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Notaro NM, Dyck DJ. Regulation of peripheral tissue substrate metabolism by the gut-derived hormone ghrelin. Metabol Open 2024; 21:100279. [PMID: 38487670 PMCID: PMC10937159 DOI: 10.1016/j.metop.2024.100279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 02/21/2024] [Accepted: 02/22/2024] [Indexed: 03/17/2024] Open
Abstract
Ghrelin increases in the circulation prior to entrained mealtimes, with the acylated (AG) form functioning to stimulate food intake and growth hormone release. Acutely, AG induces whole-body insulin resistance, potentially to maintain glycemia between meals. Alternatively, chronic administration of both AG and the unacylated isoform of ghrelin (unAG) is associated with improved skeletal muscle insulin sensitivity as well as reduced intramuscular lipids and inflammation. This may be due to effects on lipid metabolism, with ghrelin promoting storage of fat in adipose and liver while stimulating oxidation in skeletal muscle, preventing ectopic lipid accumulation. This is of specific relevance in the handling of meal-derived lipids, as ghrelin rises preprandially with effects persisting for 2-3 h following exposure in skeletal muscle, coinciding with elevated plasma FFAs. We hypothesize that ghrelin acts as a preparatory signal for incoming lipids, as well as a regulatory hormone for their use and storage. The effects of ghrelin on skeletal muscle are lost with high fat diet feeding and physical inactivity, potentially being implicated in the pathogenesis of metabolic disease. This review summarizes the metabolic effects of both ghrelin isoforms on peripheral tissues including the pancreas, adipose, liver, and skeletal muscle. Additionally, we speculate on the physiological relevance of these effects in vivo and suggest that ghrelin may be a key regulatory hormone for nutrient handling in the postprandial state.
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Affiliation(s)
- Nicole M. Notaro
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - David J. Dyck
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
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Cho CH, Patel S, Rajbhandari P. Adipose tissue lipid metabolism: lipolysis. Curr Opin Genet Dev 2023; 83:102114. [PMID: 37738733 DOI: 10.1016/j.gde.2023.102114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 08/15/2023] [Accepted: 08/23/2023] [Indexed: 09/24/2023]
Abstract
White adipose tissue stores fatty acid (FA) as triglyceride in the lipid droplet organelle of highly specialized cells known as fat cells or adipocytes. Depending on the nutritional state and energy demand, hormonal and biochemical signals converge on activating an elegant and fundamental process known as lipolysis, which involves triglyceride hydrolysis to FAs. Almost six decades of work have vastly expanded our knowledge of lipolysis from enzymatic processes to complex protein assembly, disassembly, and post-translational modification. Research in recent decades ushered in the discovery of new lipolytic enzymes and coregulators and the characterization of numerous factors and signaling pathways that regulate lipid hydrolysis on transcriptional and post-transcriptional levels. This review will discuss recent developments with particular emphasis on the past two years in enzymatic lipolytic pathways and transcriptional regulation of lipolysis. We will summarize the positive and negative regulators of lipolysis, the adipose tissue microenvironment in lipolysis, and the systemic effects of lipolysis. The dynamic nature of adipocyte lipolysis is emerging as an essential regulator of metabolism and energy balance, and we will discuss recent developments in this area.
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Affiliation(s)
- Chung Hwan Cho
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Sanil Patel
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Prashant Rajbhandari
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Diabetes, Obesity, and Metabolism Institute, Department of Endocrinology and Bone Disease, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place New York, NY 10029 USA.
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Iwakura H, Ensho T, Ueda Y. Desacyl-ghrelin, not just an inactive form of ghrelin?-A review of current knowledge on the biological actions of desacyl-ghrelin. Peptides 2023:171050. [PMID: 37392995 DOI: 10.1016/j.peptides.2023.171050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 06/23/2023] [Accepted: 06/26/2023] [Indexed: 07/03/2023]
Abstract
Desacyl-ghrelin is a form of ghrelin which lacks acyl-modification of the third serine residue of ghrelin. Originally, desacyl-ghrelin was considered to be just an inactive form of ghrelin. More recently, however, it has been suggested to have various biological activities, including control of food intake, growth hormone, glucose metabolism, and gastric movement, and is involved in cell survival. In this review, we summarize the current knowledge of the biological actions of desacyl-ghrelin and the proposed mechanisms by which it exerts the effects.
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Affiliation(s)
- Hiroshi Iwakura
- Department of Pharmacotherapeutics, School of Pharmaceutical Science, Wakayama Medical University, 25-1 Shichibancho, Wakayama 640-8156, Japan.
| | - Takuya Ensho
- Department of Pharmacotherapeutics, School of Pharmaceutical Science, Wakayama Medical University, 25-1 Shichibancho, Wakayama 640-8156, Japan
| | - Yoko Ueda
- Department of Pharmacotherapeutics, School of Pharmaceutical Science, Wakayama Medical University, 25-1 Shichibancho, Wakayama 640-8156, Japan
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Lovell AJ, Hoecht EM, Hucik B, Cervone DT, Dyck DJ. The effects of diet and chronic exercise on skeletal muscle ghrelin response. Metabol Open 2022; 14:100182. [PMID: 35340718 PMCID: PMC8942827 DOI: 10.1016/j.metop.2022.100182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/14/2022] [Accepted: 03/16/2022] [Indexed: 11/20/2022] Open
Abstract
Background Recent findings indicate that ghrelin, particularly the unacylated form (UnAG), acutely stimulates skeletal muscle fatty acid oxidation (FAO) and can preserve insulin signaling and insulin-stimulated glucose uptake in the presence of high concentrations of saturated fatty acids. However, we recently reported that the stimulatory effect of ghrelin on FAO and subsequent ability to protect insulin stimulated glucose uptake was lost following 6-weeks (6w) of chronic high fat feeding. In the current study we examined the effects of both short-term 5 day (5d) and chronic 6w high-fat diet (HFD) on muscle ghrelin response, and whether exercise training could prevent the development of muscle ghrelin resistance with 6w of HFD Methods and Results Soleus muscle strips were isolated from male rats to determine the direct effects of acylated (AG) and UnAG isoforms on FAO and glucose uptake. A 5d HFD did not alter the response of soleus muscle to AG or UnAG. Conversely, 6w of HFD was associated with a loss of ghrelin's ability to stimulate FAO and protect insulin stimulated glucose uptake. Muscle response to UnAG remained intact following the 6w HFD with chronic exercise training. Unexpectedly, muscle response to both AG and UnAG was also lost after 6w of low-fat diet (LFD) consumption. Protein content of the classic ghrelin receptor, GHS-R1a, was not affected by diet or training. Corticotropin-releasing hormone receptor-2 (CRF-2R) content, a putative receptor for ghrelin in muscle, was significantly decreased in soleus from 6w HFD-fed animals and increased following exercise training. This may explain the protection of UnAG response with training in HFD-fed rats but does not explain why ghrelin response was also lost in LFD-fed animals. Conclusions UnAG protects muscle glucose uptake during acute lipid oversupply, likely due to its ability to stimulate FAO. This effect is lost in 6w HFD-fed animals but protected with exercise training. Unexpectedly, ghrelin response was lost in 6w LFD-fed animals. The loss of ghrelin response in muscle with a LFD cannot be explained by a change in putative ghrelin receptor content. We believe that the sedentary nature of the animals is a major factor in the development of muscle ghrelin resistance and warrants further research. Ghrelin stimulates fatty acid oxidation in skeletal muscle. This stimulation is strongly associated with protection from acute fat overload. Prolonged sedentary behaviour and a high fat diet impair ghrelin's ability to stimulate fatty acid oxidation. Exercise training preserves ghrelin's positive effects on skeletal muscle.
