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Slika H, Mansour H, Nasser SA, Shaito A, Kobeissy F, Orekhov AN, Pintus G, Eid AH. Epac as a tractable therapeutic target. Eur J Pharmacol 2023; 945:175645. [PMID: 36894048 DOI: 10.1016/j.ejphar.2023.175645] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 02/26/2023] [Accepted: 03/06/2023] [Indexed: 03/09/2023]
Abstract
In 1957, cyclic adenosine monophosphate (cAMP) was identified as the first secondary messenger, and the first signaling cascade discovered was the cAMP-protein kinase A (PKA) pathway. Since then, cAMP has received increasing attention given its multitude of actions. Not long ago, a new cAMP effector named exchange protein directly activated by cAMP (Epac) emerged as a critical mediator of cAMP's actions. Epac mediates a plethora of pathophysiologic processes and contributes to the pathogenesis of several diseases such as cancer, cardiovascular disease, diabetes, lung fibrosis, neurological disorders, and others. These findings strongly underscore the potential of Epac as a tractable therapeutic target. In this context, Epac modulators seem to possess unique characteristics and advantages and hold the promise of providing more efficacious treatments for a wide array of diseases. This paper provides an in-depth dissection and analysis of Epac structure, distribution, subcellular compartmentalization, and signaling mechanisms. We elaborate on how these characteristics can be utilized to design specific, efficient, and safe Epac agonists and antagonists that can be incorporated into future pharmacotherapeutics. In addition, we provide a detailed portfolio for specific Epac modulators highlighting their discovery, advantages, potential concerns, and utilization in the context of clinical disease entities.
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Affiliation(s)
- Hasan Slika
- Department of Pharmacology and Toxicology, American University of Beirut, Beirut, P.O. Box 11-0236, Lebanon.
| | - Hadi Mansour
- Department of Pharmacology and Toxicology, American University of Beirut, Beirut, P.O. Box 11-0236, Lebanon.
| | | | - Abdullah Shaito
- Biomedical Research Center, Qatar University, Doha, P.O. Box: 2713, Qatar.
| | - Firas Kobeissy
- Department of Neurobiology and Neuroscience, Morehouse School of Medicine, Atlanta, Georgia, USA.
| | - Alexander N Orekhov
- Laboratory of Cellular and Molecular Pathology of Cardiovascular System, Institute of Human Morphology, 3 Tsyurupa Street, Moscow, 117418, Russia; Laboratory of Angiopathology, Institute of General Pathology and Pathophysiology, 8 Baltiiskaya Street, Moscow, 125315, Russia; Institute for Atherosclerosis Research, Skolkovo Innovative Center, Osennyaya Street 4-1-207, Moscow, 121609, Russia.
| | - Gianfranco Pintus
- Department of Biomedical Sciences, University of Sassari, 07100, Sassari, Italy.
| | - Ali H Eid
- Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, Doha, P.O. Box 2713, Qatar.
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Assessing the Effect of Incretin Hormones and Other Insulin Secretagogues on Pancreatic Beta-Cell Function: Review on Mathematical Modelling Approaches. Biomedicines 2022; 10:biomedicines10051060. [PMID: 35625797 PMCID: PMC9138583 DOI: 10.3390/biomedicines10051060] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 04/25/2022] [Accepted: 04/28/2022] [Indexed: 11/16/2022] Open
Abstract
Mathematical modelling in glucose metabolism has proven very useful for different reasons. Several models have allowed deeper understanding of the relevant physiological and pathophysiological aspects and promoted new experimental activity to reach increased knowledge of the biological and physiological systems of interest. Glucose metabolism modelling has also proven useful to identify the parameters with specific physiological meaning in single individuals, this being relevant for clinical applications in terms of precision diagnostics or therapy. Among those model-based physiological parameters, an important role resides in those for the assessment of different functional aspects of the pancreatic beta cell. This study focuses on the mathematical models of incretin hormones and other endogenous substances with known effects on insulin secretion and beta-cell function, mainly amino acids, non-esterified fatty acids, and glucagon. We found that there is a relatively large number of mathematical models for the effects on the beta cells of incretin hormones, both at the cellular/organ level or at the higher, whole-body level. In contrast, very few models were identified for the assessment of the effect of other insulin secretagogues. Given the opportunities offered by mathematical modelling, we believe that novel models in the investigated field are certainly advisable.
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Mayendraraj A, Rosenkilde MM, Gasbjerg LS. GLP-1 and GIP receptor signaling in beta cells - A review of receptor interactions and co-stimulation. Peptides 2022; 151:170749. [PMID: 35065096 DOI: 10.1016/j.peptides.2022.170749] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 01/14/2022] [Accepted: 01/17/2022] [Indexed: 02/07/2023]
Abstract
Glucagon-like peptide 1 receptor (GLP-1R) and glucose-dependent insulinotropic polypeptide receptor (GIPR) are two class B1 G protein-coupled receptors, which are stimulated by the gastrointestinal hormones GLP-1 and GIP, respectively. In the pancreatic beta cells, activation of both receptors lead to increased cyclic adenosine monophosphate (cAMP) and glucose-dependent insulin secretion. Marketed GLP-1R agonists such as dulaglutide, liraglutide, exenatide and semaglutide constitute an expanding drug class with beneficial effects for persons suffering from type 2 diabetes and/or obesity. In recent years another drug class, the GLP-1R-GIPR co-agonists, has emerged. Especially the peptide-based, co-agonist tirzepatide is a promising candidate for a better treatment of type 2 diabetes by improving glycemic control and weight reduction. The mechanism of action for tirzepatide include biased signaling of the GLP-1R as well as potent GIPR signaling. Since the implications of co-targeting these closely related receptors concomitantly are challenging to study in vivo, the pharmacodynamic mechanisms and downstream signaling pathways of the GLP-1R-GIPR co-agonists in general, are not fully elucidated. In this review, we present the individual signaling pathways for GLP-1R and GIPR in the pancreatic beta cell with a focus on the shared signaling pathways of the two receptors and interpret the implications of GLP-1R-GIPR co-activation in the light of recent co-activating therapeutic compounds.
