1
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Schmidt MD, Ishahak M, Augsornworawat P, Millman JR. Comparative and integrative single cell analysis reveals new insights into the transcriptional immaturity of stem cell-derived β cells. BMC Genomics 2024; 25:105. [PMID: 38267908 PMCID: PMC10807170 DOI: 10.1186/s12864-024-10013-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 01/14/2024] [Indexed: 01/26/2024] Open
Abstract
Diabetes cell replacement therapy has the potential to be transformed by human pluripotent stem cell-derived β cells (SC-β cells). However, the precise identity of SC-β cells in relationship to primary fetal and adult β-cells remains unclear. Here, we used single-cell sequencing datasets to characterize the transcriptional identity of islets from in vitro differentiation, fetal islets, and adult islets. Our analysis revealed that SC-β cells share a core β-cell transcriptional identity with human adult and fetal β-cells, however SC-β cells possess a unique transcriptional profile characterized by the persistent expression and activation of progenitor and neural-biased gene networks. These networks are present in SC-β cells, irrespective of the derivation protocol used. Notably, fetal β-cells also exhibit this neural signature at the transcriptional level. Our findings offer insights into the transcriptional identity of SC-β cells and underscore the need for further investigation of the role of neural transcriptional networks in their development.
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Affiliation(s)
- Mason D Schmidt
- Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, MSC 8127-057-08, 660 South Euclid Avenue, St. Louis, MO, 63110, USA
| | - Matthew Ishahak
- Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, MSC 8127-057-08, 660 South Euclid Avenue, St. Louis, MO, 63110, USA
| | - Punn Augsornworawat
- Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, MSC 8127-057-08, 660 South Euclid Avenue, St. Louis, MO, 63110, USA
- Department of Biomedical Engineering, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO, 63130, USA
- Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand
| | - Jeffrey R Millman
- Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, MSC 8127-057-08, 660 South Euclid Avenue, St. Louis, MO, 63110, USA.
- Department of Biomedical Engineering, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO, 63130, USA.
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2
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Jin Z, Korol SV. GABA signalling in human pancreatic islets. Front Endocrinol (Lausanne) 2023; 14:1059110. [PMID: 36891061 PMCID: PMC9986413 DOI: 10.3389/fendo.2023.1059110] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 02/09/2023] [Indexed: 02/22/2023] Open
Abstract
The pancreatic islets are essential microorgans controlling the glucose level in the blood. The islets consist of different cell types which communicate with each other by means of auto- and paracrine interactions. One of the communication molecules produced by and released within the islets is γ-aminobutyric acid (GABA), a well-known inhibitor of neuronal excitability in the mammalian nervous system. Interestingly, GABA is also present in the blood in the nanomolar concentration range. Thus, GABA can affect not only islet function per se (e.g. hormone secretion) but also interactions between immune cells and the pancreatic islet cells in physiological conditions and in pathological states (particularly in type 1 diabetes). In the last decade the interest in GABA signalling in islets has increased. The broad research scope ranges from fundamental physiological studies at the molecular and cellular level to pathological implications and clinical trials. The aim of this mini-review is to outline the current status of the islet GABA field mostly in relation to human islets, to identify the gaps in the current knowledge and what clinical implications GABA signalling may have in islets.
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3
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Hagan DW, Ferreira SM, Santos GJ, Phelps EA. The role of GABA in islet function. Front Endocrinol (Lausanne) 2022; 13:972115. [PMID: 36246925 PMCID: PMC9558271 DOI: 10.3389/fendo.2022.972115] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 08/29/2022] [Indexed: 11/13/2022] Open
Abstract
Gamma aminobutyric acid (GABA) is a non-proteinogenic amino acid and neurotransmitter that is produced in the islet at levels as high as in the brain. GABA is synthesized by the enzyme glutamic acid decarboxylase (GAD), of which the 65 kDa isoform (GAD65) is a major autoantigen in type 1 diabetes. Originally described to be released via synaptic-like microvesicles or from insulin secretory vesicles, beta cells are now understood to release substantial quantities of GABA directly from the cytosol via volume-regulated anion channels (VRAC). Once released, GABA influences the activity of multiple islet cell types through ionotropic GABAA receptors and metabotropic GABAB receptors. GABA also interfaces with cellular metabolism and ATP production via the GABA shunt pathway. Beta cells become depleted of GABA in type 1 diabetes (in remaining beta cells) and type 2 diabetes, suggesting that loss or reduction of islet GABA correlates with diabetes pathogenesis and may contribute to dysfunction of alpha, beta, and delta cells in diabetic individuals. While the function of GABA in the nervous system is well-understood, the description of the islet GABA system is clouded by differing reports describing multiple secretion pathways and effector functions. This review will discuss and attempt to unify the major experimental results from over 40 years of literature characterizing the role of GABA in the islet.
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Affiliation(s)
- D. Walker Hagan
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States
| | - Sandra M. Ferreira
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States
| | - Gustavo J. Santos
- Islet Biology and Metabolism Lab – I.B.M. Lab, Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina - UFSC, Florianópolis, Brazil
| | - Edward A. Phelps
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States
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4
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Kamat V, Radtke JR, Hu Q, Wang W, Sweet IR, Hampe CS. Autoantibodies directed against glutamate decarboxylase interfere with glucose-stimulated insulin secretion in dispersed rat islets. Int J Exp Pathol 2022; 103:140-148. [PMID: 35246889 PMCID: PMC9264341 DOI: 10.1111/iep.12437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 01/17/2022] [Accepted: 02/20/2022] [Indexed: 11/28/2022] Open
Abstract
Islet autoantibodies, including autoantibodies directed against the 65kDa isoform of glutamate decarboxylase (GAD65Ab), are present in the majority of patients with newly diagnosed type 1 diabetes (T1D). Whereas these autoantibodies are historically viewed as an epiphenomenon of the autoimmune response with no significant pathogenic function, we consider in this study the possibility that they impact the major islet function, namely glucose-stimulated insulin secretion. Two human monoclonal GAD65Ab (GAD65 mAb) (b78 and b96.11) were investigated for uptake by live rat beta cells, subcellular localization and their effect on glucose-stimulated insulin secretion. The GAD65 mAbs were internalized by live pancreatic beta cells, where they localized to subcellular structures in an epitope-specific manner. Importantly, GAD65 mAb b78 inhibited, while GAD65 mAb b96.11 enhanced, glucose-stimulated insulin secretion (GSIS). These opposite effects on GSIS rule out non-specific effects of the antibodies and suggest that internalization of the antibody leads to epitope-specific interaction with intracellular machinery regulating insulin granule release. The most likely explanation for the alteration of GSIS by GAD65 Abs is via changes in GABA release due to inhibition or change in GAD65 enzyme activity. This is the first report indicating an active role of GAD65Ab in the pathogenesis of T1D.
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Affiliation(s)
- Varun Kamat
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Jared R Radtke
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Qingxun Hu
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, Washington, USA
| | - Wang Wang
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, Washington, USA
| | - Ian R Sweet
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Christiane S Hampe
- Department of Medicine, University of Washington, Seattle, Washington, USA
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5
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Shimizu-Okabe C, Okada S, Okamoto S, Masuzaki H, Takayama C. Specific Expression of KCC2 in the α Cells of Normal and Type 1 Diabetes Model Mouse Pancreatic Islets. Acta Histochem Cytochem 2022; 55:47-56. [PMID: 35444351 PMCID: PMC8913275 DOI: 10.1267/ahc.21-00078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 12/22/2021] [Indexed: 01/14/2023] Open
Abstract
Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter in the mature brain; however, it acts excitatory during development. This difference in action depends on the intracellular chloride ion concentration, primarily regulated by potassium chloride co-transporter2 (KCC2). Sufficient KCC2 expression results in its inhibitory action. GABA is also abundant in pancreatic islets, where it acts differentially on the islet cells, and is involved in carbohydrate metabolism. However, the mechanisms underlying the differential action remain unknown. We performed immunohistochemistry for glutamic acid decarboxylase (GAD), a synthetic enzyme for GABA, and KCC2 in normal adult islets. GAD was co-localized with insulin in β cells, whereas KCC2 was expressed in glucagon-positive α cells. These results are in line with previous observations that GABA decreases glucagon release but increases insulin release, and suggest that GABA and insulin may work together in reducing blood glucose levels under hyperglycemia. Next, we examined the streptozotocin-induced type1 diabetes mellitus mouse model. GAD and insulin expression levels were markedly decreased. KCC2 was expressed in glucagon-positive cells, whereas insulin- and somatostatin-positive cells were KCC2-negative. These findings suggest that in diabetes model, reduced GABA release may cause disinhibition of glucagon release, resulting in increased blood sugar levels and the maintenance of hyperglycemic state.
