1
|
Nargund R, Wyvratt M, Lin S, Sebhat I, Greenlee W. Annotated Bibliography of Dr. Arthur A. Patchett. J Med Chem 2023; 66:15567-15575. [PMID: 38032081 DOI: 10.1021/acs.jmedchem.3c02131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2023]
|
2
|
van Albada ME, Mohnike K, Dunne MJ, Banerjee I, Betz SF. Somatostatin receptors in congenital hyperinsulinism: Biology to bedside. Front Endocrinol (Lausanne) 2022; 13:921357. [PMID: 36237195 PMCID: PMC9552539 DOI: 10.3389/fendo.2022.921357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 08/29/2022] [Indexed: 11/29/2022] Open
Abstract
Congenital hyperinsulinism (CHI), although a rare disease, is an important cause of severe hypoglycemia in early infancy and childhood, causing preventable morbidity and mortality. Prompt diagnosis and appropriate treatment is necessary to prevent hypoglycaemia mediated brain damage. At present, the medical treatment of CHI is limited to diazoxide as first line and synthetic somatostatin receptor ligands (SRLs) as second line options; therefore understanding somatostatin biology and treatment perspectives is important. Under healthy conditions, somatostatin secreted from pancreatic islet δ-cells reduces insulin release through somatostatin receptor induced cAMP-mediated downregulation and paracrine inhibition of β- cells. Several SRLs with extended duration of action are now commercially available and are being used off-label in CHI patients. Efficacy remains variable with the present generation of SRLs, with treatment effect often being compromised by loss of initial response and adverse effects such as bowel ischaemia and hepatobiliary dysfunction. In this review we have addressed the biology of the somatostatin system contexualised to CHI. We have discussed the clinical use, limitations, and complications of somatostatin agonists and new and emerging therapies for CHI.
Collapse
Affiliation(s)
- Mirjam E. van Albada
- Department of Paediatric Endocrinology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
- *Correspondence: Mirjam E. van Albada,
| | - Klaus Mohnike
- Universitätskinderklinik, Otto-von-Guericke-Universität, Magdeburg, Germany
| | - Mark J. Dunne
- Department of Physiology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Indi Banerjee
- Department of Paediatric Endocrinology, Royal Manchester Children’s Hospital and Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | | |
Collapse
|
3
|
Ng XW, Chung YH, Piston DW. Intercellular Communication in the Islet of Langerhans in Health and Disease. Compr Physiol 2021; 11:2191-2225. [PMID: 34190340 DOI: 10.1002/cphy.c200026] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Blood glucose homeostasis requires proper function of pancreatic islets, which secrete insulin, glucagon, and somatostatin from the β-, α-, and δ-cells, respectively. Each islet cell type is equipped with intrinsic mechanisms for glucose sensing and secretory actions, but these intrinsic mechanisms alone cannot explain the observed secretory profiles from intact islets. Regulation of secretion involves interconnected mechanisms among and between islet cell types. Islet cells lose their normal functional signatures and secretory behaviors upon dispersal as compared to intact islets and in vivo. In dispersed islet cells, the glucose response of insulin secretion is attenuated from that seen from whole islets, coordinated oscillations in membrane potential and intracellular Ca2+ activity, as well as the two-phase insulin secretion profile, are missing, and glucagon secretion displays higher basal secretion profile and a reverse glucose-dependent response from that of intact islets. These observations highlight the critical roles of intercellular communication within the pancreatic islet, and how these communication pathways are crucial for proper hormonal and nonhormonal secretion and glucose homeostasis. Further, misregulated secretions of islet secretory products that arise from defective intercellular islet communication are implicated in diabetes. Intercellular communication within the islet environment comprises multiple mechanisms, including electrical synapses from gap junctional coupling, paracrine interactions among neighboring cells, and direct cell-to-cell contacts in the form of juxtacrine signaling. In this article, we describe the various mechanisms that contribute to proper islet function for each islet cell type and how intercellular islet communications are coordinated among the same and different islet cell types. © 2021 American Physiological Society. Compr Physiol 11:2191-2225, 2021.
