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Kiernan DP, O'Doherty JV, Connolly KR, Ryan M, Sweeney T. Exploring the Differential Expression of a Set of Key Genes Involved in the Regulation and Functioning of the Stomach in the Post-Weaned Pig. Vet Sci 2023; 10:473. [PMID: 37505877 PMCID: PMC10386345 DOI: 10.3390/vetsci10070473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 07/17/2023] [Accepted: 07/18/2023] [Indexed: 07/29/2023] Open
Abstract
Despite playing a key role in digestion, there is only a broad characterization of the spatiotemporal development of the three glandular regions of the stomach (cardiac, fundic and pyloric) in the weaned pig. Hence, the objective of this experiment was to explore the differential expression (DE) of a panel of key genes within the three glandular regions of the stomach. Eight pigs were sacrificed at d 8 post-weaning, and three mucosal samples were collected from each stomach's glandular regions. The expression of a panel of genes were measured using QPCR. The true cardiac gland region was characterized by increased expression of PIGR, OLFM4, CXCL8 and MUC2 relative to the two other regions (p < 0.05). The fundic gland region was characterized by increased expression of ATP4A, CLIC6, KCNQ1, HRH2, AQP4, HDC, CCKBR, CHIA, PGA5, GHRL and MBOAT4 compared to the two other regions (p < 0.05). The pyloric gland region was characterized by exclusive expression of GAST (p < 0.05). A transition region between the cardiac and fundic region (cardiac-to-oxyntic transition) was observed with a gene expression signature that resembles a cross of the signatures found in the two regions. In conclusion, unique gene expression signatures were identifiable in each of the glandular regions, with a cardiac-to-oxyntic transition region clearly identifiable in the post-weaned pigs' stomachs.
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Affiliation(s)
- Dillon P Kiernan
- School of Veterinary Medicine, University College Dublin, Belfield, D04 W6F6 Dublin, Ireland
| | - John V O'Doherty
- School of Agriculture and Food Science, University College Dublin, Belfield, D04 W6F6 Dublin, Ireland
| | - Kathryn Ruth Connolly
- School of Agriculture and Food Science, University College Dublin, Belfield, D04 W6F6 Dublin, Ireland
| | - Marion Ryan
- School of Agriculture and Food Science, University College Dublin, Belfield, D04 W6F6 Dublin, Ireland
| | - Torres Sweeney
- School of Veterinary Medicine, University College Dublin, Belfield, D04 W6F6 Dublin, Ireland
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2
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Ghrelin/GHS-R1A antagonism in memory test and its effects on central molecular signaling involved in addiction in rats. Pharmacol Biochem Behav 2023; 224:173528. [PMID: 36870422 DOI: 10.1016/j.pbb.2023.173528] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 12/23/2022] [Accepted: 02/12/2023] [Indexed: 03/06/2023]
Abstract
Central ghrelin signaling seems to play important role in addiction as well as memory processing. Antagonism of the growth hormone secretagogue receptor (GHS-R1A) has been recently proposed as a promising tool for the unsatisfactory drug addiction therapy. However, molecular aspects of GHS-R1A involvement in specific brain regions remain unclear. The present study demonstrated for the first time that acute as well as subchronic (4 days) administration of the experimental GHS-R1A antagonist JMV2959 in usual intraperitoneal doses including 3 mg/kg, had no influence on memory functions tested in the Morris Water Maze in rats as well as no significant effects on the molecular markers linked with memory processing in selected brain areas in rats, specifically on the β-actin, c-Fos, two forms of the calcium/calmodulin-dependent protein kinase II (CaMKII, p-CaMKII) and the cAMP-response element binding protein (CREB, p-CREB), within the medial prefrontal cortex (mPFC), nucleus accumbens (NAc), dorsal striatum, and hippocampus (HIPP). Furthermore, following the methamphetamine intravenous self-administration in rats, the 3 mg/kg JMV2959 pretreatment significantly reduced or prevented the methamphetamine-induced significant decrease of hippocampal β-actin and c-Fos as well as it prevented the significant decrease of CREB in the NAC and mPFC. These results imply, that the GHS-R1A antagonist/JMV2959 might reduce/prevent some of the memory-linked molecular changes elicited by methamphetamine addiction within brain structures associated with memory (HIPP), reward (NAc), and motivation (mPFC), which may contribute to the previously observed significant JMV2959-induced reduction of the methamphetamine self-administration and drug-seeking behavior in the same animals. Further research is necessary to corroborate these results.
