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Davis TR, Pierce MR, Novak SX, Hougland JL. Ghrelin octanoylation by ghrelin O-acyltransferase: protein acylation impacting metabolic and neuroendocrine signalling. Open Biol 2021; 11:210080. [PMID: 34315274 PMCID: PMC8316800 DOI: 10.1098/rsob.210080] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The acylated peptide hormone ghrelin impacts a wide range of physiological processes but is most well known for controlling hunger and metabolic regulation. Ghrelin requires a unique posttranslational modification, serine octanoylation, to bind and activate signalling through its cognate GHS-R1a receptor. Ghrelin acylation is catalysed by ghrelin O-acyltransferase (GOAT), a member of the membrane-bound O-acyltransferase (MBOAT) enzyme family. The ghrelin/GOAT/GHS-R1a system is defined by multiple unique aspects within both protein biochemistry and endocrinology. Ghrelin serves as the only substrate for GOAT within the human proteome and, among the multiple hormones involved in energy homeostasis and metabolism such as insulin and leptin, acts as the only known hormone in circulation that directly stimulates appetite and hunger signalling. Advances in GOAT enzymology, structural modelling and inhibitor development have revolutionized our understanding of this enzyme and offered new tools for investigating ghrelin signalling at the molecular and organismal levels. In this review, we briefly summarize the current state of knowledge regarding ghrelin signalling and ghrelin/GOAT enzymology, discuss the GOAT structural model in the context of recently reported MBOAT enzyme superfamily member structures, and highlight the growing complement of GOAT inhibitors that offer options for both ghrelin signalling studies and therapeutic applications.
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Affiliation(s)
- Tasha R Davis
- Department of Chemistry, Syracuse University, Syracuse, NY 13244 USA
| | - Mariah R Pierce
- Department of Chemistry, Syracuse University, Syracuse, NY 13244 USA
| | - Sadie X Novak
- Department of Chemistry, Syracuse University, Syracuse, NY 13244 USA
| | - James L Hougland
- Department of Chemistry, Syracuse University, Syracuse, NY 13244 USA.,BioInspired Syracuse, Syracuse University, Syracuse, NY 13244 USA
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Ghrelin octanoylation by ghrelin O-acyltransferase: Unique protein biochemistry underlying metabolic signaling. Biochem Soc Trans 2019; 47:169-178. [PMID: 30626708 DOI: 10.1042/bst20180436] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 11/26/2018] [Accepted: 11/28/2018] [Indexed: 02/08/2023]
Abstract
Ghrelin is a small peptide hormone that requires a unique post-translational modification, serine octanoylation, to bind and activate the GHS-R1a receptor. Ghrelin signaling is implicated in a variety of neurological and physiological processes, but is most well known for its roles in controlling hunger and metabolic regulation. Ghrelin octanoylation is catalyzed by ghrelin O-acyltransferase (GOAT), a member of the membrane-bound O-acyltransferase (MBOAT) enzyme family. From the status of ghrelin as the only substrate for GOAT in the human genome to the source and requirement for the octanoyl acyl donor, the ghrelin-GOAT system is defined by multiple unique aspects within both protein biochemistry and endocrinology. In this review, we examine recent advances in our understanding of the interactions and mechanisms leading to ghrelin modification by GOAT, discuss the potential sources for the octanoyl acyl donor required for ghrelin's activation, and summarize the current landscape of molecules targeting ghrelin octanoylation through GOAT inhibition.
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Cleverdon ER, McGovern-Gooch KR, Hougland JL. The octanoylated energy regulating hormone ghrelin: An expanded view of ghrelin's biological interactions and avenues for controlling ghrelin signaling. Mol Membr Biol 2017; 33:111-124. [PMID: 29143554 DOI: 10.1080/09687688.2017.1388930] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Ghrelin is a small peptide hormone that requires a unique post-translational modification, serine octanoylation, to bind and activate the GHS-R1a receptor. Initially demonstrated to stimulate hunger and appetite, ghrelin-dependent signaling is implicated in a variety of neurological and physiological processes influencing diseases such as diabetes, obesity, and Prader-Willi syndrome. In addition to its cognate receptor, recent studies have revealed ghrelin interacts with a range of binding partners within the bloodstream. Defining the scope of ghrelin's interactions within the body, understanding how these interactions work in concert to modulate ghrelin signaling, and developing molecular tools for controlling ghrelin signaling are essential for exploiting ghrelin for therapeutic effect. In this review, we discuss recent findings regarding the biological effects of ghrelin signaling, outline binding partners that control ghrelin trafficking and stability in circulation, and summarize the current landscape of inhibitors targeting ghrelin octanoylation.