Collapse
Affiliation(s)
- Xue W Ng
- Department of Cell Biology and Physiology, Washington University, St Louis, Missouri, USA
| | - Yong H Chung
- Department of Cell Biology and Physiology, Washington University, St Louis, Missouri, USA
| | - David W Piston
- Department of Cell Biology and Physiology, Washington University, St Louis, Missouri, USA
| |
Collapse
|
4
|
Saadi S, Ghazali HM, Saari N, Abdulkarim SM. The structural reconformation of peptides in enhancing functional and therapeutic properties: Insights into their solid state crystallizations. Biophys Chem 2021; 273:106565. [PMID: 33780688 DOI: 10.1016/j.bpc.2021.106565] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 02/09/2021] [Accepted: 02/19/2021] [Indexed: 01/05/2023]
Abstract
Therapeutic peptides derived proteins with alpha-reconformation states like antibody shape have shown potential effects in combating terrible diseases linked with earlier signs of angiogensis, mutagenesis and transgenesis. Alpha reconformation in material design refers to the folding of the peptide chains and their transitions under reversible chemical bonds of disulfide chemical bridges and further non-covalence lesions. Thus, the rational design of signal peptides into alpha-helix is intended in increasing the defending effects of peptides into cores like adjuvant antibiotic and/or vaccines. Thereby, the signal peptides are able in displaying multiple eradicating regions by changing crystal-depositions and deviation angles. These types of molecular structures could have multiple advantages in tracing disease syndromes and impurities by increasing the host defense against the fates of pathogens and viruses, eventually leading to the loss in signaling by increasing peptide susceptibility levels to folding and unfolding and therefore, formation of transgenic peptide models. Alpha reconformation peptides is aimed in triggering as well as other regulatory functions such as remodulating metabolic chain disorders of lipolysis and glucolysis by increasing the insulin and leptin resistance for best lipid storages and lipoprotein density distributions.
Collapse
Affiliation(s)
- Sami Saadi
- Institut de la Nutrition, de l'Alimentation et des Technologies Agro-alimentaires INATAA 25017, Université Frères Mentouri, Constantine 1, Algeria; Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia.
| | - Hasanah Mohd Ghazali
- Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Nazamid Saari
- Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Sabo Mohammed Abdulkarim
- Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| |
Collapse
|
5
|
Ozoux ML, Briand V, Pelat M, Barbe F, Schaeffer P, Beauverger P, Poirier B, Guillon JM, Petit F, Altenburger JM, Bidouard JP, Janiak P. Potential Therapeutic Value of Urotensin II Receptor Antagonist in Chronic Kidney Disease and Associated Comorbidities. J Pharmacol Exp Ther 2020; 374:24-37. [PMID: 32332113 DOI: 10.1124/jpet.120.265496] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 04/13/2020] [Indexed: 11/22/2022] Open
Abstract
Chronic kidney disease (CKD) remains a common disorder, leading to growing health and economic burden without curative treatment. In diabetic patients, CKD may result from a combination of metabolic and nonmetabolic-related factors, with mortality mainly driven by cardiovascular events. The marked overactivity of the urotensinergic system in diabetic patients implicates this vasoactive peptide as a possible contributor to the pathogenesis of renal as well as heart failure. Previous preclinical studies with urotensin II (UII) antagonists in chronic kidney disease were based on simple end points that did not reflect the complex etiology of the disease. Given this, our studies revisited the therapeutic value of UII antagonism in CKD and extensively characterized 1-({[6-{4-chloro-3-[3-(dimethylamino)propoxy]phenyl}-5-(2-methylphenyl)pyridin-2-yl]carbonyl}amino) cyclohexanecarboxylic acid hydrochloride (SAR101099), a potent, selective, and orally long-acting UII receptor competitive antagonist, inhibiting not only UII but also urotensin-related peptide activities. SR101099 treatment more than halved proteinurea and albumin/creatinine ratio in spontaneously hypertensive stroke-prone (SHR-SP) rats fed with salt/fat diet and Dahl-salt-sensitive rats, respectively, and it halved albuminuria in streptozotocin-induced diabetes rats. Importantly, these effects were accompanied by a decrease in mortality of 50% in SHR-SP and of 35% in the Dahl salt-sensitive rats. SAR101099 was also active on CKD-related cardiovascular pathologies and partly preserved contractile reserve in models of heart failure induced by myocardial infarction or ischemia/reperfusion in rats and pigs, respectively. SAR101099 exhibited a good safety/tolerability profile at all tested doses in clinical phase-I studies. Together, these data suggest that CKD patient selection considering comorbidities together with new stratification modalities should unveil the urotensin antagonists' therapeutic potential. SIGNIFICANCE STATEMENT: Chronic kidney disease (CKD) is a pathology with growing health and economic burden, without curative treatment. For years, the impact of urotensin II receptor (UT) antagonism to treat CKD may have been compromised by available tools or models to deeper characterize the urotensinergic system. New potent, selective, orally long-acting cross-species UT antagonist such as SAR101099 exerting reno- and cardioprotective effects could offer novel therapeutic opportunities. Its preclinical and clinical results suggest that UT antagonism remains an attractive target in CKD on top of current standard of care.
