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Berruien NNA, Smith CL. Emerging roles of melanocortin receptor accessory proteins (MRAP and MRAP2) in physiology and pathophysiology. Gene 2020; 757:144949. [PMID: 32679290 DOI: 10.1016/j.gene.2020.144949] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 07/08/2020] [Accepted: 07/09/2020] [Indexed: 01/07/2023]
Abstract
Melanocortin-2 receptor accessory protein (MRAP) has an unusual dual topology and influences the expression, localisation, signalling and internalisation of the melanocortin receptor 2 (MC2); the adrenocorticotropic hormone (ACTH) receptor. Mutations in MRAP are associated with familial glucocorticoid deficiency type-2 and evidence is emerging of the importance of MRAP in adrenal development and ACTH signalling. Human MRAP has two functional splice variants: MRAP-α and MRAP-β, unlike MRAP-β, MRAP-α has little expression in brain but is highly expressed in ovary. MRAP2, identified through whole human genome sequence analysis, has approximately 40% sequence homology to MRAP. MRAP2 facilitates MC2 localisation to the cell surface but not ACTH signalling. MRAP and MRAP2 have been found to regulate the surface expression and signalling of all melanocortin receptors (MC1-5). Additionally, MRAP2 moderates the signalling of the G-protein coupled receptors (GCPRs): orexin, prokineticin and GHSR1a; the ghrelin receptor. Whilst MRAP appears to be mainly involved in glucocorticoid synthesis, an important role is emerging for MRAP2 in regulating appetite and energy homeostasis. Transgenic models indicate the importance of MRAP in adrenal gland formation. Like MC3R and MC4R knockout mice, MRAP2 knockout mice have an obese phenotype. In vitro studies indicate that MRAP2 enhances the MC3 and MC4 response to the agonist αMSH, which, like ACTH, is produced through precursor polypeptide proopiomelanocortin (POMC) cleavage. Analysis of cohorts of individuals with obesity have revealed several MRAP2 genetic variants with loss of function mutations which are causative of monogenic hyperphagic obesity with hyperglycaemia and hypertension. MRAP2 may also be associated with female infertility. This review summarises current knowledge of MRAP and MRAP2, their influence on GPCR signalling, and focusses on pathophysiology, particularly familial glucocorticoid deficiency type-2 and obesity.
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Affiliation(s)
- Nasrin N A Berruien
- School of Life Sciences, University of Westminster, 115 New Cavendish Street, London W1W 6UW, UK.
| | - Caroline L Smith
- School of Life Sciences, University of Westminster, 115 New Cavendish Street, London W1W 6UW, UK.
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2
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Tao YX. Molecular chaperones and G protein-coupled receptor maturation and pharmacology. Mol Cell Endocrinol 2020; 511:110862. [PMID: 32389798 DOI: 10.1016/j.mce.2020.110862] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 12/15/2022]
Abstract
G protein-coupled receptors (GPCRs) are highly conserved versatile signaling molecules located at the plasma membrane that respond to diverse extracellular signals. They regulate almost all physiological processes in the vertebrates. About 35% of current drugs target these receptors. Mutations in these genes have been identified as causes of numerous diseases. The seven transmembrane domain structure of GPCRs implies that the folding of these transmembrane proteins is extremely complicated and difficult. Indeed, many wild type GPCRs are not folded optimally. The most common defect in genetic diseases caused by GPCR mutations is misfolding and failure to reach the plasma membrane where it functions. General molecular chaperones aid the folding of all proteins, including GPCRs, by preventing aggregation, promoting folding and disaggregating small aggregates. Some GPCRs need additional receptor-specific chaperones to assist their folding. Many of these receptor-specific chaperones interact with additional receptors and alter receptor pharmacology, expanding the understanding of these chaperone proteins.
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Affiliation(s)
- Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, 36849-5519, USA.