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Affiliation(s)
| | | | - James L Hougland
- a Department of Chemistry , Syracuse University , Syracuse , NY , USA
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Abstract
Purpose Hepatocyte nuclear factor 1 alpha (HNF1α) defects cause Mature Onset Diabetes of the Young type 3 (MODY3), characterized by defects in beta-cell insulin secretion. However, HNF1α is involved in many other metabolic pathways with relevance for monogenic or polygenic type 2 diabetes. We aimed to investigate gut hormones, lipids, and insulin regulation in response to a meal test in HNF1α defect carriers (MODY3) compared to non-diabetic subjects (controls) and type 2 diabetes (T2D). Methods We administered a standardized liquid meal to each participant. Over 6 hours, we measured post-meal responses of insulin regulation (blood glucose, c-peptide, insulin), gut hormones (ghrelin, glucose-dependent insulinotropic polypeptide, glucagon-like peptide-1) and lipids (non-esterified fatty acids [NEFA] and triglycerides). Results We found that MODY3 participants had lower insulin secretion indices than controls and T2D participants, showing the expected β-cell defect. MODY3 had similar glycated hemoglobin levels (HbA1c median [IQR]: 6.5 [5.6–7.6]%) compared to T2D (median: 6.6 [6.2–6.9]%; P<0.05). MODY3 had greater insulin sensitivity (Matsuda index: 71.9 [29.6; 125.5]) than T2D (3.2 [4.0; 6.0]; P<0.05). MODY3 experienced a larger decrease in the ratio of NEFA to insulin (NEFA 30–0 / insulin 30–0: -39 [-78; -30] x104) in the early post-prandial period (0–30 minutes) compared to controls and to T2D (-2.0 [-0.6; -6.4] x104; P<0.05). MODY3 had lower fasting (0.66 [0.46; 1.2] mM) and post-meal triglycerides levels compared to T2D (fasting: 2.3 [1.7; 2.7] mM; P<0.05). We did not detect significant post-meal differences in ghrelin and incretins between MODY3 and other groups. Conclusion In response to a standard meal test, MODY3 showed greater early post-prandial NEFA diminution in response to relatively low early insulin secretion, and they maintained very low post-prandial triglycerides levels.
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Effect of preduodenal lipase inhibition in suckling rats on dietary octanoic acid (C8:0) gastric absorption and plasma octanoylated ghrelin concentration. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1111-1120. [DOI: 10.1016/j.bbalip.2016.06.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 06/13/2016] [Accepted: 06/14/2016] [Indexed: 02/06/2023]
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Li S, Liu J, Lv Q, Zhang C, Xu S, Yang D, Huang B, Zeng Y, Gao Y, Wang W. AG and UAG induce β-casein expression via activation of ERK1/2 and AKT pathways. J Mol Endocrinol 2016; 56:213-25. [PMID: 26873999 PMCID: PMC5064986 DOI: 10.1530/jme-15-0287] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Accepted: 02/12/2016] [Indexed: 01/14/2023]
Abstract
The ghrelin peptides were found to circulate in two major forms: acylated ghrelin (AG) and unacylated ghrelin (UAG). Previous studies showed that AG regulates β-casein (CSN2) expression in mammary epithelial cells. However, little is known about the mechanisms by which AG regulates CSN2 gene and protein expression. Evidence suggests that UAG has biological activity through GHSR1a-independent mechanisms. Here, we investigated the possible GHSR1a-mediated effect of UAG on the expression of CSN2 in primary bovine mammary epithelial cells (pbMECs) isolated from lactating cow. We found that both AG and UAG increase the expression of CSN2 in a dose-dependent manner in pbMECs in comparison with the control group. Increased expression of CSN2 was blocked by [D-Lys3]-GHRP-6 (an antagonist of the GHSR1a) and NF449 (a Gs-α subunit inhibitor) in pbMECs. In addition, both AG and UAG activated AKT/protein kinase B (AKT) and extracellular signal-regulated kinase 1/2 (ERK1/2) pathways, whereas [D-Lys3]-GHRP-6 and NF449 inhibited the phosphorylation of AKT and ERK1/2 in pbMECs respectively. Blockade of ERK1/2 and AKT signaling pathways prevented the expression of CSN2 induced by AG or UAG. Finally, we found that both AG and UAG cause cell proliferation through identical signaling pathways. Taken together, these results demonstrate that both AG and UAG act on ERK1/2 and AKT signaling pathways to facilitate the expression of CSN2 in a GHSR1a-dependent manner.