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Li Y, Li Z, Ngandiri DA, Llerins Perez M, Wolf A, Wang Y. The Molecular Brakes of Adipose Tissue Lipolysis. Front Physiol 2022; 13:826314. [PMID: 35283787 PMCID: PMC8907745 DOI: 10.3389/fphys.2022.826314] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/10/2022] [Indexed: 12/11/2022] Open
Abstract
Adaptation to changes in energy availability is pivotal for the survival of animals. Adipose tissue, the body’s largest reservoir of energy and a major source of metabolic fuel, exerts a buffering function for fluctuations in nutrient availability. This functional plasticity ranges from energy storage in the form of triglycerides during periods of excess energy intake to energy mobilization via lipolysis in the form of free fatty acids for other organs during states of energy demands. The subtle balance between energy storage and mobilization is important for whole-body energy homeostasis; its disruption has been implicated as contributing to the development of insulin resistance, type 2 diabetes and cancer cachexia. As a result, adipocyte lipolysis is tightly regulated by complex regulatory mechanisms involving lipases and hormonal and biochemical signals that have opposing effects. In thermogenic brown and brite adipocytes, lipolysis stimulation is the canonical way for the activation of non-shivering thermogenesis. Lipolysis proceeds in an orderly and delicately regulated manner, with stimulation through cell-surface receptors via neurotransmitters, hormones, and autocrine/paracrine factors that activate various intracellular signal transduction pathways and increase kinase activity. The subsequent phosphorylation of perilipins, lipases, and cofactors initiates the translocation of key lipases from the cytoplasm to lipid droplets and enables protein-protein interactions to assemble the lipolytic machinery on the scaffolding perilipins at the surface of lipid droplets. Although activation of lipolysis has been well studied, the feedback fine-tuning is less well appreciated. This review focuses on the molecular brakes of lipolysis and discusses some of the divergent fine-tuning strategies in the negative feedback regulation of lipolysis, including delicate negative feedback loops, intermediary lipid metabolites-mediated allosteric regulation and dynamic protein–protein interactions. As aberrant adipocyte lipolysis is involved in various metabolic diseases and releasing the brakes on lipolysis in thermogenic adipocytes may activate thermogenesis, targeting adipocyte lipolysis is thus of therapeutic interest.
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Samidurai A, Xi L, Das A, Iness AN, Vigneshwar NG, Li PL, Singla DK, Muniyan S, Batra SK, Kukreja RC. Role of phosphodiesterase 1 in the pathophysiology of diseases and potential therapeutic opportunities. Pharmacol Ther 2021; 226:107858. [PMID: 33895190 DOI: 10.1016/j.pharmthera.2021.107858] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 03/17/2021] [Accepted: 04/14/2021] [Indexed: 12/15/2022]
Abstract
Cyclic nucleotide phosphodiesterases (PDEs) are superfamily of enzymes that regulate the spatial and temporal relationship of second messenger signaling in the cellular system. Among the 11 different families of PDEs, phosphodiesterase 1 (PDE1) sub-family of enzymes hydrolyze both 3',5'-cyclic adenosine monophosphate (cAMP) and 3',5'-cyclic guanosine monophosphate (cGMP) in a mutually competitive manner. The catalytic activity of PDE1 is stimulated by their binding to Ca2+/calmodulin (CaM), resulting in the integration of Ca2+ and cyclic nucleotide-mediated signaling in various diseases. The PDE1 family includes three subtypes, PDE1A, PDE1B and PDE1C, which differ for their relative affinities for cAMP and cGMP. These isoforms are differentially expressed throughout the body, including the cardiovascular, central nervous system and other organs. Thus, PDE1 enzymes play a critical role in the pathophysiology of diseases through the fundamental regulation of cAMP and cGMP signaling. This comprehensive review provides the current research on PDE1 and its potential utility as a therapeutic target in diseases including the cardiovascular, pulmonary, metabolic, neurocognitive, renal, cancers and possibly others.
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Affiliation(s)
- Arun Samidurai
- Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University, Richmond, VA 23298-0204, USA
| | - Lei Xi
- Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University, Richmond, VA 23298-0204, USA
| | - Anindita Das
- Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University, Richmond, VA 23298-0204, USA
| | - Audra N Iness
- Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University, Richmond, VA 23298-0204, USA
| | - Navin G Vigneshwar
- Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University, Richmond, VA 23298-0204, USA
| | - Pin-Lan Li
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298-0613, USA
| | - Dinender K Singla
- Division of Metabolic and Cardiovascular Sciences, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816, USA
| | - Sakthivel Muniyan
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198-5870, USA
| | - Surinder K Batra
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198-5870, USA
| | - Rakesh C Kukreja
- Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University, Richmond, VA 23298-0204, USA.
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Cervone DT, Lovell AJ, Dyck DJ. Regulation of adipose tissue and skeletal muscle substrate metabolism by the stomach-derived hormone, ghrelin. Curr Opin Pharmacol 2020; 52:25-32. [DOI: 10.1016/j.coph.2020.04.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 04/08/2020] [Accepted: 04/08/2020] [Indexed: 12/17/2022]
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Cervone DT, Sheremeta J, Kraft EN, Dyck DJ. Acylated and unacylated ghrelin directly regulate ß-3 stimulated lipid turnover in rodent subcutaneous and visceral adipose tissue ex vivo but not in vivo. Adipocyte 2019; 8:1-15. [PMID: 30265180 PMCID: PMC6768250 DOI: 10.1080/21623945.2018.1528811] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ghrelin has garnered interest as a gut-derived regulator of lipid metabolism, beyond its classical roles in driving appetite and growth hormone release. Ghrelin’s circulating concentrations follow an ultradian rhythm, peak immediately before a meal and point towards a potential metabolic role in reducing the mobilization of fatty acid stores in preparation for the storage of ingested food. Here, we demonstrate that both acylated and unacylated ghrelin have physiological roles in attenuating lipolysis in mature subcutaneous and visceral adipose tissue depots of rats. Ghrelin blunted the ß3-induction (CL 316, 243) of glycerol release (index of lipolysis) which coincided with a reduced activation of the key lipid hydrolase HSL at two of its serine residues (Ser563/660). Furthermore, ghrelin appeared to inhibit fatty acid reesterification in the presence of CL such that fatty acid concentrations in the surrounding media were maintained in spite of a reduction in lipolysis. Importantly, these aforementioned effects were not observed following ghrelin injection in vivo, as there was no attenuation of CL-induced glycerol release. This highlights the importance of exercising caution when interpreting the effects of administering ghrelin in vivo, and the necessity for uncovering the elusive mechanisms by which ghrelin regulates lipolysis and fatty acid reesterification. We conclude that both acylated and unacylated ghrelin can exert direct inhibitory effects on lipolysis and fatty acid reesterification in adipose tissue from rats. However, these effects are not observed in vivo and outline the complexity of studying ghrelin’s effects on fatty acid metabolism in the living animal.