Collapse
Affiliation(s)
- Marie-Laure Ozoux
- Cardiovascular and Metabolism Therapeutic Area, Sanofi R&D, Chilly-Mazarin, France (M.L.O., V.B., M.P., F.B., P.S., P.B., B.P., P.J.); Preclinical Safety, Sanofi R&D, Chilly-Mazarin, France (J.M.G.);and Chemistry, Sanofi R&D, Chilly-Mazarin, France (F.P., J.M.A., J.P.B.)
| | - Véronique Briand
- Cardiovascular and Metabolism Therapeutic Area, Sanofi R&D, Chilly-Mazarin, France (M.L.O., V.B., M.P., F.B., P.S., P.B., B.P., P.J.); Preclinical Safety, Sanofi R&D, Chilly-Mazarin, France (J.M.G.);and Chemistry, Sanofi R&D, Chilly-Mazarin, France (F.P., J.M.A., J.P.B.)
| | - Michel Pelat
- Cardiovascular and Metabolism Therapeutic Area, Sanofi R&D, Chilly-Mazarin, France (M.L.O., V.B., M.P., F.B., P.S., P.B., B.P., P.J.); Preclinical Safety, Sanofi R&D, Chilly-Mazarin, France (J.M.G.);and Chemistry, Sanofi R&D, Chilly-Mazarin, France (F.P., J.M.A., J.P.B.)
| | - Fabrice Barbe
- Cardiovascular and Metabolism Therapeutic Area, Sanofi R&D, Chilly-Mazarin, France (M.L.O., V.B., M.P., F.B., P.S., P.B., B.P., P.J.); Preclinical Safety, Sanofi R&D, Chilly-Mazarin, France (J.M.G.);and Chemistry, Sanofi R&D, Chilly-Mazarin, France (F.P., J.M.A., J.P.B.)
| | - Paul Schaeffer
- Cardiovascular and Metabolism Therapeutic Area, Sanofi R&D, Chilly-Mazarin, France (M.L.O., V.B., M.P., F.B., P.S., P.B., B.P., P.J.); Preclinical Safety, Sanofi R&D, Chilly-Mazarin, France (J.M.G.);and Chemistry, Sanofi R&D, Chilly-Mazarin, France (F.P., J.M.A., J.P.B.)
| | - Philippe Beauverger
- Cardiovascular and Metabolism Therapeutic Area, Sanofi R&D, Chilly-Mazarin, France (M.L.O., V.B., M.P., F.B., P.S., P.B., B.P., P.J.); Preclinical Safety, Sanofi R&D, Chilly-Mazarin, France (J.M.G.);and Chemistry, Sanofi R&D, Chilly-Mazarin, France (F.P., J.M.A., J.P.B.)
| | - Bruno Poirier
- Cardiovascular and Metabolism Therapeutic Area, Sanofi R&D, Chilly-Mazarin, France (M.L.O., V.B., M.P., F.B., P.S., P.B., B.P., P.J.); Preclinical Safety, Sanofi R&D, Chilly-Mazarin, France (J.M.G.);and Chemistry, Sanofi R&D, Chilly-Mazarin, France (F.P., J.M.A., J.P.B.)
| | - Jean-Michel Guillon
- Cardiovascular and Metabolism Therapeutic Area, Sanofi R&D, Chilly-Mazarin, France (M.L.O., V.B., M.P., F.B., P.S., P.B., B.P., P.J.); Preclinical Safety, Sanofi R&D, Chilly-Mazarin, France (J.M.G.);and Chemistry, Sanofi R&D, Chilly-Mazarin, France (F.P., J.M.A., J.P.B.)
| | - Frédéric Petit
- Cardiovascular and Metabolism Therapeutic Area, Sanofi R&D, Chilly-Mazarin, France (M.L.O., V.B., M.P., F.B., P.S., P.B., B.P., P.J.); Preclinical Safety, Sanofi R&D, Chilly-Mazarin, France (J.M.G.);and Chemistry, Sanofi R&D, Chilly-Mazarin, France (F.P., J.M.A., J.P.B.)
| | - Jean-Michel Altenburger
- Cardiovascular and Metabolism Therapeutic Area, Sanofi R&D, Chilly-Mazarin, France (M.L.O., V.B., M.P., F.B., P.S., P.B., B.P., P.J.); Preclinical Safety, Sanofi R&D, Chilly-Mazarin, France (J.M.G.);and Chemistry, Sanofi R&D, Chilly-Mazarin, France (F.P., J.M.A., J.P.B.)
| | - Jean-Pierre Bidouard
- Cardiovascular and Metabolism Therapeutic Area, Sanofi R&D, Chilly-Mazarin, France (M.L.O., V.B., M.P., F.B., P.S., P.B., B.P., P.J.); Preclinical Safety, Sanofi R&D, Chilly-Mazarin, France (J.M.G.);and Chemistry, Sanofi R&D, Chilly-Mazarin, France (F.P., J.M.A., J.P.B.)
| | - Philip Janiak
- Cardiovascular and Metabolism Therapeutic Area, Sanofi R&D, Chilly-Mazarin, France (M.L.O., V.B., M.P., F.B., P.S., P.B., B.P., P.J.); Preclinical Safety, Sanofi R&D, Chilly-Mazarin, France (J.M.G.);and Chemistry, Sanofi R&D, Chilly-Mazarin, France (F.P., J.M.A., J.P.B.)