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Affiliation(s)
- Sunan Li
- College of Veterinary MedicineJilin University
| | - Juxiong Liu
- College of Veterinary MedicineJilin University
| | - Qingkang Lv
- College of Veterinary MedicineJilin University
| | - Chuan Zhang
- Department of Endocrinology and MetabolismThe Second Hospital of Jilin University, Changchun, China
| | - Shiyao Xu
- College of Veterinary MedicineJilin University
| | | | | | - Yalong Zeng
- College of Veterinary MedicineJilin University
| | - Yingjie Gao
- College of Veterinary MedicineJilin University
| | - Wei Wang
- College of Veterinary MedicineJilin University
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Darling JE, Zhao F, Loftus RJ, Patton LM, Gibbs RA, Hougland JL. Structure–Activity Analysis of Human Ghrelin O-Acyltransferase Reveals Chemical Determinants of Ghrelin Selectivity and Acyl Group Recognition. Biochemistry 2015; 54:1100-10. [DOI: 10.1021/bi5010359] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Joseph E. Darling
- Department
of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | - Feifei Zhao
- Department
of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana 47907, United States
| | - Rosemary J. Loftus
- Department
of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | - Leslie M. Patton
- Department
of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | - Richard A. Gibbs
- Department
of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana 47907, United States
| | - James L. Hougland
- Department
of Chemistry, Syracuse University, Syracuse, New York 13244, United States
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Hara M, Nishi Y, Yamashita Y, Hirata R, Takahashi S, Nagamitsu SI, Hosoda H, Kangawa K, Kojima M, Matsuishi T. Relation between circulating levels of GH, IGF-1, ghrelin and somatic growth in Rett syndrome. Brain Dev 2014; 36:794-800. [PMID: 24377437 DOI: 10.1016/j.braindev.2013.11.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 11/06/2013] [Accepted: 11/18/2013] [Indexed: 12/14/2022]
Abstract
BACKGROUND Most cases of Rett syndrome (RTT) are caused by mutations in methyl CpG binding protein 2 (MECP2), and individuals with RTT have somatic growth failure, growth arrest of brain, epilepsy, and intellectual disability (ID). Ghrelin is a peptide hormone which stimulates growth hormone (GH) secretion from the pituitary gland. Ghrelin and GH regulate insulin-like growth factor-1 (IGF-1) synthesis, and this GH/IGF-1 axis is an endocrine axis involved in energy and sleep homeostasis and plays crucial roles in somatic and brain growth. This study aimed to determine whether circulating ghrelin, GH and IGF-1 reflect somatic and brain growth in RTT patients. METHODS We examined anthropometric data and circulating ghrelin, GH, and IGF-1 in 22 female RTT patients with epilepsy and ID (RTT-Ep/ID) and 14 age-matched females with epilepsy and ID (non-RTT-Ep/ID). RESULTS Body mass index (BMI) and height/length were significantly lower in RTT-Ep/ID than in non-RTT-Ep/ID in patients less than 20 years old. Plasma ghrelin in RTT-Ep/ID patients showed a significant inverse correlation with weight but had no significant correlations with BMI or height. Head circumference in both groups showed a significant positive correlation with circulating ghrelin and a significant negative correlation with circulating IGF-1. The ratio of octanoyl-ghrelin to total-ghrelin (O/T-ratio) is used as an indicator to estimate the biological activity of ghrelin. Among pre-adolescents, O/T-ratios were significantly higher in the RTT-Ep/ID group than in the non-RTT-Ep/ID group (P < 0.05). CONCLUSIONS Timing of growth-spurts differed between the RTT-Ep/ID and non-RTT-Ep/ID groups, possibly due to a common (but yet unknown) mechanism of growth failure. Ghrelin/GH/IGF-1 axis function was aberrant in both the RTT-Ep/ID and non-RTT-Ep/ID groups. The initial clinical course of Rett syndrome affects the development of the sleep-wake cycle and locomotion in early infancy, both of which may be based on the dysfunction of the aminergic neurons modulated by ghrelin/GH/IGF-1 axis. Further study with a larger sample size should help clarify the precise mechanisms controlling the somatic growth and hormonal features in Rett syndrome.