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Affiliation(s)
- Daniel T. Cervone
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Justin Sheremeta
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Emily N. Kraft
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - David J. Dyck
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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Miao H, Pan H, Wang L, Yang H, Zhu H, Gong F. Ghrelin Promotes Proliferation and Inhibits Differentiation of 3T3-L1 and Human Primary Preadipocytes. Front Physiol 2019; 10:1296. [PMID: 31681009 PMCID: PMC6798085 DOI: 10.3389/fphys.2019.01296] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 09/27/2019] [Indexed: 12/11/2022] Open
Abstract
Objective Ghrelin is a 28-amino-acid peptide that regulates energy hemostasis, glucose and lipid metabolism. We aimed to explore the effects of ghrelin on the proliferation and differentiation of 3T3-L1 and human primary preadipocytes. Methods 3-(4,5-Dimethylthiazol-2-yl) 2,5-diphenyl tetrazolium bromide (MTT) spectrophotometry, Oil Red O staining, intracellular glycerol-3-phosphate dehydrogenase (G-3-PDH) assays and semiquantitative reverse transcription polymerase chain reaction were used to investigate the action of ghrelin. Results Ghrelin (0.01–1000 ng/ml) significantly increased the numbers of 3T3-L1 cells, and the maximum stimulatory effect was observed with the 10 ng/ml ghrelin treatment for 24 h (p < 0.05). Ghrelin also promoted the proliferation of human primary preadipocytes from 24 h (p < 0.05) to 48 h (p < 0.05) at a concentration of 1000 ng/ml. Further investigation showed that IGF-1 levels were notably increased in ghrelin-treated 3T3-L1 and human preadipocytes, and IGF-1 antibody was capable to attenuate this stimulatory action of ghrelin (all p < 0.05). Additionally, ghrelin significantly suppressed the differentiation of 3T3-L1 and human primary preadipocytes; 10 ng/ml ghrelin notably downregulated G-3-PDH activities in 3T3-L1 cells on day 3 and in human cells from days 4 to 12 following differentiation (all p < 0.05), and the intracellular lipoprotein lipase mRNA levels were lower than that of the controls (p < 0.05). Further investigation showed that the mRNA levels of peroxisome proliferator-activated receptor γ2 (PPARγ2) and CCAAT/enhancer binding protein α (C/EBPs) were also suppressed in ghrelin-treated human differentiating adipocytes. Conclusion Ghrelin promotes the proliferation of 3T3-L1 and human primary preadipocytes by increasing the expression of IGF-1. Ghrelin inhibits murine and human adipocyte differentiation by downregulating PPARγ2 and C/EBPα levels, consequently leading to decreased lipid accumulation and lipogenic enzymes expression.
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Affiliation(s)
- Hui Miao
- Key Laboratory of Endocrinology of National Health Commission, Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Hui Pan
- Key Laboratory of Endocrinology of National Health Commission, Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Linjie Wang
- Key Laboratory of Endocrinology of National Health Commission, Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Hongbo Yang
- Key Laboratory of Endocrinology of National Health Commission, Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Huijuan Zhu
- Key Laboratory of Endocrinology of National Health Commission, Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Fengying Gong
- Key Laboratory of Endocrinology of National Health Commission, Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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Kraft EN, Cervone DT, Dyck DJ. Ghrelin stimulates fatty acid oxidation and inhibits lipolysis in isolated muscle from male rats. Physiol Rep 2019; 7:e14028. [PMID: 30963694 PMCID: PMC6453820 DOI: 10.14814/phy2.14028] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 02/27/2019] [Accepted: 02/27/2019] [Indexed: 11/24/2022] Open
Abstract
Ghrelin is classically known as a central appetite-stimulating hormone but has recently been recognized to have a significant role in peripheral tissue energy metabolism. However, the direct effects of ghrelin on skeletal muscle, a major site for glucose and lipid disposal, remain understudied. We found that the two major ghrelin isoforms, acylated and unacylated ghrelin, were able to significantly increase skeletal muscle fatty acid oxidation (~20%) while incorporation of fatty acids into major lipid pools remained unchanged. The increase in fatty acid oxidation was accompanied by increases in acetyl-CoA carboxylase phosphorylation, a downstream target of AMPK. Ghrelin isoforms had no independent effect on lipolysis under unstimulated conditions, but nearly completely abolished epinephrine-stimulated lipolysis. This effect was generally, but not consistently related to a blunting in the phosphorylation of HSL activation sites, Ser660 and 563. Taken together, these findings suggest that ghrelin isoforms have a direct, acute effect on fatty acid oxidation and lipolysis.
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Affiliation(s)
- Emily N. Kraft
- Department of Human Health and Nutritional SciencesUniversity of GuelphGuelphOntarioCanada
| | - Daniel T. Cervone
- Department of Human Health and Nutritional SciencesUniversity of GuelphGuelphOntarioCanada
| | - David J. Dyck
- Department of Human Health and Nutritional SciencesUniversity of GuelphGuelphOntarioCanada
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Maugham ML, Seim I, Thomas PB, Crisp GJ, Shah ET, Herington AC, Brown KA, Gregory LS, Nelson CC, Jeffery PL, Chopin LK. No effect of unacylated ghrelin administration on subcutaneous PC3 xenograft growth or metabolic parameters in a Rag1-/- mouse model of metabolic dysfunction. PLoS One 2018; 13:e0198495. [PMID: 30458004 PMCID: PMC6245673 DOI: 10.1371/journal.pone.0198495] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 11/02/2018] [Indexed: 12/12/2022] Open
Abstract
Ghrelin is a peptide hormone which, when acylated, regulates appetite, energy balance and a range of other biological processes. Ghrelin predominately circulates in its unacylated form (unacylated ghrelin; UAG). UAG has a number of functions independent of acylated ghrelin, including modulation of metabolic parameters and cancer progression. UAG has also been postulated to antagonise some of the metabolic effects of acyl-ghrelin, including its effects on glucose and insulin regulation. In this study, Rag1-/- mice with high-fat diet-induced obesity and hyperinsulinaemia were subcutaneously implanted with PC3 prostate cancer xenografts to investigate the effect of UAG treatment on metabolic parameters and xenograft growth. Daily intraperitoneal injection of 100 μg/kg UAG had no effect on xenograft tumour growth in mice fed normal rodent chow or 23% high-fat diet. UAG significantly improved glucose tolerance in host Rag1-/- mice on a high-fat diet, but did not significantly improve other metabolic parameters. We propose that UAG is not likely to be an effective treatment for prostate cancer, with or without associated metabolic syndrome.
