 transgenic (RBP4-Tg) overexpressing mice showed a dynamic decrease of GSIS, which appeared as early as 8 weeks old, preceding the impairment of insulin sensitivity and glucose tolerance. Islets isolated from RBP4-Tg mice showed a significant decrease of GSIS. Mechanistically, we demonstrated that the stimulated by retinoic acid 6 (STRA6), RBP4's only known specific membrane receptor, is expressed in β-cells and mediates the inhibitory effect of RBP4 on insulin synthesis through the Janus kinase 2/STAT1/ISL-1 pathway. Moreover, decreasing circulating RBP4 level could effectively restore β-cell dysfunction and ameliorate hyperglycemia in db/db mice. These observations revealed a role of RBP4 in pancreatic β-cell dysfunction, which provides new insight into the diabetogenic effect of RBP4.
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Affiliation(s)
- Rong Huang
- Guangdong Provincial Key Laboratory of Food, Nutrition, and Health and Department of Nutrition, School of Public Health, Sun Yat-sen University (Northern Campus), Guangzhou, Guangdong Province, People's Republic of China
| | - Xinxiu Bai
- Guangdong Provincial Key Laboratory of Food, Nutrition, and Health and Department of Nutrition, School of Public Health, Sun Yat-sen University (Northern Campus), Guangzhou, Guangdong Province, People's Republic of China
| | - Xueyan Li
- Guangdong Provincial Key Laboratory of Food, Nutrition, and Health and Department of Nutrition, School of Public Health, Sun Yat-sen University (Northern Campus), Guangzhou, Guangdong Province, People's Republic of China
| | - Xiaohui Wang
- Guangdong Provincial Key Laboratory of Food, Nutrition, and Health and Department of Nutrition, School of Public Health, Sun Yat-sen University (Northern Campus), Guangzhou, Guangdong Province, People's Republic of China
| | - Lina Zhao
- Guangdong Provincial Key Laboratory of Food, Nutrition, and Health and Department of Nutrition, School of Public Health, Sun Yat-sen University (Northern Campus), Guangzhou, Guangdong Province, People's Republic of China
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何 建. Human STRA6 Gene Cloning and Its Expression and Localization at Hepatoma Cells. Biophysics (Nagoya-shi) 2021. [DOI: 10.12677/biphy.2021.91003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Muñiz-Hernández S, Velázquez-Fernández JB, Díaz-Chávez J, Mondragón-Fonseca O, Mayén-Lobo Y, Ortega A, López-López M, Arrieta O. STRA6 Polymorphisms Are Associated With EGFR Mutations in Locally-Advanced and Metastatic Non-Small Cell Lung Cancer Patients. Front Oncol 2020; 10:579561. [PMID: 33324556 PMCID: PMC7723324 DOI: 10.3389/fonc.2020.579561] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 10/13/2020] [Indexed: 01/11/2023] Open
Abstract
Retinol plays a significant role in several physiological processes through their nuclear receptors, whose expression depends on retinol cytoplasmic concentration. Loss of expression of nuclear receptors and low retinol levels have been correlated with lung cancer development. Stimulated by retinoic acid 6 (STRA6) is the only described cell membrane receptor for retinol uptake. Some chronic diseases have been linked with specific polymorphisms in STRA6. This study aimed to evaluate four STRA6 single nucleotide polymorphisms (SNPs) (rs4886578, rs736118, rs351224, and rs97445) among 196 patients with locally-advanced and metastatic non-small cell lung cancer (NSCLC) patients. Genotyping, through a validated SNP assay and determined using real time-PCR, was correlated with clinical features and outcomes. NSCLC patients with a TT SNP rs4886578 and rs736118 genotype were more likely to be >60 years, non-smokers, and harboring EGFR mutations. Patients with a TT genotype compared with a CC/CT SNP rs974456 genotype had a median progression-free survival (PFS) of 3.2 vs. 4.8 months, p = 0.044, under a platinum-based regimen in the first-line. Furthermore, patients with a TT rs351224 genotype showed a prolonged overall survival (OS), 47.5 months vs. 32.0 months, p = 0.156. This study showed a correlation between clinical characteristics, such as age, non-smoking history, and EGFR mutational status and oncological outcomes depending on STRA6 SNPs. The STRA6 TT genotype SNP rs4886578 and rs736118 might be potential biomarkers in locally-advanced and metastatic NSCLC patients.