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Affiliation(s)
- Ashok Mayendraraj
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mette M Rosenkilde
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lærke S Gasbjerg
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
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Diz-Chaves Y, Toba L, Fandiño J, González-Matías LC, Garcia-Segura LM, Mallo F. The GLP-1 analog, liraglutide prevents the increase of proinflammatory mediators in the hippocampus of male rat pups submitted to maternal perinatal food restriction. J Neuroinflammation 2018; 15:337. [PMID: 30518432 PMCID: PMC6282252 DOI: 10.1186/s12974-018-1370-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 11/18/2018] [Indexed: 12/17/2022] Open
Abstract
Background Perinatal maternal malnutrition is related to altered growth of tissues and organs. The nervous system development is very sensitive to environmental insults, being the hippocampus a vulnerable structure, in which altered number of neurons and granular cells has been observed. Moreover, glial cells are also affected, and increased expression of proinflammatory mediators has been observed. We studied the effect of Glucagon-like peptide-1 receptor (GLP-1R) agonists, liraglutide, which have very potent metabolic and neuroprotective effects, in order to ameliorate/prevent the glial alterations present in the hippocampus of the pups from mothers with food restriction during pregnancy and lactation (maternal perinatal food restriction—MPFR). Methods Pregnant Sprague-Dawley rats were randomly assigned to 50% food restriction (FR; n = 12) or ad libitum controls (CT, n = 12) groups at day of pregnancy 12 (GD12). From GD14 to parturition, pregnant FR and CT rats were treated with liraglutide (100 μg/kg) or vehicle. At postnatal day 21 and before weaning, 48 males and 45 females (CT and MPFR) were sacrificed. mRNA expression levels of interleukin-1β (IL1β), interleukin-6 (IL-6), nuclear factor-κβ, major histocompatibility complex-II (MHCII), interleukin 10 (IL10), arginase 1 (Arg1), and transforming growth factor (TGFβ) were assessed in the hippocampus by quantitative real-time polymerase chain reaction. Iba1 and GFAP-immunoreactivity were assessed by immunocytochemistry. Results The mRNA expression IL1β, IL6, NF-κB, and MHCII increased in the hippocampus of male but not in female pups from MPFR. In addition, there was an increase in the percentage of GFAP and Iba1-immupositive cells in the dentate gyrus compared to controls, indicating an inflammatory response in the brain. On the other hand, liraglutide treatment prevented the neuroinflammatory process, promoting the production of anti-inflammatory molecules such as IL10, TGFβ, and arginase 1, and decreasing the number and reactivity of microglial cells and astrocytes in the hippocampus of male pups. Conclusion Therefore, the GLP-1 analog, liraglutide, emerges as neuroprotective drug that minimizes the harmful effects of maternal food restriction, decreasing neuroinflammation in the hippocampus in a very early stage.
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Affiliation(s)
- Y Diz-Chaves
- Laboratory of Endocrinology, Biomedical Research Center (CINBIO), University of Vigo, Campus As Lagoas-Marcosende, E-36310, Vigo (Pontevedra), Spain.
| | - L Toba
- Laboratory of Endocrinology, Biomedical Research Center (CINBIO), University of Vigo, Campus As Lagoas-Marcosende, E-36310, Vigo (Pontevedra), Spain
| | - J Fandiño
- Laboratory of Endocrinology, Biomedical Research Center (CINBIO), University of Vigo, Campus As Lagoas-Marcosende, E-36310, Vigo (Pontevedra), Spain
| | - L C González-Matías
- Laboratory of Endocrinology, Biomedical Research Center (CINBIO), University of Vigo, Campus As Lagoas-Marcosende, E-36310, Vigo (Pontevedra), Spain
| | - L M Garcia-Segura
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avenida Doctor Arce 37, E-28002, Madrid, Spain.,Centro de Investigación en Red Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - F Mallo
- Laboratory of Endocrinology, Biomedical Research Center (CINBIO), University of Vigo, Campus As Lagoas-Marcosende, E-36310, Vigo (Pontevedra), Spain
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Kimura T, Obata A, Shimoda M, Okauchi S, Kanda-Kimura Y, Nogami Y, Moriuchi S, Hirukawa H, Kohara K, Nakanishi S, Mune T, Kaku K, Kaneto H. Protective effects of the SGLT2 inhibitor luseogliflozin on pancreatic β-cells in db/db mice: The earlier and longer, the better. Diabetes Obes Metab 2018; 20:2442-2457. [PMID: 29873444 DOI: 10.1111/dom.13400] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 05/14/2018] [Accepted: 05/25/2018] [Indexed: 02/06/2023]
Abstract
AIMS We compared the protective effects of sodium glucose co-transporter (SGLT) 2 inhibitor luseogliflozin on pancreatic β-cells between early and advanced stages of diabetes and between short- and long-term use. MATERIALS AND METHODS Diabetic db/db mice were treated with luseogliflozin for 2 weeks in an early stage of diabetes (7-9 weeks of age) and an advanced stage of diabetes (16-18 weeks) for a longer period of time (7-18 weeks). We performed various morphological analyses of pancreatic islets and examined gene expression profiles in islets after such treatment. RESULTS In diabetic db/db mice, insulin biosynthesis and secretion were markedly increased by luseogliflozin in an early stage of diabetes but not in an advanced stage. In addition, β-cell mass was preserved by luseogliflozin only in an early stage. Furthermore, when db/db mice were treated with luseogliflozin for a longer period of time, starting from an early stage, β-cell function and mass were markedly preserved even after a longer period of time compared to untreated db/db mice. CONCLUSION Luseogliflozin exerts more protective effects in an early stage of diabetes compared to an advanced stage, and longer-term use of luseogliflozin exerts more beneficial effects on pancreatic β-cells compared to short-term use.
