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Buchanan CM, Lee KL, Shepherd PR. For Better or Worse: The Potential for Dose Limiting the On-Target Toxicity of PI 3-Kinase Inhibitors. Biomolecules 2019; 9:biom9090402. [PMID: 31443495 PMCID: PMC6770514 DOI: 10.3390/biom9090402] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 08/15/2019] [Accepted: 08/21/2019] [Indexed: 02/07/2023] Open
Abstract
The hyper-activation of the phosphoinositide (PI) 3-kinase signaling pathway is a hallmark of many cancers and overgrowth syndromes, and as a result, there has been intense interest in the development of drugs that target the various isoforms of PI 3-kinase. Given the key role PI 3-kinases play in many normal cell functions, there is significant potential for the disruption of essential cellular functions by PI 3-kinase inhibitors in normal tissues; so-called on-target drug toxicity. It is, therefore, no surprise that progress within the clinical development of PI 3-kinase inhibitors as single-agent anti-cancer therapies has been slowed by the difficulty of identifying a therapeutic window. The aim of this review is to place the cellular, tissue and whole-body effects of PI 3-kinase inhibition in the context of understanding the potential for dose limiting on-target toxicities and to introduce possible strategies to overcome these.
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Affiliation(s)
- Christina M Buchanan
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Kate L Lee
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Peter R Shepherd
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
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2
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Mizgier ML, Fernández-Verdejo R, Cherfan J, Pinget M, Bouzakri K, Galgani JE. Insights on the Role of Putative Muscle-Derived Factors on Pancreatic Beta Cell Function. Front Physiol 2019; 10:1024. [PMID: 31440170 PMCID: PMC6694406 DOI: 10.3389/fphys.2019.01024] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 07/24/2019] [Indexed: 01/02/2023] Open
Abstract
Skeletal muscle is a main target of insulin action that plays a pivotal role in postprandial glucose disposal. Importantly, skeletal muscle insulin sensitivity relates inversely with pancreatic insulin secretion, which prompted the hypothesis of the existence of a skeletal muscle-pancreas crosstalk mediated through an endocrine factor. The observation that changes in skeletal muscle glucose metabolism are accompanied by altered insulin secretion supports this hypothesis. Meanwhile, a muscle-derived circulating factor affecting in vivo insulin secretion remains elusive. This factor may correspond to peptides/proteins (so called myokines), exosomes and their cargo, and metabolites. We hereby review the most remarkable evidence encouraging the possibility of such inter-organ communication, with special focus on muscle-derived factors that may potentially mediate such skeletal muscle-pancreas crosstalk.
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Affiliation(s)
- Maria L Mizgier
- UMR DIATHEC, EA 7294, Centre Européen d'Etude du Diabète, Université de Strasbourg, Strasbourg, France
| | - Rodrigo Fernández-Verdejo
- Departamento de Ciencias de la Salud, Nutrición y Dietética, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Julien Cherfan
- UMR DIATHEC, EA 7294, Centre Européen d'Etude du Diabète, Université de Strasbourg, Strasbourg, France
| | - Michel Pinget
- UMR DIATHEC, EA 7294, Centre Européen d'Etude du Diabète, Université de Strasbourg, Strasbourg, France
| | - Karim Bouzakri
- UMR DIATHEC, EA 7294, Centre Européen d'Etude du Diabète, Université de Strasbourg, Strasbourg, France
| | - Jose E Galgani
- Departamento de Ciencias de la Salud, Nutrición y Dietética, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Departamento de Nutrición, Diabetes y Metabolismo, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
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3
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Burke SJ, Batdorf HM, Burk DH, Martin TM, Mendoza T, Stadler K, Alami W, Karlstad MD, Robson MJ, Blakely RD, Mynatt RL, Collier JJ. Pancreatic deletion of the interleukin-1 receptor disrupts whole body glucose homeostasis and promotes islet β-cell de-differentiation. Mol Metab 2018; 14:95-107. [PMID: 29914854 PMCID: PMC6034063 DOI: 10.1016/j.molmet.2018.06.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 05/30/2018] [Accepted: 06/02/2018] [Indexed: 02/06/2023] Open
Abstract
Objective Pancreatic tissue, and islets in particular, are enriched in expression of the interleukin-1 receptor type I (IL-1R). Because of this enrichment, islet β-cells are exquisitely sensitive to the IL-1R ligands IL-1α and IL-1β, suggesting that signaling through this pathway regulates health and function of islet β-cells. Methods Herein, we report a targeted deletion of IL-1R in pancreatic tissue (IL-1RPdx1−/−) in C57BL/6J mice and in db/db mice on the C57 genetic background. Islet morphology, β-cell transcription factor abundance, and expression of the de-differentiation marker Aldh1a3 were analyzed by immunofluorescent staining. Glucose and insulin tolerance tests were used to examine metabolic status of these genetic manipulations. Glucose-stimulated insulin secretion was evaluated in vivo and in isolated islets ex vivo by perifusion. Results Pancreatic deletion of IL-1R leads to impaired glucose tolerance, a phenotype that is exacerbated by age. Crossing the IL-1RPdx1−/− with db/db mice worsened glucose tolerance without altering body weight. There were no detectable alterations in insulin tolerance between IL-1RPdx1−/− mice and littermate controls. However, glucose-stimulated insulin secretion was reduced in islets isolated from IL-1RPdx1−/− relative to control islets. Insulin output in vivo after a glucose challenge was also markedly reduced in IL-1RPdx1−/− mice when compared with littermate controls. Pancreatic islets from IL-1RPdx1−/− mice displayed elevations in Aldh1a3, a marker of de-differentiation, and reduction in nuclear abundance of the β-cell transcription factor MafA. Nkx6.1 abundance was unaltered. Conclusions There is an important physiological role for pancreatic IL-1R to promote glucose homeostasis by suppressing expression of Aldh1a3, sustaining MafA abundance, and supporting glucose-stimulated insulin secretion in vivo. Pancreatic deletion of IL-1R impairs glucose tolerance in young and old male mice. Pancreatic deletion of IL-1R worsens glucose tolerance in obese db/db mice. Deletion of IL-1R triggers expression of the de-differentiation marker Aldh1a3. IL-1 signaling in pancreatic tissue influences islet health and function.