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Tao M, Ji RL, Huang L, Fan SY, Liu T, Liu SJ, Tao YX. Regulation of Melanocortin-4 Receptor Pharmacology by Two Isoforms of Melanocortin Receptor Accessory Protein 2 in Topmouth Culter ( Culter alburnus). Front Endocrinol (Lausanne) 2020; 11:538. [PMID: 32922362 PMCID: PMC7456811 DOI: 10.3389/fendo.2020.00538] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 07/02/2020] [Indexed: 01/03/2023] Open
Abstract
Melanocortin-4 receptor (MC4R) plays important roles in regulation of multiple physiological processes, and interaction of MC4R and melanocortin receptor accessory protein 2 (MRAP2) is suggested to play pivotal role in energy balance of vertebrates. Topmouth culter (Culter alburnus) is an economically important freshwater fish in China. Herein we cloned culter mc4r, mrap2a, and mrap2b. Culter mc4r consisted of a 981 bp open reading frame encoding a protein of 326 amino acids. qRT-PCR revealed that mc4r, mrap2a, and mrap2b were primarily expressed in the central nervous system. In the periphery, mc4r and mrap2b were expressed more widely in the male, while mrap2a was expressed more widely in the female. Culter MC4R could bind to four peptide agonists and increase intracellular cAMP production dose dependently. Culter MC4R was constitutively active in both cAMP and ERK1/2 pathways, which was differentially regulated by culter MRAP2a and MRAP2b. Culter MRAP2a significantly increased Bmax and decreased agonist-stimulated cAMP, while MRAP2b increased cell surface and total expression but did not affect Bmax and agonist-stimulated cAMP. These results will aid the investigation of the potential physiological processes that MC4R might be involved in topmouth culter.
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Affiliation(s)
- Min Tao
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Ren-Lei Ji
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Lu Huang
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Si-Yu Fan
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Ting Liu
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Shao-Jun Liu
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
- *Correspondence: Shao-Jun Liu
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
- Ya-Xiong Tao
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Rao YZ, Chen R, Zhang Y, Tao YX. Orange-spotted grouper melanocortin-4 receptor: Modulation of signaling by MRAP2. Gen Comp Endocrinol 2019; 284:113234. [PMID: 31398355 DOI: 10.1016/j.ygcen.2019.113234] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 07/02/2019] [Accepted: 07/28/2019] [Indexed: 02/06/2023]
Abstract
Melanocortin-4 receptor (MC4R) and melanocortin receptor accessory protein 2 (MRAP2) play important roles in the melanocortin system, and interaction of MC4R and MRAP2 is suggested to play pivotal role in energy balance of vertebrates. Orange-spotted grouper (Epinephelus coioides) is a widely cultured marine fish with high economic value in Asia. To explore potential interaction between grouper MC4R and MRAP2, herein we cloned grouper mc4r and mrap2. Grouper mc4r consisted of a 981 bp ORF encoding a putative protein of 327 amino acids, while the grouper mrap2 consisted of a 696 bp ORF encoding a putative protein of 232 amino acids. Sequence and phylogenetic analysis revealed that the grouper MC4R and MRAP2 were highly homologous at amino acid levels to several teleost MC4Rs and MRAP2s, respectively. qRT-PCR results showed that both mc4r and mrap2 were expressed primarily in the central nervous system. In the periphery, these genes were expressed more widely in male fish. The cloned grouper MC4R was functional, exhibiting high constitutive activity in cAMP pathway, capable of binding to three peptide agonists and increasing intracellular cAMP production dose-dependently. MRAP2 significantly decreased basal and agonist-stimulated cAMP signaling. MRAP2 also increased basal ERK1/2 activation but decreased ligand-induced stimulation when expressed at high levels. These data will facilitate future investigation of these molecules in regulating diverse physiological processes in orange-spotted grouper.
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Affiliation(s)
- Ying-Zhu Rao
- Institute of Applied Biotechnology, Life Science and Technology School, Lingnan Normal University, Zhanjiang 524048, Guangdong, China; Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Rong Chen
- Institute of Applied Biotechnology, Life Science and Technology School, Lingnan Normal University, Zhanjiang 524048, Guangdong, China
| | - Yong Zhang
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266373, China
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States.