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Affiliation(s)
| | - Shigeki Okada
- Department of Molecular Anatomy, School of Medicine, University of the Ryukyus
| | - Shiki Okamoto
- Division of Endocrinology, Diabetes and Metabolism, Hematology, Rheumatology School of Medicine, University of the Ryukyus
| | - Hiroaki Masuzaki
- Division of Endocrinology, Diabetes and Metabolism, Hematology, Rheumatology School of Medicine, University of the Ryukyus
| | - Chitoshi Takayama
- Department of Molecular Anatomy, School of Medicine, University of the Ryukyus
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6
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Thompson B, Satin LS. Beta-Cell Ion Channels and Their Role in Regulating Insulin Secretion. Compr Physiol 2021; 11:1-21. [PMID: 34636409 PMCID: PMC8935893 DOI: 10.1002/cphy.c210004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Beta cells of the pancreatic islet express many different types of ion channels. These channels reside in the β-cell plasma membrane as well as subcellular organelles and their coordinated activity and sensitivity to metabolism regulate glucose-dependent insulin secretion. Here, we review the molecular nature, expression patterns, and functional roles of many β-cell channels, with an eye toward explaining the ionic basis of glucose-induced insulin secretion. Our primary focus is on KATP and voltage-gated Ca2+ channels as these primarily regulate insulin secretion; other channels in our view primarily help to sculpt the electrical patterns generated by activated β-cells or indirectly regulate metabolism. Lastly, we discuss why understanding the physiological roles played by ion channels is important for understanding the secretory defects that occur in type 2 diabetes. © 2021 American Physiological Society. Compr Physiol 11:1-21, 2021.
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7
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GABA B-Receptor Agonist-Based Immunotherapy for Type 1 Diabetes in NOD Mice. Biomedicines 2021; 9:biomedicines9010043. [PMID: 33418884 PMCID: PMC7825043 DOI: 10.3390/biomedicines9010043] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 12/26/2020] [Accepted: 12/30/2020] [Indexed: 12/17/2022] Open
Abstract
Some immune system cells express type A and/or type B γ-aminobutyric acid receptors (GABAA-Rs and/or GABAB-Rs). Treatment with GABA, which activates both GABAA-Rs and GABAB-Rs), and/or a GABAA-R-specific agonist inhibits disease progression in mouse models of type 1 diabetes (T1D), multiple sclerosis, rheumatoid arthritis, and COVID-19. Little is known about the clinical potential of specifically modulating GABAB-Rs. Here, we tested lesogaberan, a peripherally restricted GABAB-R agonist, as an interventive therapy in diabetic NOD mice. Lesogaberan treatment temporarily restored normoglycemia in most newly diabetic NOD mice. Combined treatment with a suboptimal dose of lesogaberan and proinsulin/alum immunization in newly diabetic NOD mice or a low-dose anti-CD3 in severely hyperglycemic NOD mice greatly increased T1D remission rates relative to each monotherapy. Mice receiving combined lesogaberan and anti-CD3 displayed improved glucose tolerance and, unlike mice that received anti-CD3 alone, had some islets with many insulin+ cells, suggesting that lesogaberan helped to rapidly inhibit β-cell destruction. Hence, GABAB-R-specific agonists may provide adjunct therapies for T1D. Finally, the analysis of microarray and RNA-Seq databases suggested that the expression of GABAB-Rs and GABAA-Rs, as well as GABA production/secretion-related genes, may be a more common feature of immune cells than currently recognized.
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8
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Chloride transporters and channels in β-cell physiology: revisiting a 40-year-old model. Biochem Soc Trans 2020; 47:1843-1855. [PMID: 31697318 PMCID: PMC6925527 DOI: 10.1042/bst20190513] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/14/2019] [Accepted: 10/17/2019] [Indexed: 12/13/2022]
Abstract
It is accepted that insulin-secreting β-cells release insulin in response to glucose even in the absence of functional ATP-sensitive K+ (KATP)-channels, which play a central role in a 'consensus model' of secretion broadly accepted and widely reproduced in textbooks. A major shortcoming of this consensus model is that it ignores any and all anionic mechanisms, known for more than 40 years, to modulate β-cell electrical activity and therefore insulin secretion. It is now clear that, in addition to metabolically regulated KATP-channels, β-cells are equipped with volume-regulated anion (Cl-) channels (VRAC) responsive to glucose concentrations in the range known to promote electrical activity and insulin secretion. In this context, the electrogenic efflux of Cl- through VRAC and other Cl- channels known to be expressed in β-cells results in depolarization because of an outwardly directed Cl- gradient established, maintained and regulated by the balance between Cl- transporters and channels. This review will provide a succinct historical perspective on the development of a complex hypothesis: Cl- transporters and channels modulate insulin secretion in response to nutrients.
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9
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Korol SV, Jin Z, Birnir B. GABA A Receptor-Mediated Currents and Hormone mRNAs in Cells Expressing More Than One Hormone Transcript in Intact Human Pancreatic Islets. Int J Mol Sci 2020; 21:E600. [PMID: 31963438 PMCID: PMC7013858 DOI: 10.3390/ijms21020600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 01/15/2020] [Accepted: 01/16/2020] [Indexed: 11/16/2022] Open
Abstract
In pancreatic islets, the major cell-types are α, β and δ cells. The γ-aminobutyric acid (GABA) signalling system is expressed in human pancreatic islets. In single hormone transcript-expressing cells, we have previously characterized the functional properties of islet GABAA receptors (iGABAARs). Here, we extended these studies to islet cells expressing mRNAs for more than one hormone and sought for correlation between iGABAAR activity level and relative mRNA expression ratio. The single-cell RT-PCR in combination with the patch-clamp current recordings was used to examine functional properties of iGABAARs in the multiple hormone mRNA-expressing cells. We detected cells expressing double (α/β, α/δ, β/δ cell-types) and triple (α/β/δ cell-type) hormone transcripts. The most common mixed-identity cell-type was the α/β group where the cells could be grouped into β- and α-like subgroups. The β-like cells had low GCG/INS expression ratio (<0.6) and significantly higher frequency of iGABAAR single-channel openings than the α-like cells where the GCG/INS expression ratio was high (>1.2). The hormone expression levels and iGABAAR single-channel characteristics varied in the α/β/δ cell-type. Clearly, multiple hormone transcripts can be expressed in islet cells whereas iGABAAR single-channel functional properties appear to be α or β cell specific.
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Affiliation(s)
- Sergiy V. Korol
- Department of Medical Cell Biology, Uppsala University, BMC, Box 593, 75124 Uppsala, Sweden; (Z.J.); (B.B.)
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10
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Yi Z, Waseem Ghani M, Ghani H, Jiang W, Waseem Birmani M, Ye L, Bin L, Cun LG, Lilong A, Mei X. Gimmicks of gamma-aminobutyric acid (GABA) in pancreatic β-cell regeneration through transdifferentiation of pancreatic α- to β-cells. Cell Biol Int 2020; 44:926-936. [PMID: 31903671 DOI: 10.1002/cbin.11302] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 01/04/2020] [Indexed: 02/06/2023]
Abstract
In vivo regeneration of lost or dysfunctional islet β cells can fulfill the promise of improved therapy for diabetic patients. To achieve this, many mitogenic factors have been attempted, including gamma-aminobutyric acid (GABA). GABA remarkably affects pancreatic islet cells' (α cells and β cells) function through paracrine and/or autocrine binding to its membrane receptors on these cells. GABA has also been studied for promoting the transformation of α cells to β cells. Nonetheless, the gimmickry of GABA-induced α-cell transformation to β cells has two different perspectives. On the one hand, GABA was found to induce α-cell transformation to β cells in vivo and insulin-secreting β-like cells in vitro. On the other hand, GABA treatment showed that it has no α- to β-cell transformation response. Here, we will summarize the physiological effects of GABA on pancreatic islet β cells with an emphasis on its regenerative effects for transdifferentiation of islet α cells to β cells. We will also critically discuss the controversial results about GABA-mediated transdifferentiation of α cells to β cells.