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Affiliation(s)
- Michelle L. Maugham
- Ghrelin Research Group, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Comparative and Endocrine Biology Laboratory, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Skeletal Biology and Forensic Anthropology Research Laboratory, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Inge Seim
- Ghrelin Research Group, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Comparative and Endocrine Biology Laboratory, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Integrative Biology Laboratory, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Patrick B. Thomas
- Ghrelin Research Group, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Comparative and Endocrine Biology Laboratory, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Gabrielle J. Crisp
- Ghrelin Research Group, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Comparative and Endocrine Biology Laboratory, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Esha T. Shah
- Ghrelin Research Group, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Comparative and Endocrine Biology Laboratory, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Adrian C. Herington
- Ghrelin Research Group, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Kristy A. Brown
- Department of Medicine, Weill Cornell Medicine, New York City, New York, United States of America
| | - Laura S. Gregory
- Skeletal Biology and Forensic Anthropology Research Laboratory, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Colleen C. Nelson
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Penny L. Jeffery
- Ghrelin Research Group, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Comparative and Endocrine Biology Laboratory, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Lisa K. Chopin
- Ghrelin Research Group, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Comparative and Endocrine Biology Laboratory, Translational Research Institute – Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
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KOŁODZIEJSKI PA, PRUSZYŃSKA-OSZMAŁEK E, KOREK E, SASSEK M, SZCZEPANKIEWICZ D, KACZMAREK P, NOGOWSKI L, MAĆKOWIAK P, NOWAK KW, KRAUSS H, STROWSKI MZ. Serum Levels of Spexin and Kisspeptin Negatively Correlate With Obesity and Insulin Resistance in Women. Physiol Res 2018; 67:45-56. [DOI: 10.33549/physiolres.933467] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Spexin (SPX) and kisspeptin (KISS) are novel peptides relevant in the context of regulation of metabolism, food intake, puberty and reproduction. Here, we studied changes of serum SPX and KISS levels in female non-obese volunteers (BMI<25 kg/m2) and obese patients (BMI>35 kg/m2). Correlations between SPX or KISS with BMI, McAuley index, QUICKI, HOMA IR, serum levels of insulin, glucagon, leptin, adiponectin, orexin-A, obestatin, ghrelin and GLP-1 were assessed. Obese patients had lower SPX and KISS levels as compared to non-obese volunteers (SPX: 4.48±0.19 ng/ml vs. 6.63±0.29 ng/ml; p<0.001, KISS: 1.357±0.15 nmol/l vs. 2.165±0.174 nmol/l; p<0.01). SPX negatively correlated with BMI, HOMA-IR, insulin, glucagon, active ghrelin and leptin. Positive correlations were found between SPX and QUICKI index, McAuley index, serum levels of obestatin, GLP-1 and adiponectin and orexin-A Serum KISS negatively correlated with BMI, HOMA-IR, serum levels of insulin, glucagon, active ghrelin and leptin. KISS positively correlated with QUICKI index, McAuley index and adiponectin. In summary, SPX and KISS show negative correlations with obesity, insulin resistance indices, and hormones known to affect insulin sensitivity in females. Both, SPX and KISS could be therefore relevant in the pathophysiology of obesity and insulin resistance.
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Affiliation(s)
- P. A. KOŁODZIEJSKI
- Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Poznan, Poland
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Abstract
PURPOSE OF REVIEW In spite of its relevance, treatments for the cancer anorexia and cachexia syndrome (CACS) are not available. One of the agents that recently reached phase III clinical trials is anamorelin. Its development, along with that of other agents for this indication, will be reviewed here, with a focus on the gaps in the current knowledge and future directions. RECENT FINDINGS In spite of several targets showing promising results in early development, their difficulties obtaining regulatory approval underscore the need to reconsider the current strategies in drug development and the challenges in the field of CACS. SUMMARY Further research is needed in order to meet the challenges of developing treatments for CACS. Preclinical studies should expand our understanding about key regulators of appetite, muscle, and energy metabolism in this setting using models that can be translated reliably to humans. Clinical research efforts should focus on validating the entry criteria, endpoints, outcomes, and the potential synergistic effects and interaction between different targets, nutrition, and exercise interventions. Clinical meaningfulness and significance should be taken into account in the design of clinical trials. It is essential that all key stakeholders are included in the design of future strategies.
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Affiliation(s)
- Jose M. Garcia
- Geriatric Research, Education and Clinical Center (GRECC), VA Puget Sound Health Care System, Seattle, WA
- Department of Medicine, Division of Gerontology & Geriatric Medicine, University of Washington School of Medicine, Seattle, WA
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14
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Diao HY, Shao JG, Bian ZL, Chen L, Ju LL, Zhang Y. Role of phosphoinositide-3 kinase signaling pathways in pathogenesis of acute pancreatitis. Shijie Huaren Xiaohua Zazhi 2016; 24:3002-3008. [DOI: 10.11569/wcjd.v24.i19.3002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Acute pancreatitis (AP) as a common acute disease poses a great threat to people's health. According to statistics, about one-fifth of cases develop acute respiratory distress syndrome and multiple organ dysfunction, which result in high mortality. The early understanding of the pathogenesis of this disease is limited to an inflammatory response resulting in autodigestion, edema, hemorrhage and necrosis of pancreatic tissue after the abnormal activation of trypsin. In recent years, researchers have focused their research on the role of immune inflammatory response in the pathogenesis of AP. Here we discuss the relationship between the immune inflammation and PI3K signaling pathways in AP.