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Affiliation(s)
- Susan J Burke
- Pennington Biomedical Research Center, Baton Rouge, LA, 70808, USA
| | - Heidi M Batdorf
- Pennington Biomedical Research Center, Baton Rouge, LA, 70808, USA
| | - David H Burk
- Pennington Biomedical Research Center, Baton Rouge, LA, 70808, USA
| | - Thomas M Martin
- Pennington Biomedical Research Center, Baton Rouge, LA, 70808, USA
| | - Tamra Mendoza
- Pennington Biomedical Research Center, Baton Rouge, LA, 70808, USA
| | | | - Wateen Alami
- Department of Surgery, University of Tennessee Health Science Center, Knoxville, TN, 37920, USA
| | - Michael D Karlstad
- Department of Surgery, University of Tennessee Health Science Center, Knoxville, TN, 37920, USA
| | - Matthew J Robson
- Division of Pharmaceutical Sciences, James L. Winkle College of Pharmacy, University of Cincinnati, Cincinnati, OH, 45267, USA
| | - Randy D Blakely
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter FL, 33458, USA
| | - Randall L Mynatt
- Pennington Biomedical Research Center, Baton Rouge, LA, 70808, USA
| | - J Jason Collier
- Pennington Biomedical Research Center, Baton Rouge, LA, 70808, USA.
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Karandrea S, Yin H, Liang X, Heart EA. BDE-47 and BDE-85 stimulate insulin secretion in INS-1 832/13 pancreatic β-cells through the thyroid receptor and Akt. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2017; 56:29-34. [PMID: 28869857 DOI: 10.1016/j.etap.2017.08.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 08/28/2017] [Accepted: 08/29/2017] [Indexed: 05/12/2023]
Abstract
PBDEs (polybrominated diphenyl ethers) are environmental pollutants that have been linked to the development of type 2 diabetes, however, the precise mechanisms are not clear. Particularly, their direct effect on insulin secretion is unknown. In this study, we show that two PBDE congeners, BDE-47 and BDE-85, potentiate glucose-stimulated insulin secretion (GSIS) in INS-1 832/13 cells. This effect of BDE-47 and BDE-85 on GSIS was dependent on thyroid receptor (TR). Both BDE-47 and BDE-85 (10μM) activated Akt during an acute exposure. The activation of Akt by BDE-47 and BDE-85 plays a role in their potentiation of GSIS, as pharmacological inhibition of PI3K, an upstream activator of Akt, significantly lowers GSIS compared to compounds alone. This study shows that BDE-47 and BDE-85 directly act on pancreatic β-cells to stimulate GSIS, and that this effect is mediated by the thyroid receptor (TR) and Akt activation.
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Affiliation(s)
- Shpetim Karandrea
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, FL, 33612, United States
| | - Huquan Yin
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, FL, 33612, United States
| | - Xiaomei Liang
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, FL, 33612, United States
| | - Emma A Heart
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, FL, 33612, United States.