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Affiliation(s)
- Munetsugu Hara
- Department of Neonatology, Medical Center for Maternal and Child Health, St. Mary's Hospital, Kurume, Fukuoka 830-8543, Japan
| | - Yoshihiro Nishi
- Department of Physiology, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan
| | - Yushiro Yamashita
- Department of Pediatrics and Child Health, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan
| | - Rumiko Hirata
- Department of Pediatrics and Child Health, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan
| | - Satoru Takahashi
- Department of Pediatrics, Asahikawa Medical University, Asahikawa, Hokkaido 078-8510, Japan
| | - Shin-Ichiro Nagamitsu
- Department of Pediatrics and Child Health, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan
| | - Hiroshi Hosoda
- Department of Biochemistry, National Cardiovascular Center Research Institute, Suita, Osaka 565-8565, Japan
| | - Kenji Kangawa
- Department of Biochemistry, National Cardiovascular Center Research Institute, Suita, Osaka 565-8565, Japan
| | - Masayasu Kojima
- Institute of Life Science, Kurume University, Hyakunenkohen, Kurume, Fukuoka 839-0864, Japan
| | - Toyojiro Matsuishi
- Department of Pediatrics and Child Health, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan.
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Kaiya H, Kangawa K, Miyazato M. Update on ghrelin biology in birds. Gen Comp Endocrinol 2013; 190:170-5. [PMID: 23631903 DOI: 10.1016/j.ygcen.2013.04.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Revised: 04/01/2013] [Accepted: 04/04/2013] [Indexed: 12/21/2022]
Abstract
Ghrelin is a peptide found in the mucosal layer of the rat stomach that exhibits growth hormone-releasing and appetite-stimulating activities. Since the discovery of ghrelin in chicken in 2002, information on its structure, distribution, function, and receptors has been accumulated, mainly in poultry. Here, we summarize the following findings since 2008 in birds: (1) central ghrelin acts as an anorexigenic neuropeptide, but the effect of peripheral ghrelin differs depending on the chicken strain and light conditions the birds are kept in; (2) central ghrelin inhibits not only food intake but also water drinking, and it may be mediated by urocortin, a member of the corticotropin-releasing factor family; (3) peripheral ghrelin acts as an anti-lipogenic factor in broiler chickens but not in rats; (4) the enzyme involved in ghrelin acylation (ghrelin-O-acyltransferase [GOAT]) has been identified in chickens; (5) dietary lipids are used for ghrelin acylation; (6) des-acyl ghrelin administered alone or with ghrelin does not affect feeding behavior; (7) the existence and physiological function of obestatin must now be carefully examined in birds; (8) other than the growth hormone secretagogue receptors (GHS) R1a and 1b, GHS-R variants not found in mammals have been found in chicken and Japanese quail; and finally (9) little is known about the involvement of the ghrelin system in wild birds and in avian-specific behavior such as brooding and migration.
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Affiliation(s)
- Hiroyuki Kaiya
- Department of Biochemistry, National Cerebral and Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan.
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Nishi Y, Mifune H, Yabuki A, Tajiri Y, Hirata R, Tanaka E, Hosoda H, Kangawa K, Kojima M. Changes in Subcellular Distribution of n-Octanoyl or n-Decanoyl Ghrelin in Ghrelin-Producing Cells. Front Endocrinol (Lausanne) 2013; 4:84. [PMID: 23847595 PMCID: PMC3705199 DOI: 10.3389/fendo.2013.00084] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 06/26/2013] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND The enzyme ghrelin O-acyltransferase (GOAT) catalyzes the acylation of ghrelin. The molecular form of GOAT, together with its reaction in vitro, has been reported previously. However, the subcellular processes governing the acylation of ghrelin remain to be elucidated. METHODS Double immunoelectron microscopy was used to examine changes in the relative proportions of secretory granules containing n-octanoyl ghrelin (C8-ghrelin) or n-decanoyl ghrelin (C10-ghrelin) in ghrelin-producing cells of mouse stomachs. The dynamics of C8-type (possessing C8-ghrelin exclusively), C10-type (possessing C10-ghrelin only), and mixed-type secretory granules (possessing both C8- and C10-ghrelin) were investigated after fasting for 48 h or after 2 weeks feeding with chow containing glyceryl-tri-octanoate (C8-MCT) or glyceryl-tri-decanoate (C10-MCT). The dynamics of C8- or C10-ghrelin-immunoreactivity (ir-C8- or ir-C10-ghrelin) within the mixed-type granules were also investigated. RESULTS Immunoelectron microscopic analysis revealed the co-existence of C8- and C10-ghrelin within the same secretory granules (mixed-type) in ghrelin-producing cells. Compared to control mice fed standard chow, the ratio of C10-type secretory granules increased significantly after ingestion of C10-MCT, whereas that of C8-type granules declined significantly under the same treatment. After ingestion of C8-MCT, the proportion of C8-type secretory granules increased significantly. Within the mixed-type granules the ratio of ir-C10-ghrelin increased significantly and that of ir-C8-ghrelin decreased significantly upon fasting. CONCLUSION These findings confirmed that C10-ghrelin, another acyl-form of active ghrelin, is stored within the same secretory granules as C8-ghrelin, and suggested that the types of medium-chain acyl-molecules surrounding and available to the ghrelin-GOAT system may affect the physiological processes of ghrelin acylation.