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Affiliation(s)
- Saé Muñiz-Hernández
- Laboratorio de Oncología Experimental, Subdirección de Investigación Básica, Instituto Nacional de Cancerología, Ciudad de México, Mexico
| | | | - José Díaz-Chávez
- Laboratorio de Carcinogénesis, Dirección de Investigación, Instituto Nacional de Cancerología, Ciudad de México, Mexico
| | - Omar Mondragón-Fonseca
- Laboratorio de Oncología Experimental, Subdirección de Investigación Básica, Instituto Nacional de Cancerología, Ciudad de México, Mexico
| | - Yerye Mayén-Lobo
- Laboratorio de Oncología Experimental, Subdirección de Investigación Básica, Instituto Nacional de Cancerología, Ciudad de México, Mexico.,Laboratorio de Genética Molecular, Departamento de Sistemas Biológicos, Universidad Autónoma Metropolitana-Xochimilco, Ciudad de México, Mexico
| | - Alberto Ortega
- Laboratorio de Genética Molecular, Departamento de Sistemas Biológicos, Universidad Autónoma Metropolitana-Xochimilco, Ciudad de México, Mexico
| | - Marisol López-López
- Laboratorio de Genética Molecular, Departamento de Sistemas Biológicos, Universidad Autónoma Metropolitana-Xochimilco, Ciudad de México, Mexico
| | - Oscar Arrieta
- Laboratorio de Oncología Experimental, Subdirección de Investigación Básica, Instituto Nacional de Cancerología, Ciudad de México, Mexico.,Unidad de Oncología Torácica, Instituto Nacional de Cancerología, Ciudad de México, Mexico
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38
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Shin SJ, Chen CH, Kuo WC, Chan HC, Chan HC, Lin KD, Ke LY. Disruption of retinoid homeostasis induces RBP4 overproduction in diabetes: O-GlcNAcylation involved. Metabolism 2020; 113:154403. [PMID: 33065162 DOI: 10.1016/j.metabol.2020.154403] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 08/10/2020] [Accepted: 10/09/2020] [Indexed: 12/20/2022]
Abstract
BACKGROUND Retinol-binding protein 4 (RBP4) is elevated and associated with inflammation in metabolic diseases. Disruption of the retinol cascade and O-GlcNAcylation of the RBP4 receptor (STRA6) are found in diabetic kidneys. OBJECTIVES We investigated whether the disruption of the retinol cascade induces RBP4 overproduction and if O-linked GlcNAc modification targets RBPR2 and contributes to the disruption of retinol cascades in diabetic livers. METHODS Western blot or immunohistochemistry for RBPR2, CRBP1, LRAT, RALDH, RARα, RARγ, RXRα, RBP4, GFAT, OGT, OGA and inflammatory markers, as well as ELISA for RBP4, were performed in livers of db/db and ob/ob mice and high glucose-cultured hepatocytes. Immunoprecipitation and dual fluorescence staining were used to explore O-GlcNAc-modified RBPR2 and RBP4 binding activity on RBPR2. Transfection of the CRBP1 gene was done to verify whether a disrupted retinol cascade induces RBP4 overproduction. OGT silencing was done to investigate the association of O-GlcNAcylation with the disruption of retinol cascade. RESULTS Disruption of retinol cascade, RBP4 overproduction, O-GlcNAcylation of RBPR2, decreased RBP4 binding activity on RBPR2 and inflammation were found in livers of db/db and ob/ob mice and high glucose-cultured hepatocytes. CRBP1 gene transfection reversed the suppression of the cellular retinol cascade and simultaneously attenuated the RBP4 overproduction and inflammation in high glucose-treated hepatocytes. The silencing of OGT reversed the disruption of the cellular retinol cascade, RBP4 overproduction and inflammation induced by high glucose in hepatocytes. CONCLUSIONS This study indicates that the disruption of cellular retinol cascade is strongly associated with RBP4 overproduction and inflammation in diabetic livers. RBPR2 is one target for high glucose-mediated O-linked GlcNAc modification, which causes liver retinol dyshomeostasis.