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5
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Kolic J, Manning Fox JE, Chepurny OG, Spigelman AF, Ferdaoussi M, Schwede F, Holz GG, MacDonald PE. PI3 kinases p110α and PI3K-C2β negatively regulate cAMP via PDE3/8 to control insulin secretion in mouse and human islets. Mol Metab 2016; 5:459-471. [PMID: 27408772 PMCID: PMC4921792 DOI: 10.1016/j.molmet.2016.05.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Revised: 04/26/2016] [Accepted: 05/04/2016] [Indexed: 01/09/2023] Open
Abstract
OBJECTIVES Phosphatidylinositol-3-OH kinase (PI3K) signalling in the endocrine pancreas contributes to glycaemic control. However, the mechanism by which PI3K modulates insulin secretion from the pancreatic beta cell is poorly understood. Thus, our objective was two-fold; to determine the signalling pathway by which acute PI3K inhibition enhances glucose-stimulated insulin secretion (GSIS) and to examine the role of this pathway in islets from type-2 diabetic (T2D) donors. METHODS Isolated islets from mice and non-diabetic or T2D human donors, or INS 832/13 cells, were treated with inhibitors of PI3K and/or phosphodiesterases (PDEs). The expression of PI3K-C2β was knocked down using siRNA. We measured insulin release, single-cell exocytosis, intracellular Ca(2+) responses ([Ca(2+)]i) and Ca(2+) channel currents, intracellular cAMP concentrations ([cAMP]i), and activation of cAMP-dependent protein kinase A (PKA) and protein kinase B (PKB/AKT). RESULTS The non-specific PI3K inhibitor wortmannin amplifies GSIS, raises [cAMP]i and activates PKA, but is without effect in T2D islets. Direct inhibition of specific PDE isoforms demonstrates a role for PDE3 (in humans and mice) and PDE8 (in mice) downstream of PI3K, and restores glucose-responsiveness of T2D islets. We implicate a role for the Class II PI3K catalytic isoform PI3K-C2β in this effect by limiting beta cell exocytosis. CONCLUSIONS PI3K limits GSIS via PDE3 in human islets. While inhibition of p110α or PIK-C2β signalling per se, may promote nutrient-stimulated insulin release, we now suggest that this signalling pathway is perturbed in islets from T2D donors.
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Affiliation(s)
- Jelena Kolic
- Department of Pharmacology, and the Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada.
| | - Jocelyn E Manning Fox
- Department of Pharmacology, and the Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - Oleg G Chepurny
- Department of Medicine, State University of New York, Upstate Medical University, Syracuse, NY 13210, USA
| | - Aliya F Spigelman
- Department of Pharmacology, and the Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - Mourad Ferdaoussi
- Department of Pharmacology, and the Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - Frank Schwede
- BIOLOG Life Science Institute, 28199 Bremen, Germany
| | - George G Holz
- Department of Medicine, State University of New York, Upstate Medical University, Syracuse, NY 13210, USA; Department of Pharmacology, State University of New York, Upstate Medical University, Syracuse, NY 13210, USA
| | - Patrick E MacDonald
- Department of Pharmacology, and the Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
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6
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Inhibition of voltage-gated potassium channels mediates uncarboxylated osteocalcin-regulated insulin secretion in rat pancreatic β cells. Eur J Pharmacol 2016; 777:41-8. [DOI: 10.1016/j.ejphar.2016.02.060] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 02/23/2016] [Accepted: 02/26/2016] [Indexed: 01/17/2023]
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Abstract
Type 2 diabetes is a complex disease. It results from a failure of the body to maintain energy homoeostasis. Multicellular organisms have evolved complex strategies to preserve a relatively stable internal nutrient environment, despite fluctuations in external nutrient availability. This complex strategy involves the co-ordinated responses of multiple organs to promote storage or mobilization of energy sources according to the availability of nutrients and cellular bioenergetics needs. The endocrine pancreas plays a central role in these processes by secreting insulin and glucagon. When this co-ordinated effort fails, hyperglycaemia and hyperlipidaemia develops, characterizing a state of metabolic imbalance and ultimately overt diabetes. Although diabetes is most likely a collection of diseases, scientists are starting to identify genetic components and environmental triggers. Genome-wide association studies revealed that by and large, gene variants associated with type 2 diabetes are implicated in pancreatic β-cell function, suggesting that the β-cell may be the weakest link in the chain of events that results in diabetes. Thus, it is critical to understand how environmental cues affect the β-cell. Phosphoinositides are important 'decoders' of environmental cues. As such, these lipids have been implicated in cellular responses to a wide range of growth factors, hormones, stress agents, nutrients and metabolites. Here we will review some of the well-established and potential new roles for phosphoinositides in β-cell function/dysfunction and discuss how our knowledge of phosphoinositide signalling could aid in the identification of potential strategies for treating or preventing type 2 diabetes.
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Affiliation(s)
- Lucia E Rameh
- Department of Medicine, Boston University School of Medicine, 650 Albany Street, Boston, MA 02118, U.S.A.