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Affiliation(s)
- Yoshihiro Nishi
- Department of Physiology, School of Medicine, Kurume University, Kurume, Japan
- *Correspondence: Yoshihiro Nishi, Department of Physiology, School of Medicine, Kurume University, 67 Asahi-machi, Kurume 830-0011, Japan e-mail: ; Hiroharu Mifune, Institute of Animal Experimentation, Asahi-machi, Kurume University, 67 Asahi-machi, Kurume 830-0011, Japan e-mail:
| | - Hiroharu Mifune
- Institute of Animal Experimentation, School of Medicine, Kurume University, Kurume, Fukuoka, Japan
- *Correspondence: Yoshihiro Nishi, Department of Physiology, School of Medicine, Kurume University, 67 Asahi-machi, Kurume 830-0011, Japan e-mail: ; Hiroharu Mifune, Institute of Animal Experimentation, Asahi-machi, Kurume University, 67 Asahi-machi, Kurume 830-0011, Japan e-mail:
| | - Akira Yabuki
- Laboratory of Veterinary Clinical Pathology, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan
| | - Yuji Tajiri
- Division of Endocrinology and Metabolism, School of Medicine, Kurume University, Kurume, Fukuoka, Japan
| | - Rumiko Hirata
- Department of Physiology, School of Medicine, Kurume University, Kurume, Japan
- Department of Pediatrics and Child Health, School of Medicine, Kurume University, Kurume, Fukuoka, Japan
| | - Eiichiro Tanaka
- Department of Physiology, School of Medicine, Kurume University, Kurume, Japan
| | - Hiroshi Hosoda
- Department of Biochemistry, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan
| | - Kenji Kangawa
- Department of Biochemistry, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan
| | - Masayasu Kojima
- Molecular Genetics, Institute of Life Science, Kurume University, Kurume, Fukuoka, Japan
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Kaiya H, Andoh T, Ichikawa T, Amiya N, Matsuda K, Kangawa K, Miyazato M. Determination of Ghrelin Structure in the Barfin Flounder (Verasper moseri) and Involvement of Ingested Fatty Acids in Ghrelin Acylation. Front Endocrinol (Lausanne) 2013; 4:117. [PMID: 24027560 PMCID: PMC3760443 DOI: 10.3389/fendo.2013.00117] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 08/20/2013] [Indexed: 11/13/2022] Open
Abstract
Ghrelin is a peptide hormone that is acylated with a fatty acid, usually n-octanoic acid, at the third amino acid (aa) residue (usually a serine or threonine), and this acylation is known to be essential for ghrelin activity not only in mammals but also in non-mammals, such as fish. However, the modification mechanisms of ghrelin modification in fish are not known. In this study, we elucidated the structure of ghrelin in a teleost, the barfin flounder (Verasper moseri), and determined whether ingested free fatty acids of various chain lengths participated in ghrelin acylation. Complementary DNA cloning revealed the barfin flounder prepro-ghrelin to be a 106-aa peptide and the mature ghrelin to be a 20-aa peptide (GSSFLSPSHKPPNKGKPPRA). However, purification of ghrelin peptides from stomach extracts demonstrated that the major form of the hormone was a 19-aa decanoylated peptide [GSS(C10:0)FLSPSHKPPNKGKPPR] missing the last alanine of the 20-aa peptide. Ingestion of feed enriched with n-heptanoic acid (C7), n-octanoic acid (C8), or n-non-anoic acid (C9) changed the modification status of the peptide: ingestion of C8 or C9 increased the amount of C8:0 or C9:0 19-aa ghrelin, respectively, but no C7:0 ghrelin was isolated after ingestion of C7. These results indicate that ingested free fatty acids are substrates for ghrelin acylation in the barfin flounder, but the types of free fatty acids utilized as substrates may be limited.