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Affiliation(s)
- Tomohiko Kimura
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Okayama, Japan
| | - Atsushi Obata
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Okayama, Japan
| | - Masashi Shimoda
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Okayama, Japan
| | - Seizo Okauchi
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Okayama, Japan
| | - Yukiko Kanda-Kimura
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Okayama, Japan
| | - Yuka Nogami
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Okayama, Japan
| | - Saeko Moriuchi
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Okayama, Japan
| | - Hidenori Hirukawa
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Okayama, Japan
| | - Kenji Kohara
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Okayama, Japan
| | - Shuhei Nakanishi
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Okayama, Japan
| | - Tomoatsu Mune
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Okayama, Japan
| | - Kohei Kaku
- Department of General Internal Medicine 1, Kawasaki Hospital, Kawasaki Medical School, Okayama, Japan
| | - Hideaki Kaneto
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Okayama, Japan
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Frühbeck G, Gómez-Ambrosi J, Rodríguez A, Ramírez B, Valentí V, Moncada R, Becerril S, Unamuno X, Silva C, Salvador J, Catalán V. Novel protective role of kallistatin in obesity by limiting adipose tissue low grade inflammation and oxidative stress. Metabolism 2018; 87:123-135. [PMID: 29679615 DOI: 10.1016/j.metabol.2018.04.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 03/19/2018] [Accepted: 04/09/2018] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Kallistatin plays an important role in the inhibition of inflammation, oxidative stress, fibrosis and angiogenesis. We aimed to determine the impact of kallistatin on obesity and its associated metabolic alterations as well as its role in adipocyte inflammation and oxidative stress. METHODS Samples obtained from 95 subjects were used in a case-control study. Circulating concentrations and expression levels of kallistatin as well as key inflammation, oxidative stress and extracellular matrix remodelling-related genes were analyzed. Circulating kallistatin concentrations were measured before and after weight loss achieved by Roux-en-Y gastric bypass (RYGB). The impact of kallistatin on lipopolysaccharide (LPS)- and tumour necrosis factor (TNF)-α-mediated inflammatory as well as oxidative stress signalling pathways was evaluated. RESULTS We show that the reduced (P < 0.00001) circulating levels of kallistatin in obese patients increased (P < 0.00001) after RYGB. Moreover, gene expression levels of SERPINA4, the gene coding for kallistatin, were downregulated (P < 0.01) in the liver from obese subjects with non-alcoholic fatty liver disease. Additionally, we revealed that kallistatin reduced (P < 0.05) the expression of inflammation-related genes (CCL2, IL1B, IL6, IL8, TNFA, TGFB) and, conversely, upregulated (P < 0.05) mRNA levels of ADIPOQ and KLF4 in human adipocytes in culture. Kallistatin inhibited (P < 0.05) LPS- and TNF-α-induced inflammation in human adipocytes via downregulating the expression and secretion of key inflammatory markers. Furthermore, kallistatin also blocked (P < 0.05) TNF-α-mediated lipid peroxidation as well as NOX2 and HIF1A expression while stimulating (P < 0.05) the expression of SIRT1 and FOXO1. CONCLUSIONS These findings provide, for the first time, evidence of a novel role of kallistatin in obesity and its associated comorbidities by limiting adipose tissue inflammation and oxidative stress.
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Affiliation(s)
- Gema Frühbeck
- Metabolic Research Laboratory, Clínica Universidad de Navarra, Pamplona, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Pamplona, Spain; Obesity and Adipobiology Group, Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain; Department of Endocrinology & Nutrition, Clínica Universidad de Navarra, Pamplona, Spain.
| | - Javier Gómez-Ambrosi
- Metabolic Research Laboratory, Clínica Universidad de Navarra, Pamplona, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Pamplona, Spain; Obesity and Adipobiology Group, Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain
| | - Amaia Rodríguez
- Metabolic Research Laboratory, Clínica Universidad de Navarra, Pamplona, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Pamplona, Spain; Obesity and Adipobiology Group, Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain
| | - Beatriz Ramírez
- Metabolic Research Laboratory, Clínica Universidad de Navarra, Pamplona, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Pamplona, Spain; Obesity and Adipobiology Group, Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain
| | - Víctor Valentí
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Pamplona, Spain; Obesity and Adipobiology Group, Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain; Department of Surgery, Clínica Universidad de Navarra, Pamplona, Spain
| | - Rafael Moncada
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Pamplona, Spain; Obesity and Adipobiology Group, Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain; Department of Anesthesia, Clínica Universidad de Navarra, Pamplona, Spain
| | - Sara Becerril
- Metabolic Research Laboratory, Clínica Universidad de Navarra, Pamplona, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Pamplona, Spain
| | - Xabier Unamuno
- Metabolic Research Laboratory, Clínica Universidad de Navarra, Pamplona, Spain
| | - Camilo Silva
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Pamplona, Spain; Department of Endocrinology & Nutrition, Clínica Universidad de Navarra, Pamplona, Spain
| | - Javier Salvador
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Pamplona, Spain; Department of Endocrinology & Nutrition, Clínica Universidad de Navarra, Pamplona, Spain
| | - Victoria Catalán
- Metabolic Research Laboratory, Clínica Universidad de Navarra, Pamplona, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Pamplona, Spain; Obesity and Adipobiology Group, Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain.
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Tengholm A, Gylfe E. cAMP signalling in insulin and glucagon secretion. Diabetes Obes Metab 2017; 19 Suppl 1:42-53. [PMID: 28466587 DOI: 10.1111/dom.12993] [Citation(s) in RCA: 130] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 04/24/2017] [Accepted: 04/26/2017] [Indexed: 01/24/2023]
Abstract
The "second messenger" archetype cAMP is one of the most important cellular signalling molecules with central functions including the regulation of insulin and glucagon secretion from the pancreatic β- and α-cells, respectively. cAMP is generally considered as an amplifier of insulin secretion triggered by Ca2+ elevation in the β-cells. Both messengers are also positive modulators of glucagon release from α-cells, but in this case cAMP may be the important regulator and Ca2+ have a more permissive role. The actions of cAMP are mediated by protein kinase A (PKA) and the guanine nucleotide exchange factor Epac. The present review focuses on how cAMP is regulated by nutrients, hormones and neural factors in β- and α-cells via adenylyl cyclase-catalysed generation and phosphodiesterase-mediated degradation. We will also discuss how PKA and Epac affect ion fluxes and the secretory machinery to transduce the stimulatory effects on insulin and glucagon secretion. Finally, we will briefly describe disturbances of the cAMP system associated with diabetes and how cAMP signalling can be targeted to normalize hypo- and hypersecretion of insulin and glucagon, respectively, in diabetic patients.