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3
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Rahman QFA, Jufri NF, Hamid A. Hyperphagia in Prader-Willi syndrome with obesity: From development to pharmacological treatment. Intractable Rare Dis Res 2023; 12:5-12. [PMID: 36873672 PMCID: PMC9976092 DOI: 10.5582/irdr.2022.01127] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 02/10/2023] [Accepted: 02/25/2023] [Indexed: 03/03/2023] Open
Abstract
Prader-Willi syndrome (PWS) is a rare genetic disorder due to lack of genes expression inherited from the paternal chromosome 15q11-q13 region usually from paternal deletions, maternal uniparental disomy 15 or imprinting defect. There are two different nutritional stages reported in an individual with PWS; first stage during infancy marked by feeding and growth difficulties and second stage where hyperphagia starts and leads to development of obesity. However, the exact mechanism of hyperphagia development, from having difficulties in feeding during early years to insatiable appetite after they grow is still unknown and is the focused in this review. The keywords used for literature search such as "Prader-Willi syndrome", "hyperphagia", "obesity", and "treatment" were used to create the search strings by using synonyms in order to retrieve the relevant records from PubMed, Scopus and Science Direct. The possible mechanism of hyperphagia can be classed into hormonal abnormalities such as increase in ghrelin and leptin from infancy to adulthood. Low level of hormones was observed in the thyroid, insulin and peptide YY at certain ages. Neuronal abnormalities contributed by Orexin A and brain structure alteration was documented at 4-30 years old. Treatment in the form of drugs such as livoletide, topiramate, and diazoxide could potentially alleviate these abnormalities and make hyperphagia less prominent in PWS. The approaches are important to regulate the hormonal changes and neuronal involvement as potentially controlling hyperphagia and obesity.
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Affiliation(s)
| | - Nurul Farhana Jufri
- Address correspondence to:Nurul Farhana Jufri, Biomedical Science Program, Center for Toxicology and Health Risk Studies, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur 50300, Malaysia. E-mail:
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4
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Wang Y, Wu Q, Zhou Q, Chen Y, Lei X, Chen Y, Chen Q. Circulating acyl and des-acyl ghrelin levels in obese adults: a systematic review and meta-analysis. Sci Rep 2022; 12:2679. [PMID: 35177705 PMCID: PMC8854418 DOI: 10.1038/s41598-022-06636-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 02/01/2022] [Indexed: 12/15/2022] Open
Abstract
Ghrelin is the only known orexigenic gut hormone, and its synthesis, secretion and degradation are affected by different metabolic statuses. This meta-analysis aimed to investigate the potential differences in plasma acyl ghrelin (AG) and des-acyl ghrelin (DAG) concentrations between normal weight and obese adults. Systematic literature searches of PubMed, Embase and Web of Science through October 2021 were conducted for articles reporting AG or DAG levels in obesity and normal weight, and 34 studies with 1863 participants who met the eligibility criteria were identified. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated to evaluate group differences in circulating AG and DAG levels. Pooled effect size showed significantly lower levels of baseline AG (SMD: - 0.85; 95% CI: - 1.13 to - 0.57; PSMD < 0.001) and DAG (SMD: - 1.06; 95% CI: - 1.43 to - 0.69; PSMD < 0.001) in obese groups compared with healthy controls, and similar results were observed when subgroup analyses were stratified by the assay technique or storage procedure. Postprandial AG levels in obese subjects were significantly lower than those in controls when stratified by different time points (SMD 30 min: - 0.85, 95% CI: - 1.18 to - 0.53, PSMD < 0.001; SMD 60 min: - 1.00, 95% CI: - 1.37 to - 0.63, PSMD < 0.001; SMD 120 min: - 1.21, 95% CI: - 1.59 to - 0.83, PSMD < 0.001). In healthy subjects, a postprandial decline in AG was observed at 120 min (SMD: - 0.42; 95% CI: - 0.77 to - 0.06; PSMD = 0.021) but not in obese subjects (SMD: - 0.28; 95% CI: - 0.60 to 0.03; PSMD = 0.074). The mean change in AG concentration was similar in both the obese and lean health groups at each time point (ΔSMD30min: 0.31, 95% CI: - 0.35 to 0.97, PSMD = 0.359; ΔSMD60min: 0.17, 95% CI: - 0.12 to 0.46, PSMD = 0.246; ΔSMD120min: 0.21, 95% CI: - 0.13 to 0.54, PSMD = 0.224). This meta-analysis strengthens the clinical evidence supporting the following: lower baseline levels of circulating AG and DAG in obese individuals; declines in postprandial circulating AG levels, both for the healthy and obese individuals; a shorter duration of AG suppression in obese subjects after meal intake. These conclusions have significance for follow-up studies to elucidate the role of various ghrelin forms in energy homeostasis.