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Affiliation(s)
- Shyi-Jang Shin
- Grander Clinic, Kaohsiung, Taiwan; School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Chao-Hung Chen
- The Graduate Institute of Animal Vaccine Technology, National Pingtung University of Science and Technology, Pingtung, Taiwan; General Research Service Center, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Wen-Chen Kuo
- Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Hua-Chen Chan
- Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Hsiu-Chuan Chan
- Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Kun-Der Lin
- School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Liang-Yin Ke
- Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan; Department of Medical Laboratory Science and Biotechnology, College of Health Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan.
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39
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Punjani A, Zhang H, Fleet DJ. Non-uniform refinement: adaptive regularization improves single-particle cryo-EM reconstruction. Nat Methods 2020; 17:1214-1221. [PMID: 33257830 DOI: 10.1038/s41592-020-00990-8] [Citation(s) in RCA: 604] [Impact Index Per Article: 151.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 10/06/2020] [Indexed: 11/09/2022]
Abstract
Cryogenic electron microscopy (cryo-EM) is widely used to study biological macromolecules that comprise regions with disorder, flexibility or partial occupancy. For example, membrane proteins are often kept in solution with detergent micelles and lipid nanodiscs that are locally disordered. Such spatial variability negatively impacts computational three-dimensional (3D) reconstruction with existing iterative refinement algorithms that assume rigidity. We introduce non-uniform refinement, an algorithm based on cross-validation optimization, which automatically regularizes 3D density maps during refinement to account for spatial variability. Unlike common shift-invariant regularizers, non-uniform refinement systematically removes noise from disordered regions, while retaining signal useful for aligning particle images, yielding dramatically improved resolution and 3D map quality in many cases. We obtain high-resolution reconstructions for multiple membrane proteins as small as 100 kDa, demonstrating increased effectiveness of cryo-EM for this class of targets critical in structural biology and drug discovery. Non-uniform refinement is implemented in the cryoSPARC software package.
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Affiliation(s)
- Ali Punjani
- Department of Computer Sciences, University of Toronto, Toronto, Ontario, Canada. .,Vector Institute, Toronto, Ontario, Canada. .,Structura Biotechnology Inc., Toronto, Ontario, Canada.
| | - Haowei Zhang
- Department of Computer Sciences, University of Toronto, Toronto, Ontario, Canada
| | - David J Fleet
- Department of Computer Sciences, University of Toronto, Toronto, Ontario, Canada. .,Vector Institute, Toronto, Ontario, Canada.
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40
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Sharma A, Wasson LK, Willcox JA, Morton SU, Gorham JM, DeLaughter DM, Neyazi M, Schmid M, Agarwal R, Jang MY, Toepfer CN, Ward T, Kim Y, Pereira AC, DePalma SR, Tai A, Kim S, Conner D, Bernstein D, Gelb BD, Chung WK, Goldmuntz E, Porter G, Tristani-Firouzi M, Srivastava D, Seidman JG, Seidman CE. GATA6 mutations in hiPSCs inform mechanisms for maldevelopment of the heart, pancreas, and diaphragm. eLife 2020; 9:53278. [PMID: 33054971 PMCID: PMC7593088 DOI: 10.7554/elife.53278] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 10/14/2020] [Indexed: 12/18/2022] Open
Abstract
Damaging GATA6 variants cause cardiac outflow tract defects, sometimes with pancreatic and diaphragmic malformations. To define molecular mechanisms for these diverse developmental defects, we studied transcriptional and epigenetic responses to GATA6 loss of function (LoF) and missense variants during cardiomyocyte differentiation of isogenic human induced pluripotent stem cells. We show that GATA6 is a pioneer factor in cardiac development, regulating SMYD1 that activates HAND2, and KDR that with HAND2 orchestrates outflow tract formation. LoF variants perturbed cardiac genes and also endoderm lineage genes that direct PDX1 expression and pancreatic development. Remarkably, an exon 4 GATA6 missense variant, highly associated with extra-cardiac malformations, caused ectopic pioneer activities, profoundly diminishing GATA4, FOXA1/2, and PDX1 expression and increasing normal retinoic acid signaling that promotes diaphragm development. These aberrant epigenetic and transcriptional signatures illuminate the molecular mechanisms for cardiovascular malformations, pancreas and diaphragm dysgenesis that arise in patients with distinct GATA6 variants.