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Affiliation(s)
- Zhao Yi
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.,Department of Animal Breeding, Genetics and Reproduction, Agricultural Collage, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Muhammad Waseem Ghani
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.,Department of Animal Breeding, Genetics and Reproduction, Agricultural Collage, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Hammad Ghani
- Nawaz Sharif Medical College, University of Gujrat, Punjab, 50180, Pakistan
| | - Wu Jiang
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.,Department of Animal Breeding, Genetics and Reproduction, Agricultural Collage, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Muhammad Waseem Birmani
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Li Ye
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.,Department of Animal Breeding, Genetics and Reproduction, Agricultural Collage, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Liu Bin
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.,Department of Animal Breeding, Genetics and Reproduction, Agricultural Collage, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Lang Guan Cun
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.,Department of Animal Breeding, Genetics and Reproduction, Agricultural Collage, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - An Lilong
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Xiao Mei
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.,Department of Animal Breeding, Genetics and Reproduction, Agricultural Collage, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
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11
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Menegaz D, Hagan DW, Almaça J, Cianciaruso C, Rodriguez-Diaz R, Molina J, Dolan RM, Becker MW, Schwalie PC, Nano R, Lebreton F, Kang C, Sah R, Gaisano HY, Berggren PO, Baekkeskov S, Caicedo A, Phelps EA. Mechanism and effects of pulsatile GABA secretion from cytosolic pools in the human beta cell. Nat Metab 2019; 1:1110-1126. [PMID: 32432213 PMCID: PMC7236889 DOI: 10.1038/s42255-019-0135-7] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Pancreatic beta cells synthesize and secrete the neurotransmitter γ-aminobutyric acid (GABA) as a paracrine and autocrine signal to help regulate hormone secretion and islet homeostasis. Islet GABA release has classically been described as a secretory vesicle-mediated event. Yet, a limitation of the hypothesized vesicular GABA release from islets is the lack of expression of a vesicular GABA transporter in beta cells. Consequentially, GABA accumulates in the cytosol. Here we provide evidence that the human beta cell effluxes GABA from a cytosolic pool in a pulsatile manner, imposing a synchronizing rhythm on pulsatile insulin secretion. The volume regulatory anion channel (VRAC), functionally encoded by LRRC8A or Swell1, is critical for pulsatile GABA secretion. GABA content in beta cells is depleted and secretion is disrupted in islets from type 1 and type 2 diabetic patients, suggesting that loss of GABA as a synchronizing signal for hormone output may correlate with diabetes pathogenesis.
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Affiliation(s)
- Danusa Menegaz
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, USA
| | - D Walker Hagan
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Joana Almaça
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Chiara Cianciaruso
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Rayner Rodriguez-Diaz
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Judith Molina
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Robert M Dolan
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Matthew W Becker
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Petra C Schwalie
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Rita Nano
- Pancreatic Islet Processing Facility, Diabetes Research Institute, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Fanny Lebreton
- Cell Isolation and Transplantation Center, Faculty of Medicine, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Chen Kang
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO, USA
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Iowa, Carver College of Medicine, Iowa City, IA, USA
| | - Rajan Sah
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO, USA
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Iowa, Carver College of Medicine, Iowa City, IA, USA
| | - Herbert Y Gaisano
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Per-Olof Berggren
- Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, FL, USA
- The Rolf Luft Research Center for Diabetes & Endocrinology, Karolinska Institutet, Stockholm, Sweden
- Division of Integrative Biosciences and Biotechnology, WCU Program, University of Science and Technology, Pohang, Korea
| | - Steinunn Baekkeskov
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
- Departments of Medicine and Microbiology/Immunology, Diabetes Center, University of California San Francisco, San Francisco, CA, USA.
| | - Alejandro Caicedo
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, USA.
- Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, FL, USA.
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL, USA.
- Program in Neuroscience, Miller School of Medicine, University of Miami, Miami, FL, USA.
| | - Edward A Phelps
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA.
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
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12
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Neumann S, Boothman-Burrell L, Gowing EK, Jacobsen TA, Ahring PK, Young SL, Sandager-Nielsen K, Clarkson AN. The Delta-Subunit Selective GABA A Receptor Modulator, DS2, Improves Stroke Recovery via an Anti-inflammatory Mechanism. Front Neurosci 2019; 13:1133. [PMID: 31736685 PMCID: PMC6828610 DOI: 10.3389/fnins.2019.01133] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 10/07/2019] [Indexed: 12/22/2022] Open
Abstract
Inflammatory processes are known to contribute to tissue damage in the central nervous system (CNS) across a broad range of neurological conditions, including stroke. Gamma amino butyric acid (GABA), the main inhibitory neurotransmitter in the CNS, has been implicated in modulating peripheral immune responses by acting on GABA A receptors on antigen-presenting cells and lymphocytes. Here, we investigated the effects and mechanism of action of the delta-selective compound, DS2, to improve stroke recovery and modulate inflammation. We report a decrease in nuclear factor (NF)-κB activation in innate immune cells over a concentration range in vitro. Following a photochemically induced motor cortex stroke, treatment with DS2 at 0.1 mg/kg from 1 h post-stroke significantly decreased circulating tumor necrosis factor (TNF)-α, interleukin (IL)-17, and IL-6 levels, reduced infarct size and improved motor function in mice. Free brain concentrations of DS2 were found to be lower than needed for robust modulation of central GABA A receptors and were not affected by the presence and absence of elacridar, an inhibitor of both P-glycoprotein and breast cancer resistance protein (BCRP). Finally, as DS2 appears to dampen peripheral immune activation and only shows limited brain exposure, we assessed the role of DS2 to promote functional recovery after stroke when administered from 3-days after the stroke. Treatment with DS2 from 3-days post-stroke improved motor function on the grid-walking, but not on the cylinder task. These data highlight the need to further develop subunit-selective compounds to better understand change in GABA receptor signaling pathways both centrally and peripherally. Importantly, we show that GABA compounds such as DS2 that only shows limited brain exposure can still afford significant protection and promote functional recovery most likely via modulation of peripheral immune cells and could be given as an adjunct treatment.
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Affiliation(s)
- Silke Neumann
- Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand.,Department of Anatomy, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Dunedin, New Zealand
| | - Lily Boothman-Burrell
- Department of Anatomy, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Dunedin, New Zealand
| | - Emma K Gowing
- Department of Anatomy, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Dunedin, New Zealand
| | | | - Philip K Ahring
- School of Pharmacy, University of Sydney, Sydney, NSW, Australia
| | - Sarah L Young
- Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | | | - Andrew N Clarkson
- Department of Anatomy, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Dunedin, New Zealand
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13
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Tian J, Dang H, O'Laco KA, Song M, Tiu BC, Gilles S, Zakarian C, Kaufman DL. Homotaurine Treatment Enhances CD4 + and CD8 + Regulatory T Cell Responses and Synergizes with Low-Dose Anti-CD3 to Enhance Diabetes Remission in Type 1 Diabetic Mice. Immunohorizons 2019; 3:498-510. [PMID: 31636084 PMCID: PMC6823932 DOI: 10.4049/immunohorizons.1900019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 10/02/2019] [Indexed: 12/16/2022] Open
Abstract
Immune cells express γ-aminobutyric acid receptors (GABA-R), and GABA administration can inhibit effector T cell responses in models of autoimmune disease. The pharmacokinetic properties of GABA, however, may be suboptimal for clinical applications. The amino acid homotaurine is a type A GABA-R (GABAA-R) agonist with good pharmacokinetics and appears safe for human consumption. In this study, we show that homotaurine inhibits in vitro T cell proliferation to a similar degree as GABA but at lower concentrations. In vivo, oral homotaurine treatment had a modest ability to reverse hyperglycemia in newly hyperglycemic NOD mice but was ineffective after the onset of severe hyperglycemia. In severely diabetic NOD mice, the combination of homotaurine and low-dose anti-CD3 treatment significantly increased 1) disease remission, 2) the percentages of splenic CD4+ and CD8+ regulatory T cells compared with anti-CD3 alone, and 3) the frequencies of CD4+ and CD8+ regulatory T cells in the pancreatic lymph nodes compared with homotaurine monotherapy. Histological examination of their pancreata provided no evidence of the large-scale GABAA-R agonist–mediated replenishment of islet β-cells that has been reported by others. However, we did observe a few functional islets in mice that received combined therapy. Thus, GABAA-R activation enhanced CD4+ and CD8+ regulatory T cell responses following the depletion of effector T cells, which was associated with the preservation of some functional islets. Finally, we observed that homotaurine treatment enhanced β-cell replication and survival in a human islet xenograft model. Hence, GABAA-R agonists, such as homotaurine, are attractive candidates for testing in combination with other therapeutic agents in type 1 diabetes clinical trials.