| | - Jude T Deeney
- Department of Medicine, Boston University School of Medicine, 650 Albany Street, Boston, MA 02118, U.S.A
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8
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Burke SJ, Stadler K, Lu D, Gleason E, Han A, Donohoe DR, Rogers RC, Hermann GE, Karlstad MD, Collier JJ. IL-1β reciprocally regulates chemokine and insulin secretion in pancreatic β-cells via NF-κB. Am J Physiol Endocrinol Metab 2015; 309:E715-26. [PMID: 26306596 PMCID: PMC4609876 DOI: 10.1152/ajpendo.00153.2015] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 08/17/2015] [Indexed: 01/04/2023]
Abstract
Proinflammatory cytokines impact islet β-cell mass and function by altering the transcriptional activity within pancreatic β-cells, producing increases in intracellular nitric oxide abundance and the synthesis and secretion of immunomodulatory proteins such as chemokines. Herein, we report that IL-1β, a major mediator of inflammatory responses associated with diabetes development, coordinately and reciprocally regulates chemokine and insulin secretion. We discovered that NF-κB controls the increase in chemokine transcription and secretion as well as the decrease in both insulin secretion and proliferation in response to IL-1β. Nitric oxide production, which is markedly elevated in pancreatic β-cells exposed to IL-1β, is a negative regulator of both glucose-stimulated insulin secretion and glucose-induced increases in intracellular calcium levels. By contrast, the IL-1β-mediated production of the chemokines CCL2 and CCL20 was not influenced by either nitric oxide levels or glucose concentration. Instead, the synthesis and secretion of CCL2 and CCL20 in response to IL-1β were dependent on NF-κB transcriptional activity. We conclude that IL-1β-induced transcriptional reprogramming via NF-κB reciprocally regulates chemokine and insulin secretion while also negatively regulating β-cell proliferation. These findings are consistent with NF-κB as a major regulatory node controlling inflammation-associated alterations in islet β-cell function and mass.
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Affiliation(s)
- Susan J Burke
- Laboratory of Islet Biology and Inflammation, Pennington Biomedical Research Center, Baton Rouge, Louisiana
| | - Krisztian Stadler
- Laboratory of Oxidative Stress and Disease, Pennington Biomedical Research Center, Baton Rouge, Louisiana
| | - Danhong Lu
- Duke Molecular Physiology Institute, Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina
| | - Evanna Gleason
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana
| | - Anna Han
- Department of Nutrition, University of Tennessee, Knoxville, Knoxville, Tennessee
| | - Dallas R Donohoe
- Department of Nutrition, University of Tennessee, Knoxville, Knoxville, Tennessee
| | - Richard C Rogers
- Laboratory of Autonomic Neuroscience, Pennington Biomedical Research Center, Baton Rouge, Louisiana; and
| | - Gerlinda E Hermann
- Laboratory of Autonomic Neuroscience, Pennington Biomedical Research Center, Baton Rouge, Louisiana; and
| | - Michael D Karlstad
- Department of Surgery, Graduate School of Medicine, University of Tennessee Medical Center, Knoxville, Tennessee
| | - J Jason Collier
- Laboratory of Islet Biology and Inflammation, Pennington Biomedical Research Center, Baton Rouge, Louisiana;
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Burke SJ, May AL, Noland RC, Lu D, Brissova M, Powers AC, Sherrill EM, Karlstad MD, Campagna SR, Stephens JM, Collier JJ. Thiobenzothiazole-modified Hydrocortisones Display Anti-inflammatory Activity with Reduced Impact on Islet β-Cell Function. J Biol Chem 2015; 290:13401-16. [PMID: 25851902 DOI: 10.1074/jbc.m114.632190] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Indexed: 12/20/2022] Open
Abstract
Glucocorticoids signal through the glucocorticoid receptor (GR) and are administered clinically for a variety of situations, including inflammatory disorders, specific cancers, rheumatoid arthritis, and organ/tissue transplantation. However, glucocorticoid therapy is also associated with additional complications, including steroid-induced diabetes. We hypothesized that modification of the steroid backbone is one strategy to enhance the therapeutic potential of GR activation. Toward this goal, two commercially unavailable, thiobenzothiazole-containing derivatives of hydrocortisone (termed MS4 and MS6) were examined using 832/13 rat insulinoma cells as well as rodent and human islets. We found that MS4 had transrepression properties but lacked transactivation ability, whereas MS6 retained both transactivation and transrepression activities. In addition, MS4 and MS6 both displayed anti-inflammatory activity. Furthermore, MS4 displayed reduced impact on islet β-cell function in both rodent and human islets. Similar to dexamethasone, MS6 promoted adipocyte development in vitro, whereas MS4 did not. Moreover, neither MS4 nor MS6 activated the Pck1 (Pepck) gene in primary rat hepatocytes. We conclude that modification of the functional groups attached to the D-ring of the hydrocortisone steroid molecule produces compounds with altered structure-function GR agonist activity with decreased impact on insulin secretion and reduced adipogenic potential but with preservation of anti-inflammatory activity.