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Phosphoinositide 3-Kinase Gamma Contributes to Neuroinflammation in a Rat Model of Surgical Brain Injury. J Neurosci 2015. [PMID: 26203135 DOI: 10.1523/jneurosci.0546-15.2015] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Neuroinflammation plays an important role in the pathophysiology of surgical brain injury (SBI). Phosphoinositide 3-kinase gamma (PI3Kγ), predominately expressed in immune and endothelial cells, activates multiple inflammatory responses. In the present study, we investigated the role of PI3Kγ and PI3Kγ-activated phosphodiesterase 3B (PDE3B) in neuroinflammation in a rat model of SBI. One hundred and fifty-two male Sprague Dawley rats (weight 280-350 g) were subjected to a partial right frontal lobe corticotomy model of SBI. A PI3Kγ pharmacological inhibitor (AS252424 or AS605240) was administered intraperitoneally. PI3Kγ siRNA, human recombinant active-PI3Kγ protein, or human recombinant active-PDE3B protein were administered intracerebroventricularly. Post-SBI assessments included neurobehavioral tests, brain water content, Western blot, and immunohistochemistry. Endogenous PI3Kγ levels were increased within peri-resection brain tissues after SBI, accompanied by increased brain water content and neurological functional deficits. There was a trend toward increased endogenous PDE3B phosphorylation after SBI. The selective PI3Kγ inhibitors AS252424 and AS605240 reduced brain water content surrounding corticotomy and improved neurological function after SBI. SBI increased and PI3Kγ inhibitor decreased levels of myeloperoxidase, cluster of differentiation 3, mast cell degranulation, E-selectin, and IL-1 in peri-resection brain tissues. Direct administration of human recombinant active-PI3Kγ protein and active-PDE3B protein countered the protective effect of AS252424. PI3Kγ siRNA reduced PI3Kγ levels, decreased brain water content within peri-resection brain tissues, and improved neurological function after SBI. Collectively, our findings suggest that PI3Kγ contributed to neuroinflammation after SBI. The use of selective PI3Kγ inhibitors may be a novel approach to ameliorating SBI via their anti-inflammation effects. Significance statement: Life-saving or elective neurosurgeries often involve unavoidable damages to neighboring, nondiseased brain tissues. Such surgical brain injury (SBI) is attributable exclusively to the neurosurgical procedure itself and may cause postoperative complications that exacerbate neurological function. Although the importance of this medical problem is fully acknowledged, intraoperative administration of adjunctive treatment such as steroids and mannitol to patients undergoing neurosurgery appear not to be efficient remedies for SBI. To date, the issue of perioperative neuroprotection specifically against SBI has not been well studied. Using a clinically relevant rat model of SBI, we are exploring a new neuroprotective strategy targeting phosphoinositide 3-kinase gamma (PI3Kγ). PI3Kγ activates multiple inflammatory responses. By attenuating neuroinflammation, selective PI3Kγ inhibition would limit postoperative complications and benefit neurological outcomes.
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Pei XM, Yung BY, Yip SP, Chan LW, Wong CS, Ying M, Siu PM. Protective effects of desacyl ghrelin on diabetic cardiomyopathy. Acta Diabetol 2015; 52:293-306. [PMID: 25192951 DOI: 10.1007/s00592-014-0637-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 07/23/2014] [Indexed: 01/03/2023]
Abstract
AIM Diabetic cardiomyopathy is a specific complication of type 2 diabetes mellitus, which causes progressive cardiac dysfunction. Desacyl ghrelin has been preliminarily demonstrated to have beneficial effects on cardiovascular system and glucose metabolism, which are both related to diabetic cardiomyopathy. The aim of this study was to investigate the protective effects of desacyl ghrelin on cardiac dysfunction, cardiac fibrosis, and cellular autophagy in a type 2 diabetic mouse model. MATERIALS AND METHODS Fourteen- to eighteen-week-old db/db diabetic and db/+ non-diabetic mice were intraperitoneally treated with desacyl ghrelin at a dosage of 100 μg/kg for ten consecutive days. Ventricular fractional shortening was examined as an indicator of cardiac function by transthoracic echocardiography. RESULTS The presence of diabetic cardiomyopathy was evident by the reduction in fractional shortening shown in our examined db/db mice. Intriguingly, this reduction in fractional shortening was not observed in the hearts of db/db mice treated with desacyl ghrelin. Cardiac fibrosis (indicated by excessive collagen deposition, decreased by Adiponectin and Mmp13 expression, and up-regulated by Mmp8 expression) and impairment of autophagic signalling (indicated by decreases in Foxo3 and LC3 II-to-LC3 I ratio) were shown in the hearts of diabetic mice. All these cellular and molecular alterations were alleviated by desacyl ghrelin treatment. The key cardiac pro-survival cellular signals including AMPK, Akt, ERK1/2, and GSK3α/β were impaired in the diabetic hearts, but the administration of desacyl ghrelin attenuated these signalling impairments. CONCLUSIONS These results collectively demonstrate that desacyl ghrelin protects the heart against cardiac dysfunction in type 2 diabetic mice by inhibiting excessive collagen deposition and enhancing cardiac autophagic signalling via the pro-survival cellular AMPK/ERK1/2 signalling pathways.
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Affiliation(s)
- Xiao M Pei
- Department of Health Technology and Informatics, Faculty of Health and Social Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
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Benso A, Gramaglia E, Olivetti I, Tomelini M, Belcastro S, Calvi E, Dotta A, St-Pierre D, Ghigo E, Broglio F. Acute effects of acylated ghrelin on salbutamol-induced metabolic actions in humans. Endocrine 2015; 48:937-41. [PMID: 25012253 DOI: 10.1007/s12020-014-0343-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 06/18/2014] [Indexed: 10/25/2022]
Abstract
The aim of this study is to describe a potential modulatory effect of acute acylated ghrelin (AG) administration on the glucose, insulin, and free fatty acids (FFA) responses to salbutamol (SALBU). Six healthy young male volunteers underwent the following four testing sessions in random order at least 7 days apart: (a) acute AG administration (1.0 μg/kg i.v. as bolus at 0'); (b) SALBU infusion (0.06 μg/kg/min i.v. from -15' to +45'); (c) SALBU infusion+AG; and (d) isotonic saline infusion. Blood samples for glucose, insulin, and FFA levels were collected every 15 min. As expected, with respect to saline, SALBU infusion induced a remarkable increase in glucose (10.8±5.6 mmol/l×min; P<0.05), insulin (2436.8±556.9 pmol/l×min; P<0.05), and FFA (18.9±4.5 mmol/l×min; P<0.01) levels. A significant increase in glucose (7.4±3.9 mmol/l×min; P<0.05) and FFA levels (10.0±2.8 mmol/l×min; P<0.01) without significant variations in insulin levels were recorded after AG administration. Interestingly, the hyperglycemic effect of AG appeared to be significantly potentiated during SALBU infusion (26.7±4.8 mmol/l×min; P<0.05). On the other hand, the stimulatory effect of SALBU on insulin and FFA was not significantly modified by AG administration. The results of this study show that acute AG administration has a synergic effect with β2-adrenergic receptor activation by SALBU on blood glucose increase, suggesting that their pharmacological hyperglycemic action takes place via different mechanisms. On the other hand, AG has a negligible influence on the other pharmacological metabolic effects of SALBU infusion.