| |
Collapse
|
6
|
Niclosamide reduces glucagon sensitivity via hepatic PKA inhibition in obese mice: Implications for glucose metabolism improvements in type 2 diabetes. Sci Rep 2017; 7:40159. [PMID: 28054648 PMCID: PMC5214666 DOI: 10.1038/srep40159] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 12/02/2016] [Indexed: 02/06/2023] Open
Abstract
Type 2 diabetes (T2D) is a global pandemic. Currently, the drugs used to treat T2D improve hyperglycemic symptom of the disease but the underlying mechanism causing the high blood glucose levels have not been fully resolved. Recently published data showed that salt form of niclosamide improved glucose metabolism in high fat fed mice via mitochondrial uncoupling. However, based on our previous work we hypothesised that niclosamide might also improve glucose metabolism via inhibition of the glucagon signalling in liver in vivo. In this study, mice were fed either a chow or high fat diet containing two different formulations of niclosamide (niclosamide ethanolamine salt - NENS or niclosamide - Nic) for 10 weeks. We identified both forms of niclosamide significantly improved whole body glucose metabolism without altering total body weight or body composition, energy expenditure or insulin secretion or sensitivity. Our study provides evidence that inhibition of the glucagon signalling pathway contributes to the beneficial effects of niclosamide (NENS or Nic) on whole body glucose metabolism. In conclusion, our results suggest that the niclosamide could be a useful adjunctive therapeutic strategy to treat T2D, as hepatic glucose output is elevated in people with T2D and current drugs do not redress this adequately.
Collapse
|
7
|
Sandoval DA, D'Alessio DA. Physiology of proglucagon peptides: role of glucagon and GLP-1 in health and disease. Physiol Rev 2015; 95:513-48. [PMID: 25834231 DOI: 10.1152/physrev.00013.2014] [Citation(s) in RCA: 286] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The preproglucagon gene (Gcg) is expressed by specific enteroendocrine cells (L-cells) of the intestinal mucosa, pancreatic islet α-cells, and a discrete set of neurons within the nucleus of the solitary tract. Gcg encodes multiple peptides including glucagon, glucagon-like peptide-1, glucagon-like peptide-2, oxyntomodulin, and glicentin. Of these, glucagon and GLP-1 have received the most attention because of important roles in glucose metabolism, involvement in diabetes and other disorders, and application to therapeutics. The generally accepted model is that GLP-1 improves glucose homeostasis indirectly via stimulation of nutrient-induced insulin release and by reducing glucagon secretion. Yet the body of literature surrounding GLP-1 physiology reveals an incompletely understood and complex system that includes peripheral and central GLP-1 actions to regulate energy and glucose homeostasis. On the other hand, glucagon is established principally as a counterregulatory hormone, increasing in response to physiological challenges that threaten adequate blood glucose levels and driving glucose production to restore euglycemia. However, there also exists a potential role for glucagon in regulating energy expenditure that has recently been suggested in pharmacological studies. It is also becoming apparent that there is cross-talk between the proglucagon derived-peptides, e.g., GLP-1 inhibits glucagon secretion, and some additive or synergistic pharmacological interaction between GLP-1 and glucagon, e.g., dual glucagon/GLP-1 agonists cause more weight loss than single agonists. In this review, we discuss the physiological functions of both glucagon and GLP-1 by comparing and contrasting how these peptides function, variably in concert and opposition, to regulate glucose and energy homeostasis.
Collapse
Affiliation(s)
- Darleen A Sandoval
- Division of Endocrinology and Metabolism, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - David A D'Alessio
- Division of Endocrinology and Metabolism, University of Cincinnati College of Medicine, Cincinnati, Ohio
| |
Collapse
|
8
|
Koh DS, Cho JH, Chen L. Paracrine interactions within islets of Langerhans. J Mol Neurosci 2012; 48:429-40. [PMID: 22528452 DOI: 10.1007/s12031-012-9752-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 03/12/2012] [Indexed: 01/05/2023]
Abstract
Glucose supply fluctuates between meal and fasting periods and its consumption by the body varies greatly depending on bodily metabolism. Pancreatic islets of Langerhans secrete various endocrine hormones including insulin and glucagon to keep blood glucose level relatively constant. Additionally, islet hormones regulate activity of neighboring cells as local autocrine or paracrine modulators. Moreover, islet cells release neurotransmitters such as glutamate and γ-aminobutyric acid (GABA) to gain more precise regulation of hormones release kinetics. Excitatory glutamate is co-released with glucagon from α-cells and activates glutamate receptors in the neighboring cells. GABA released from β-cells was shown to inhibit α-cells but to activate β-cells by acting GABA(A) receptors. This review summarizes the recent progress in understanding the paracrine/autocrine interactions in islets.