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Affiliation(s)
- Anders Tengholm
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Erik Gylfe
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
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Takeda Y. [Theoretical Investigations into the Quantitative Mechanisms Underlying the Regulation of [cAMP]i, Membrane Excitability and [Ca(2+)]i during GLP-1 Stimulation in Pancreatic β Cells]. YAKUGAKU ZASSHI 2017; 136:467-71. [PMID: 26935088 DOI: 10.1248/yakushi.15-00246-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Upon elevation of plasma glucose concentration, pancreatic β-cells generate bursts of action potentials to induce cyclic changes in [Ca(2+)]i regulating insulin release. Glucose-dependent insulin secretion is synergistically enhanced by glucagon-like peptide-1 (GLP-1), which increases [cAMP]i and activates protein kinase A (PKA) and exchange protein activated by cAMP (Epac). The insulinotropic effect of GLP-1 is mediated, at least in part, by modulating multiple ion channels/transporters at the plasma membrane and ER through PKA- and EPAC-dependent mechanisms, which increase membrane excitability and intracellular Ca(2+) release. However, because of complex interactions between multiple cellular factors involved in the GLP-1 effects, quantitative aspects of the molecular/ionic mechanisms have not yet been determined. We thus performed simulation studies and mathematical analysis to investigate how GLP-1 signals control [cAMP]i and subsequently modify the bursting activities and Ca(2+) dynamics. First, a GLP-1 receptor signal transduction model was developed and introduced to our β-cells model. Secondly, modulatory effects of PKA/Epac on ion channels/transporters were incorporated based on experimental studies. Increases in the frequency and duration of the bursting activity observed during GLP-1 stimulation were well reconstructed by our model, and lead potential analysis quantitatively determined the functional role of each ion channel/transporter in modifying the burst pattern. Finally, an IP3R model was developed to reproduce GLP-1-induced Ca(2+) transients/oscillations. Instantaneous equilibrium analysis and bifurcation analysis also elucidated the quantitative mechanisms involved in generating IP3R-mediated Ca(2+) mobilization. The results of this theoretical analysis of the effects of GLP-1 on membrane excitability/Ca(2+) dynamics are discussed in this review.
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Affiliation(s)
- Yukari Takeda
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University
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Pancreatic Beta Cell G-Protein Coupled Receptors and Second Messenger Interactions: A Systems Biology Computational Analysis. PLoS One 2016; 11:e0152869. [PMID: 27138453 PMCID: PMC4854486 DOI: 10.1371/journal.pone.0152869] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 03/21/2016] [Indexed: 12/17/2022] Open
Abstract
Insulin secretory in pancreatic beta-cells responses to nutrient stimuli and hormonal modulators include multiple messengers and signaling pathways with complex interdependencies. Here we present a computational model that incorporates recent data on glucose metabolism, plasma membrane potential, G-protein-coupled-receptors (GPCR), cytoplasmic and endoplasmic reticulum calcium dynamics, cAMP and phospholipase C pathways that regulate interactions between second messengers in pancreatic beta-cells. The values of key model parameters were inferred from published experimental data. The model gives a reasonable fit to important aspects of experimentally measured metabolic and second messenger concentrations and provides a framework for analyzing the role of metabolic, hormones and neurotransmitters changes on insulin secretion. Our analysis of the dynamic data provides support for the hypothesis that activation of Ca2+-dependent adenylyl cyclases play a critical role in modulating the effects of glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and catecholamines. The regulatory properties of adenylyl cyclase isoforms determine fluctuations in cytoplasmic cAMP concentration and reveal a synergistic action of glucose, GLP-1 and GIP on insulin secretion. On the other hand, the regulatory properties of phospholipase C isoforms determine the interaction of glucose, acetylcholine and free fatty acids (FFA) (that act through the FFA receptors) on insulin secretion. We found that a combination of GPCR agonists activating different messenger pathways can stimulate insulin secretion more effectively than a combination of GPCR agonists for a single pathway. This analysis also suggests that the activators of GLP-1, GIP and FFA receptors may have a relatively low risk of hypoglycemia in fasting conditions whereas an activator of muscarinic receptors can increase this risk. This computational analysis demonstrates that study of second messenger pathway interactions will improve understanding of critical regulatory sites, how different GPCRs interact and pharmacological targets for modulating insulin secretion in type 2 diabetes.
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Schwede F, Chepurny OG, Kaufholz M, Bertinetti D, Leech CA, Cabrera O, Zhu Y, Mei F, Cheng X, Manning Fox JE, MacDonald PE, Genieser HG, Herberg FW, Holz GG. Rp-cAMPS Prodrugs Reveal the cAMP Dependence of First-Phase Glucose-Stimulated Insulin Secretion. Mol Endocrinol 2015; 29:988-1005. [PMID: 26061564 DOI: 10.1210/me.2014-1330] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
cAMP-elevating agents such as the incretin hormone glucagon-like peptide-1 potentiate glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells. However, a debate has existed since the 1970s concerning whether or not cAMP signaling is essential for glucose alone to stimulate insulin secretion. Here, we report that the first-phase kinetic component of GSIS is cAMP-dependent, as revealed through the use of a novel highly membrane permeable para-acetoxybenzyl (pAB) ester prodrug that is a bioactivatable derivative of the cAMP antagonist adenosine-3',5'-cyclic monophosphorothioate, Rp-isomer (Rp-cAMPS). In dynamic perifusion assays of human or rat islets, a step-wise increase of glucose concentration leads to biphasic insulin secretion, and under these conditions, 8-bromoadenosine-3',5'-cyclic monophosphorothioate, Rp-isomer, 4-acetoxybenzyl ester (Rp-8-Br-cAMPS-pAB) inhibits first-phase GSIS by up to 80%. Surprisingly, second-phase GSIS is inhibited to a much smaller extent (≤20%). Using luciferase, fluorescence resonance energy transfer, and bioluminescence resonance energy transfer assays performed in living cells, we validate that Rp-8-Br-cAMPS-pAB does in fact block cAMP-dependent protein kinase activation. Novel effects of Rp-8-Br-cAMPS-pAB to block the activation of cAMP-regulated guanine nucleotide exchange factors (Epac1, Epac2) are also validated using genetically encoded Epac biosensors, and are independently confirmed in an in vitro Rap1 activation assay using Rp-cAMPS and Rp-8-Br-cAMPS. Thus, in addition to revealing the cAMP dependence of first-phase GSIS from human and rat islets, these findings establish a pAB-based chemistry for the synthesis of highly membrane permeable prodrug derivatives of Rp-cAMPS that act with micromolar or even nanomolar potency to inhibit cAMP signaling in living cells.