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Affiliation(s)
- Arun Sharma
- Department of Genetics, Harvard Medical School, Boston, United States.,Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, United States.,Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, United States
| | - Lauren K Wasson
- Department of Genetics, Harvard Medical School, Boston, United States.,Howard Hughes Medical Institute, Harvard Medical School, Boston, United States
| | - Jon Al Willcox
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Sarah U Morton
- Department of Genetics, Harvard Medical School, Boston, United States.,Division of Newborn Medicine, Boston Children's Hospital, Boston, United States
| | - Joshua M Gorham
- Department of Genetics, Harvard Medical School, Boston, United States
| | | | - Meraj Neyazi
- Department of Genetics, Harvard Medical School, Boston, United States.,Hannover Medical School, Hannover, Germany
| | - Manuel Schmid
- Department of Genetics, Harvard Medical School, Boston, United States.,Deutsches Herzzentrum München, Technische Universität München, Munich, Germany
| | - Radhika Agarwal
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Min Young Jang
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Christopher N Toepfer
- Department of Genetics, Harvard Medical School, Boston, United States.,Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.,Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Tarsha Ward
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Yuri Kim
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Alexandre C Pereira
- Department of Genetics, Harvard Medical School, Boston, United States.,Laboratory of Genetics and Molecular Cardiology, Heart Institute, Medical School of University of Sao Paulo, Sao Paulo, Brazil
| | - Steven R DePalma
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Angela Tai
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Seongwon Kim
- Department of Genetics, Harvard Medical School, Boston, United States
| | - David Conner
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Daniel Bernstein
- Department of Pediatrics, Stanford University School of Medicine, Stanford, United States
| | - Bruce D Gelb
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, United States
| | - Wendy K Chung
- Department of Medicine, Columbia University Medical Center, New York, United States
| | - Elizabeth Goldmuntz
- Department of Pediatrics, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - George Porter
- Department of Pediatrics, University of Rochester Medical Center, Rochester, United States
| | - Martin Tristani-Firouzi
- Division of Pediatric Cardiology, University of Utah School of Medicine, Salt Lake City, United States
| | | | | | - Christine E Seidman
- Department of Genetics, Harvard Medical School, Boston, United States.,Howard Hughes Medical Institute, Harvard Medical School, Boston, United States.,Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Boston, United States
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Sun N, Dou X, Tang Z, Zhang D, Ni N, Wang J, Gao H, Ju Y, Dai X, Zhao C, Gu P, Ji J, Feng C. Bio-inspired chiral self-assemblies promoted neuronal differentiation of retinal progenitor cells through activation of metabolic pathway. Bioact Mater 2020; 6:990-997. [PMID: 33102941 PMCID: PMC7560590 DOI: 10.1016/j.bioactmat.2020.09.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/22/2020] [Accepted: 09/27/2020] [Indexed: 12/30/2022] Open
Abstract
Retinal degeneration is a main class of ocular diseases. So far, retinal progenitor cell (RPC) transplantation has been the most potential therapy for it, in which promoting RPCs neuronal differentiation remains an unmet challenge. To address this issue, innovatively designed L/ d - phenylalanine based chiral nanofibers (LPG and DPG) are employed and it finds that chirality of fibers can efficiently regulate RPCs differentiation. qPCR, western blot, and immunofluorescence analysis show that right-handed helical DPG nanofibers significantly promote RPCs neuronal differentiation, whereas left-handed LPG nanofibers decrease this effect. These effects are mainly ascribed to the stereoselective interaction between chiral helical nanofibers and retinol-binding protein 4 (RBP4, a key protein in the retinoic acid (RA) metabolic pathway). The findings of chirality-dependent neuronal differentiation provide new strategies for treatment of neurodegenerative diseases via optimizing differentiation of transplanted stem cells on chiral nanofibers.