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Affiliation(s)
- Yanmei Wang
- Hospital of Chengdu University of Traditional Chinese Medicine, No. 39 Shi-er-qiao Road, Jinniu District, Chengdu, 610075, Sichuan, China.,Ya'an Polytechnic College, No. 130 Yucai Road, Yucheng District, Yaan, 625000, Sichuan, China
| | - Qianxian Wu
- Ya'an Polytechnic College, No. 130 Yucai Road, Yucheng District, Yaan, 625000, Sichuan, China
| | - Qian Zhou
- Hospital of Chengdu University of Traditional Chinese Medicine, No. 39 Shi-er-qiao Road, Jinniu District, Chengdu, 610075, Sichuan, China
| | - Yuyu Chen
- Halifa Regional Centre for Education, No. 33 Spectacle Lake Dr, Dartmouth, NS, B3B1X7, Canada
| | - Xingxing Lei
- Hospital of Chengdu University of Traditional Chinese Medicine, No. 39 Shi-er-qiao Road, Jinniu District, Chengdu, 610075, Sichuan, China
| | - Yiding Chen
- Hospital of Chengdu University of Traditional Chinese Medicine, No. 39 Shi-er-qiao Road, Jinniu District, Chengdu, 610075, Sichuan, China
| | - Qiu Chen
- Hospital of Chengdu University of Traditional Chinese Medicine, No. 39 Shi-er-qiao Road, Jinniu District, Chengdu, 610075, Sichuan, China.
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Sustkova-Fiserova M, Charalambous C, Khryakova A, Certilina A, Lapka M, Šlamberová R. The Role of Ghrelin/GHS-R1A Signaling in Nonalcohol Drug Addictions. Int J Mol Sci 2022; 23:761. [PMID: 35054944 PMCID: PMC8776007 DOI: 10.3390/ijms23020761] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 01/27/2023] Open
Abstract
Drug addiction causes constant serious health, social, and economic burden within the human society. The current drug dependence pharmacotherapies, particularly relapse prevention, remain limited, unsatisfactory, unreliable for opioids and tobacco, and even symptomatic for stimulants and cannabinoids, thus, new more effective treatment strategies are researched. The antagonism of the growth hormone secretagogue receptor type A (GHS-R1A) has been recently proposed as a novel alcohol addiction treatment strategy, and it has been intensively studied in experimental models of other addictive drugs, such as nicotine, stimulants, opioids and cannabinoids. The role of ghrelin signaling in these drugs effects has also been investigated. The present review aims to provide a comprehensive overview of preclinical and clinical studies focused on ghrelin's/GHS-R1A possible involvement in these nonalcohol addictive drugs reinforcing effects and addiction. Although the investigation is still in its early stage, majority of the existing reviewed experimental results from rodents with the addition of few human studies, that searched correlations between the genetic variations of the ghrelin signaling or the ghrelin blood content with the addictive drugs effects, have indicated the importance of the ghrelin's/GHS-R1As involvement in the nonalcohol abused drugs pro-addictive effects. Further research is necessary to elucidate the exact involved mechanisms and to verify the future potential utilization and safety of the GHS-R1A antagonism use for these drug addiction therapies, particularly for reducing the risk of relapse.