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Affiliation(s)
- Susan J Burke
- From the Laboratory of Islet Biology and Inflammation, the Departments of Nutrition and
| | - Amanda L May
- Chemistry, University of Tennessee, Knoxville, Tennessee 37996
| | | | - Danhong Lu
- the Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina 27701
| | - Marcela Brissova
- the Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, and
| | - Alvin C Powers
- the Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, and the Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee 37232, the Tennessee Valley Healthcare System, Department of Veterans Affairs, Nashville, Tennessee 37212
| | | | - Michael D Karlstad
- the Department of Surgery, Graduate School of Medicine, University of Tennessee Medical Center, Knoxville, Tennessee 37920, and
| | | | - Jacqueline M Stephens
- the Adipocyte Biology Laboratory, Pennington Biomedical Research Center, Baton Rouge, Louisiana 70808
| | - J Jason Collier
- From the Laboratory of Islet Biology and Inflammation, the Departments of Nutrition and the Department of Surgery, Graduate School of Medicine, University of Tennessee Medical Center, Knoxville, Tennessee 37920, and
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10
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Li X, Guo Q, Gao J, Yang J, Zhang W, Liang Y, Wu D, Liu Y, Weng J, Li Q, Zhang Y. The adenylyl cyclase inhibitor MDL-12,330A potentiates insulin secretion via blockade of voltage-dependent K(+) channels in pancreatic beta cells. PLoS One 2013; 8:e77934. [PMID: 24205033 PMCID: PMC3812155 DOI: 10.1371/journal.pone.0077934] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 09/06/2013] [Indexed: 12/25/2022] Open
Abstract
Objective Adenylyl cyclases (ACs) play important role in regulating pancreatic beta cell growth, survival and secretion through the synthesis of cyclic AMP (cAMP). MDL-12,330A and SQ 22536 are two AC inhibitors used widely to establish the role of ACs. The goal of this study was to examine the effects of MDL-12,330A and SQ 22536 on insulin secretion and underlying mechanisms. Methods Patch-clamp recording, Ca2+ fluorescence imaging and radioimmunoassay were used to measure outward K+ currents, action potentials (APs), intracellular Ca2+ ([Ca2+]i) and insulin secretion from rat pancreatic beta cells. Results MDL-12,330A (10 µmol/l) potentiated insulin secretion to 1.7 times of control in the presence of 8.3 mmol/l glucose, while SQ 22536 did not show significant effect on insulin secretion. MDL-12,330A prolonged AP durations (APDs) by inhibiting voltage-dependent K+ (KV) channels, leading to an increase in [Ca2+]i levels. It appeared that these effects induced by MDL-12,330A did not result from AC inhibition, since SQ 22536 did not show such effects. Furthermore, inhibition of the downstream effectors of AC/cAMP signaling by PKA inhibitor H89 and Epac inhibitor ESI-09, did not affect KV channels and insulin secretion. Conclusion The putative AC inhibitor MDL-12,330A enhances [Ca2+]i and insulin secretion via inhibition of KV channels rather than AC antagonism in beta cells, suggesting that the non-specific effects is needed to be considered for the right interpretation of the experimental results using this agent in the analyses of the role of AC in cell function.
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Affiliation(s)
- Xiaodong Li
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Qing Guo
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Jingying Gao
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Jing Yang
- Department of Endocrinology, the First Hospital of Shanxi Medical University, Shanxi Medical University, Taiyuan, China
| | - Wan Zhang
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Yueqin Liang
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Dongmei Wu
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Yunfeng Liu
- Department of Endocrinology, the First Hospital of Shanxi Medical University, Shanxi Medical University, Taiyuan, China
- * E-mail: (YL); (YZ)
| | - Jianping Weng
- Department of Endocrinology, the Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | - Qingshan Li
- School of Pharmaceutical Sciences, Shanxi Medical University, Taiyuan, China
| | - Yi Zhang
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
- * E-mail: (YL); (YZ)
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11
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Abstract
Phosphoinositides (PIs) make up only a small fraction of cellular phospholipids, yet they control almost all aspects of a cell's life and death. These lipids gained tremendous research interest as plasma membrane signaling molecules when discovered in the 1970s and 1980s. Research in the last 15 years has added a wide range of biological processes regulated by PIs, turning these lipids into one of the most universal signaling entities in eukaryotic cells. PIs control organelle biology by regulating vesicular trafficking, but they also modulate lipid distribution and metabolism via their close relationship with lipid transfer proteins. PIs regulate ion channels, pumps, and transporters and control both endocytic and exocytic processes. The nuclear phosphoinositides have grown from being an epiphenomenon to a research area of its own. As expected from such pleiotropic regulators, derangements of phosphoinositide metabolism are responsible for a number of human diseases ranging from rare genetic disorders to the most common ones such as cancer, obesity, and diabetes. Moreover, it is increasingly evident that a number of infectious agents hijack the PI regulatory systems of host cells for their intracellular movements, replication, and assembly. As a result, PI converting enzymes began to be noticed by pharmaceutical companies as potential therapeutic targets. This review is an attempt to give an overview of this enormous research field focusing on major developments in diverse areas of basic science linked to cellular physiology and disease.