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Affiliation(s)
- Jide Tian
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, Los Angeles, CA 90095
| | - Hoa Dang
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, Los Angeles, CA 90095
| | - Karen Anne O'Laco
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, Los Angeles, CA 90095
| | - Min Song
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, Los Angeles, CA 90095
| | - Bryan-Clement Tiu
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, Los Angeles, CA 90095
| | - Spencer Gilles
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, Los Angeles, CA 90095
| | - Christina Zakarian
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, Los Angeles, CA 90095
| | - Daniel L Kaufman
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, Los Angeles, CA 90095
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14
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Wang Q, Ren L, Wan Y, Prud'homme GJ. GABAergic regulation of pancreatic islet cells: Physiology and antidiabetic effects. J Cell Physiol 2019; 234:14432-14444. [PMID: 30693506 DOI: 10.1002/jcp.28214] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 01/15/2019] [Indexed: 01/24/2023]
Abstract
Diabetes occurs when pancreatic β-cell death exceeds β-cell growth, which leads to loss of β-cell mass. An effective therapy must have two actions: promotion of β-cell replication and suppression of β-cell death. Previous studies have established an important role for γ-aminobutyric acid (GABA) in islet-cell hormone homeostasis, as well as the maintenance of the β-cell mass. GABA exerts paracrine actions on α cells in suppressing glucagon secretion, and it has autocrine actions on β cells that increase insulin secretion. Multiple studies have shown that GABA increases the mitotic rate of β cells. In mice, following β-cell depletion with streptozotocin, GABA therapy can restore the β-cell mass. Enhanced β-cell replication appears to depend on growth and survival pathways involving Akt activation. Some studies have also suggested that it induces transdifferentiation of α cells into β cells, but this has been disputed and requires further investigation. In addition to proliferative effects, GABA protects β cells against injury and markedly reduces their apoptosis under a variety of conditions. The antiapoptotic effects depend at least in part on the enhancement of sirtuin-1 and Klotho activity, which both inhibit activation of the NF-κB inflammatory pathway. Importantly, in xenotransplanted human islets, GABA therapy stimulates β-cell replication and insulin secretion. Thus, the intraislet GABAergic system is a target for the amelioration of diabetes therapy, including β-cell survival and regeneration. GABA (or GABAergic drugs) can be combined with other antidiabetic drugs for greater effect.
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Affiliation(s)
- Qinghua Wang
- Department of Endocrinology and Metabolism, Huashan Hospital, Shanghai Medical School, Fudan University, Shanghai, China.,Keenan Research Centre for Biomedical Science, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.,Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Liwei Ren
- Department of Endocrinology and Metabolism, Huashan Hospital, Shanghai Medical School, Fudan University, Shanghai, China
| | - Yun Wan
- Department of Endocrinology and Metabolism, Huashan Hospital, Shanghai Medical School, Fudan University, Shanghai, China
| | - Gerald J Prud'homme
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.,Department of Laboratory Medicine, St. Michael's Hospital, Toronto, Ontario, Canada
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15
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Mathies LD, Ray S, Lopez-Alvillar K, Arbeitman MN, Davies AG, Bettinger JC. mRNA profiling reveals significant transcriptional differences between a multipotent progenitor and its differentiated sister. BMC Genomics 2019; 20:427. [PMID: 31138122 PMCID: PMC6540470 DOI: 10.1186/s12864-019-5821-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 05/21/2019] [Indexed: 12/15/2022] Open
Abstract
Background The two Caenorhabditis elegans somatic gonadal precursors (SGPs) are multipotent progenitors that generate all somatic tissues of the adult reproductive system. The sister cells of the SGPs are two head mesodermal cells (hmcs); one hmc dies by programmed cell death and the other terminally differentiates. Thus, a single cell division gives rise to one multipotent progenitor and one differentiated cell with identical lineage histories. We compared the transcriptomes of SGPs and hmcs in order to learn the determinants of multipotency and differentiation in this lineage. Results We generated a strain that expressed fluorescent markers specifically in SGPs (ehn-3A::tdTomato) and hmcs (bgal-1::GFP). We dissociated cells from animals after the SGP/hmc cell division, but before the SGPs had further divided, and subjected the dissociated cells to fluorescence-activated cell sorting to collect isolated SGPs and hmcs. We analyzed the transcriptomes of these cells and found that 5912 transcripts were significantly differentially expressed, with at least two-fold change in expression, between the two cell types. The hmc-biased genes were enriched with those that are characteristic of neurons. The SGP-biased genes were enriched with those indicative of cell proliferation and development. We assessed the validity of our differentially expressed genes by examining existing reporters for five of the 10 genes with the most significantly biased expression in SGPs and found that two showed expression in SGPs. For one reporter that did not show expression in SGPs, we generated a GFP knock-in using CRISPR/Cas9. This reporter, in the native genomic context, was expressed in SGPs. Conclusions We found that the transcriptional profiles of SGPs and hmcs are strikingly different. The hmc-biased genes are enriched with those that encode synaptic transmission machinery, which strongly suggests that it has neuron-like signaling properties. In contrast, the SGP-biased genes are enriched with genes that encode factors involved in transcription and translation, as would be expected from a cell preparing to undergo proliferative divisions. Mediators of multipotency are likely to be among the genes differentially expressed in SGPs. Electronic supplementary material The online version of this article (10.1186/s12864-019-5821-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Laura D Mathies
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, PO Box 980613, Richmond, VA, 23298, USA.
| | - Surjyendu Ray
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL, 32306, USA
| | - Kayla Lopez-Alvillar
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, PO Box 980613, Richmond, VA, 23298, USA
| | - Michelle N Arbeitman
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL, 32306, USA
| | - Andrew G Davies
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, PO Box 980613, Richmond, VA, 23298, USA
| | - Jill C Bettinger
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, PO Box 980613, Richmond, VA, 23298, USA
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16
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Untereiner A, Abdo S, Bhattacharjee A, Gohil H, Pourasgari F, Ibeh N, Lai M, Batchuluun B, Wong A, Khuu N, Liu Y, Al Rijjal D, Winegarden N, Virtanen C, Orser BA, Cabrera O, Varga G, Rocheleau J, Dai FF, Wheeler MB. GABA promotes β-cell proliferation, but does not overcome impaired glucose homeostasis associated with diet-induced obesity. FASEB J 2018; 33:3968-3984. [PMID: 30509117 DOI: 10.1096/fj.201801397r] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
γ-Aminobutyric acid (GABA) administration has been shown to increase β-cell mass, leading to a reversal of type 1 diabetes in mice. Whether GABA has any effect on β cells of healthy and prediabetic/glucose-intolerant obese mice remains unknown. In the present study, we show that oral GABA administration ( ad libitum) to mice indeed increased pancreatic β-cell mass, which led to a modest enhancement in insulin secretion and glucose tolerance. However, GABA treatment did not further increase insulin-positive islet area in high fat diet-fed mice and was unable to prevent or reverse glucose intolerance and insulin resistance. Mechanistically, whether in vivo or in vitro, GABA treatment increased β-cell proliferation. In vitro, the effect was shown to be mediated via the GABAA receptor. Single-cell RNA sequencing analysis revealed that GABA preferentially up-regulated pathways linked to β-cell proliferation and simultaneously down-regulated those networks required for other processes, including insulin biosynthesis and metabolism. Interestingly, single-cell differential expression analysis revealed GABA treatment gave rise to a distinct subpopulation of β cells with a unique transcriptional signature, including urocortin 3 ( ucn3), wnt4, and hepacam2. Taken together, this study provides new mechanistic insight into the proliferative nature of GABA but suggests that β-cell compensation associated with prediabetes overlaps with, and negates, its proliferative effects.-Untereiner, A., Abdo, S., Bhattacharjee, A., Gohil, H., Pourasgari, F., Ibeh, N., Lai, M., Batchuluun, B., Wong, A., Khuu, N., Liu, Y., Al Rijjal, D., Winegarden, N., Virtanen, C., Orser, B. A., Cabrera, O., Varga, G., Rocheleau, J., Dai, F. F., Wheeler, M. B. GABA promotes β-cell proliferation, but does not overcome impaired glucose homeostasis associated with diet-induced obesity.