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Affiliation(s)
- Magdalena Sustkova-Fiserova
- Department of Pharmacology, Third Faculty of Medicine, Charles University, Ruska 87, 100 00 Prague, Czech Republic; (C.C.); (A.K.); (A.C.); (M.L.)
| | - Chrysostomos Charalambous
- Department of Pharmacology, Third Faculty of Medicine, Charles University, Ruska 87, 100 00 Prague, Czech Republic; (C.C.); (A.K.); (A.C.); (M.L.)
| | - Anna Khryakova
- Department of Pharmacology, Third Faculty of Medicine, Charles University, Ruska 87, 100 00 Prague, Czech Republic; (C.C.); (A.K.); (A.C.); (M.L.)
| | - Alina Certilina
- Department of Pharmacology, Third Faculty of Medicine, Charles University, Ruska 87, 100 00 Prague, Czech Republic; (C.C.); (A.K.); (A.C.); (M.L.)
| | - Marek Lapka
- Department of Pharmacology, Third Faculty of Medicine, Charles University, Ruska 87, 100 00 Prague, Czech Republic; (C.C.); (A.K.); (A.C.); (M.L.)
| | - Romana Šlamberová
- Department of Physiology, Third Faculty of Medicine, Charles University, Ke Karlovu 4, 120 00 Prague, Czech Republic;
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6
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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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7
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Suazo KF, Park KY, Distefano MD. A Not-So-Ancient Grease History: Click Chemistry and Protein Lipid Modifications. Chem Rev 2021; 121:7178-7248. [PMID: 33821625 PMCID: PMC8820976 DOI: 10.1021/acs.chemrev.0c01108] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Protein lipid modification involves the attachment of hydrophobic groups to proteins via ester, thioester, amide, or thioether linkages. In this review, the specific click chemical reactions that have been employed to study protein lipid modification and their use for specific labeling applications are first described. This is followed by an introduction to the different types of protein lipid modifications that occur in biology. Next, the roles of click chemistry in elucidating specific biological features including the identification of lipid-modified proteins, studies of their regulation, and their role in diseases are presented. A description of the use of protein-lipid modifying enzymes for specific labeling applications including protein immobilization, fluorescent labeling, nanostructure assembly, and the construction of protein-drug conjugates is presented next. Concluding remarks and future directions are presented in the final section.
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Affiliation(s)
- Kiall F. Suazo
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455 USA
| | - Keun-Young Park
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455 USA
| | - Mark D. Distefano
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455 USA
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8
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Cannabinoid-Induced Conditioned Place Preference, Intravenous Self-Administration, and Behavioral Stimulation Influenced by Ghrelin Receptor Antagonism in Rats. Int J Mol Sci 2021; 22:ijms22052397. [PMID: 33673659 PMCID: PMC7957642 DOI: 10.3390/ijms22052397] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 02/13/2021] [Accepted: 02/21/2021] [Indexed: 11/24/2022] Open
Abstract
Cannabis/cannabinoids are widely used for recreational and therapy purposes, but their risks are largely disregarded. However, cannabinoid-associated use disorders and dependence are alarmingly increasing and an effective treatment is lacking. Recently, the growth hormone secretagogue receptor (GHSR1A) antagonism was proposed as a promising mechanism for drug addiction therapy. However, the role of GHS-R1A and its endogenous ligand ghrelin in cannabinoid abuse remains unclear. Therefore, the aim of our study was to investigate whether the GHS-R1A antagonist JMV2959 could reduce the tetrahydrocannabinol (THC)-induced conditioned place preference (CPP) and behavioral stimulation, the WIN55,212-2 intravenous self-administration (IVSA), and the tendency to relapse. Following an ongoing WIN55,212-2 self-administration, JMV2959 3 mg/kg was administered intraperitoneally 20 min before three consequent daily 120-min IVSA sessions under a fixed ratio FR1, which significantly reduced the number of the active lever-pressing, the number of infusions, and the cannabinoid intake. Pretreatment with JMV2959 suggested reduction of the WIN55,212-2-seeking/relapse-like behavior tested in rats on the twelfth day of the forced abstinence period. On the contrary, pretreatment with ghrelin significantly increased the cannabinoid IVSA as well as enhanced the relapse-like behavior. Co-administration of ghrelin with JMV2959 abolished/reduced the significant efficacy of the GHS-R1A antagonist in the cannabinoid IVSA. Pretreatment with JMV2959 significantly and dose-dependently reduced the manifestation of THC-induced CPP. The THC-CPP development was reduced after the simultaneous administration of JMV2959 with THC during conditioning. JMV2959 also significantly reduced the THC-induced behavioral stimulation in the LABORAS cage. Our findings suggest that GHS-R1A importantly participates in the rewarding/reinforcing effects of cannabinoids.