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Affiliation(s)
- Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
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12
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Kolic J, Spigelman AF, Plummer G, Leung E, Hajmrle C, Kin T, Shapiro AMJ, Manning Fox JE, MacDonald PE. Distinct and opposing roles for the phosphatidylinositol 3-OH kinase catalytic subunits p110α and p110β in the regulation of insulin secretion from rodent and human beta cells. Diabetologia 2013; 56:1339-49. [PMID: 23568272 DOI: 10.1007/s00125-013-2882-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 02/18/2013] [Indexed: 02/07/2023]
Abstract
AIMS/HYPOTHESIS Phosphatidylinositol 3-OH kinases (PI3Ks) regulate beta cell mass, gene transcription, and function, although the contribution of the specific isoforms is unknown. As reduced type 1A PI3K signalling is thought to contribute to impaired insulin secretion, we investigated the role of the type 1A PI3K catalytic subunits α and β (p110α and -β) in insulin granule recruitment and exocytosis in rodent and human islets. METHODS The p110α and p110β subunits were inhibited pharmacologically or by small hairpin (sh)RNA-mediated knockdown, and were directly infused or overexpressed in mouse and human islets, beta cells and INS-1 832/13 cells. Glucose-stimulated insulin secretion (GSIS), single-cell exocytosis, Ca(2+) signalling, plasma membrane granule localisation, and actin density were monitored. RESULTS Inhibition or knockdown of p110α increased GSIS. This was not due to altered Ca(2+) responses, depolymerisation of cortical actin or increased cortical granule density, but to enhanced Ca(2+)-dependent exocytosis. Intracellular infusion of recombinant PI3Kα (p110α/p85β) blocked exocytosis. Conversely, knockdown (but not pharmacological inhibition) of p110β blunted GSIS, reduced cortical granule density and impaired exocytosis. Exocytosis was rescued by direct intracellular infusion of recombinant PI3Kβ (p110β/p85β) even when p110β catalytic activity was inhibited. Conversely, both the wild-type p110β and a catalytically inactive mutant directly facilitated exocytosis. CONCLUSIONS/INTERPRETATION Type 1A PI3K isoforms have distinct and opposing roles in the acute regulation of insulin secretion. While p110α acts as a negative regulator of beta cell exocytosis and insulin secretion, p110β is a positive regulator of insulin secretion through a mechanism separate from its catalytic activity.
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Affiliation(s)
- J Kolic
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada T6G 2E1
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13
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Chronic treatment with LY294002, an inhibitor of phosphatidylinositol 3-kinase, attenuates ischemia/reperfusion-induced cardiac dysfunction in normotensive and hypertensive diabetic animals. Mol Cell Biochem 2012; 373:259-64. [PMID: 23124851 DOI: 10.1007/s11010-012-1497-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 10/25/2012] [Indexed: 10/27/2022]
Abstract
Diabetes is associated with increased incidence of cardiovascular disease. Mechanisms that contribute to development of diabetic cardiopathy are not well understood. Phosphatidylinositol 3-kinase (PI3K) is a family of protein kinases that play an important role in regulation of cardiac function. It has been shown that inhibition of certain PI3K enzymes may produce cardiovascular protection. The aim of the present study was to determine whether chronic treatment with LY294002, an inhibitor of PI3K, can attenuate diabetes-induced cardiac dysfunction in isolated hearts obtained from normotensive and hypertensive rats. Recovery of cardiac function after 40 min of global ischemia and 30 min of reperfusion, measured as left ventricular developed pressure, left ventricular end-diastolic pressure, coronary flow and coronary vascular resistance, was worse in hearts obtained from diabetic and/or hypertensive animals compared to their respective controls. Treatment with LY294002 (1.2 mg/kg/day) for 4 weeks significantly prevented diabetes-induced cardiac dysfunction in both normotensive and hypertensive rats. Treatment with LY294002 did not significantly alter blood pressure or blood glucose levels. These results suggest that inhibition of PI3K signaling pathways can prevent ischemia/reperfusion-induced cardiac dysfunction in normotensive and hypertensive rats without correcting hyperglycemia or high blood pressure.
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Aoyagi K, Ohara-Imaizumi M, Nishiwaki C, Nakamichi Y, Ueki K, Kadowaki T, Nagamatsu S. Acute inhibition of PI3K-PDK1-Akt pathway potentiates insulin secretion through upregulation of newcomer granule fusions in pancreatic β-cells. PLoS One 2012; 7:e47381. [PMID: 23077605 PMCID: PMC3471824 DOI: 10.1371/journal.pone.0047381] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 09/12/2012] [Indexed: 02/03/2023] Open
Abstract
In glucose-induced insulin secretion from pancreatic β-cells, a population of insulin granules fuses with the plasma membrane without the typical docking process (newcomer granule fusions), however, its mechanism is unclear. In this study, we investigated the PI3K signaling pathways involved in the upregulation of newcomer granule fusions. Acute treatment with the class IA-selective PI3K inhibitors, PIK-75 and PI-103, enhanced the glucose-induced insulin secretion. Total internal reflection fluorescent microscopy revealed that the PI3K inhibitors increased the fusion events from newcomer granules. We developed a new system for transfection into pancreatic islets and demonstrated the usefulness of this system in order for evaluating the effect of transfected genes on the glucose-induced secretion in primary cultured pancreatic islets. Using this transfection system together with a series of constitutive active mutants, we showed that the PI3K-3-phosphoinositide dependent kinase-1 (PDK1)-Akt pathway mediated the potentiation of insulin secretion. The Akt inhibitor also enhanced the glucose-induced insulin secretion in parallel with the upregulation of newcomer granule fusions, probably via increased motility of intracellular insulin granules. These data suggest that the PI3K-PDK1-Akt pathway plays a significant role in newcomer granule fusions, probably through an alteration of the dynamics of the intracellular insulin granules.
