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Tugaeva KV, Sluchanko NN. Steroidogenic Acute Regulatory Protein: Structure, Functioning, and Regulation. BIOCHEMISTRY (MOSCOW) 2019; 84:S233-S253. [PMID: 31213205 DOI: 10.1134/s0006297919140141] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Steroidogenesis takes place mainly in adrenal and gonadal cells that produce a variety of structurally similar hormones regulating numerous body functions. The rate-limiting stage of steroidogenesis is cholesterol delivery to the inner mitochondrial membrane, where it is converted by cytochrome P450scc into pregnenolone, a common precursor of all steroid hormones. The major role of supplying mitochondria with cholesterol belongs to steroidogenic acute regulatory protein (STARD1). STARD1, which is synthesized de novo as a precursor containing mitochondrial localization sequence and sterol-binding domain, significantly accelerates cholesterol transport and production of pregnenolone. Despite a tremendous interest in STARD1 fueled by its involvement in hereditary diseases and extensive efforts of numerous laboratories worldwide, many aspects of STARD1 structure, functioning, and regulation remain obscure and debatable. This review presents current concepts on the structure of STARD1 and other lipid transfer proteins, the role of STARD1 in steroidogenesis, and the mechanism of its functioning, as well as identifies the most controversial and least studied questions related to the activity of this protein.
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Affiliation(s)
- K V Tugaeva
- Bach Institute of Biochemistry, Federal Research Center of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia. .,Lomonosov Moscow State University, Biological Faculty, Department of Biochemistry, Moscow, 119234, Russia
| | - N N Sluchanko
- Bach Institute of Biochemistry, Federal Research Center of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia. .,Lomonosov Moscow State University, Biological Faculty, Department of Biophysics, Moscow, 119991, Russia
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Rosado-Olivieri EA, Ramos-Ortiz GA, Hernández-Pasos J, Díaz-Balzac CA, Vázquez-Rosa E, Valentín-Tirado G, Vega IE, García-Arrarás JE. A START-domain-containing protein is a novel marker of nervous system components of the sea cucumber Holothuria glaberrima. Comp Biochem Physiol B Biochem Mol Biol 2017; 214:57-65. [PMID: 28864221 DOI: 10.1016/j.cbpb.2017.08.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 08/10/2017] [Accepted: 08/19/2017] [Indexed: 12/21/2022]
Abstract
One of the main challenges faced by investigators studying the nervous system of members of the phylum Echinodermata is the lack of markers to identify nerve cells and plexi. Previous studies have utilized an antibody, RN1, that labels most of the nervous system structures of the sea cucumber Holothuria glaberrima and other echinoderms. However, the antigen recognized by RN1 remained unknown. In the present work, the antigen has been characterized by immunoprecipitation, tandem mass spectrometry, and cDNA cloning. The RN1 antigen contains a START lipid-binding domain found in Steroidogenic Acute Regulatory (StAR) proteins and other lipid-binding proteins. Phylogenetic tree assembly showed that the START domain is highly conserved among echinoderms. We have named this antigen HgSTARD10 for its high sequence similarity to the vertebrate orthologs. Gene and protein expression analyses revealed an abundance of HgSTARD10 in most H. glaberrima tissues including radial nerve, intestine, muscle, esophagus, mesentery, hemal system, gonads and respiratory tree. Molecular cloning of HgSTARD10, consequent protein expression and polyclonal antibody production revealed the STARD10 ortholog as the antigen recognized by the RN1 antibody. Further characterization into this START domain-containing protein will provide important insights for the biochemistry, physiology and evolution of deuterostomes.