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Zhu M, Xu B, Wang M, Liu S, Zhang Y, Zhang C. Pharmacological modulation of MRAP2 protein on melanocortin receptors in the sea lamprey. Endocr Connect 2019; 8:378-388. [PMID: 30856611 PMCID: PMC6454295 DOI: 10.1530/ec-19-0019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 03/11/2019] [Indexed: 12/28/2022]
Abstract
Melanocortin receptors (MCRs) and their accessory proteins (MRAPs) evolutionarily first appear in the genome of sea lamprey. The most ancient melanocortin system consists of only two melanocortin receptors (slMCa and slMCb) and one MRAP2 (slMRAP2) protein, but the physiological roles have not been fully explored in this primitive species. Here, we synthesize and characterize the pharmacological features of slMRAP2 protein on two slMCRs. Our results show that the slMRAP2 protein lacks the long carboxyl terminus; it directly interacts and decreases the surface expression but enhances the α-MSH-induced agonism of slMCa and slMCb. In comparison with higher organisms such as elephant shark and zebrafish, we also demonstrate the constantly evolving regulatory function of the carboxyl terminus of MRAP2 protein, the unique antiparallel topology of slMRAP2 dimer and the homo- and hetero-dimerization of two slMCRs. This study elucidates the presence and modulation of melanocortin receptor by the accessory protein of the agnathans for the first time, which provides a better insight of the melanocortin system in ancient species of chordates.
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Affiliation(s)
- Ming Zhu
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Bingxin Xu
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Meng Wang
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Shangyun Liu
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Yue Zhang
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Chao Zhang
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
- Correspondence should be addressed to C Zhang:
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Tang X, Liu Y, Xiao Q, Yao Q, Allen M, Wang Y, Gao L, Qi Y, Zhang P. Pathological cyclic strain promotes proliferation of vascular smooth muscle cells via the ACTH/ERK/STAT3 pathway. J Cell Biochem 2018; 119:8260-8270. [DOI: 10.1002/jcb.26839] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 03/09/2018] [Indexed: 01/10/2023]
Affiliation(s)
- Xia Tang
- Institute of Mechanobiology and Medical EngineeringSchool of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Yanyan Liu
- Institute of Mechanobiology and Medical EngineeringSchool of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Qian Xiao
- Institute of Mechanobiology and Medical EngineeringSchool of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Qingping Yao
- Institute of Mechanobiology and Medical EngineeringSchool of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Molly Allen
- Department of BioengineeringUniversity of CaliforniaSan DiegoCalifornia
| | - Yingxiao Wang
- Department of BioengineeringUniversity of CaliforniaSan DiegoCalifornia
| | - Lizhi Gao
- Institute of Mechanobiology and Medical EngineeringSchool of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Yingxin Qi
- Institute of Mechanobiology and Medical EngineeringSchool of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Ping Zhang
- Institute of Mechanobiology and Medical EngineeringSchool of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
- National Experimental Teaching Demonstration of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
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Ren J, Li Y, Xu N, Li H, Li C, Han R, Wang Y, Li Z, Kang X, Liu X, Tian Y. Association of estradiol on expression of melanocortin receptors and their accessory proteins in the liver of chicken (Gallus gallus). Gen Comp Endocrinol 2017; 240:182-190. [PMID: 27793723 DOI: 10.1016/j.ygcen.2016.10.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 10/18/2016] [Accepted: 10/24/2016] [Indexed: 12/31/2022]
Abstract
The melanocortin receptor accessory proteins (MRAP and MRAP2) are small single-pass transmembrane proteins that regulate the biological functions of the melanocortin receptor (MCR) family. MCRs comprise five receptors (MC1R-MC5R) with diverse physiological roles in mammals. Five MCR members and two MRAPs were also predicted in the chicken (Gallus gallus) genome. However, little is known about their expression, regulation and biological functions. In this study, we cloned the MRAP and MRAP2 genes. Sequencing analysis revealed that the functional domains of MRAP and MRAP2 were conserved among species, suggesting that the physiological roles of chicken MRAP and MRAP2 could be similar to their mammalian counterparts. Tissue expression analysis demonstrated that MRAP was expressed in the adrenal gland, liver, spleen, glandular stomach and lungs, while MRAP2 is predominantly expressed in the adrenal gland. All five MCRs were present in the adrenal gland, but showed different expression patterns in other tissues. The MC5R was the only MCR member that was expressed in the chicken liver. The expression levels of MRAP in chicken liver were significantly increased at sexual maturity stage, and were significantly up-regulated (P<0.05) when chickens and chicken primary hepatocytes were treated with 17β-estradiol in vivo and in vitro, respectively; however, expression levels of PPARγ were down-regulated, and no effect on MC5R was observed. Our results suggested that estrogen could stimulate the expression of MRAP in the liver of chicken through inhibiting the expression of transcription regulation factor PPARγ, and MRAP might play its biological role in a different way rather than forming an MRAP/MC2R complex in chicken liver during the egg-laying period.