Collapse
Affiliation(s)
- Duk-Su Koh
- University of Washington, Seattle, WA, USA.
| | | | | |
Collapse
|
9
|
Tsoukas P, Kane E, Giaid A. Potential Clinical Implications of the Urotensin II Receptor Antagonists. Front Pharmacol 2011; 2:38. [PMID: 21811463 PMCID: PMC3143724 DOI: 10.3389/fphar.2011.00038] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Accepted: 07/05/2011] [Indexed: 12/20/2022] Open
Abstract
Urotensin II (UII) binds to its receptor, UT, playing an important role in the heart, kidneys, pancreas, adrenal gland, and central nervous system. In the vasculature, it acts as a potent endothelium-independent vasoconstrictor and endothelium-dependent vasodilator. In disease states, however, this constriction–dilation equilibrium is disrupted. There is an upregulation of the UII system in heart disease, metabolic syndrome, and kidney failure. The increase in UII release and UT expression suggest that UII system may be implicated in the pathology and pathogenesis of these diseases by causing an increase in acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT-1) activity leading to smooth muscle cell proliferation and foam cell infiltration, insulin resistance (DMII), as well as inflammation, high blood pressure, and plaque formation. Recently, UT antagonists such as SB-611812, palosuran, and most recently a piperazino-isoindolinone based antagonist have been developed in the hope of better understanding the UII system and treating its associated diseases.
Collapse
Affiliation(s)
- Philip Tsoukas
- Division of Cardiology, Department of Medicine, Montreal General Hospital, McGill University Health Center Montreal, QC, Canada
| | | | | |
Collapse
|
10
|
Tudurí E, Marroquí L, Soriano S, Ropero AB, Batista TM, Piquer S, López-Boado MA, Carneiro EM, Gomis R, Nadal A, Quesada I. Inhibitory effects of leptin on pancreatic alpha-cell function. Diabetes 2009; 58:1616-24. [PMID: 19401420 PMCID: PMC2699864 DOI: 10.2337/db08-1787] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Leptin released from adipocytes plays a key role in the control of food intake, energy balance, and glucose homeostasis. In addition to its central action, leptin directly affects pancreatic beta-cells, inhibiting insulin secretion, and, thus, modulating glucose homeostasis. However, despite the importance of glucagon secretion in glucose homeostasis, the role of leptin in alpha-cell function has not been studied in detail. In the present study, we have investigated this functional interaction. RESEARCH DESIGN AND METHODS The presence of leptin receptors (ObR) was demonstrated by RT-PCR analysis, Western blot, and immunocytochemistry. Electrical activity was analyzed by patch-clamp and Ca(2+) signals by confocal microscopy. Exocytosis and glucagon secretion were assessed using fluorescence methods and radioimmunoassay, respectively. RESULTS The expression of several ObR isoforms (a-e) was detected in glucagon-secreting alphaTC1-9 cells. ObRb, the main isoform involved in leptin signaling, was identified at the protein level in alphaTC1-9 cells as well as in mouse and human alpha-cells. The application of leptin (6.25 nmol/l) hyperpolarized the alpha-cell membrane potential, suppressing the electrical activity induced by 0.5 mmol/l glucose. Additionally, leptin inhibited Ca(2+) signaling in alphaTC1-9 cells and in mouse and human alpha-cells within intact islets. A similar result occurred with 0.625 nmol/l leptin. These effects were accompanied by a decrease in glucagon secretion from mouse islets and were counteracted by the phosphatidylinositol 3-kinase inhibitor, wortmannin, suggesting the involvement of this pathway in leptin action. CONCLUSIONS These results demonstrate that leptin inhibits alpha-cell function, and, thus, these cells are involved in the adipoinsular communication.