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Affiliation(s)
- Edwin A Rosado-Olivieri
- Department of Biology, University of Puerto Rico-Río Piedras Campus, San Juan PR 00931, Puerto Rico.
| | - Gibram A Ramos-Ortiz
- Department of Biology, University of Puerto Rico-Río Piedras Campus, San Juan PR 00931, Puerto Rico.
| | - Josué Hernández-Pasos
- Department of Biology, University of Puerto Rico-Río Piedras Campus, San Juan PR 00931, Puerto Rico
| | - Carlos A Díaz-Balzac
- Department of Biology, University of Puerto Rico-Río Piedras Campus, San Juan PR 00931, Puerto Rico.
| | - Edwin Vázquez-Rosa
- Department of Chemistry, University of Puerto Rico Río Piedras Campus, San Juan PR 00931, Puerto Rico
| | - Griselle Valentín-Tirado
- Department of Biology, University of Puerto Rico-Río Piedras Campus, San Juan PR 00931, Puerto Rico
| | - Irving E Vega
- Translational Science & Molecular Medicine, Michigan State University, Grand Rapids, MI 49503, United States
| | - José E García-Arrarás
- Department of Biology, University of Puerto Rico-Río Piedras Campus, San Juan PR 00931, Puerto Rico.
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Elustondo P, Martin LA, Karten B. Mitochondrial cholesterol import. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:90-101. [PMID: 27565112 DOI: 10.1016/j.bbalip.2016.08.012] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 08/15/2016] [Accepted: 08/19/2016] [Indexed: 02/06/2023]
Abstract
All animal subcellular membranes require cholesterol, which influences membrane fluidity and permeability, fission and fusion processes, and membrane protein function. The distribution of cholesterol among subcellular membranes is highly heterogeneous and the cholesterol content of each membrane must be carefully regulated. Compared to other subcellular membranes, mitochondrial membranes are cholesterol-poor, particularly the inner mitochondrial membrane (IMM). As a result, steroidogenesis can be controlled through the delivery of cholesterol to the IMM, where it is converted to pregnenolone. The low basal levels of cholesterol also make mitochondria sensitive to changes in cholesterol content, which can have a relatively large impact on the biophysical and functional characteristics of mitochondrial membranes. Increased mitochondrial cholesterol levels have been observed in diverse pathological conditions including cancer, steatohepatitis, Alzheimer disease and Niemann-Pick Type C1-deficiency, and are associated with increased oxidative stress, impaired oxidative phosphorylation, and changes in the susceptibility to apoptosis, among other alterations in mitochondrial function. Mitochondria are not included in the vesicular trafficking network; therefore, cholesterol transport to mitochondria is mostly achieved through the activity of lipid transfer proteins at membrane contact sites or by cytosolic, diffusible lipid transfer proteins. Here we will give an overview of the main mechanisms involved in mitochondrial cholesterol import, focusing on the steroidogenic acute regulatory protein StAR/STARD1 and other members of the StAR-related lipid transfer (START) domain protein family, and we will discuss how changes in mitochondrial cholesterol levels can arise and affect mitochondrial function. This article is part of a Special Issue entitled: Lipids of Mitochondria edited by Guenther Daum.
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Affiliation(s)
- Pia Elustondo
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Laura A Martin
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Barbara Karten
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada.
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STARD6 on steroids: solution structure, multiple timescale backbone dynamics and ligand binding mechanism. Sci Rep 2016; 6:28486. [PMID: 27340016 PMCID: PMC4919784 DOI: 10.1038/srep28486] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 06/03/2016] [Indexed: 12/17/2022] Open
Abstract
START domain proteins are conserved α/β helix-grip fold that play a role in the non-vesicular and intracellular transport of lipids and sterols. The mechanism and conformational changes permitting the entry of the ligand into their buried binding sites is not well understood. Moreover, their functions and the identification of cognate ligands is still an active area of research. Here, we report the solution structure of STARD6 and the characterization of its backbone dynamics on multiple time-scales through 15N spin-relaxation and amide exchange studies. We reveal for the first time the presence of concerted fluctuations in the Ω1 loop and the C-terminal helix on the microsecond-millisecond time-scale that allows for the opening of the binding site and ligand entry. We also report that STARD6 binds specifically testosterone. Our work represents a milestone for the study of ligand binding mechanism by other START domains and the elucidation of the biological function of STARD6.