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MESH Headings
- Amino Acid Sequence
- Animals
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Chickens/genetics
- Cloning, Molecular
- Estradiol/pharmacology
- Gene Expression Profiling
- Gene Expression Regulation, Developmental/drug effects
- Hepatocytes/drug effects
- Hepatocytes/metabolism
- Humans
- Liver/drug effects
- Liver/metabolism
- PPAR gamma/genetics
- PPAR gamma/metabolism
- Phylogeny
- Receptor, Melanocortin, Type 2/chemistry
- Receptor, Melanocortin, Type 2/genetics
- Receptor, Melanocortin, Type 2/metabolism
- Receptors, Melanocortin/chemistry
- Receptors, Melanocortin/genetics
- Receptors, Melanocortin/metabolism
- Sequence Alignment
- Tissue Distribution/drug effects
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Affiliation(s)
- Junxiao Ren
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China
| | - Yanmin Li
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China
| | - Naiyi Xu
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China
| | - Hong Li
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China
| | - Cuicui Li
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China
| | - Ruili Han
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China; Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Henan Agricultural University, Zhengzhou 450002, China; International Joint Research Laboratory for Poultry Breeding of Henan, Henan Agricultural University, Zhengzhou 450002, China
| | - Yanbin Wang
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China; Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Henan Agricultural University, Zhengzhou 450002, China; International Joint Research Laboratory for Poultry Breeding of Henan, Henan Agricultural University, Zhengzhou 450002, China
| | - Zhuanjian Li
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China; Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Henan Agricultural University, Zhengzhou 450002, China; International Joint Research Laboratory for Poultry Breeding of Henan, Henan Agricultural University, Zhengzhou 450002, China
| | - Xiangtao Kang
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China; Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Henan Agricultural University, Zhengzhou 450002, China; International Joint Research Laboratory for Poultry Breeding of Henan, Henan Agricultural University, Zhengzhou 450002, China
| | - Xiaojun Liu
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China; Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Henan Agricultural University, Zhengzhou 450002, China; International Joint Research Laboratory for Poultry Breeding of Henan, Henan Agricultural University, Zhengzhou 450002, China.
| | - Yadong Tian
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China; Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Henan Agricultural University, Zhengzhou 450002, China; International Joint Research Laboratory for Poultry Breeding of Henan, Henan Agricultural University, Zhengzhou 450002, China.