Collapse
Affiliation(s)
- Eva Tudurí
- Instituto de Bioingeniería, Universidad Miguel Hernandez, Elche, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Barcelona, Spain
| | - Laura Marroquí
- Instituto de Bioingeniería, Universidad Miguel Hernandez, Elche, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Barcelona, Spain
| | - Sergi Soriano
- Instituto de Bioingeniería, Universidad Miguel Hernandez, Elche, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Barcelona, Spain
| | - Ana B. Ropero
- Instituto de Bioingeniería, Universidad Miguel Hernandez, Elche, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Barcelona, Spain
| | - Thiago M. Batista
- Instituto Nacional de Pesquisa em Obesidade e Diabetes, Departmento de Anatomia, Biologia Celulare Fisiologia, Institute of Biology, Unicamp, Campinas, Brazil
| | - Sandra Piquer
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Barcelona, Spain
- Endocrinology and Diabetes Unit, Laboratory of Diabetes and Obesity, IDIBAPS-Fundació Clínic, Hospital Clínic, Barcelona, Spain
| | | | - Everardo M. Carneiro
- Instituto Nacional de Pesquisa em Obesidade e Diabetes, Departmento de Anatomia, Biologia Celulare Fisiologia, Institute of Biology, Unicamp, Campinas, Brazil
| | - Ramón Gomis
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Barcelona, Spain
- Endocrinology and Diabetes Unit, Laboratory of Diabetes and Obesity, IDIBAPS-Fundació Clínic, Hospital Clínic, Barcelona, Spain
| | - Angel Nadal
- Instituto de Bioingeniería, Universidad Miguel Hernandez, Elche, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Barcelona, Spain
| | - Ivan Quesada
- Instituto de Bioingeniería, Universidad Miguel Hernandez, Elche, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Barcelona, Spain
- Corresponding author: Ivan Quesada,
| |
Collapse
|
11
|
Van Op den Bosch J, Adriaensen D, Van Nassauw L, Timmermans JP. The role(s) of somatostatin, structurally related peptides and somatostatin receptors in the gastrointestinal tract: a review. ACTA ACUST UNITED AC 2009; 156:1-8. [PMID: 19362110 DOI: 10.1016/j.regpep.2009.04.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Accepted: 04/05/2009] [Indexed: 12/19/2022]
Abstract
Extensive functional and morphological research has demonstrated the pivotal role of somatostatin (SOM) in the regulation of a wide variety of gastrointestinal activities. In addition to its profound inhibitory effects on gastrointestinal motility and exocrine and endocrine secretion processes along the entire gastrointestinal tract, SOM modulates several organ-specific activities. In contrast to these well-known SOM-dependent effects, knowledge on the SOM receptors (SSTR) involved in these effects is much less conclusive. Experimental data on the identities of the SSTRs, although species- and tissue-dependent, point towards the involvement of multiple receptor subtypes in the vast majority of gastrointestinal SOM-mediated effects. Recent evidence demonstrating the role of SOM in intestinal pathologies has extended the interest of gastrointestinal research in this peptide even further. More specifically, SOM is supposed to suppress intestinal inflammatory responses by interfering with the extensive bidirectional communication between mucosal mast cells and neurons. This way, SOM not only acts as a powerful inhibitor of the inflammatory cascade at the site of inflammation, but exerts a profound antinociceptive effect through the modulation of extrinsic afferent nerve fibres. The combination of these physiological and pathological activities opens up new opportunities to explore the potential of stable SOM analogues in the treatment of GI inflammatory pathologies.
Collapse
Affiliation(s)
- Joeri Van Op den Bosch
- Laboratory of Cell Biology & Histology, Department of Veterinary Sciences, University of Antwerp, Antwerp, Belgium
| | | | | | | |
Collapse
|
12
|
Palosuran inhibits binding to primate UT receptors in cell membranes but demonstrates differential activity in intact cells and vascular tissues. Br J Pharmacol 2008; 155:374-86. [PMID: 18587423 DOI: 10.1038/bjp.2008.266] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
BACKGROUND AND PURPOSE The recent development of the UT ligand palosuran (1-[2-(4-benzyl-4-hydroxy-piperidin-1-yl)-ethyl]-3-(2-methyl-quinolin-4-yl)-urea sulphate salt) has led to the proposition that urotensin-II (U-II) plays a significant pathological role in acute and chronic renal injury in the rat. EXPERIMENTAL APPROACH In the present study, the pharmacological properties of palosuran were investigated further using a series of radioligand binding and functional bioassays. KEY RESULTS Palosuran functioned as a 'primate-selective' UT ligand in recombinant cell membranes (monkey and human UT K(i) values of 4 +/- 1 and 5 +/- 1 nM), lacking appreciable affinity at other mammalian UT isoforms (rodent and feline K(i) values >1 microM). Paradoxically, however, palosuran lost significant (10- to 54-fold) affinity for native and recombinant human UT when radioligand binding was performed in intact cells (K(i) values of 50 +/- 3 and 276 +/- 67 nM). In accordance, palosuran also exhibited diminished activity in hUT (human urotensin-II receptor)-CHO (Chinese hamster ovary) cells (IC50 323 +/- 67 nM) and isolated arteries (K(b)>10 microM in rat aorta; K(b)>8.5 microM in cat arteries; K(b)>1.6 microM in monkey arteries; K(b) 2.2 +/- 0.6 microM in hUT transgenic mouse aorta). Relative to recombinant binding K(i) values, palosuran was subjected to a 392- to 690-fold reduction in functional activity in monkey isolated arteries. Such phenomena were peculiar to palosuran and were not apparent with an alternative chemotype, SB-657510 (2-bromo-N-[4-chloro-3-((R)-1-methyl-pyrrolidin-3-yloxy)-phenyl]-4,5-dimethoxybenzenesulphonamide HCl). CONCLUSIONS AND IMPLICATIONS Collectively, such findings suggest that caution should be taken when interpreting data generated using palosuran. The loss of UT affinity/activity observed in intact cells and tissues cf. membranes offers a potential explanation for the disappointing clinical efficacy reported with palosuran in diabetic nephropathy patients. As such, the (patho)physiological significance of U-II in diabetic renal dysfunction remains uncertain.