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Létourneau D, Lefebvre A, Lavigne P, LeHoux JG. The binding site specificity of STARD4 subfamily: Breaking the cholesterol paradigm. Mol Cell Endocrinol 2015; 408:53-61. [PMID: 25542846 DOI: 10.1016/j.mce.2014.12.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 12/19/2014] [Accepted: 12/19/2014] [Indexed: 11/16/2022]
Abstract
Steroidogenic acute regulatory protein (StAR)-related lipid transfer (START) domain proteins display diverse expression patterns and cellular localisations. They bind a large variety of lipids and sterols and are involved in lipid metabolism, lipid transfer and cell signalling. The START domain tertiary structure is an α-helix/β-grip fold module of approximately 210 amino acids delimiting an internal cavity forming the binding site. However, the determinants that dictate ligand specificity and the mechanism of ligand entry and exit are ill-defined. Herein, we review and discuss the current knowledge on ligand specificity and binding mechanism of START domains. More specifically, we highlight that the conserved residues of STARD1, STARD3, STARD4, STARD5 and STARD6 START domains binding sterol play an important structural role for the global protein fold, whereas the residues forming the cavity that fits the shape of their respective ligand are divergent, suggesting their participation in ligand specificity. We also explore the potential binding of steroids to STARD6 in the context of ligand selectivity.
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Affiliation(s)
- Danny Létourneau
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
| | - Andrée Lefebvre
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
| | - Pierre Lavigne
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
| | - Jean-Guy LeHoux
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada.
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Chang IY, Ohn T, Jeon YJ, Lee KH, Kim JW, Kim IY, Yoon SP. A comparison of the steroidogenic acute regulatory protein-related lipid transfer (START) domain-containing 6 on the brain and testes between young and aged rats. Acta Histochem 2014; 116:551-8. [PMID: 24360190 DOI: 10.1016/j.acthis.2013.11.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 11/12/2013] [Accepted: 11/13/2013] [Indexed: 11/24/2022]
Abstract
The START domain-containing 6 (StarD6) was originally reported to play a role during male germ cell maturation. We have since reported on StarD6 in the developing hypothyroid rat brain. Therefore, we investigated qualitative and quantitative changes of StarD6 in the aging rat brain and testes of male Sprague-Dawley rats. Serum testosterone levels decreased with aging and total protein levels of StarD6 in the testes decreased. While the immunolocalization of StarD6 in the spermatocytes decreased, cytoplasmic localization appeared in the aged testes. Compared with young rats, aged rats showed decreased StarD6 in the cerebrum and cerebellum without changes in immunolocalization in the cortical neurons of the cerebral cortex and Purkinje cells of the cerebellar cortex. Aged rats also showed increases in StarD6 in the hippocampus with changes in its immunolocalization from the Stratum pyramidale to the Stratum radiatum and Stratum lacunosum-moleculare. Taken together, StarD6 decreased with aging in the testes, which implies that StarD6 might play a role in impaired spermatogenesis in the aged rat. StarD6 decreased in the cerebrum and the cerebellum, but slightly increased in the hippocampus, which suggests that StarD6 might also play a role for neurosteroidogenesis in the hippocampus of aged rats.
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Calderon-Dominguez M, Gil G, Medina MA, Pandak WM, Rodríguez-Agudo D. The StarD4 subfamily of steroidogenic acute regulatory-related lipid transfer (START) domain proteins: new players in cholesterol metabolism. Int J Biochem Cell Biol 2014; 49:64-8. [PMID: 24440759 DOI: 10.1016/j.biocel.2014.01.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 12/18/2013] [Accepted: 01/02/2014] [Indexed: 11/19/2022]
Abstract
Cholesterol levels in the body are maintained through the coordinated regulation of its uptake, synthesis, distribution, storage and efflux. However, the way cholesterol is sorted within cells remains poorly defined. The discovery of the newly described StarD4 subfamily, part of the steroidogenic acute regulatory lipid transfer (START) domain family of proteins, affords an opportunity for the study of intracellular cholesterol movement, metabolism and its disorders. The three members of this intracellular subfamily of proteins (StarD4, StarD5 and StarD6) have a similar lipid binding pocket specific for sterols (cholesterol in particular), but differing regulation and localization. The ability to bind and transport cholesterol through a non-vesicular mean suggests that they play a previously unappreciated role in cholesterol homeostasis.