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Maben ZJ, Malik S, Jiang LH, Hinkle PM. Dual Topology of the Melanocortin-2 Receptor Accessory Protein Is Stable. Front Endocrinol (Lausanne) 2016; 7:96. [PMID: 27486435 PMCID: PMC4947873 DOI: 10.3389/fendo.2016.00096] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 07/05/2016] [Indexed: 01/02/2023] Open
Abstract
Melanocortin 2 receptor accessory protein (MRAP) facilitates trafficking of melanocortin 2 (MC2) receptors and is essential for ACTH binding and signaling. MRAP is a single transmembrane domain protein that forms antiparallel homodimers. These studies ask when MRAP first acquires this dual topology, whether MRAP architecture is static or stable, and whether the accessory protein undergoes rapid turnover. To answer these questions, we developed an approach that capitalizes on the specificity of bacterial biotin ligase, which adds biotin to lysine in a short acceptor peptide sequence; the distinct mobility of MRAP protomers of opposite orientations based on their N-linked glycosylation; and the ease of identifying biotin-labeled proteins. We inserted biotin ligase acceptor peptides at the N- or C-terminal ends of MRAP and expressed the modified proteins in mammalian cells together with either cytoplasmic or endoplasmic reticulum-targeted biotin ligase. MRAP assumed dual topology early in biosynthesis in both CHO and OS3 adrenal cells. Once established, MRAP orientation was stable. Despite its conformational stability, MRAP displayed a half-life of under 2 h in CHO cells. The amount of MRAP was increased by the proteasome inhibitor MG132 and MRAP underwent ubiquitylation on lysine and other amino acids. Nonetheless, when protein synthesis was blocked with cycloheximide, MRAP was rapidly degraded even when MG132 was included and all lysines were replaced by arginines, implicating non-proteasomal degradation pathways. The results show that although MRAP does not change orientations during trafficking, its synthesis and degradation are dynamically regulated.
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Affiliation(s)
- Zachary J. Maben
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
| | - Sundeep Malik
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
| | - Liyi H. Jiang
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
| | - Patricia M. Hinkle
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
- *Correspondence: Patricia M. Hinkle,
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Malik S, Dolan TM, Maben ZJ, Hinkle PM. Adrenocorticotropic Hormone (ACTH) Responses Require Actions of the Melanocortin-2 Receptor Accessory Protein on the Extracellular Surface of the Plasma Membrane. J Biol Chem 2015; 290:27972-85. [PMID: 26424796 DOI: 10.1074/jbc.m115.668491] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Indexed: 01/26/2023] Open
Abstract
The melanocortin-2 (MC2) receptor is a G protein-coupled receptor that mediates responses to ACTH. The MC2 receptor acts in concert with the MC2 receptor accessory protein (MRAP) that is absolutely required for ACTH binding and signaling. MRAP has a single transmembrane domain and forms a highly unusual antiparallel homodimer that is stably associated with MC2 receptors at the plasma membrane. Despite the physiological importance of the interaction between the MC2 receptor and MRAP, there is little understanding of how the accessory protein works. The dual topology of MRAP has made it impossible to determine whether highly conserved and necessary regions of MRAP are required on the intracellular or extracellular face of the plasma membrane. The strategy used here was to fix the orientation of two antiparallel MRAP molecules and then introduce inactivating mutations on one side of the membrane or the other. This was achieved by engineering proteins containing tandem copies of MRAP fused to the amino terminus of the MC2 receptor. The data firmly establish that only the extracellular amino terminus (Nout) copy of MRAP, oriented with critical segments on the extracellular side of the membrane, is essential. The transmembrane domain of MRAP is also required in only the Nout orientation. Finally, activity of MRAP-MRAP-MC2-receptor fusion proteins with inactivating mutations in either MRAP or the receptor was rescued by co-expression of free wild-type MRAP or free wild-type receptor. These results show that the basic MRAP-MRAP-receptor signaling unit forms higher order complexes and that these multimers signal.