Collapse
|
13
|
Zeyda T, Hochgeschwender U. Null mutant mouse models of somatostatin and cortistatin, and their receptors. Mol Cell Endocrinol 2008; 286:18-25. [PMID: 18206294 DOI: 10.1016/j.mce.2007.11.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 08/25/2007] [Accepted: 11/28/2007] [Indexed: 01/08/2023]
Abstract
Somatostatin (somatotropin release inhibitory factor, SRIF) and the related cortistatin (CST) are multifunctional peptide molecules attributed with neurohormone, neurotransmitter/modulator, and autocrine/paracrine actions. The physiological responses of SRIF and CST are mediated by five widely distributed G protein-coupled receptors (sst1-5) which have been implicated in regulating numerous biological processes. Much of the information on the effects of somatostatin has been gained through pharmacological studies with analogs and antagonists. The possibility of targeted mutagenesis in the mouse has resulted, over the last 10 years, in the generation of mouse models which genetically lack somatostatin ligands or receptors. We will review here the mouse models generated, the studies undertaken with them, and what has been learned so far.
Collapse
Affiliation(s)
- T Zeyda
- John A. Burns School of Medicine, Honolulu, HI, USA
| | | |
Collapse
|
14
|
Strowski MZ, Blake AD. Function and expression of somatostatin receptors of the endocrine pancreas. Mol Cell Endocrinol 2008; 286:169-79. [PMID: 18375050 DOI: 10.1016/j.mce.2008.02.007] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Revised: 02/03/2008] [Accepted: 02/12/2008] [Indexed: 01/26/2023]
Abstract
Somatostatin (SST) regulates multiple biological processes via five genetically distinct, G-protein coupled receptors. Clinical interest in therapy for neuroendocrine and metabolic disorders has resulted in the development of new tools for exploring the function of somatostatin receptors (SSTRs). The development of highly SSTR-selective agonists and antagonists, animal models with the deletion of individual SSTRs, as well as SSTR-specific antibodies have all been utilized in delineating SSTR functions. In the pancreas, SST is a potent regulator of insulin and glucagon secretion. Indeed, the inappropriate regulation of pancreatic A- and B-cell function in metabolic diseases provides an impetus to evaluate the SSTRs as therapeutic targets. By combining the results obtained from molecular biology, pharmacology and immunochemical studies the current review provides a summary of important recent developments which have extended our knowledge of SST actions in the endocrine pancreas.
Collapse
Affiliation(s)
- Mathias Z Strowski
- Medizinische Klinik mit Schwerpunkt Hepatologie und Gastroenterologie, Charité-Universitätsmedizin Berlin, Berlin, Germany.
| | | |
Collapse
|
15
|
Göncz E, Strowski MZ, Grötzinger C, Nowak KW, Kaczmarek P, Sassek M, Mergler S, El-Zayat BF, Theodoropoulou M, Stalla GK, Wiedenmann B, Plöckinger U. Orexin-A inhibits glucagon secretion and gene expression through a Foxo1-dependent pathway. Endocrinology 2008; 149:1618-26. [PMID: 18162514 DOI: 10.1210/en.2007-1257] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Orexin-A (OXA) regulates food intake and energy homeostasis. It increases insulin secretion in vivo and in vitro, although controversial effects of OXA on plasma glucagon are reported. We characterized the effects of OXA on glucagon secretion and identify intracellular target molecules in glucagon-producing cells. Glucagon secretion from in situ perfused rat pancreas, isolated rat pancreatic islets, and clonal pancreatic A-cells (InR1-G9) were measured by RIA. The expression of orexin receptor 1 (OXR1) was detected by Western blot and immunofluorescence. The effects of OXA on cAMP, adenylate-cyclase-kinase (AKT), phosphoinositide-dependent kinase (PDK)-1, forkhead box O-1 (Foxo1), and cAMP response element-binding protein were measured by ELISA and Western blot. Intracellular calcium (Ca(2+)(i)) concentration was detected by fura-2and glucagon expression by real-time PCR. Foxo1 was silenced in InR1-G9 cells by transfecting cells with short interfering RNA. OXR1 was expressed on pancreatic A and InR1-G9 cells. OXA reduced glucagon secretion from perfused rat pancreas, isolated rat pancreatic islets, and InR1-G9 cells. OXA inhibited proglucagon gene expression via the phosphatidylinositol 3-kinase-dependent pathway. OXA decreased cAMP and Ca(2+)(i) concentration and increased AKT, PDK-1, and Foxo1 phosphorylation. Silencing of Foxo1 caused a reversal of the inhibitory effect of OXA on proglucagon gene expression. Our study provides the first in vitro evidence for the interaction of OXA with pancreatic A cells. OXA inhibits glucagon secretion and reduces intracellular cAMP and Ca(2+)(i) concentration. OXA increases AKT/PDK-1 phosphorylation and inhibits proglucagon expression via phosphatidylinositol 3-kinase- and Foxo-1-dependent pathways. As a physiological inhibitor of glucagon secretion, OXA may have a therapeutic potential to reduce hyperglucagonemia in type 2 diabetes.