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Affiliation(s)
- Kyota Aoyagi
- Department of Biochemistry, Kyorin University School of Medicine, Tokyo, Japan
| | - Mica Ohara-Imaizumi
- Department of Biochemistry, Kyorin University School of Medicine, Tokyo, Japan
| | - Chiyono Nishiwaki
- Department of Biochemistry, Kyorin University School of Medicine, Tokyo, Japan
| | - Yoko Nakamichi
- Department of Biochemistry, Kyorin University School of Medicine, Tokyo, Japan
| | - Kohjiro Ueki
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Takashi Kadowaki
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Shinya Nagamatsu
- Department of Biochemistry, Kyorin University School of Medicine, Tokyo, Japan
- * E-mail:
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15
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Bansal P, Wang S, Liu S, Xiang YY, Lu WY, Wang Q. GABA coordinates with insulin in regulating secretory function in pancreatic INS-1 β-cells. PLoS One 2011; 6:e26225. [PMID: 22031825 PMCID: PMC3198728 DOI: 10.1371/journal.pone.0026225] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 09/22/2011] [Indexed: 11/18/2022] Open
Abstract
Pancreatic islet β-cells produce large amounts of γ-aminobutyric acid (GABA), which is co-released with insulin. GABA inhibits glucagon secretion by hyperpolarizing α-cells via type-A GABA receptors (GABA(A)Rs). We and others recently reported that islet β-cells also express GABA(A)Rs and that activation of GABA(A)Rs increases insulin release. Here we investigate the effects of insulin on the GABA-GABA(A)R system in the pancreatic INS-1 cells using perforated-patch recording. The results showed that GABA produces a rapid inward current and depolarizes INS-1 cells. However, pre-treatment of the cell with regular insulin (1 µM) suppressed the GABA-induced current (I(GABA)) by 43%. Zinc-free insulin also suppressed I(GABA) to the same extent of inhibition by regular insulin. The inhibition of I(GABA) occurs within 30 seconds after application of insulin. The insulin-induced inhibition of I(GABA) persisted in the presence of PI3-kinase inhibitor, but was abolished upon inhibition of ERK, indicating that insulin suppresses GABA(A)Rs through a mechanism that involves ERK activation. Radioimmunoassay revealed that the secretion of C-peptide was enhanced by GABA, which was blocked by pre-incubating the cells with picrotoxin (50 µM, p<0.01) and insulin (1 µM, p<0.01), respectively. Together, these data suggest that autocrine GABA, via activation of GABA(A)Rs, depolarizes the pancreatic β-cells and enhances insulin secretion. On the other hand, insulin down-regulates GABA-GABA(A)R signaling presenting a feedback mechanism for fine-tuning β-cell secretion.
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Affiliation(s)
- Paul Bansal
- Departments of Physiology and Medicine, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Division of Endocrinology and Metabolism, The Keenan Research Centre in the Li Ka-Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada
| | - Shuanglian Wang
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada
| | - Shenghao Liu
- Departments of Physiology and Medicine, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Division of Endocrinology and Metabolism, The Keenan Research Centre in the Li Ka-Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada
| | - Yun-Yan Xiang
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada
| | - Wei-Yang Lu
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada
- * E-mail: (W-YL); (QW)
| | - Qinghua Wang
- Departments of Physiology and Medicine, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Division of Endocrinology and Metabolism, The Keenan Research Centre in the Li Ka-Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada
- * E-mail: (W-YL); (QW)
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Sharma G, Prossnitz ER. Mechanisms of estradiol-induced insulin secretion by the G protein-coupled estrogen receptor GPR30/GPER in pancreatic beta-cells. Endocrinology 2011; 152:3030-9. [PMID: 21673097 PMCID: PMC3138237 DOI: 10.1210/en.2011-0091] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Sexual dimorphism and supplementation studies suggest an important role for estrogens in the amelioration of glucose intolerance and diabetes. Because little is known regarding the signaling mechanisms involved in estradiol-mediated insulin secretion, we investigated the role of the G protein-coupled receptor 30, now designated G protein-coupled estrogen receptor (GPER), in activating signal transduction cascades in β-cells, leading to secretion of insulin. GPER function in estradiol-induced signaling in the pancreatic β-cell line MIN6 was assessed using small interfering RNA and GPER-selective ligands (G-1 and G15) and in islets isolated from wild-type and GPER knockout mice. GPER is expressed in MIN6 cells, where estradiol and the GPER-selective agonist G-1 mediate calcium mobilization and activation of ERK and phosphatidylinositol 3-kinase. Both estradiol and G-1 induced insulin secretion under low- and high-glucose conditions, which was inhibited by pretreatment with GPER antagonist G15 as well as depletion of GPER by small interfering RNA. Insulin secretion in response to estradiol and G-1 was dependent on epidermal growth factor receptor and ERK activation and further modulated by phosphatidylinositol 3-kinase activity. In islets isolated from wild-type mice, the GPER antagonist G15 inhibited insulin secretion induced by estradiol and G-1, both of which failed to induce insulin secretion in islets obtained from GPER knockout mice. Our results indicate that GPER activation of the epidermal growth factor receptor and ERK in response to estradiol treatment plays a critical role in the secretion of insulin from β-cells. The results of this study suggest that the activation of downstream signaling pathways by the GPER-selective ligand G-1 could represent a novel therapeutic strategy in the treatment of diabetes.