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9
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Tan Q, Orsso CE, Deehan EC, Triador L, Field CJ, Tun HM, Han JC, Müller TD, Haqq AM. Current and emerging therapies for managing hyperphagia and obesity in Prader-Willi syndrome: A narrative review. Obes Rev 2020; 21:e12992. [PMID: 31889409 DOI: 10.1111/obr.12992] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/07/2019] [Accepted: 12/09/2019] [Indexed: 12/16/2022]
Abstract
In early childhood, individuals with Prader-Willi syndrome (PWS) experience excess weight gain and severe hyperphagia with food compulsivity, which often leads to early onset morbid obesity. Effective treatments for appetite suppression and weight control are currently unavailable for PWS. Our aim to further understand the pathogenesis of PWS led us to carry out a comprehensive search of the current and emerging therapies for managing hyperphagia and extreme weight gain in PWS. A literature search was performed using PubMed and the following keywords: "PWS" AND "therapy" OR "[drug name]"; reference lists, pharmaceutical websites, and the ClinicalTrials.gov registry were also reviewed. Articles presenting data from current standard treatments in PWS and also clinical trials of pharmacological agents in the pipeline were selected. Current standard treatments include dietary restriction/modifications, exercise, and growth hormone replacement, which appear to have limited efficacy for appetite and weight control in patients with PWS. The long-term safety and effectiveness of bariatric surgery in PWS remains unknown. However, many promising pharmacotherapies are in development and, if approved, will bring much needed choices into the PWS pharmacological armamentarium. With the progress that is currently being made in our understanding of PWS, an effective treatment may not be far off.
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Affiliation(s)
- Qiming Tan
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Camila E Orsso
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
| | - Edward C Deehan
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
| | - Lucila Triador
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Catherine J Field
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
| | - Hein Min Tun
- HKU-Pasteur Research Pole, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, China
| | - Joan C Han
- Departments of Pediatrics and Physiology, College of Medicine, University of Tennessee Health Science Center and Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, Tennessee, USA
| | - Timo D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, Neuherberg, Germany.,Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, Tübingen, Germany
| | - Andrea M Haqq
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada.,Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
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10
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Abizaid A, Hougland JL. Ghrelin Signaling: GOAT and GHS-R1a Take a LEAP in Complexity. Trends Endocrinol Metab 2020; 31:107-117. [PMID: 31636018 PMCID: PMC7299083 DOI: 10.1016/j.tem.2019.09.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/25/2019] [Accepted: 09/27/2019] [Indexed: 12/30/2022]
Abstract
Ghrelin and the growth hormone secretagogue receptor 1a (GHS-R1a) are important targets for disorders related to energy balance and metabolic regulation. Pharmacological control of ghrelin signaling is a promising avenue to address health issues involving appetite, weight gain, obesity, and related metabolic disorders, and may be an option for patients suffering from wasting conditions like cachexia. In this review, we summarize recent developments in the biochemistry of ghrelin and GHS-R1a signaling. These include unravelling the enzymatic transformations that generate active ghrelin and the discovery of multiple proteins that interact with ghrelin and GHS-R1a to regulate signaling. Furthermore, we propose that harnessing these processes will lead to highly selective treatments to address obesity, diabetes, and other metabolism-linked disorders.
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Affiliation(s)
- Alfonso Abizaid
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - James L Hougland
- Department of Chemistry, Syracuse University, Syracuse, NY, USA.