Collapse
Affiliation(s)
- Eva Göncz
- Endokrinologie, Diabetes, und Stoffwechsel Medizinische Klinik mit Schwerpunkt Hepatologie und Gastroenterologie, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Singh V, Grötzinger C, Nowak KW, Zacharias S, Göncz E, Pless G, Sauer IM, Eichhorn I, Pfeiffer-Guglielmi B, Hamprecht B, Wiedenmann B, Plöckinger U, Strowski MZ. Somatostatin receptor subtype-2-deficient mice with diet-induced obesity have hyperglycemia, nonfasting hyperglucagonemia, and decreased hepatic glycogen deposition. Endocrinology 2007; 148:3887-99. [PMID: 17525126 DOI: 10.1210/en.2006-1659] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Hypersecretion of glucagon contributes to abnormally increased hepatic glucose output in type 2 diabetes. Somatostatin (SST) inhibits murine glucagon secretion from isolated pancreatic islets via somatostatin receptor subtype-2 (sst2). Here, we characterize the role of sst2 in controlling glucose homeostasis in mice with diet-induced obesity. Sst2-deficient (sst2(-/-)) and control mice were fed high-fat diet for 14 wk, and the parameters of glucose homeostasis were monitored. Hepatic glycogen and lipid contents were quantified enzymatically and visualized histomorphologically. Enzymes regulating glycogen and lipid synthesis and breakdown were measured by real-time PCR and/or Western blot. Gluconeogenesis and glycogenolysis were determined from isolated primary hepatocytes and glucagon or insulin secretion from isolated pancreatic islets. Nonfasting glucose, glucagon, and fasting nonesterified fatty acids of sst2(-/-) mice were increased. Inhibition of glucagon secretion from sst2-deficient pancreatic islets by glucose or somatostatin was impaired. Insulin less potently reduced blood glucose concentration in sst2-deficient mice as compared with wild-type mice. Sst2-deficient mice had decreased nonfasting hepatic glycogen and lipid content. The activity/expression of enzymes controlling hepatic glycogen synthesis of sst2(-/-) mice was decreased, whereas enzymes facilitating glycogenolysis and lipolysis were increased. Somatostatin and an sst2-selective agonist decreased glucagon-induced glycogenolysis, without influencing de novo glucose production using cultured primary hepatocytes. This study demonstrates that ablation of sst2 leads to hyperglucagonemia. Increased glucagon concentration is associated with impaired glucose control in sst2(-/-) mice, resulting from decreased hepatic glucose storage, increased glycogen breakdown, and reduced lipid accumulation. Sst2 may constitute a therapeutic target to lower hyperglucagonemia in type 2 diabetes.
Collapse
Affiliation(s)
- Vandana Singh
- Medizinische Klinik mit Schwerpunkt Hepatologie und Gastroenterologie, Interdisziplinäres Stoffwechsel-Centrum: Endokrinologie, Diabetes und Stoffwechsel, Charité-Universitätsmedizin, 13353 Berlin, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Gromada J, Franklin I, Wollheim CB. Alpha-cells of the endocrine pancreas: 35 years of research but the enigma remains. Endocr Rev 2007; 28:84-116. [PMID: 17261637 DOI: 10.1210/er.2006-0007] [Citation(s) in RCA: 419] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Glucagon, a hormone secreted from the alpha-cells of the endocrine pancreas, is critical for blood glucose homeostasis. It is the major counterpart to insulin and is released during hypoglycemia to induce hepatic glucose output. The control of glucagon secretion is multifactorial and involves direct effects of nutrients on alpha-cell stimulus-secretion coupling as well as paracrine regulation by insulin and zinc and other factors secreted from neighboring beta- and delta-cells within the islet of Langerhans. Glucagon secretion is also regulated by circulating hormones and the autonomic nervous system. In this review, we describe the components of the alpha-cell stimulus secretion coupling and how nutrient metabolism in the alpha-cell leads to changes in glucagon secretion. The islet cell composition and organization are described in different species and serve as a basis for understanding how the numerous paracrine, hormonal, and nervous signals fine-tune glucagon secretion under different physiological conditions. We also highlight the pathophysiology of the alpha-cell and how hyperglucagonemia represents an important component of the metabolic abnormalities associated with diabetes mellitus. Therapeutic inhibition of glucagon action in patients with type 2 diabetes remains an exciting prospect.
Collapse
Affiliation(s)
- Jesper Gromada
- Novartis Institutes for BioMedical Research, 100 Technology Square, Cambridge, Massachusetts 02139, USA.
| | | | | |
Collapse
|