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Affiliation(s)
- Hiroyuki Kaiya
- Department of Biochemistry, National Cerebral and Cardiovascular Center, Suita, Japan
- *Correspondence: Hiroyuki Kaiya, Department of Biochemistry, National Cerebral and Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan e-mail:
| | - Tadashi Andoh
- Seikai National Fisheries Research Institute, Fisheries Research Agency, Nagasaki, Japan
| | - Takashi Ichikawa
- Hokkaido National Fisheries Research Institute, Fisheries Research Agency, Akkeshi, Japan
| | - Noriko Amiya
- School of Marine Biosciences, Kitasato University, Sagamihara, Japan
| | - Kouhei Matsuda
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, Toyama, Japan
| | - Kenji Kangawa
- National Cerebral and Cardiovascular Center, Suita, Japan
| | - Mikiya Miyazato
- Department of Biochemistry, National Cerebral and Cardiovascular Center, Suita, Japan
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Chopin LK, Seim I, Walpole CM, Herington AC. The ghrelin axis--does it have an appetite for cancer progression? Endocr Rev 2012; 33:849-91. [PMID: 22826465 DOI: 10.1210/er.2011-1007] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ghrelin, the endogenous ligand for the GH secretagogue receptor (GHSR), is a peptide hormone with diverse physiological roles. Ghrelin regulates GH release, appetite and feeding, gut motility, and energy balance and also has roles in the cardiovascular, immune, and reproductive systems. Ghrelin and the GHSR are expressed in a wide range of normal and tumor tissues, and a fluorescein-labeled, truncated form of ghrelin is showing promise as a biomarker for prostate cancer. Plasma ghrelin levels are generally inversely related to body mass index and are unlikely to be useful as a biomarker for cancer, but may be useful as a marker for cancer cachexia. Some single nucleotide polymorphisms in the ghrelin and GHSR genes have shown associations with cancer risk; however, larger studies are required. Ghrelin regulates processes associated with cancer, including cell proliferation, apoptosis, cell migration, cell invasion, inflammation, and angiogenesis; however, the role of ghrelin in cancer is currently unclear. Ghrelin has predominantly antiinflammatory effects and may play a role in protecting against cancer-related inflammation. Ghrelin and its analogs show promise as treatments for cancer-related cachexia. Further studies using in vivo models are required to determine whether ghrelin has a role in cancer progression.
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Affiliation(s)
- Lisa K Chopin
- Ghrelin Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology and Australian Prostate Cancer Research Centre-Queensland, Brisbane, Queensland 4001, Australia.
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Nishi Y, Mifune H, Kojima M. Ghrelin Acylation by Ingestion of Medium-Chain Fatty Acids. Methods Enzymol 2012; 514:303-15. [DOI: 10.1016/b978-0-12-381272-8.00019-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Nishi Y, Yoh J, Hiejima H, Kojima M. Structures and molecular forms of the ghrelin-family peptides. Peptides 2011; 32:2175-82. [PMID: 21839128 DOI: 10.1016/j.peptides.2011.07.024] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2011] [Revised: 07/08/2011] [Accepted: 07/22/2011] [Indexed: 11/23/2022]
Abstract
Ghrelin is an acylated peptide hormone produced mainly from the stomach. The major active products of the ghrelin gene in the stomach of rats, mice and humans are 28-amino acid peptides acylated at the serine-3 position with an n-octanoyl group (C8:0), called simply ghrelin. However, recent studies have revealed that the ghrelin gene can generate a variety of bioactive molecules besides ghrelin. These include acyl forms of ghrelin other than C8:0-ghrelin (i.e., n-decanoyl ghrelin or n-decenoyl ghrelin), des-acyl ghrelin, obestatin and ghrelin-associated peptides originated from the ghrelin gene. This review surveys the structures of the ghrelin peptides and molecular forms of ghrelin gene-derived products, and summarizes the knowledge about the functions of these peptides, with an emphasis on the acyl forms of the ghrelin peptide.
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Affiliation(s)
- Yoshihiro Nishi
- Department of Physiology, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan.
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