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Affiliation(s)
- A Benso
- Division of Endocrinology, Diabetology and Metabolism, Department of Medical Sciences, University of Turin, A.O. Città della Salute e della Scienza - Molinette, Corso Dogliotti 14, 10126, Turin, Italy
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18
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Sheriff S, Kadeer N, Friend LA, James JH, Alexander JW, Balasubramaniam A. Des-acyl-ghrelin (DAG) normalizes hyperlactacidemia and improves survival in a lethal rat model of burn trauma. Peptides 2014; 60:1-7. [PMID: 25063053 DOI: 10.1016/j.peptides.2014.07.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 07/14/2014] [Accepted: 07/14/2014] [Indexed: 12/17/2022]
Abstract
Critical illness, including burn injury, results in elevated plasma lactate levels. Dysregulation of PI3K/Akt signaling has been shown to play a predominant role in the inactivation of skeletal muscle PDC and, hence, in hyperlactacidemia in rat models of sepsis and endotoxemia. This observation, and our previous finding that DAG can reverse burn-induced skeletal muscle proteolysis through the activation of PI3K/Akt pathway, led us to hypothesize that DAG may also attenuate hyperlactacidemia in burn injury. Our investigations revealed that burn injury significantly elevated both skeletal muscle lactate production and plasma lactate levels. Moreover, this was accompanied in skeletal muscle by a 5-7 fold increase in mRNA expression of pyruvate dehydrogenase kinases (PDK) 2 and 4, and a ∼30% reduction in PDC activity. DAG treatment of burn rats completely normalized not only the mRNA expression of the PDKs and PDC activity, but also hyperlactacidemia within 24h of burn injury. DAG also normalized epinephrine-induced lactate production by isolated skeletal muscles from normal rats. Moreover, DAG also improved survival in a lethal rat model of burn trauma. These findings with DAG may have clinical implications because chances of survival for critically ill patients are greatly improved if plasma lactate levels are normalized within 24h of injury.
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Affiliation(s)
- Sulaiman Sheriff
- Department of Surgery, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267, USA; Shriners Hospital for Children, 3229 Burnet Avenue, Cincinnati, OH 45229, USA
| | - Nijiati Kadeer
- Department of Surgery, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267, USA; Shriners Hospital for Children, 3229 Burnet Avenue, Cincinnati, OH 45229, USA
| | - Lou Ann Friend
- Department of Surgery, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267, USA; Shriners Hospital for Children, 3229 Burnet Avenue, Cincinnati, OH 45229, USA
| | - J Howard James
- Department of Surgery, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267, USA; Shriners Hospital for Children, 3229 Burnet Avenue, Cincinnati, OH 45229, USA
| | - J Wesley Alexander
- Department of Surgery, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267, USA; Shriners Hospital for Children, 3229 Burnet Avenue, Cincinnati, OH 45229, USA
| | - Ambikaipakan Balasubramaniam
- Department of Surgery, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267, USA; Shriners Hospital for Children, 3229 Burnet Avenue, Cincinnati, OH 45229, USA; Cincinnati Veterans Affairs Medical Center, 3200 Vine Street, Cincinnati, OH 45220, USA.
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Callaghan B, Furness JB. Novel and Conventional Receptors for Ghrelin, Desacyl-Ghrelin, and Pharmacologically Related Compounds. Pharmacol Rev 2014; 66:984-1001. [DOI: 10.1124/pr.113.008433] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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20
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Abstract
In adipocytes the hydrolysis of TAG to produce fatty acids and glycerol under fasting conditions or times of elevated energy demands is tightly regulated by neuroendocrine signals, resulting in the activation of lipolytic enzymes. Among the classic regulators of lipolysis, adrenergic stimulation and the insulin-mediated control of lipid mobilisation are the best known. Initially, hormone-sensitive lipase (HSL) was thought to be the rate-limiting enzyme of the first lipolytic step, while we now know that adipocyte TAG lipase is the key enzyme for lipolysis initiation. Pivotal, previously unsuspected components have also been identified at the protective interface of the lipid droplet surface and in the signalling pathways that control lipolysis. Perilipin, comparative gene identification-58 (CGI-58) and other proteins of the lipid droplet surface are currently known to be key regulators of the lipolytic machinery, protecting or exposing the TAG core of the droplet to lipases. The neuroendocrine control of lipolysis is prototypically exerted by catecholaminergic stimulation and insulin-induced suppression, both of which affect cyclic AMP levels and hence the protein kinase A-mediated phosphorylation of HSL and perilipin. Interestingly, in recent decades adipose tissue has been shown to secrete a large number of adipokines, which exert direct effects on lipolysis, while adipocytes reportedly express a wide range of receptors for signals involved in lipid mobilisation. Recently recognised mediators of lipolysis include some adipokines, structural membrane proteins, atrial natriuretic peptides, AMP-activated protein kinase and mitogen-activated protein kinase. Lipolysis needs to be reanalysed from the broader perspective of its specific physiological or pathological context since basal or stimulated lipolytic rates occur under diverse conditions and by different mechanisms.
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Chen YC, Chiang CF, Chen LF, Liao SC, Hsieh WY, Lin WL. Polymersomes conjugated with des-octanoyl ghrelin for the delivery of therapeutic and imaging agents into brain tissues. Biomaterials 2014; 35:2051-65. [DOI: 10.1016/j.biomaterials.2013.11.051] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Accepted: 11/17/2013] [Indexed: 12/28/2022]
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Gesmundo I, Gallo D, Favaro E, Ghigo E, Granata R. Obestatin: a new metabolic player in the pancreas and white adipose tissue. IUBMB Life 2013; 65:976-82. [PMID: 24217898 DOI: 10.1002/iub.1226] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 10/10/2013] [Accepted: 10/11/2013] [Indexed: 01/14/2023]
Abstract
Obestatin is a 23 amino acid amidated peptide, member of the preproghrelin gene-derived peptides. Initially, obestatin was reported to exert opposite effects to those of ghrelin on food intake and body weight gain, through interaction with GPR39; however, these findings are still strongly debated and obestatin biological role remains largely unknown. Interestingly, binding of obestatin to the glucagon-like peptide 1 receptor has been recently suggested. Despite being a controversial peptide, recent findings have clearly indicated that obestatin is indeed a multifunctional peptide, exerting a variety of effects, such as stimulation of cell proliferation, survival and differentiation, influence on glucose and lipid metabolism, as well as anti-inflammatory and cardioprotective actions. Its positive effects on glucose and lipid metabolism candidate this peptide as a potential therapeutic tool in pathological conditions such as insulin resistance and diabetes.
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Affiliation(s)
- Iacopo Gesmundo
- Division of Endocrinology, Diabetology and Metabolism, Department of Medical Sciences, University of Torino, Torino, Italy
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23
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Abstract
GH regulates several physiological processes in vertebrates, including the promotion of growth, an anabolic process, and the mobilization of stored lipids, a catabolic process. In this study, we used hepatocytes isolated from rainbow trout (Oncorhynchus mykiss) as a model to examine the mechanism of GH action on lipolysis. GH stimulated lipolysis as measured by increased glycerol release in both a time- and a concentration-related manner. The promotion of lipolysis was accompanied by GH-stimulated phosphorylation of the lipolytic enzyme hormone-sensitive lipase (HSL). GH-stimulated lipolysis was also manifested by an increased expression of the two HSL-encoding mRNAs, HSL1 and HSL2. The signaling pathways that underlie GH-stimulated lipolysis were also studied. GH resulted in the activation of phospholipase C (PLC)/protein kinase C (PKC) and the MEK/ERK pathway, whereas JAK-STAT and the PI3K-Akt pathway were deactivated. The blockade of PLC/PKC and the MEK/ERK pathway inhibited GH-stimulated lipolysis and GH-stimulated phosphorylation of HSL as well as GH-stimulated HSL mRNA expression, whereas the blockade of JAK-STAT or the PI3K-Akt pathway had no effect on the activation of lipolysis or the expression of HSL stimulated by GH. These results indicate that GH promotes lipolysis by activating HSL and by enhancing the de novo expression of HSL mRNAs via the activation of PKC and ERK. These findings also suggest molecular mechanisms for activating the lipid catabolic actions of GH while simultaneously deactivating anabolic processes such as antilipolysis and the growth-promoting actions of GH.