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Affiliation(s)
- Na Sun
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Xiaoqiu Dou
- State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiaotong University, Dongchuan Road 800, 200240, Shanghai, China
| | - Zhimin Tang
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Dandan Zhang
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Ni Ni
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Jiajing Wang
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Huiqin Gao
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Yahan Ju
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Xiaochan Dai
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Changli Zhao
- State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiaotong University, Dongchuan Road 800, 200240, Shanghai, China
| | - Ping Gu
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Jing Ji
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Chuanliang Feng
- State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiaotong University, Dongchuan Road 800, 200240, Shanghai, China
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Abstract
The visual phototransduction cascade begins with a cis-trans photoisomerization of a retinylidene chromophore associated with the visual pigments of rod and cone photoreceptors. Visual opsins release their all-trans-retinal chromophore following photoactivation, which necessitates the existence of pathways that produce 11-cis-retinal for continued formation of visual pigments and sustained vision. Proteins in the retinal pigment epithelium (RPE), a cell layer adjacent to the photoreceptor outer segments, form the well-established "dark" regeneration pathway known as the classical visual cycle. This pathway is sufficient to maintain continuous rod function and support cone photoreceptors as well although its throughput has to be augmented by additional mechanism(s) to maintain pigment levels in the face of high rates of photon capture. Recent studies indicate that the classical visual cycle works together with light-dependent processes in both the RPE and neural retina to ensure adequate 11-cis-retinal production under natural illuminances that can span ten orders of magnitude. Further elucidation of the interplay between these complementary systems is fundamental to understanding how cone-mediated vision is sustained in vivo. Here, we describe recent advances in understanding how 11-cis-retinal is synthesized via light-dependent mechanisms.
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Solanki AK, Kondkar AA, Fogerty J, Su Y, Kim SH, Lipschutz JH, Nihalani D, Perkins BD, Lobo GP. A Functional Binding Domain in the Rbpr2 Receptor Is Required for Vitamin A Transport, Ocular Retinoid Homeostasis, and Photoreceptor Cell Survival in Zebrafish. Cells 2020; 9:E1099. [PMID: 32365517 PMCID: PMC7290320 DOI: 10.3390/cells9051099] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 04/20/2020] [Accepted: 04/25/2020] [Indexed: 12/21/2022] Open
Abstract
Dietary vitamin A/all-trans retinol/ROL plays a critical role in human vision. ROL circulates bound to the plasma retinol-binding protein (RBP4) as RBP4-ROL. In the eye, the STRA6 membrane receptor binds to circulatory RBP4 and internalizes ROL. STRA6 is, however, not expressed in systemic tissues, where there is high affinity RBP4 binding and ROL uptake. We tested the hypothesis that the second retinol binding protein 4 receptor 2 (Rbpr2), which is highly expressed in systemic tissues of zebrafish and mouse, contains a functional RBP4 binding domain, critical for ROL transport. As for STRA6, modeling and docking studies confirmed three conserved RBP4 binding residues in zebrafish Rbpr2. In cell culture studies, disruption of the RBP4 binding residues on Rbpr2 almost completely abolished uptake of exogenous vitamin A. CRISPR-generated rbpr2-RBP4 domain zebrafish mutants showed microphthalmia, shorter photoreceptor outer segments, and decreased opsins, which were attributed to impaired ocular retinoid content. Injection of WT-Rbpr2 mRNA into rbpr2 mutant or all-trans retinoic acid treatment rescued the mutant eye phenotypes. In conclusion, zebrafish Rbpr2 contains a putative extracellular RBP4-ROL ligand-binding domain, critical for yolk vitamin A transport to the eye for ocular retinoid production and homeostasis, for photoreceptor cell survival.
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Affiliation(s)
- Ashish K. Solanki
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA; (A.K.S.); (Y.S.); (S.-H.K.); (J.H.L.); (D.N.)
| | - Altaf A. Kondkar
- Glaucoma Research Chair, Department of Ophthalmology, College of Medicine, King Saud University, Riyadh 11411, Saudi Arabia;
| | - Joseph Fogerty
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (J.F.); (B.D.P.)
| | - Yanhui Su
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA; (A.K.S.); (Y.S.); (S.-H.K.); (J.H.L.); (D.N.)
| | - Seok-Hyung Kim
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA; (A.K.S.); (Y.S.); (S.-H.K.); (J.H.L.); (D.N.)
| | - Joshua H. Lipschutz
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA; (A.K.S.); (Y.S.); (S.-H.K.); (J.H.L.); (D.N.)
- Ralph H. Johnson VA Medical Center, Division of Research, Charleston, SC 29420, USA
| | - Deepak Nihalani
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA; (A.K.S.); (Y.S.); (S.-H.K.); (J.H.L.); (D.N.)
| | - Brian D. Perkins
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (J.F.); (B.D.P.)
| | - Glenn P. Lobo
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA; (A.K.S.); (Y.S.); (S.-H.K.); (J.H.L.); (D.N.)