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Affiliation(s)
- Ashley Untereiner
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Shaaban Abdo
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Alpana Bhattacharjee
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Himaben Gohil
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | | | - Neke Ibeh
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Mi Lai
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | | | - Anthony Wong
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Nicholas Khuu
- Princess Margaret Genomics Centre, University Health Network, Toronto, Ontario, Canada
| | - Ying Liu
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Dana Al Rijjal
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Neil Winegarden
- Princess Margaret Genomics Centre, University Health Network, Toronto, Ontario, Canada
| | - Carl Virtanen
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Beverley A Orser
- Department of Anesthesia, University of Toronto, Toronto, Ontario, Canada
| | - Over Cabrera
- Diabetes and Complications Research, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana, USA
| | - Gabor Varga
- Diabetes and Complications Research, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana, USA
| | - Jonathan Rocheleau
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada.,Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Feihan F Dai
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada.,Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Michael B Wheeler
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada.,Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
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17
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Functional Characterization of Native, High-Affinity GABA A Receptors in Human Pancreatic β Cells. EBioMedicine 2018; 30:273-282. [PMID: 29606630 PMCID: PMC5952339 DOI: 10.1016/j.ebiom.2018.03.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Revised: 02/02/2018] [Accepted: 03/12/2018] [Indexed: 01/19/2023] Open
Abstract
In human pancreatic islets, the neurotransmitter γ-aminobutyric acid (GABA) is an extracellular signaling molecule synthesized by and released from the insulin-secreting β cells. The effective, physiological GABA concentration range within human islets is unknown. Here we use native GABAA receptors in human islet β cells as biological sensors and reveal that 100–1000 nM GABA elicit the maximal opening frequency of the single-channels. In saturating GABA, the channels desensitized and stopped working. GABA modulated insulin exocytosis and glucose-stimulated insulin secretion. GABAA receptor currents were enhanced by the benzodiazepine diazepam, the anesthetic propofol and the incretin glucagon-like peptide-1 (GLP-1) but not affected by the hypnotic zolpidem. In type 2 diabetes (T2D) islets, single-channel analysis revealed higher GABA affinity of the receptors. The findings reveal unique GABAA receptors signaling in human islets β cells that is GABA concentration-dependent, differentially regulated by drugs, modulates insulin secretion and is altered in T2D. In human islets GABA (≤μM) activates β cell-specific GABAA receptors that become supersensitive to GABA in type 2 diabetes. GABAA receptors activity in β cells is enhanced by diazepam, anesthetics, the incretin GLP-1 but not the hypnotic zolpidem. GABA modulates rate of insulin granule exocytosis and glucose-stimulated insulin secretion.
GABA is a signal molecule in the brain but is also secreted by the insulin-producing β cells in pancreatic islets. GABA has many roles in human islets that most aim at optimizing function and survival of β cells. In the report by Korol, Jin et al. the authors identify and characterize the molecular unit that GABA binds to in human β cells, the GABAA receptors. These receptors normally sensitive become super-sensitive to GABA in type 2 diabetes. The GABAA receptors regulate insulin secretion and can themselves be regulated by the anxiolytic diazepam, anesthetics, the incretin GLP-1 but not the hypnotic zolpidem. Targeting GABA signaling in human islets in diabetes mellitus is likely to be a part of the solution when curing diabetes.
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18
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Rorsman P, Ashcroft FM. Pancreatic β-Cell Electrical Activity and Insulin Secretion: Of Mice and Men. Physiol Rev 2018; 98:117-214. [PMID: 29212789 PMCID: PMC5866358 DOI: 10.1152/physrev.00008.2017] [Citation(s) in RCA: 430] [Impact Index Per Article: 71.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/30/2017] [Accepted: 06/18/2017] [Indexed: 12/14/2022] Open
Abstract
The pancreatic β-cell plays a key role in glucose homeostasis by secreting insulin, the only hormone capable of lowering the blood glucose concentration. Impaired insulin secretion results in the chronic hyperglycemia that characterizes type 2 diabetes (T2DM), which currently afflicts >450 million people worldwide. The healthy β-cell acts as a glucose sensor matching its output to the circulating glucose concentration. It does so via metabolically induced changes in electrical activity, which culminate in an increase in the cytoplasmic Ca2+ concentration and initiation of Ca2+-dependent exocytosis of insulin-containing secretory granules. Here, we review recent advances in our understanding of the β-cell transcriptome, electrical activity, and insulin exocytosis. We highlight salient differences between mouse and human β-cells, provide models of how the different ion channels contribute to their electrical activity and insulin secretion, and conclude by discussing how these processes become perturbed in T2DM.
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Affiliation(s)
- Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom; Department of Neuroscience and Physiology, Metabolic Research Unit, Göteborg, Sweden; and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Frances M Ashcroft
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom; Department of Neuroscience and Physiology, Metabolic Research Unit, Göteborg, Sweden; and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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19
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Indrowati M, Pratiwi R, Rumiyati, Astuti P. Levels of Blood Glucose and Insulin Expression of Beta-cells in Streptozotocin-induced Diabetic Rats Treated with Ethanolic Extract of Artocarpus altilis Leaves and GABA. Pak J Biol Sci 2017; 20:28-35. [PMID: 29023012 DOI: 10.3923/pjbs.2017.28.35] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND AND OBJECTIVE Information about the Artocarpus altilis leaf as an antidiabetic associated with the active compounds Gamma Amino Butyric Acid (GABA) is still limited. This study was conducted to determine the effects of ethanolic extract of A. altilis leaves decoction and GABA on blood glucose levels and insulin expression of beta-cells in streptozotocin-induced diabetic rats. MATERIAL AND METHODS This study was done by using completely randomized design and male Sprague Dewley rats. The rats were devided into normal control group and diabetic rats groups. Levels of bood glucose were measured using strip rapid test. The insulin expression in beta-cells was assessed using immunohistochemistry. Quantitative data were analyzed using ANOVA at 5% confidence level. RESULTS The result indicated that 50 mg k-1 b.wt., GABA, 400 and 800 mg k-1 b.wt., ethanolic extract of A. altilis leaves decreased the level of blood glucose and increased the insulin expression in pancreas beta-cells. CONCLUSION The GABA and ethanolic extract of A. altilis leaves with a minimum dose of 400 mg k-1 b.wt., can be used as an antidiabetic. Pancreas is the target organ was affected by GABA and A. altilis leaves as antidiabetic agents. Results of this study may support the development of research on the potency of GABA in natural materials as antidiabetic particularly type 1 diabetes.
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Affiliation(s)
- Meti Indrowati
- Department of Biological Education, Faculty of Teacher Training and Education, Universitas Sebelas Maret, Jalan Ir. Sutami 36A 57126, Surakarta, Indonesia
| | - Rarastoeti Pratiwi
- Faculty of Biology, Universitas Gadjah Mada, Jalan Te knika Selatan Sekip Utara, 55281 Yogyakarta, Indonesia
| | - Rumiyati
- Faculty of Pharmacy, Universitas Gadj ah Mada, 55281 Yogyakarta, Indonesia
| | - Pudji Astuti
- Faculty of Veterinary Medicine, Universitas Gadjah Mada, Jalan Fauna No. 2, Karangmalang, 55281 Yogyakarta, Indonesia
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20
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Tian J, Dang H, Hu A, Xu W, Kaufman DL. Repurposing Lesogaberan to Promote Human Islet Cell Survival and β-Cell Replication. J Diabetes Res 2017; 2017:6403539. [PMID: 29018828 PMCID: PMC5605788 DOI: 10.1155/2017/6403539] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 07/26/2017] [Indexed: 12/15/2022] Open
Abstract
The activation of β-cell's A- and B-type gamma-aminobutyric acid receptors (GABAA-Rs and GABAB-Rs) can promote their survival and replication, and the activation of α-cell GABAA-Rs promotes their conversion into β-cells. However, GABA and the most clinically applicable GABA-R ligands may be suboptimal for the long-term treatment of diabetes due to their pharmacological properties or potential side-effects on the central nervous system (CNS). Lesogaberan (AZD3355) is a peripherally restricted high-affinity GABAB-R-specific agonist, originally developed for the treatment of gastroesophageal reflux disease (GERD) that appears to be safe for human use. This study tested the hypothesis that lesogaberan could be repurposed to promote human islet cell survival and β-cell replication. Treatment with lesogaberan significantly enhanced replication of human islet cells in vitro, which was abrogated by a GABAB-R antagonist. Immunohistochemical analysis of human islets that were grafted into immune-deficient mice revealed that oral treatment with lesogaberan promoted human β-cell replication and islet cell survival in vivo as effectively as GABA (which activates both GABAA-Rs and GABAB-Rs), perhaps because of its more favorable pharmacokinetics. Lesogaberan may be a promising drug candidate for clinical studies of diabetes intervention and islet transplantation.