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Affiliation(s)
- Frank Schwede
- BIOLOG Life Science Institute (F.S., H.-G.G.), 28199 Bremen, Germany; Departments of Medicine (O.G.C., C.A.L., G.G.H.) and Pharmacology (G.G.H.), State University of New York, Upstate Medical University, Syracuse, New York 13210; Department of Biochemistry (M.K., D.B., F.W.H.), University of Kassel, 34132 Kassel, Germany; Eli Lilly and Company (O.C.), Indianapolis, Indiana 46225; Department of Integrative Biology and Pharmacology (Y.Z., F.M., X.C.), Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, Texas 77030; Department of Pharmacology and the Alberta Diabetes Institute (J.E.M.F., P.E.M.), University of Alberta, Edmonton, Canada AB T6G 2E1
| | - Oleg G Chepurny
- BIOLOG Life Science Institute (F.S., H.-G.G.), 28199 Bremen, Germany; Departments of Medicine (O.G.C., C.A.L., G.G.H.) and Pharmacology (G.G.H.), State University of New York, Upstate Medical University, Syracuse, New York 13210; Department of Biochemistry (M.K., D.B., F.W.H.), University of Kassel, 34132 Kassel, Germany; Eli Lilly and Company (O.C.), Indianapolis, Indiana 46225; Department of Integrative Biology and Pharmacology (Y.Z., F.M., X.C.), Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, Texas 77030; Department of Pharmacology and the Alberta Diabetes Institute (J.E.M.F., P.E.M.), University of Alberta, Edmonton, Canada AB T6G 2E1
| | - Melanie Kaufholz
- BIOLOG Life Science Institute (F.S., H.-G.G.), 28199 Bremen, Germany; Departments of Medicine (O.G.C., C.A.L., G.G.H.) and Pharmacology (G.G.H.), State University of New York, Upstate Medical University, Syracuse, New York 13210; Department of Biochemistry (M.K., D.B., F.W.H.), University of Kassel, 34132 Kassel, Germany; Eli Lilly and Company (O.C.), Indianapolis, Indiana 46225; Department of Integrative Biology and Pharmacology (Y.Z., F.M., X.C.), Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, Texas 77030; Department of Pharmacology and the Alberta Diabetes Institute (J.E.M.F., P.E.M.), University of Alberta, Edmonton, Canada AB T6G 2E1
| | - Daniela Bertinetti
- BIOLOG Life Science Institute (F.S., H.-G.G.), 28199 Bremen, Germany; Departments of Medicine (O.G.C., C.A.L., G.G.H.) and Pharmacology (G.G.H.), State University of New York, Upstate Medical University, Syracuse, New York 13210; Department of Biochemistry (M.K., D.B., F.W.H.), University of Kassel, 34132 Kassel, Germany; Eli Lilly and Company (O.C.), Indianapolis, Indiana 46225; Department of Integrative Biology and Pharmacology (Y.Z., F.M., X.C.), Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, Texas 77030; Department of Pharmacology and the Alberta Diabetes Institute (J.E.M.F., P.E.M.), University of Alberta, Edmonton, Canada AB T6G 2E1
| | - Colin A Leech
- BIOLOG Life Science Institute (F.S., H.-G.G.), 28199 Bremen, Germany; Departments of Medicine (O.G.C., C.A.L., G.G.H.) and Pharmacology (G.G.H.), State University of New York, Upstate Medical University, Syracuse, New York 13210; Department of Biochemistry (M.K., D.B., F.W.H.), University of Kassel, 34132 Kassel, Germany; Eli Lilly and Company (O.C.), Indianapolis, Indiana 46225; Department of Integrative Biology and Pharmacology (Y.Z., F.M., X.C.), Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, Texas 77030; Department of Pharmacology and the Alberta Diabetes Institute (J.E.M.F., P.E.M.), University of Alberta, Edmonton, Canada AB T6G 2E1
| | - Over Cabrera
- BIOLOG Life Science Institute (F.S., H.-G.G.), 28199 Bremen, Germany; Departments of Medicine (O.G.C., C.A.L., G.G.H.) and Pharmacology (G.G.H.), State University of New York, Upstate Medical University, Syracuse, New York 13210; Department of Biochemistry (M.K., D.B., F.W.H.), University of Kassel, 34132 Kassel, Germany; Eli Lilly and Company (O.C.), Indianapolis, Indiana 46225; Department of Integrative Biology and Pharmacology (Y.Z., F.M., X.C.), Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, Texas 77030; Department of Pharmacology and the Alberta Diabetes Institute (J.E.M.F., P.E.M.), University of Alberta, Edmonton, Canada AB T6G 2E1
| | - Yingmin Zhu
- BIOLOG Life Science Institute (F.S., H.-G.G.), 28199 Bremen, Germany; Departments of Medicine (O.G.C., C.A.L., G.G.H.) and Pharmacology (G.G.H.), State University of New York, Upstate Medical University, Syracuse, New York 13210; Department of Biochemistry (M.K., D.B., F.W.H.), University of Kassel, 34132 Kassel, Germany; Eli Lilly and Company (O.C.), Indianapolis, Indiana 46225; Department of Integrative Biology and Pharmacology (Y.Z., F.M., X.C.), Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, Texas 77030; Department of Pharmacology and the Alberta Diabetes Institute (J.E.M.F., P.E.M.), University of Alberta, Edmonton, Canada AB T6G 2E1
| | - Fang Mei
- BIOLOG Life Science Institute (F.S., H.-G.G.), 28199 Bremen, Germany; Departments of Medicine (O.G.C., C.A.L., G.G.H.) and Pharmacology (G.G.H.), State University of New York, Upstate Medical University, Syracuse, New York 13210; Department of Biochemistry (M.K., D.B., F.W.H.), University of Kassel, 34132 Kassel, Germany; Eli Lilly and Company (O.C.), Indianapolis, Indiana 46225; Department of Integrative Biology and Pharmacology (Y.Z., F.M., X.C.), Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, Texas 77030; Department of Pharmacology and the Alberta Diabetes Institute (J.E.M.F., P.E.M.), University of Alberta, Edmonton, Canada AB T6G 2E1
| | - Xiaodong Cheng