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Affiliation(s)
- Maria Calderon-Dominguez
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, Universidad de Barcelona, Spain
| | - Gregorio Gil
- Department of Biochemistry, Virginia Commonwealth University, Richmond, VA, United States
| | - Miguel Angel Medina
- Department of Molecular Biology and Biochemistry, Universidad de Malaga, Spain
| | - William M Pandak
- Department of Medicine, Veterans Affairs Medical Center and Virginia Commonwealth University, Richmond, VA, United States
| | - Daniel Rodríguez-Agudo
- Department of Medicine, Veterans Affairs Medical Center and Virginia Commonwealth University, Richmond, VA, United States.
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Létourneau D, Lefebvre A, Lavigne P, LeHoux JG. STARD5 specific ligand binding: comparison with STARD1 and STARD4 subfamilies. Mol Cell Endocrinol 2013; 371:20-5. [PMID: 23337244 DOI: 10.1016/j.mce.2013.01.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 01/09/2013] [Accepted: 01/09/2013] [Indexed: 10/27/2022]
Abstract
We present herein a review of our recent results on the characterization of the binding sites of STARD1, STARD5 and STARD6 using NMR and other biophysical techniques. Whereas STARD1 and STARD6 bind cholesterol, no cholesterol binding could be detected for STARD5. However, titration of STARD5 with cholic acid and chenodeoxycholic acid led to specific binding. Using perturbation of the (1)H-(15)N-HSQC spectra and the sequence specific NMR assignments, we identified the amino acids in contact with those ligands. The most perturbed residues in presence of ligands are lining the internal cavity of the protein. Interestingly, these residues are not conserved in STARD1 and STARD6 and could therefore be key structural determinants of the specificity of START domains toward their ligands. We highlight three tissues expressing STARD5 that are affected by bile acids.
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Affiliation(s)
- Danny Létourneau
- Département de Biochimie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec, Canada J1H 5N4
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Chang IY, Kim JH, Cho KW, Yoon SP. Acute responses of DNA repair proteins and StarD6 in rat hippocampus after domoic acid-induced excitotoxicity. Acta Histochem 2013; 115:234-9. [PMID: 22883302 DOI: 10.1016/j.acthis.2012.07.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 07/04/2012] [Accepted: 07/05/2012] [Indexed: 10/28/2022]
Abstract
StarD6, which might be considered to be neuroprotective, and DNA repair proteins can play a role against oxidative damages by excitotoxin in the nervous system. In order to investigate the relationship between StarD6 and DNA repair proteins, excitotoxicity was induced by domoic acid in male Sprague-Dawley rats. Western blot analysis revealed transitorily elevated levels in StarD6, apurinic/apyrimidinic endonuclease (APE) and 8-oxoguanine DNA-glycosylase (Ogg1) in accord with the DNA damage marker phosphorylated H2AX. Immunohistochemistry revealed that increased intensity was transiently seen not only in the Stratum (Str.) radiatum and Str. lacunosum-moleculare with StarD6 and APE, but also in the Str. pyramidale with Ogg1. Intensities decreased 24h after domoic acid injection in CA3 with APE and Ogg1 as well as in the Str. radiatum and Str. lacunosum-moleculare with StarD6 and APE. These results suggested that StarD6 may not be closely related with DNA repair proteins in the hippocampus after domoic acid-induced excitotoxicity, although the activities of these proteins might be positively affected by excitotoxic stimuli.