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC 29425, USA
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von Lintig J, Moon J, Babino D. Molecular components affecting ocular carotenoid and retinoid homeostasis. Prog Retin Eye Res 2020; 80:100864. [PMID: 32339666 DOI: 10.1016/j.preteyeres.2020.100864] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/13/2020] [Accepted: 04/17/2020] [Indexed: 12/15/2022]
Abstract
The photochemistry of vision employs opsins and geometric isomerization of their covalently bound retinylidine chromophores. In different animal classes, these light receptors associate with distinct G proteins that either hyperpolarize or depolarize photoreceptor membranes. Vertebrates also use the acidic form of chromophore, retinoic acid, as the ligand of nuclear hormone receptors that orchestrate eye development. To establish and sustain these processes, animals must acquire carotenoids from the diet, transport them, and metabolize them to chromophore and retinoic acid. The understanding of carotenoid metabolism, however, lagged behind our knowledge about the biology of their receptor molecules. In the past decades, much progress has been made in identifying the genes encoding proteins that mediate the transport and enzymatic transformations of carotenoids and their retinoid metabolites. Comparative analysis in different animal classes revealed how evolutionary tinkering with a limited number of genes evolved different biochemical strategies to supply photoreceptors with chromophore. Mutations in these genes impair carotenoid metabolism and induce various ocular pathologies. This review summarizes this advancement and introduces the involved proteins, including the homeostatic regulation of their activities.
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Affiliation(s)
- Johannes von Lintig
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
| | - Jean Moon
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Darwin Babino
- Department of Ophthalmology, School of Medicine, University of Washington, Seattle, WA, USA
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Regulatory mechanism for the transmembrane receptor that mediates bidirectional vitamin A transport. Proc Natl Acad Sci U S A 2020; 117:9857-9864. [PMID: 32300017 DOI: 10.1073/pnas.1918540117] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Vitamin A has diverse biological functions and is essential for human survival at every point from embryogenesis to adulthood. Vitamin A and its derivatives have been used to treat human diseases including vision diseases, skin diseases, and cancer. Both insufficient and excessive vitamin A uptake are detrimental, but how its transport is regulated is poorly understood. STRA6 is a multitransmembrane domain cell-surface receptor and mediates vitamin A uptake from plasma retinol binding protein (RBP). STRA6 can mediate both cellular vitamin A influx and efflux, but what regulates these opposing activities is unknown. To answer this question, we purified and identified STRA6-associated proteins in a native mammalian cell type that takes up vitamin A through STRA6 using mass spectrometry. We found that the major protein repeatedly identified as STRA6-associated protein is calmodulin, consistent with the cryogenic electron microscopy (cryo-EM) study of zebrafish STRA6 associated with calmodulin. Using radioactivity-based, high-performance liquid chromatography (HPLC)-based and real-time fluorescence techniques, we found that calmodulin profoundly affects STRA6's vitamin A transport activity. Increased calcium/calmodulin promotes cellular vitamin A efflux and suppresses vitamin A influx through STRA6. Further mechanistic studies revealed that calmodulin enhances the binding of apo-RBP to STRA6, and this enhancement is much more pronounced for apo-RBP than holo-RBP. This study revealed that calmodulin regulates STRA6's vitamin A influx or efflux activity by modulating its preferential interaction with apo-RBP or holo-RBP. This molecular mechanism of regulating vitamin A transport may point to new directions to treat human diseases associated with insufficient or excessive vitamin A uptake.
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Abstract
Vitamin A and derivatives, the natural retinoids, underpin signaling pathways of cellular differentiation, and are key chromophores in vision. These functions depend on transfer across membranes, and carrier proteins to shuttle retinoids to specific cell compartments. Natural retinoids, ultimately derived from plant carotenoids by metabolism to all-trans retinol, are lipophilic and consist of a cyclohexenyl (β-ionone) moiety linked to a polyene chain. This structure constrains the orientation of retinoids within lipid membranes. Cis-trans isomerization at double bonds of the polyene chain and s-cis/s-trans rotational isomerization at single bonds define the functional dichotomy of retinoids (signaling/vision) and specificities of interactions with specific carrier proteins and receptors. Metabolism of all-trans retinol to 11-cis retinal, transfer to photoreceptors, and removal and recycling of all-trans retinal generated by photoreceptor irradiation, is the key process underlying vision. All-trans retinol transferred into cells is metabolized to all-trans retinoic acid and shuttled to the cell nucleus to regulate gene expression controlling organ, tissue and cell differentiation, and cellular homeostasis. Research methods need to address the potential of photoisomerization in vitro to confound research results, and data should be interpreted in the context of membrane-association properties of retinoids and physiological concentrations in vivo. Despite a century of research, there are many fundamental questions of retinoid cellular biochemistry and molecular biology still to be answered. Computational modeling techniques will have an important role for understanding the nuances of vitamin A signaling and function.