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Affiliation(s)
- Jide Tian
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
| | - Hoa Dang
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
| | - Angela Hu
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
| | - Willem Xu
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
| | - Daniel L. Kaufman
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
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21
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Nikmaram N, Dar BN, Roohinejad S, Koubaa M, Barba FJ, Greiner R, Johnson SK. Recent advances in γ-aminobutyric acid (GABA) properties in pulses: an overview. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2017; 97:2681-2689. [PMID: 28230263 DOI: 10.1002/jsfa.8283] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 02/06/2017] [Accepted: 02/15/2017] [Indexed: 06/06/2023]
Abstract
Beans, peas, and lentils are all types of pulses that are extensively used as foods around the world due to their beneficial effects on human health including their low glycaemic index, cholesterol lowering effects, ability to decrease the risk of heart diseases and their protective effects against some cancers. These health benefits are a result of their components such as bioactive proteins, dietary fibre, slowly digested starches, minerals and vitamins, and bioactive compounds. Among these bioactive compounds, γ-aminobutyric acid (GABA), a non-proteinogenic amino acid with numerous reported health benefits (e.g. anti-diabetic and hypotensive effects, depression and anxiety reduction) is of particular interest. GABA is primarily synthesised in plant tissues by the decarboxylation of l-glutamic acid in the presence of glutamate decarboxylase (GAD). It is widely reported that during various processes including enzymatic treatment, gaseous treatment (e.g. with carbon dioxide), and fermentation (with lactic acid bacteria), GABA content increases in the plant matrix. The objective of this review paper is to highlight the current state of knowledge on the occurrence of GABA in pulses with special focus on mechanisms by which GABA levels are increased and the analytical extraction and estimation methods for this bioactive phytochemical. © 2017 Society of Chemical Industry.
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Affiliation(s)
- Nooshin Nikmaram
- Young Researchers and Elite Club, Islamic Azad University, Sabzevar, Iran
| | - B N Dar
- Department of Food Technology, IUST, Awantipora, Jammu and Kashmir, India
- Department of Food Science, Cornell University, Ithaca, NY, USA
| | - Shahin Roohinejad
- Department of Food Technology and Bioprocess Engineering, Federal Research Institute of Nutrition and Food, Karlsruhe, Germany
- Burn and Wound Healing Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohamed Koubaa
- Département de Génie des Procédés Industriels, Laboratoire Transformations Intégrées de la Matière Renouvelable, Université de Technologie de Compiègne, France
| | - Francisco J Barba
- Preventive Medicine and Public Health, Food Sciences, Toxicology and Forensic Medicine Department, University of Valencia, Burjassot, València, Spain
| | - Ralf Greiner
- Department of Food Technology and Bioprocess Engineering, Federal Research Institute of Nutrition and Food, Karlsruhe, Germany
| | - Stuart K Johnson
- School of Public Health, Curtin University, Perth, WA, Australia
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22
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Yan-Do R, Duong E, Manning Fox JE, Dai X, Suzuki K, Khan S, Bautista A, Ferdaoussi M, Lyon J, Wu X, Cheley S, MacDonald PE, Braun M. A Glycine-Insulin Autocrine Feedback Loop Enhances Insulin Secretion From Human β-Cells and Is Impaired in Type 2 Diabetes. Diabetes 2016; 65:2311-21. [PMID: 27207556 DOI: 10.2337/db15-1272] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 04/26/2016] [Indexed: 11/13/2022]
Abstract
The secretion of insulin from pancreatic islet β-cells is critical for glucose homeostasis. Disrupted insulin secretion underlies almost all forms of diabetes, including the most common form, type 2 diabetes (T2D). The control of insulin secretion is complex and affected by circulating nutrients, neuronal inputs, and local signaling. In the current study, we examined the contribution of glycine, an amino acid and neurotransmitter that activates ligand-gated Cl(-) currents, to insulin secretion from islets of human donors with and without T2D. We find that human islet β-cells express glycine receptors (GlyR), notably the GlyRα1 subunit, and the glycine transporter (GlyT) isoforms GlyT1 and GlyT2. β-Cells exhibit significant glycine-induced Cl(-) currents that promote membrane depolarization, Ca(2+) entry, and insulin secretion from β-cells from donors without T2D. However, GlyRα1 expression and glycine-induced currents are reduced in β-cells from donors with T2D. Glycine is actively cleared by the GlyT expressed within β-cells, which store and release glycine that acts in an autocrine manner. Finally, a significant positive relationship exists between insulin and GlyR, because insulin enhances the glycine-activated current in a phosphoinositide 3-kinase-dependent manner, a positive feedback loop that we find is completely lost in β-cells from donors with T2D.
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Affiliation(s)
- Richard Yan-Do
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Eric Duong
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Jocelyn E Manning Fox
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Xiaoqing Dai
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Kunimasa Suzuki
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Shara Khan
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Austin Bautista
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Mourad Ferdaoussi
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - James Lyon
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Xichen Wu
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Stephen Cheley
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Patrick E MacDonald
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Matthias Braun
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
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23
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Gylfe E. Glucose control of glucagon secretion-'There's a brand-new gimmick every year'. Ups J Med Sci 2016; 121:120-32. [PMID: 27044660 PMCID: PMC4900067 DOI: 10.3109/03009734.2016.1154905] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 02/10/2016] [Accepted: 02/11/2016] [Indexed: 11/13/2022] Open
Abstract
Glucagon from the pancreatic α-cells is a major blood glucose-regulating hormone whose most important role is to prevent hypoglycaemia that can be life-threatening due to the brain's strong dependence on glucose as energy source. Lack of blood glucose-lowering insulin after malfunction or autoimmune destruction of the pancreatic β-cells is the recognized cause of diabetes, but recent evidence indicates that diabetic hyperglycaemia would not develop unless lack of insulin was accompanied by hypersecretion of glucagon. Glucagon release has therefore become an increasingly important target in diabetes management. Despite decades of research, an understanding of how glucagon secretion is regulated remains elusive, and fundamentally different mechanisms continue to be proposed. The autonomous nervous system is an important determinant of glucagon release, but it is clear that secretion is also directly regulated within the pancreatic islets. The present review focuses on pancreatic islet mechanisms involved in glucose regulation of glucagon release. It will be argued that α-cell-intrinsic processes are most important for regulation of glucagon release during recovery from hypoglycaemia and that paracrine inhibition by somatostatin from the δ-cells shapes pulsatile glucagon release in hyperglycaemia. The electrically coupled β-cells ultimately determine islet hormone pulsatility by releasing synchronizing factors that affect the α- and δ-cells.
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Affiliation(s)
- Erik Gylfe
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
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24
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Li J, Zhang Z, Liu X, Wang Y, Mao F, Mao J, Lu X, Jiang D, Wan Y, Lv JY, Cao G, Zhang J, Zhao N, Atkinson M, Greiner DL, Prud'homme GJ, Jiao Z, Li Y, Wang Q. Study of GABA in Healthy Volunteers: Pharmacokinetics and Pharmacodynamics. Front Pharmacol 2015; 6:260. [PMID: 26617516 PMCID: PMC4639630 DOI: 10.3389/fphar.2015.00260] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 10/20/2015] [Indexed: 01/13/2023] Open
Abstract
Preclinical studies show that GABA exerts anti-diabetic effects in rodent models of type 1 diabetes. Because little is known about its absorption and effects in humans, we investigated the pharmacokinetics and pharmacodynamics of GABA in healthy volunteers. Twelve subjects were subjected to an open-labeled, three-period trial involving sequential oral administration of placebo, 2 g GABA once, and 2 g GABA three times/day for 7 days, with a 7-day washout between each period. GABA was rapidly absorbed (Tmax: 0.5 ~ 1 h) with the half-life (t1/2) of 5 h. No accumulation was observed after repeated oral GABA administration for 7 days. Remarkably, GABA significantly increased circulating insulin levels in the subjects under either fasting (1.6-fold, single dose; 2.0-fold, repeated dose; p < 0.01) or fed conditions (1.4-fold, single dose; 1.6-fold, repeated dose; p < 0.01). GABA also increased glucagon levels only under fasting conditions (1.3-fold, single dose, p < 0.05; 1.5-fold, repeated dose, p < 0.01). However, there were no significant differences in the insulin-to-glucagon ratio and no significant change in glucose levels in these healthy subjects during the study period. Importantly, GABA significantly decreased glycated albumin levels in the repeated dosing period. Subjects with repeated dosing showed an elevated incidence of minor adverse events in comparison to placebo or the single dosing period, most notably transient discomforts such as dizziness and sore throat. However, there were no serious adverse events observed throughout the study. Our data show that GABA is rapidly absorbed and tolerated in human beings; its endocrine effects, exemplified by increasing islet hormonal secretion, suggest potential therapeutic benefits for diabetes.