- BIOLOG Life Science Institute (F.S., H.-G.G.), 28199 Bremen, Germany; Departments of Medicine (O.G.C., C.A.L., G.G.H.) and Pharmacology (G.G.H.), State University of New York, Upstate Medical University, Syracuse, New York 13210; Department of Biochemistry (M.K., D.B., F.W.H.), University of Kassel, 34132 Kassel, Germany; Eli Lilly and Company (O.C.), Indianapolis, Indiana 46225; Department of Integrative Biology and Pharmacology (Y.Z., F.M., X.C.), Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, Texas 77030; Department of Pharmacology and the Alberta Diabetes Institute (J.E.M.F., P.E.M.), University of Alberta, Edmonton, Canada AB T6G 2E1
| | - Jocelyn E Manning Fox
- BIOLOG Life Science Institute (F.S., H.-G.G.), 28199 Bremen, Germany; Departments of Medicine (O.G.C., C.A.L., G.G.H.) and Pharmacology (G.G.H.), State University of New York, Upstate Medical University, Syracuse, New York 13210; Department of Biochemistry (M.K., D.B., F.W.H.), University of Kassel, 34132 Kassel, Germany; Eli Lilly and Company (O.C.), Indianapolis, Indiana 46225; Department of Integrative Biology and Pharmacology (Y.Z., F.M., X.C.), Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, Texas 77030; Department of Pharmacology and the Alberta Diabetes Institute (J.E.M.F., P.E.M.), University of Alberta, Edmonton, Canada AB T6G 2E1
| | - Patrick E MacDonald
- BIOLOG Life Science Institute (F.S., H.-G.G.), 28199 Bremen, Germany; Departments of Medicine (O.G.C., C.A.L., G.G.H.) and Pharmacology (G.G.H.), State University of New York, Upstate Medical University, Syracuse, New York 13210; Department of Biochemistry (M.K., D.B., F.W.H.), University of Kassel, 34132 Kassel, Germany; Eli Lilly and Company (O.C.), Indianapolis, Indiana 46225; Department of Integrative Biology and Pharmacology (Y.Z., F.M., X.C.), Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, Texas 77030; Department of Pharmacology and the Alberta Diabetes Institute (J.E.M.F., P.E.M.), University of Alberta, Edmonton, Canada AB T6G 2E1
| | - Hans-G Genieser
- BIOLOG Life Science Institute (F.S., H.-G.G.), 28199 Bremen, Germany; Departments of Medicine (O.G.C., C.A.L., G.G.H.) and Pharmacology (G.G.H.), State University of New York, Upstate Medical University, Syracuse, New York 13210; Department of Biochemistry (M.K., D.B., F.W.H.), University of Kassel, 34132 Kassel, Germany; Eli Lilly and Company (O.C.), Indianapolis, Indiana 46225; Department of Integrative Biology and Pharmacology (Y.Z., F.M., X.C.), Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, Texas 77030; Department of Pharmacology and the Alberta Diabetes Institute (J.E.M.F., P.E.M.), University of Alberta, Edmonton, Canada AB T6G 2E1
| | - Friedrich W Herberg
- BIOLOG Life Science Institute (F.S., H.-G.G.), 28199 Bremen, Germany; Departments of Medicine (O.G.C., C.A.L., G.G.H.) and Pharmacology (G.G.H.), State University of New York, Upstate Medical University, Syracuse, New York 13210; Department of Biochemistry (M.K., D.B., F.W.H.), University of Kassel, 34132 Kassel, Germany; Eli Lilly and Company (O.C.), Indianapolis, Indiana 46225; Department of Integrative Biology and Pharmacology (Y.Z., F.M., X.C.), Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, Texas 77030; Department of Pharmacology and the Alberta Diabetes Institute (J.E.M.F., P.E.M.), University of Alberta, Edmonton, Canada AB T6G 2E1
| | - George G Holz
- BIOLOG Life Science Institute (F.S., H.-G.G.), 28199 Bremen, Germany; Departments of Medicine (O.G.C., C.A.L., G.G.H.) and Pharmacology (G.G.H.), State University of New York, Upstate Medical University, Syracuse, New York 13210; Department of Biochemistry (M.K., D.B., F.W.H.), University of Kassel, 34132 Kassel, Germany; Eli Lilly and Company (O.C.), Indianapolis, Indiana 46225; Department of Integrative Biology and Pharmacology (Y.Z., F.M., X.C.), Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, Texas 77030; Department of Pharmacology and the Alberta Diabetes Institute (J.E.M.F., P.E.M.), University of Alberta, Edmonton, Canada AB T6G 2E1
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11
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Kimura T, Kaneto H, Shimoda M, Hirukawa H, Okauchi S, Kohara K, Hamamoto S, Tawaramoto K, Hashiramoto M, Kaku K. Protective effects of pioglitazone and/or liraglutide on pancreatic β-cells in db/db mice: Comparison of their effects between in an early and advanced stage of diabetes. Mol Cell Endocrinol 2015; 400:78-89. [PMID: 25463759 DOI: 10.1016/j.mce.2014.11.018] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 11/14/2014] [Accepted: 11/20/2014] [Indexed: 12/24/2022]
Abstract
The aim was to compare the protective effects of pioglitazone (PIO) and/or liraglutide (LIRA) on β-cells with the progression of diabetes. Male db/db mice were treated with PIO and/or LIRA for 2 weeks in an early and advanced stage. In an early stage insulin biosynthesis and secretion were markedly increased by PIO and LIRA which was not observed in an advanced stage. In concomitant with such phenomena, expression levels of various β-cell-related factors were up-regulated by PIO and LIRA only in an early stage. Furthermore, β-cell mass was also increased by the treatment only in an early stage. Although there was no difference in apoptosis ratio between the two stages, β-cell proliferation was augmented by the treatment only in an early stage. In conclusion, protective effects of pioglitazone and/or liraglutide on β-cells were more powerful in an early stage of diabetes compared to an advanced stage.