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Affiliation(s)
- Geetanjali Sharma
- Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, USA
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Abstract
The appropriate function of insulin-producing pancreatic beta-cells is crucial for the regulation of glucose homeostasis, and its impairment leads to diabetes mellitus, the most common metabolic disorder in man. In addition to glucose, the major nutrient factor, inputs from the nervous system, humoral components, and cell-cell communication within the islet of Langerhans act together to guarantee the release of appropriate amounts of insulin in response to changes in blood glucose levels. Data obtained within the past decade in several laboratories have revitalized controversy over the autocrine feedback action of secreted insulin on beta-cell function. Although insulin historically has been suggested to exert a negative effect on beta-cells, recent data provide evidence for a positive role of insulin in transcription, translation, ion flux, insulin secretion, proliferation, and beta-cell survival. Current insights on the role of insulin on pancreatic beta-cell function are discussed.
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Affiliation(s)
- Ingo B Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden.
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Eckert DT, Zhang P, Collier JJ, O'Doherty RM, Scott DK. Detailed molecular analysis of the induction of the L-PK gene by glucose. Biochem Biophys Res Commun 2008; 372:131-6. [PMID: 18468514 DOI: 10.1016/j.bbrc.2008.05.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Accepted: 05/01/2008] [Indexed: 01/22/2023]
Abstract
Glucose has powerful effects on gene expression and participates in the fasted-to-fed transition of the liver. However, the molecular mechanism of glucose-regulated gene expression has not been completely described. In the present study, we performed a detailed analysis of the molecular events of the insulin-independent glucose response of the liver-type pyruvate kinase (L-PK) gene. L-PK mRNA was increased by glucose at the transcriptional level as determined by real-time RT-PCR, mRNA stability measurements, and nuclear run-on assays. LY294002 and LY303511 inhibited the glucose response of the L-PK gene at the transcriptional level. Histones H3 and H4 associated with the L-PK gene promoter were hyperacetylated and HNF4alpha was constitutively bound in low and high glucose. Treatment with 20mM glucose increased recruitment of ChREBP, additional HNF4alpha, and RNA polymerase II. Glucose-stimulated the phosphorylation of the C-terminal domain of RNA polymerase II, with increased Ser5 phosphorylation near the transcription start site and increased Ser2 phosphorylation near the termination signal. LY294002 and LY303511 blocked the recruitment of RNA polymerase II to the L-PK gene, reducing the rate of transcription. The results of these studies demonstrate fundamental details of the molecular mechanism of glucose activated gene expression.
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Affiliation(s)
- David T Eckert
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, New Orleans, LA, USA
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Cheng H, Straub SG, Sharp GWG. Inhibitory role of Src family tyrosine kinases on Ca2+-dependent insulin release. Am J Physiol Endocrinol Metab 2007; 292:E845-52. [PMID: 17122086 DOI: 10.1152/ajpendo.00103.2006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Both neurotransmitter release and insulin secretion occur via regulated exocytosis and share a variety of similar regulatory mechanisms. It has been suggested that Src family tyrosine kinases inhibit neurotransmitter release from neuronal cells (H. Ohnishi, S. Yamamori, K. Ono, K. Aoyagi, S. Kondo, and M. Takahashi. Proc Natl Acad Sci USA 98: 10930-10935, 2001). Thus the potential role of Src family kinases in the regulation of insulin secretion was investigated in this study. Two structurally different inhibitors of Src family kinases, SU-6656 and PP2, but not the inactive compound, PP3, enhanced Ca2+-induced insulin secretion in both rat pancreatic islets and INS-1 cells in a concentration-dependent and time-dependent manner. Furthermore, Src family kinase-mediated insulin secretion appears to be dependent on elevated intracellular Ca2+ and independent of glucose metabolism, the ATP-dependent K+ channel, adenylyl cyclase, classical PKC isoforms, extracellular signal-regulated kinase 1/2, and insulin synthesis. The sites of action for Src family kinases seem to be distal to the elevation of intracellular Ca2+ level. These results indicate that one or more Src family tyrosine kinases exert a tonic inhibitory role on Ca2+-dependent insulin secretion.
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Affiliation(s)
- Haiying Cheng
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853-6401, USA
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