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11
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Rhea EM, Salameh TS, Gray S, Niu J, Banks WA, Tong J. Ghrelin transport across the blood-brain barrier can occur independently of the growth hormone secretagogue receptor. Mol Metab 2018; 18:88-96. [PMID: 30293893 PMCID: PMC6308033 DOI: 10.1016/j.molmet.2018.09.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 09/10/2018] [Accepted: 09/18/2018] [Indexed: 12/22/2022] Open
Abstract
OBJECTIVE The blood-brain barrier (BBB) regulates the entry of substrates and peptides into the brain. Ghrelin is mainly produced in the stomach but exerts its actions in the central nervous system (CNS) by crossing the BBB. Once present in the CNS, ghrelin can act in the hypothalamus to regulate food intake, in the hippocampus to regulate neurogenesis, and in the olfactory bulb to regulate food-seeking behavior. The goal of this study was to determine whether the primary signaling receptor for ghrelin, the growth hormone secretagogue receptor (GHSR), mediates the transport of ghrelin from blood to brain. METHODS We utilized the sensitive and quantitative multiple-time regression analysis technique to determine the transport rate of mouse and human acyl ghrelin (AG) and desacyl ghrelin (DAG) in wildtype and Ghsr null mice. We also measured the regional distribution of these ghrelin peptides throughout the brain. Lastly, we characterized the transport characteristics of human DAG by measuring the stability in serum and brain, saturability of transport, and the complete transfer across the brain endothelial cell. RESULTS We found the transport rate across the BBB of both forms of ghrelin, AG, and DAG, were not affected by the loss of GHSR. We did find differences in the transport rate between the two isoforms, with DAG being faster than AG; this was dependent on the species of ghrelin, human being faster than mouse. Lastly, based on the ubiquitous properties of ghrelin throughout the CNS, we looked at regional distribution of ghrelin uptake and found the highest levels of uptake in the olfactory bulb. CONCLUSIONS The data presented here suggest that ghrelin transport can occur independently of the GHSR, and ghrelin uptake varies regionally throughout the brain. These findings better our understanding of the gut-brain communication and may lead to new understandings of ghrelin physiology.
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Affiliation(s)
- Elizabeth M Rhea
- VA Puget Sound Health Care System, Seattle, WA, USA; Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Therese S Salameh
- VA Puget Sound Health Care System, Seattle, WA, USA; Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Sarah Gray
- Division of Endocrinology, Metabolism, and Nutrition, Duke Molecular Physiology Institute, Department of Medicine, Duke University, Durham, NC, USA
| | - Jingjing Niu
- Division of Endocrinology, Metabolism, and Nutrition, Duke Molecular Physiology Institute, Department of Medicine, Duke University, Durham, NC, USA
| | - William A Banks
- VA Puget Sound Health Care System, Seattle, WA, USA; Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Jenny Tong
- Division of Endocrinology, Metabolism, and Nutrition, Duke Molecular Physiology Institute, Department of Medicine, Duke University, Durham, NC, USA.
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12
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Cleverdon ER, Davis TR, Hougland JL. Functional group and stereochemical requirements for substrate binding by ghrelin O-acyltransferase revealed by unnatural amino acid incorporation. Bioorg Chem 2018; 79:98-106. [PMID: 29738973 DOI: 10.1016/j.bioorg.2018.04.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 04/02/2018] [Accepted: 04/13/2018] [Indexed: 12/22/2022]
Abstract
Ghrelin is a small peptide hormone that undergoes a unique posttranslational modification, serine octanoylation, to play its physiological roles in processes including hunger signaling and glucose metabolism. Ghrelin O-acyltransferase (GOAT) catalyzes this posttranslational modification, which is essential for ghrelin to bind and activate its cognate GHS-R1a receptor. Inhibition of GOAT offers a potential avenue for modulating ghrelin signaling for therapeutic effect. Defining the molecular characteristics of ghrelin that lead to binding and recognition by GOAT will facilitate the development and optimization of GOAT inhibitors. We show that small peptide mimics of ghrelin substituted with 2,3-diaminopropanoic acid in place of the serine at the site of octanoylation act as submicromolar inhibitors of GOAT. Using these chemically modified analogs of desacyl ghrelin, we define key functional groups within the N-terminal sequence of ghrelin essential for binding to GOAT and determine GOAT's tolerance to backbone methylations and altered amino acid stereochemistry within ghrelin. Our study provides a structure-activity analysis of ghrelin binding to GOAT that expands upon activity-based investigations of ghrelin recognition and establishes a new class of potent substrate-mimetic GOAT inhibitors for further investigation and therapeutic interventions targeting ghrelin signaling.
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Affiliation(s)
| | - Tasha R Davis
- Department of Chemistry, Syracuse University, Syracuse, NY 13244, USA
| | - James L Hougland
- Department of Chemistry, Syracuse University, Syracuse, NY 13244, USA.
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