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Affiliation(s)
- Chris P F Redfern
- School of Natural & Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom.
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Greene AG, Eivers SB, Dervan EWJ, O'Brien CJ, Wallace DM. Lysyl Oxidase Like 1: Biological roles and regulation. Exp Eye Res 2020; 193:107975. [PMID: 32070696 DOI: 10.1016/j.exer.2020.107975] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 01/12/2020] [Accepted: 02/13/2020] [Indexed: 12/11/2022]
Abstract
Lysyl Oxidase Like 1 (LOXL1) is a gene that encodes for the LOXL1 enzyme. This enzyme is required for elastin biogenesis and collagen cross-linking, polymerising tropoelastin monomers into elastin polymers. Its main role is in elastin homeostasis and matrix remodelling during injury, fibrosis and cancer development. Because of its vast range of biological functions, abnormalities in LOXL1 underlie many disease processes. Decreased LOXL1 expression is observed in disorders of elastin such as Cutis Laxa and increased expression is reported in fibrotic disease such as Idiopathic Pulmonary Fibrosis. LOXL1 is also downregulated in the lamina cribrosa in pseudoexfoliation glaucoma and genetic variants in the LOXL1 gene have been linked with an increased risk of developing pseudoexfoliation glaucoma and pseudoexfoliation syndrome. However the two major risk alleles are reversed in certain ethnic groups and are present in a large proportion of the normal population, implying complex genetic and environmental regulation is involved in disease pathogenesis. It also appears that the non-coding variants in intron 1 of LOXL1 may be involved in the regulation of LOXL1 expression. Gene alteration may occur via a number of epigenetic and post translational mechanisms such as DNA methylation, long non-coding RNAs and microRNAs. These may represent future therapeutic targets for disease. Environmental factors such as hypoxia, oxidative stress and ultraviolet radiation exposure alter LOXL1 expression, and it is likely a combination of these genetic and environmental factors that influence disease development and progression. In this review, we discuss LOXL1 properties, biological roles and regulation in detail with a focus on pseudoexfoliation syndrome and glaucoma.
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Affiliation(s)
- Alison G Greene
- UCD Clinical Research Centre, School of Medicine, University College Dublin, Ireland.
| | - Sarah B Eivers
- UCD Clinical Research Centre, School of Medicine, University College Dublin, Ireland
| | - Edward W J Dervan
- Dept. of Ophthalmology, Mater Misericordiae University Hospital, Eccles Street, Dublin 7, Ireland
| | - Colm J O'Brien
- UCD Clinical Research Centre, School of Medicine, University College Dublin, Ireland; Dept. of Ophthalmology, Mater Misericordiae University Hospital, Eccles Street, Dublin 7, Ireland
| | - Deborah M Wallace
- UCD Clinical Research Centre, School of Medicine, University College Dublin, Ireland
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Miller AP, Coronel J, Amengual J. The role of β-carotene and vitamin A in atherogenesis: Evidences from preclinical and clinical studies. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158635. [PMID: 31978554 DOI: 10.1016/j.bbalip.2020.158635] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/14/2020] [Accepted: 01/16/2020] [Indexed: 02/07/2023]
Abstract
Atherosclerotic cardiovascular disease (ASCVD) is the principal contributor to myocardial infarction, the leading cause of death worldwide. Epidemiological and mechanistic studies indicate that β-carotene and its vitamin A derivatives stimulate lipid catabolism in several tissues to reduce the incidence of obesity, but their roles within ASCVD are elusive. Herein, we review the mechanisms by which β-carotene and vitamin A modulate ASCVD. First, we summarize the current knowledge linking these nutrients with epidemiological studies and lipoprotein metabolism as one of the initiating factors of ASCVD. Next, we focus on different aspects of vitamin A metabolism in immune cells such as the mechanisms of carotenoid uptake and conversion to the vitamin A metabolite, retinoic acid. Lastly, we review the effects of retinoic acid on immuno-metabolism, differentiation, and function of macrophages and T cells, the two pillars of the innate and adaptive immune response in ASCVD, respectively. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.