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Affiliation(s)
- Heather E Bergan
- Department of Biological Sciences, North Dakota State University, Fargo, North Dakota 58105, USA
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24
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Porteiro B, Díaz-Ruíz A, Martínez G, Senra A, Vidal A, Serrano M, Gualillo O, López M, Malagón MM, Diéguez C, Nogueiras R. Ghrelin requires p53 to stimulate lipid storage in fat and liver. Endocrinology 2013; 154:3671-9. [PMID: 23832961 DOI: 10.1210/en.2013-1176] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Ghrelin, a stomach-derived peptide, stimulates feeding behavior and adiposity. For its orexigenic action, ghrelin triggers a central SIRT1/p53/AMPK pathway. The tumor suppressor p53 also plays an important role in white adipose tissue (WAT), where it is up-regulated in the adipocytes of obese mice. It is not known, however, whether p53 has any role in mediating the peripheral action of ghrelin. In the present study, chronic peripheral ghrelin treatment resulted in increased body weight and fat-mass gain in wild-type mice. Correspondingly, mRNA levels of several adipogenic and fat-storage-promoting enzymes were up-regulated in WAT, whereas hepatic triglyceride content and lipogenic enzymes were also increased in wild-type mice following ghrelin treatment. In contrast, mice lacking p53 failed to respond to ghrelin treatment, with their body weight, fat mass, and adipocyte and hepatic metabolism remaining unchanged. Thus, our results show that p53 is necessary for the actions of ghrelin on WAT and liver, leading to changes in expression levels of lipogenic and adipogenic genes, and modifying body weight.
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Affiliation(s)
- Begoña Porteiro
- Department of Physiology, Centre of Research in Molecular Medicine and Chronic Diseases of the University of Santiago de Compostela (CIMUS), University of Santiago de Compostela-Instituto de Investigación Sanitaria, Avda Barcelona s/n, 15782, Santiago de Compostela (A Coruña), Spain, and CIBER "Fisiopatología de la Obesidad y Nutrición," Instituto de Salud Carlos III, Spain.
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Meltzer-Mats E, Babai-Shani G, Pasternak L, Uritsky N, Getter T, Viskind O, Eckel J, Cerasi E, Senderowitz H, Sasson S, Gruzman A. Synthesis and mechanism of hypoglycemic activity of benzothiazole derivatives. J Med Chem 2013; 56:5335-50. [PMID: 23750537 DOI: 10.1021/jm4001488] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Adenosine 5'-monophosphate activated protein kinase (AMPK) has emerged as a major potential target for novel antidiabetic drugs. We studied the structure of 2-chloro-5-((Z)-((E)-5-((5-(4,5-dimethyl-2-nitrophenyl)furan-2-yl)methylene)-4-oxothiazolidin-2-ylidene)amino)benzoic acid (PT-1), which attenuates the autoinhibition of the enzyme AMPK, for the design and synthesis of different benzothiazoles with potential antidiabetic activity. We synthesized several structurally related benzothiazole derivatives that increased the rate of glucose uptake in L6 myotubes in an AMPK-dependent manner. One compound, 2-(benzo[d]thiazol-2-ylmethylthio)-6-ethoxybenzo[d]thiazole (34), augmented the rate of glucose uptake up to 2.5-fold compared with vehicle-treated cells and up to 1.1-fold compared to PT-1. Concomitantly, it elevated the abundance of GLUT4 in the plasma membrane of the myotubes and activated AMPK. Subcutaneous administration of 34 to hyperglycemic Kuo Kondo rats carrying the Ay-yellow obese gene (KKAy) mice lowered blood glucose levels toward the normoglycemic range. In accord with its activity, compound 34 showed a high fit value to a pharmacophore model derived from the PT-1.
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Affiliation(s)
- Ella Meltzer-Mats
- Division of Medicinal Chemistry, Department of Chemistry, Faculty of Exact Sciences, Bar Ilan University , Ramat Gan, 5290002, Israel
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Schmidt C, Schneble N, Müller JP, Bauer R, Perino A, Marone R, Rybalkin SD, Wymann MP, Hirsch E, Wetzker R. Phosphoinositide 3-kinase γ mediates microglial phagocytosis via lipid kinase-independent control of cAMP. Neuroscience 2012; 233:44-53. [PMID: 23276671 DOI: 10.1016/j.neuroscience.2012.12.036] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 12/18/2012] [Accepted: 12/19/2012] [Indexed: 02/08/2023]
Abstract
Microglial phagocytosis plays a key role in neuroprotective and neurodegenerative responses of the innate immune system in the brain. Here we investigated the regulatory function of phosphoinositide 3-kinase γ (PI3Kγ) in phagocytosis of bacteria and Zymosan particles by mouse brain microglia in vitro and in vivo. Using genetic and pharmacological approaches our data revealed PI3Kγ as an essential mediator of microglial phagocytosis. Unexpectedly, microglia expressing lipid kinase deficient mutant PI3Kγ exhibited similar phagocytosis as wild-type cells. These data suggest kinase-independent stimulation of cAMP phosphodiesterase activity by PI3Kγ as a crucial mediator of phagocytosis. In sum our findings indicate PI3Kγ-dependent suppression of cAMP signaling as a critical regulatory element of microglial phagocytosis.
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Affiliation(s)
- C Schmidt
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine, Jena University Hospital, 07745 Jena, Germany
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27
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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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Delhanty PJD, Neggers SJ, van der Lely AJ. Mechanisms in endocrinology: Ghrelin: the differences between acyl- and des-acyl ghrelin. Eur J Endocrinol 2012; 167:601-8. [PMID: 22898499 DOI: 10.1530/eje-12-0456] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Des-acyl ghrelin (DAG) is one of the three preproghrelin gene-encoded peptides. Compared with ghrelin and obestatin, it has not received the attention it deserves. DAG has long been considered an inert degradation product of acyl ghrelin (AG). Recent evidence, however, indicates that DAG behaves like a separate hormone. DAG can act together with AG, can antagonize AG, and seems to have AG-independent effects. Therefore, it is believed that DAG must activate its own receptor and that it may also interact with AG at this receptor. Of potential clinical importance is that an increasing number of studies suggest that DAG might be a functional inhibitor of ghrelin and that DAG can suppress ghrelin levels in humans. Therefore, DAG or DAG analogs might be good candidates for future treatment of metabolic disorders or other conditions in which antagonism of AG actions could be beneficial, such as diabetes, obesity, and Prader-Willi syndrome.