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MESH Headings
- Animals
- Apoptosis/drug effects
- Blood Glucose/metabolism
- Caspases/genetics
- Caspases/metabolism
- Cell Proliferation/drug effects
- Diabetes Mellitus, Type 2/drug therapy
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/pathology
- Disease Models, Animal
- Disease Progression
- Gene Expression/drug effects
- Glucagon/blood
- Glucagon-Like Peptide 1/analogs & derivatives
- Glucagon-Like Peptide 1/pharmacology
- Hypoglycemic Agents/pharmacology
- Insulin/blood
- Insulin-Secreting Cells/drug effects
- Insulin-Secreting Cells/metabolism
- Insulin-Secreting Cells/pathology
- Ki-67 Antigen/genetics
- Ki-67 Antigen/metabolism
- Liraglutide
- Male
- Mice
- Mice, Transgenic
- Organ Size/drug effects
- Pioglitazone
- Proto-Oncogene Proteins c-bcl-2/genetics
- Proto-Oncogene Proteins c-bcl-2/metabolism
- RNA, Ribosomal, 18S/genetics
- RNA, Ribosomal, 18S/metabolism
- Thiazolidinediones/pharmacology
- Time Factors
- Triglycerides/blood
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Affiliation(s)
- Tomohiko Kimura
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, 577 Matsushima, Kurashiki-city, Okayama 701-0192, Japan.
| | - Hideaki Kaneto
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, 577 Matsushima, Kurashiki-city, Okayama 701-0192, Japan
| | - Masashi Shimoda
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, 577 Matsushima, Kurashiki-city, Okayama 701-0192, Japan
| | - Hidenori Hirukawa
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, 577 Matsushima, Kurashiki-city, Okayama 701-0192, Japan
| | - Seizo Okauchi
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, 577 Matsushima, Kurashiki-city, Okayama 701-0192, Japan
| | - Kenji Kohara
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, 577 Matsushima, Kurashiki-city, Okayama 701-0192, Japan
| | - Sumiko Hamamoto
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, 577 Matsushima, Kurashiki-city, Okayama 701-0192, Japan
| | - Kazuhito Tawaramoto
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, 577 Matsushima, Kurashiki-city, Okayama 701-0192, Japan
| | - Mitsuru Hashiramoto
- Division of Diabetes and Endocrinology, Yodogawa Christian Hospital, 1-7-50 Shibajima, Osaka-city, Osaka 533-0024, Japan
| | - Kohei Kaku
- Division of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, 577 Matsushima, Kurashiki-city, Okayama 701-0192, Japan; Department of General Internal Medicine 1, Kawasaki Hospital, Kawasaki Medical School, 2-1-80 Nakasange, Okayama-city, Okayama 700-8505, Japan
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12
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Yosida M, Dezaki K, Uchida K, Kodera S, Lam NV, Ito K, Rita RS, Yamada H, Shimomura K, Ishikawa SE, Sugawara H, Kawakami M, Tominaga M, Yada T, Kakei M. Involvement of cAMP/EPAC/TRPM2 activation in glucose- and incretin-induced insulin secretion. Diabetes 2014; 63:3394-403. [PMID: 24824430 DOI: 10.2337/db13-1868] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In pancreatic β-cells, closure of the ATP-sensitive K(+) (K(ATP)) channel is an initial process triggering glucose-stimulated insulin secretion. In addition, constitutive opening of background nonselective cation channels (NSCCs) is essentially required to effectively evoke depolarization as a consequence of K(ATP) channel closure. Thus, it is hypothesized that further opening of NSCC facilitates membrane excitability. We identified a class of NSCC that was activated by exendin (ex)-4, GLP-1, and its analog liraglutide at picomolar levels. This NSCC was also activated by increasing the glucose concentration. NSCC activation by glucose and GLP-1 was a consequence of the activated cAMP/EPAC-mediated pathway and was attenuated in TRPM2-deficient mice. The NSCC was not activated by protein kinase A (PKA) activators and was activated by ex-4 in the presence of PKA inhibitors. These results suggest that glucose- and incretin-activated NSCC (TRPM2) works in concert with closure of the KATP channel to effectively induce membrane depolarization to initiate insulin secretion. The current study reveals a new mechanism for regulating electrical excitability in β-cells and for mediating the action of glucose and incretin to evoke insulin secretion, thereby providing an innovative target for the treatment of type 2 diabetes.
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Affiliation(s)
- Masashi Yosida
- Internal Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Katsuya Dezaki
- Integrative Physiology, Jichi Medical University, Shimotsuke, Japan
| | | | - Shiho Kodera
- Internal Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Nien V Lam
- Internal Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Kiyonori Ito
- Internal Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Rauza S Rita
- Integrative Physiology, Jichi Medical University, Shimotsuke, Japan
| | - Hodaka Yamada
- Internal Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Kenju Shimomura
- Integrative Physiology, Jichi Medical University, Shimotsuke, Japan
| | - San-e Ishikawa
- Internal Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Hitoshi Sugawara
- Internal Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Masanobu Kawakami
- Internal Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan Nerima Hikarigaoka Hospital, Nerima, Japan
| | - Makoto Tominaga
- National Institute for Physiological Sciences, Okazaki, Japan
| | - Toshihiko Yada
- Integrative Physiology, Jichi Medical University, Shimotsuke, Japan National Institute for Physiological Sciences, Okazaki, Japan
| | - Masafumi Kakei
- Internal Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
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13
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Holz GG, Leech CA, Chepurny OG. New insights concerning the molecular basis for defective glucoregulation in soluble adenylyl cyclase knockout mice. Biochim Biophys Acta Mol Basis Dis 2014; 1842:2593-600. [PMID: 24980705 DOI: 10.1016/j.bbadis.2014.06.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 06/17/2014] [Accepted: 06/18/2014] [Indexed: 01/09/2023]
Abstract
Recently published findings indicate that a knockout (KO) of soluble adenylyl cyclase (sAC, also known as AC-10) gene expression in mice leads to defective glucoregulation that is characterized by reduced pancreatic insulin secretion and reduced intraperitoneal glucose tolerance. Summarized here are current concepts regarding the molecular basis for this phenotype, with special emphasis on the potential role of sAC as a determinant of glucose-stimulated insulin secretion. Highlighted is new evidence that in pancreatic beta cells, oxidative glucose metabolism stimulates mitochondrial CO₂production that in turn generates bicarbonate ion (HCO(3)(-)). Since HCO(3)(-) binds to and directly stimulates the activity of sAC, we propose that glucose-stimulated cAMP production in beta cells is mediated not simply by transmembrane adenylyl cyclases (TMACs), but also by sAC. Based on evidence that sAC is expressed in mitochondria, there exists the possibility that beta-cell glucose metabolism is linked to mitochondrial cAMP production with consequent facilitation of oxidative phosphorylation. Since sAC is also expressed in the cytoplasm, sAC catalyzed cAMP production may activate cAMP sensors such as PKA and Epac2 to control ion channel function, intracellular Ca²⁺ handling, and Ca²⁺-dependent exocytosis. Thus, we propose that the existence of sAC in beta cells provides a new and unexpected explanation for previously reported actions of glucose metabolism to stimulate cAMP production. It seems possible that alterations of sAC activity might be of importance when evaluating new strategies for the treatment of type 2 diabetes (T2DM), or when evaluating why glucose metabolism fails to stimulate insulin secretion in patients diagnosed with T2DM. This article is part of a Special Issue entitled: The role of soluble adenylyl cyclase in health and disease.