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Affiliation(s)
- Junfeng Li
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University Shanghai, China
| | - Zhaoyun Zhang
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University Shanghai, China
| | - Xiaoxia Liu
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University Shanghai, China
| | - Yi Wang
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University Shanghai, China
| | - Fei Mao
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University Shanghai, China
| | - Junjun Mao
- Department of Pharmacy, Huashan Hospital, Fudan University Shanghai, China
| | - Xiaolan Lu
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University Shanghai, China
| | - Dongdong Jiang
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University Shanghai, China
| | - Yun Wan
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University Shanghai, China
| | - Jia-Ying Lv
- Department of Biostatistics, School of Public Health, Fudan University Shanghai, China
| | - Guoying Cao
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Institute of Antibiotics, Huashan Hospital, Fudan University Shanghai, China
| | - Jing Zhang
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Institute of Antibiotics, Huashan Hospital, Fudan University Shanghai, China
| | - Naiqing Zhao
- Department of Biostatistics, School of Public Health, Fudan University Shanghai, China
| | - Mark Atkinson
- Department of Pathology, College of Medicine, University of Florida Gainesville, FL, USA
| | - Dale L Greiner
- Department of Molecular Medicine, University of Massachusetts Medical School Worcester, MA, USA
| | - Gerald J Prud'homme
- Department of Laboratory Medicine and Pathobiology, Keenan Research Centre for Biomedical Science of St. Michael's Hospital, University of Toronto Toronto, ON, Canada
| | - Zheng Jiao
- Department of Pharmacy, Huashan Hospital, Fudan University Shanghai, China
| | - Yiming Li
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University Shanghai, China
| | - Qinghua Wang
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University Shanghai, China ; Division of Endocrinology and Metabolism, The Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital Toronto, ON, Canada ; Department of Physiology and Medicine, University of Toronto ON, Canada
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25
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Arrojo e Drigo R, Ali Y, Diez J, Srinivasan DK, Berggren PO, Boehm BO. New insights into the architecture of the islet of Langerhans: a focused cross-species assessment. Diabetologia 2015. [PMID: 26215305 DOI: 10.1007/s00125-015-3699-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The human genome project and its search for factors underlying human diseases has fostered a major human research effort. Therefore, unsurprisingly, in recent years we have observed an increasing number of studies on human islet cells, including disease approaches focusing on type 1 and type 2 diabetes. Yet, the field of islet and diabetes research relies on the legacy of rodent-based investigations, which have proven difficult to translate to humans, particularly in type 1 diabetes. Whole islet physiology and pathology may differ between rodents and humans, and thus a comprehensive cross-species as well as species-specific view on islet research is much needed. In this review we summarise the current knowledge of interspecies islet cytoarchitecture, and discuss its potential impact on islet function and future perspectives in islet pathophysiology research.
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Affiliation(s)
- Rafael Arrojo e Drigo
- Lee Kong Chian School of Medicine, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, Level 4, 637 553, Singapore, Singapore
| | - Yusuf Ali
- Lee Kong Chian School of Medicine, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, Level 4, 637 553, Singapore, Singapore
| | - Juan Diez
- Lee Kong Chian School of Medicine, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, Level 4, 637 553, Singapore, Singapore
| | - Dinesh Kumar Srinivasan
- Lee Kong Chian School of Medicine, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, Level 4, 637 553, Singapore, Singapore
| | - Per-Olof Berggren
- Lee Kong Chian School of Medicine, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, Level 4, 637 553, Singapore, Singapore.
- Imperial College London, London, UK.
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska University Hospital L1, Karolinska Institutet, SE-171 76, Stockholm, Sweden.
| | - Bernhard O Boehm
- Lee Kong Chian School of Medicine, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, Level 4, 637 553, Singapore, Singapore.
- Imperial College London, London, UK.
- Department of Internal Medicine 1, Ulm University Medical Centre, Ulm, Germany.
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Di Cairano ES, Moretti S, Marciani P, Sacchi VF, Castagna M, Davalli A, Folli F, Perego C. Neurotransmitters and Neuropeptides: New Players in the Control of Islet of Langerhans' Cell Mass and Function. J Cell Physiol 2015; 231:756-67. [PMID: 26332080 DOI: 10.1002/jcp.25176] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 08/27/2015] [Indexed: 12/19/2022]
Abstract
Islets of Langerhans control whole body glucose homeostasis, as they respond, releasing hormones, to changes in nutrient concentrations in the blood stream. The regulation of hormone secretion has been the focus of attention for a long time because it is related to many metabolic disorders, including diabetes mellitus. Endocrine cells of the islet use a sophisticate system of endocrine, paracrine and autocrine signals to synchronize their activities. These signals provide a fast and accurate control not only for hormone release but also for cell differentiation and survival, key aspects in islet physiology and pathology. Among the different categories of paracrine/autocrine signals, this review highlights the role of neurotransmitters and neuropeptides. In a manner similar to neurons, endocrine cells synthesize, accumulate, release neurotransmitters in the islet milieu, and possess receptors able to decode these signals. In this review, we provide a comprehensive description of neurotransmitter/neuropetide signaling pathways present within the islet. Then, we focus on evidence supporting the concept that neurotransmitters/neuropeptides and their receptors are interesting new targets to preserve β-cell function and mass. A greater understanding of how this network of signals works in physiological and pathological conditions would advance our knowledge of islet biology and physiology and uncover potentially new areas of pharmacological intervention. J. Cell. Physiol. 231: 756-767, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Eliana S Di Cairano
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Laboratory of Molecular and Cellular Physiology, Universit, à, degli Studi di Milano, Milan, Italy
| | - Stefania Moretti
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Laboratory of Molecular and Cellular Physiology, Universit, à, degli Studi di Milano, Milan, Italy
| | - Paola Marciani
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Laboratory of Molecular and Cellular Physiology, Universit, à, degli Studi di Milano, Milan, Italy
| | - Vellea Franca Sacchi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Laboratory of Molecular and Cellular Physiology, Universit, à, degli Studi di Milano, Milan, Italy
| | - Michela Castagna
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Laboratory of Molecular and Cellular Physiology, Universit, à, degli Studi di Milano, Milan, Italy
| | - Alberto Davalli
- Department of Internal Medicine, Diabetes and Endocrinology Unit, San Raffaele Scientific Institute, Milan, Italy
| | - Franco Folli
- Division of Diabetes, Department of Medicine, University of Texas Health Science Center at San Antonio, Texas.,Department of Internal Medicine, Obesity and Comorbidities Research Center (OCRC), University of Campinas, UNICAMP, Campinas, Sao Paulo State, Brazil
| | - Carla Perego
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Laboratory of Molecular and Cellular Physiology, Universit, à, degli Studi di Milano, Milan, Italy
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27
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Spégel P, Andersson LE, Storm P, Sharoyko V, Göhring I, Rosengren AH, Mulder H. Unique and Shared Metabolic Regulation in Clonal β-Cells and Primary Islets Derived From Rat Revealed by Metabolomics Analysis. Endocrinology 2015; 156:1995-2005. [PMID: 25774549 DOI: 10.1210/en.2014-1391] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
As models for β-cell metabolism, rat islets are, to some extent, a, heterogeneous cell population stressed by the islet isolation procedure, whereas rat-derived clonal β-cells exhibit a tumor-like phenotype. To describe to what extent either of these models reflect normal cellular metabolism, we compared metabolite profiles and gene expression in rat islets and the INS-1 832/13 line, a widely used clonal β-cell model. We found that insulin secretion and metabolic regulation provoked by glucose were qualitatively similar in these β-cell models. However, rat islets exhibited a more pronounced glucose-provoked increase of glutamate, glycerol-3-phosphate, succinate, and lactate levels, whereas INS-1 832/13 cells showed a higher glucose-elicited increase in glucose-6-phosphate, alanine, isocitrate, and α-ketoglutarate levels. Glucose induced a decrease in levels of γ-aminobutyrate (GABA) and aspartate in rat islets and INS-1 832/13 cells, respectively. Genes with cellular functions related to proliferation and the cell cycle were more highly expressed in the INS-1 832/13 cells. Most metabolic pathways that were differentially expressed included GABA metabolism, in line with altered glucose responsiveness of GABA. Also, lactate dehydrogenase A, which is normally expressed at low levels in mature β-cells, was more abundant in rat islets than in INS-1 832/13 cells, confirming the finding of elevated glucose-provoked lactate production in the rat islets. Overall, our results suggest that metabolism in rat islets and INS-1 832/13 cells is qualitatively similar, albeit with quantitative differences. Differences may be accounted for by cellular heterogeneity of islets and proliferation of the INS-1 832/13 cells.