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Affiliation(s)
- Sundeep Malik
- From the Department of Pharmacology and Physiology, University of Rochester Medical Center Rochester, New York 14642
| | - Terrance M Dolan
- From the Department of Pharmacology and Physiology, University of Rochester Medical Center Rochester, New York 14642
| | - Zachary J Maben
- From the Department of Pharmacology and Physiology, University of Rochester Medical Center Rochester, New York 14642
| | - Patricia M Hinkle
- From the Department of Pharmacology and Physiology, University of Rochester Medical Center Rochester, New York 14642
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Cortés R, Navarro S, Agulleiro MJ, Guillot R, García-Herranz V, Sánchez E, Cerdá-Reverter JM. Evolution of the melanocortin system. Gen Comp Endocrinol 2014; 209:3-10. [PMID: 24768673 DOI: 10.1016/j.ygcen.2014.04.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 04/01/2014] [Accepted: 04/03/2014] [Indexed: 11/17/2022]
Abstract
The melanocortin system is one of the most complex of the hormonal systems. It involves different agonists encoded in the multiplex precursor proopiomelanocortin (POMC) or in different genes as β-defensins, endogenous antagonist, like agouti-signalling protein (ASIP) or agouti-related protein (AGRP), and five different melanocortin receptors (MCRs). Rounds of whole genome duplication events have preceded the functional and molecular diversification of the family in addition some co-evolutionary and tandem duplication processes have been proposed. The evolutionary patterns of the different partners are controversial and different hypotheses have emerged from a study of the sequenced genomes. In this review, we summarize the different evolutionary hypotheses proposed for the different melanocortin partners.
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Affiliation(s)
- Raúl Cortés
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - Sandra Navarro
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - Maria Josep Agulleiro
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - Raúl Guillot
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - Víctor García-Herranz
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - Elisa Sánchez
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - José Miguel Cerdá-Reverter
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain.
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11
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Caruso V, Lagerström MC, Olszewski PK, Fredriksson R, Schiöth HB. Synaptic changes induced by melanocortin signalling. Nat Rev Neurosci 2014; 15:98-110. [PMID: 24588018 DOI: 10.1038/nrn3657] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The melanocortin system has a well-established role in the regulation of energy homeostasis, but there is growing evidence of its involvement in memory, nociception, mood disorders and addiction. In this Review, we focus on the role of the melanocortin 4 receptor and provide an integrative view of the molecular mechanisms that lead to melanocortin-induced changes in synaptic plasticity within these diverse physiological systems. We also highlight the importance of melanocortin peptides and receptors in chronic pain syndromes, memory impairments, depression and drug abuse, and the possibility of targeting them for therapeutic purposes.
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Josep Agulleiro M, Cortés R, Fernández-Durán B, Navarro S, Guillot R, Meimaridou E, Clark AJL, Cerdá-Reverter JM. Melanocortin 4 receptor becomes an ACTH receptor by coexpression of melanocortin receptor accessory protein 2. Mol Endocrinol 2013; 27:1934-45. [PMID: 24085819 DOI: 10.1210/me.2013-1099] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Melanocortin 2 receptor (MC2R) is the only canonical ACTH receptor. Its functional expression requires the presence of an accessory protein, known as melanocortin receptor 2 accessory protein 1 (MRAP1). The vertebrate genome exhibits a paralogue gene called MRAP2, which is duplicated in zebrafish (MRAP2a and MRAP2b), although its function remains unknown. In this paper, we demonstrate that MRAP2a enables MC4R, a canonical MSH receptor, to be activated by ACTH with a similar sensitivity to that exhibited by MC2R. Both proteins physically interact and are coexpressed in the neurons of the preoptic area, a key region in the control of the energy balance and hypophyseal secretion in fish. ACTH injections inhibit food intake in wild-type zebrafish but not in fish lacking functional MC4R. Both MRAP1 and MRAP2a are hormonally regulated, suggesting that these proteins are substrates for feed-back regulatory pathways of melanocortin signaling. Fasting has no effect on the central expression of MRAP2a but stimulates MRAP2b expression. This protein interacts and is colocalized with MC4R in the tuberal hypothalamic neurons but has no effect on the pharmacologic profile of MC4R. However, MRPA2b is able to decrease basal reporter activity in cell lines expressing MC4R. It is plausible that MRAP2b decreases the constitutive activity of the MC4R during fasting periods, driving the animal toward a positive energy balance. Our data indicate that MRAP2s control the activity of MC4R, opening up new pathways for the regulation of melanocortin signaling and, by extension, for the regulation of the energy balance and obesity.
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Affiliation(s)
- Maria Josep Agulleiro
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, 12595 Torre de la Sal, Ribera de Cabanes, Castellón, Spain.
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