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Affiliation(s)
- Anthony P Miller
- Department of Food Science and Human Nutrition, University of Illinois Urbana Champaign, Urbana, IL 61801, United States of America
| | - Johana Coronel
- Department of Food Science and Human Nutrition, University of Illinois Urbana Champaign, Urbana, IL 61801, United States of America
| | - Jaume Amengual
- Department of Food Science and Human Nutrition, University of Illinois Urbana Champaign, Urbana, IL 61801, United States of America; Division of Nutritional Sciences, University of Illinois Urbana Champaign, Urbana, IL 61801, United States of America.
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Serio RN, Gudas LJ. Modification of stem cell states by alcohol and acetaldehyde. Chem Biol Interact 2019; 316:108919. [PMID: 31846616 PMCID: PMC7036011 DOI: 10.1016/j.cbi.2019.108919] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 11/13/2019] [Accepted: 12/10/2019] [Indexed: 12/20/2022]
Abstract
Ethanol (EtOH) is a recreationally ingested compound that is both teratogenic and carcinogenic in humans. Because of its abundant consumption worldwide and the vital role of stem cells in the formation of birth defects and cancers, delineating the effects of EtOH on stem cell function is currently an active and urgent pursuit of scientific investigation to explicate some of the mechanisms contributing to EtOH toxicity. Stem cells represent a primordial, undifferentiated phase of development; thus encroachment on normal physiologic processes of differentiation into terminal lineages by EtOH can greatly alter the function of progenitors and terminally differentiated cells, leading to pathological consequences that manifest as fetal alcohol spectrum disorders and cancers. In this review we explore the disruptive role of EtOH in differentiation of stem cells. Our primary objective is to elucidate the mechanisms by which EtOH alters differentiation-related gene expression and lineage specifications, thus modifying stem cells to promote pathological outcomes. We additionally review the effects of a reactive metabolite of EtOH, acetaldehyde (AcH), in causing both differentiation defects in stem cells as well as genomic damage that incites cellular aging and carcinogenesis.
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Affiliation(s)
- Ryan N Serio
- Department of Pharmacology, Weill Cornell Graduate School of Medical Sciences of Cornell University, USA.
| | - Lorraine J Gudas
- Department of Pharmacology, Weill Cornell Graduate School of Medical Sciences of Cornell University, USA; Department of Pharmacology, Weill Cornell Medical College of Cornell University, USA.
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Isoherranen N, Zhong G. Biochemical and physiological importance of the CYP26 retinoic acid hydroxylases. Pharmacol Ther 2019; 204:107400. [PMID: 31419517 PMCID: PMC6881548 DOI: 10.1016/j.pharmthera.2019.107400] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 08/06/2019] [Indexed: 12/19/2022]
Abstract
The Cytochrome P450 (CYP) family 26 enzymes contribute to retinoic acid (RA) metabolism and homeostasis in humans, mammals and other chordates. The three CYP26 family enzymes, CYP26A1, CYP26B1 and CYP26C1 have all been shown to metabolize all-trans-retinoic acid (atRA) it's 9-cisRA and 13-cisRA isomers and primary metabolites 4-OH-RA and 4-oxo-RA with high efficiency. While no crystal structures of CYP26 enzymes are available, the binding of various ligands has been extensively explored via homology modeling. All three CYP26 enzymes are inducible by treatment with atRA in various prenatal and postnatal tissues and cell types. However, current literature shows that in addition to regulation by atRA, CYP26 enzyme expression is also regulated by other endogenous processes and inflammatory cytokines. In humans and in animal models the expression patterns of CYP26 enzymes have been shown to be tissue and cell type specific, and the expression of the CYP26 enzymes is believed to regulate the formation of critical atRA concentration gradients in various tissue types. Yet, very little data exists on direct disease associations of altered CYP26 expression or activity. Nevertheless, data is emerging describing a variety of human genetic variations in the CYP26 enzymes that are associated with different pathologies. Interestingly, some of these genetic variants result in increased activity of the CYP26 enzymes potentially leading to complex gene-environment interactions due to variability in dietary intake of retinoids. This review highlights the current knowledge of structure-function of CYP26 enzymes and focuses on their role in human retinoid metabolism in different tissues.
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Affiliation(s)
- Nina Isoherranen
- Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, WA, USA.
| | - Guo Zhong
- Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, WA, USA
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