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Affiliation(s)
- Patric J D Delhanty
- Department of Medicine, Erasmus University MC, CA Rotterdam, The Netherlands
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Rodríguez A, Gómez-Ambrosi J, Catalán V, Rotellar F, Valentí V, Silva C, Mugueta C, Pulido MR, Vázquez R, Salvador J, Malagón MM, Colina I, Frühbeck G. The ghrelin O-acyltransferase-ghrelin system reduces TNF-α-induced apoptosis and autophagy in human visceral adipocytes. Diabetologia 2012; 55:3038-50. [PMID: 22869322 DOI: 10.1007/s00125-012-2671-5] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 06/25/2012] [Indexed: 12/19/2022]
Abstract
AIMS/HYPOTHESIS Proinflammatory and proapoptotic cytokines such as TNF-α are upregulated in human obesity. We evaluated the association between ghrelin isoforms (acylated and desacyl ghrelin) and TNF-α in obesity and obesity-associated type 2 diabetes, as well as the potential role of ghrelin in the control of apoptosis and autophagy in human adipocytes. METHODS Plasma concentrations of the ghrelin isoforms and TNF-α were measured in 194 participants. Ghrelin and ghrelin O-acyltransferase (GOAT) levels were analysed by western-blot, immunohistochemistry and real-time PCR in 53 biopsies of human omental adipose tissue. We also determined the effect of acylated and desacyl ghrelin (10 to 1,000 pmol/l) on TNF-α-induced apoptosis and autophagy-related molecules in omental adipocytes. RESULTS Circulating concentrations of acylated ghrelin and TNF-α were increased, whereas desacyl ghrelin levels were decreased in obesity-associated type 2 diabetes. Ghrelin and GOAT were produced in omental and subcutaneous adipose tissue. Visceral adipose tissue from obese patients with type 2 diabetes showed higher levels of GOAT, increased adipocyte apoptosis and increased expression of the autophagy-related genes ATG5, BECN1 and ATG7. In differentiating human omental adipocytes, incubation with acylated and desacyl ghrelin reduced TNF-α-induced activation of caspase-8 and caspase-3, and cell death. In addition, acylated ghrelin reduced the basal expression of the autophagy-related genes ATG5 and ATG7, while desacyl ghrelin inhibited the TNF-α-induced increase of ATG5, BECN1 and ATG7 expression. CONCLUSIONS/INTERPRETATION Apoptosis and autophagy are upregulated in human visceral adipose tissue of patients with type 2 diabetes. Acylated and desacyl ghrelin reduce TNF-α-induced apoptosis and autophagy in human visceral adipocytes.
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Affiliation(s)
- A Rodríguez
- Metabolic Research Laboratory, Clínica Universidad de Navarra, Pamplona, Spain
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Granata R, Gallo D, Luque RM, Baragli A, Scarlatti F, Grande C, Gesmundo I, Córdoba-Chacón J, Bergandi L, Settanni F, Togliatto G, Volante M, Garetto S, Annunziata M, Chanclón B, Gargantini E, Rocchietto S, Matera L, Datta G, Morino M, Brizzi MF, Ong H, Camussi G, Castaño JP, Papotti M, Ghigo E. Obestatin regulates adipocyte function and protects against diet-induced insulin resistance and inflammation. FASEB J 2012; 26:3393-411. [PMID: 22601779 DOI: 10.1096/fj.11-201343] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The metabolic actions of the ghrelin gene-derived peptide obestatin are still unclear. We investigated obestatin effects in vitro, on adipocyte function, and in vivo, on insulin resistance and inflammation in mice fed a high-fat diet (HFD). Obestatin effects on apoptosis, differentiation, lipolysis, and glucose uptake were determined in vitro in mouse 3T3-L1 and in human subcutaneous (hSC) and omental (hOM) adipocytes. In vivo, the influence of obestatin on glucose metabolism was assessed in mice fed an HFD for 8 wk. 3T3-L1, hSC, and hOM preadipocytes and adipocytes secreted obestatin and showed specific binding for the hormone. Obestatin prevented apoptosis in 3T3-L1 preadipocytes by increasing phosphoinositide 3-kinase (PI3K)/Akt and extracellular signal-regulated kinase (ERK)1/2 signaling. In both mice and human adipocytes, obestatin inhibited isoproterenol-induced lipolysis, promoted AMP-activated protein kinase phosphorylation, induced adiponectin, and reduced leptin secretion. Obestatin also enhanced glucose uptake in either the absence or presence of insulin, promoted GLUT4 translocation, and increased Akt phosphorylation and sirtuin 1 (SIRT1) protein expression. Inhibition of SIRT1 by small interfering RNA reduced obestatin-induced glucose uptake. In HFD-fed mice, obestatin reduced insulin resistance, increased insulin secretion from pancreatic islets, and reduced adipocyte apoptosis and inflammation in metabolic tissues. These results provide evidence of a novel role for obestatin in adipocyte function and glucose metabolism and suggest potential therapeutic perspectives in insulin resistance and metabolic dysfunctions.
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Affiliation(s)
- Riccarda Granata
- Laboratory of Molecular and Cellular Endocrinology, Department of Internal Medicine, University of Turin, Corso Dogliotti 14-10126 Turin, Italy.
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Baragli A, Lanfranco F, Allasia S, Granata R, Ghigo E. Neuroendocrine and metabolic activities of ghrelin gene products. Peptides 2011; 32:2323-32. [PMID: 22056513 DOI: 10.1016/j.peptides.2011.10.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 10/03/2011] [Accepted: 10/25/2011] [Indexed: 12/15/2022]
Abstract
Acylated ghrelin (AG) is a 28 amino acid gastric peptide a natural ligand for the growth hormone secretagogue (GHS) receptor type 1a (GHS-R1a), endowed with GH-secreting and orexigenic properties. Besides, ghrelin exerts several peripheral metabolic actions, including modulation of glucose homeostasis and stimulation of adipogenesis. Notably, AG administration causes hyperglycemia in rodents as in humans. Ghrelin pleiotropy is supported by a widespread expression of the ghrelin gene, of GHS-R1a and other unknown ghrelin binding sites. The existence of alternative receptors for AG, of several natural ligands for GHS-R1a and of acylation-independent ghrelin non-neuroendocrine activities, suggests that there might be a complex 'ghrelin system' not yet completely explored. Moreover, the patho-physiological implications of unacylated ghrelin (UAG), and obestatin (Ob), the other two ghrelin gene-derived peptides, need to be clarified. Within the next few years, we may better understand the 'ghrelin system', where we might envisage clinical applications.
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Affiliation(s)
- Alessandra Baragli
- Laboratory of Molecular and Cellular Endocrinology, Division of Endocrinology, Department of Internal Medicine, University of Turin, Turin, Italy.
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