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Létourneau D, Lorin A, Lefebvre A, Frappier V, Gaudreault F, Najmanovich R, Lavigne P, LeHoux JG. StAR-related lipid transfer domain protein 5 binds primary bile acids. J Lipid Res 2012; 53:2677-89. [PMID: 23018617 DOI: 10.1194/jlr.m031245] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Steroidogenic acute regulatory-related lipid transfer (START) domain proteins are involved in the nonvesicular intracellular transport of lipids and sterols. The STARD1 (STARD1 and STARD3) and STARD4 subfamilies (STARD4-6) have an internal cavity large enough to accommodate sterols. To provide a deeper understanding on the structural biology of this domain, the binding of sterols to STARD5, a member of the STARD4 subfamily, was monitored. The SAR by NMR [(1)H-(15)N heteronuclear single-quantum coherence (HSQC)] approach, complemented by circular dichroism (CD) and isothermal titration calorimetry (ITC), was used. Titration of STARD5 with cholic (CA) and chenodeoxycholic acid (CDCA), ligands of the farnesoid X receptor (FXR), leads to drastic perturbation of the (1)H-(15)N HSQC spectra and the identification of the residues in contact with those ligands. The most perturbed residues in presence of ligands are lining the internal cavity of the protein. Ka values of 1.8·10-(4) M(-1) and 6.3·10(4) M(-1) were measured for CA and CDCA, respectively. This is the first report of a START domain protein in complex with a sterol ligand. Our original findings indicate that STARD5 may be involved in the transport of bile acids rather than cholesterol.
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Affiliation(s)
- Danny Létourneau
- Département de Biochimie, Faculté de médecine et des sciences de lsanté, Université de Sherbrooke, Sherbrooke, Québec, Canada, J1H 5N4
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Chang IY, Ohn T, Ko GS, Yoon Y, Kim JW, Yoon SP. Immunolocalization of steroidogenic acute regulatory protein-related lipid transfer (START) domain-containing proteins in the developing cerebellum of normal and hypothyroid rats. J Chem Neuroanat 2011; 43:28-33. [PMID: 22024186 DOI: 10.1016/j.jchemneu.2011.10.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 10/10/2011] [Accepted: 10/10/2011] [Indexed: 10/16/2022]
Abstract
Cholesterol transport proteins are a prerequisite for neurosteroidogenesis. Steroidogenic acute regulatory protein (StAR)-related lipid transfer (START) domain-containing proteins, such as StAR and START domain-containing 6 (StarD6), are known to be distributed in the brain. Since perinatal hypothyroidism affects cerebellar development, we examined postnatal changes in StAR and StarD6 immunolocalization in the developing cerebellum of control and hypothyroid rats. Pregnant Sprague-Dawley rats were given 0.05% 6-propyl-2-thiouracil (PTU) or water from gestation day 11 until postnatal day (P) 28, and were then killed together with age-matched control rats. As shown by calbindin D-28k immunostaining, the developing cerebellar cytoarchitecture and Purkinje cells were affected by PTU-induced hypothyroidism as compared to control rats. The immunolocalization of StAR and StarD6 generally followed the maturation pattern of Purkinje cells from the vermis to the cerebellar hemisphere. StAR immunostaining first appeared in the Purkinje cells of the vermis at P7 in both control and hypothyroid rats. In control rats, a few StarD6 immunoreactive cells were seen at birth and a nuclear localization of StarD6 in Purkinje cells was obvious at P14. PTU-induced hypothyroidism delayed the appearance of StarD6 immunopositive cells until P7. Moreover, the nuclear localization of StarD6 in PTU-treated rats was not obvious at P14. An adult-like distribution of StAR and StarD6 was achieved by P21 in control and hypothyroid rats. These results suggest that StarD6 may affect the development of Purkinje cells during the first and second postnatal weeks, a known period of thyroid hormone action.
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Affiliation(s)
- In Youb Chang
- Department of Anatomy, College of Medicine, Chosun University, Gwangju, Republic of Korea
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