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Affiliation(s)
- George G Holz
- Department of Medicine, State University of New York (SUNY), Upstate Medical University, Syracuse, NY 13210, USA; Department of Pharmacology, State University of New York (SUNY), Upstate Medical University, Syracuse, NY 13210, USA.
| | - Colin A Leech
- Department of Medicine, State University of New York (SUNY), Upstate Medical University, Syracuse, NY 13210, USA
| | - Oleg G Chepurny
- Department of Medicine, State University of New York (SUNY), Upstate Medical University, Syracuse, NY 13210, USA
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14
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Xiong X, Shao W, Jin T. New insight into the mechanisms underlying the function of the incretin hormone glucagon-like peptide-1 in pancreatic β-cells: the involvement of the Wnt signaling pathway effector β-catenin. Islets 2012; 4:359-65. [PMID: 23314611 PMCID: PMC3605164 DOI: 10.4161/isl.23345] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
During the past two decades, the exploration of function of two incretin hormones, namely glucagon-like peptide-1 (GLP-1) and gastric inhibitory peptide (GIP), has led to the development of two categories of novel therapeutic agents for diabetes and its complications, known as GLP-1 receptor (GLP-1R) agonists and DPP-IV inhibitors. Mechanisms underlying the function of GLP-1, however, still need to be further explored. GLP-1 not only functions as an incretin hormone in stimulating insulin secretion in response to nutritional, hormonal and neuronal stimulations, but also acts as an "insulin-like" factor in β-cell and extra-pancreatic organs. In addition to these insulinotropic and insulinomimetic effects, GLP-1 was shown to exert its protective effect in β-cell by repressing the expression of TxNIP, a mediator of glucolipotoxicity. A number of recent studies have shown that the Wnt signaling pathway effector, the bipartite transcription factor β-catenin/TCF, controls not only the production of GLP-1, but also the function of GLP-1. Furthermore, previously assumed "degradation" products of GLP-1(7-36)amide, including GLP-1(9-36)amide and GLP-1(28-36)amide, have been shown to exert beneficial effect in pancreas and extra-pancreatic tissues or cell lineages. Here we summarized our current knowledge on the metabolic, proliferative and protective effects of GLP-1(7-36)amide and its cleavage fragments, mainly focusing on pancreatic β-cells and the involvement of the Wnt signaling pathway effector β-catenin.
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Affiliation(s)
- Xiaoquan Xiong
- Department of Physiology; University of Toronto; Toronto, ON Canada
- Toronto General Research Institute, University Health Network; Toronto, ON Canada
| | - Weijuan Shao
- Department of Physiology; University of Toronto; Toronto, ON Canada
- Toronto General Research Institute, University Health Network; Toronto, ON Canada
| | - Tianru Jin
- Department of Physiology; University of Toronto; Toronto, ON Canada
- Institute of Medical Science; University of Toronto; Toronto, ON Canada
- Toronto General Research Institute, University Health Network; Toronto, ON Canada
- Correspondence to: Tianru Jin;
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15
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Abstract
Insulin secretion from pancreatic β-cells is tightly regulated by glucose and other nutrients, hormones, and neural factors. The exocytosis of insulin granules is triggered by an elevation of the cytoplasmic Ca(2+) concentration ([Ca(2+)](i)) and is further amplified by cyclic AMP (cAMP). Cyclic AMP is formed primarily in response to glucoincretin hormones and other G(s)-coupled receptor agonists, but generation of the nucleotide is critical also for an optimal insulin secretory response to glucose. Nutrient and receptor stimuli trigger oscillations of the cAMP concentration in β-cells. The oscillations arise from variations in adenylyl cyclase-mediated cAMP production and phosphodiesterase-mediated degradation, processes controlled by factors like cell metabolism and [Ca(2+)](i). Protein kinase A and the guanine nucleotide exchange factor Epac2 mediate the actions of cAMP in β-cells and operate at multiple levels to promote exocytosis and pulsatile insulin secretion. The cAMP signaling system contains important targets for pharmacological improvement of insulin secretion in type 2 diabetes.
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Affiliation(s)
- Anders Tengholm
- Department of Medical Cell Biology, Uppsala University, Biomedical Centre , Box 571, SE-751 23 Uppsala, Sweden.
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16
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Han L, Yu Y, Sun X, Wang B. Exendin-4 directly improves endothelial dysfunction in isolated aortas from obese rats through the cAMP or AMPK-eNOS pathways. Diabetes Res Clin Pract 2012; 97:453-60. [PMID: 22560150 DOI: 10.1016/j.diabres.2012.04.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 03/30/2012] [Accepted: 04/02/2012] [Indexed: 02/07/2023]
Abstract
AIMS To determine whether exendin-4 might directly improve endothelial dysfunction in aorta isolated from high-fat diet-induced obese rats. METHODS Wistar rats were randomly divided into control and obesity (OB) groups and fed. Vascular segments of obese rats were incubated in organ bath in the presence or absence of exendin-4. Nitric oxide (NO) production and nuclear transcription factor kappa B expression in vascular rings were measured. The aortic rings of the obese rats were then incubated in an organ bath with exendin-4 in the presence or absence of the following inhibitors: the AMPK, the adenylate cyclase and the NO synthase inhibitor. RESULTS The maximum endothelium-dependent vasodilatation (EDV) value was severely reduced in the OB group. Exendin-4 treatment significantly increased the NO level, improved endothelium-dependent vasodilatation and reduced expression of NF-κB in the obese group. The beneficial effect of exendin-4 on EDV in obese rats was partly attenuated in the presence of the specific inhibitors. CONCLUSION Exendin-4 directly improves impaired EDV of aortae from obese rats. The beneficial effect of exendin-4 appears to be mediated in part via stimulation of cAMP/AMPK-related signalling pathways and enhancement of endothelial nitric oxide synthase activity.
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Affiliation(s)
- Lina Han
- Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu 610041, China
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17
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Harvey RD. How uniform is cAMP signaling? Focus on “Systems analysis of GLP-1 receptor signaling in pancreatic β-cells”. Am J Physiol Cell Physiol 2011; 301:C775-6. [DOI: 10.1152/ajpcell.00245.2011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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