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Affiliation(s)
- Peter Spégel
- Unit of Molecular Metabolism (P.S., L.E.A., V.S., I.G., H.M.), Lund University Diabetes Centre, Clinical Research Center, Skåne University Hospital, and Lund University Diabetes Centre (P.S., A.H.R.), Clinical Research Center, Skåne University Hospital, 205 02 Malmö, Sweden
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28
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Kanaani J, Cianciaruso C, Phelps EA, Pasquier M, Brioudes E, Billestrup N, Baekkeskov S. Compartmentalization of GABA synthesis by GAD67 differs between pancreatic beta cells and neurons. PLoS One 2015; 10:e0117130. [PMID: 25647668 PMCID: PMC4315522 DOI: 10.1371/journal.pone.0117130] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 12/19/2014] [Indexed: 11/22/2022] Open
Abstract
The inhibitory neurotransmitter GABA is synthesized by the enzyme glutamic acid decarboxylase (GAD) in neurons and in pancreatic β-cells in islets of Langerhans where it functions as a paracrine and autocrine signaling molecule regulating the function of islet endocrine cells. The localization of the two non-allelic isoforms GAD65 and GAD67 to vesicular membranes is important for rapid delivery and accumulation of GABA for regulated secretion. While the membrane anchoring and trafficking of GAD65 are mediated by intrinsic hydrophobic modifications, GAD67 remains hydrophilic, and yet is targeted to vesicular membrane pathways and synaptic clusters in neurons by both a GAD65-dependent and a distinct GAD65-independent mechanism. Herein we have investigated the membrane association and targeting of GAD67 and GAD65 in monolayer cultures of primary rat, human, and mouse islets and in insulinoma cells. GAD65 is primarily detected in Golgi membranes and in peripheral vesicles distinct from insulin vesicles in β-cells. In the absence of GAD65, GAD67 is in contrast primarily cytosolic in β-cells; its co-expression with GAD65 is necessary for targeting to Golgi membranes and vesicular compartments. Thus, the GAD65-independent mechanism for targeting of GAD67 to synaptic vesicles in neurons is not functional in islet β-cells. Therefore, only GAD65:GAD65 homodimers and GAD67:GAD65 heterodimers, but not the GAD67:GAD67 homodimer gain access to vesicular compartments in β-cells to facilitate rapid accumulation of newly synthesized GABA for regulated secretion and fine tuning of GABA-signaling in islets of Langerhans.
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Affiliation(s)
- Jamil Kanaani
- Departments of Medicine and Microbiology/Immunology, Diabetes Center, University of California San Francisco, San Francisco, California, United States of America
| | - Chiara Cianciaruso
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Edward A. Phelps
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Miriella Pasquier
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Estelle Brioudes
- Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Nils Billestrup
- Institute of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Steinunn Baekkeskov
- Departments of Medicine and Microbiology/Immunology, Diabetes Center, University of California San Francisco, San Francisco, California, United States of America
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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29
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Rorsman P, Zhang Q. Matthias Braun, 23 July 1966-16 November 2013. Diabetologia 2014; 57:2431-2. [PMID: 25312812 DOI: 10.1007/s00125-014-3401-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Patrik Rorsman
- Radcliffe Department of Medicine, OCDEM, University of Oxford, Churchill Hospital, Oxford, OX3 7LJ, UK
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30
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Gylfe E, Tengholm A. Neurotransmitter control of islet hormone pulsatility. Diabetes Obes Metab 2014; 16 Suppl 1:102-10. [PMID: 25200303 DOI: 10.1111/dom.12345] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 04/15/2014] [Indexed: 12/26/2022]
Abstract
Pulsatile secretion is an inherent property of hormone-releasing pancreatic islet cells. This secretory pattern is physiologically important and compromised in diabetes. Neurotransmitters released from islet cells may shape the pulses in auto/paracrine feedback loops. Within islets, glucose-stimulated β-cells couple via gap junctions to generate synchronized insulin pulses. In contrast, α- and δ-cells lack gap junctions, and glucagon release from islets stimulated by lack of glucose is non-pulsatile. Increasing glucose concentrations gradually inhibit glucagon secretion by α-cell-intrinsic mechanism/s. Further glucose elevation will stimulate pulsatile insulin release and co-secretion of neurotransmitters. Excitatory ATP may synchronize β-cells with δ-cells to generate coinciding pulses of insulin and somatostatin. Inhibitory neurotransmitters from β- and δ-cells can then generate antiphase pulses of glucagon release. Neurotransmitters released from intrapancreatic ganglia are required to synchronize β-cells between islets to coordinate insulin pulsatility from the entire pancreas, whereas paracrine intra-islet effects still suffice to explain coordinated pulsatile release of glucagon and somatostatin. The present review discusses how neurotransmitters contribute to the pulsatility at different levels of integration.
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Affiliation(s)
- E Gylfe
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
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31
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Analysis of synaptic-like microvesicle exocytosis of B-cells using a live imaging technique. PLoS One 2014; 9:e87758. [PMID: 24503905 PMCID: PMC3913683 DOI: 10.1371/journal.pone.0087758] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 01/02/2014] [Indexed: 11/19/2022] Open
Abstract
Pancreatic β-cells play central roles in blood glucose homeostasis. Beside insulin, these cells release neurotransmitters and other signaling molecules stored in synaptic-like microvesicles (SLMVs). We monitored SLMV exocytosis by transfecting a synaptophysin-pHluorin construct and by visualizing the cells by Total Internal Reflection Fluorescence (TIRF) microscopy. SLMV fusion was elicited by 20 mM glucose and by depolarizing K+ concentrations with kinetics comparable to insulin secretion. SLMV exocytosis was prevented by Tetanus and Botulinum-C neurotoxins indicating that the fusion machinery of these organelles includes VAMP-2/-3 and Syntaxin-1, respectively. Sequential visualization of SLMVs by TIRF and epifluorescence microscopy showed that after fusion the vesicle components are rapidly internalized and the organelles re-acidified. Analysis of single fusion episodes revealed the existence of two categories of events. While under basal conditions transient fusion events prevailed, long-lasting episodes were more frequent upon secretagogue exposure. Our observations unveiled similarities between the mechanism of exocytosis of insulin granules and SLMVs. Thus, diabetic conditions characterized by defective insulin secretion are most probably associated also with inappropriate release of molecules stored in SLMVs. The assessment of the contribution of SLMV exocytosis to the manifestation of the disease will be facilitated by the use of the imaging approach described in this study.
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Abstract
Glucagon secreted by pancreatic α-cells is the major hyperglycemic hormone correcting acute hypoglycaemia (glucose counterregulation). In diabetes the glucagon response to hypoglycaemia becomes compromised and chronic hyperglucagonemia appears. There is increasing awareness that glucagon excess may underlie important manifestations of diabetes. However opinions differ widely how glucose controls glucagon secretion. The autonomous nervous system plays an important role in the glucagon response to hypoglycaemia. But it is clear that glucose controls glucagon secretion also by mechanisms involving direct effects on α-cells or indirect effects via paracrine factors released from non-α-cells within the pancreatic islets. The present review discusses these mechanisms and argues that different regulatory processes are involved in a glucose concentration-dependent manner. Direct glucose effects on the α-cell and autocrine mechanisms are probably most significant for the glucagon response to hypoglycaemia. During hyperglycaemia, when secretion from β- and δ-cells is stimulated, paracrine inhibitory factors generate pulsatile glucagon release in opposite phase to pulsatile release of insulin and somatostatin. High concentrations of glucose have also stimulatory effects on glucagon secretion that tend to balance and even exceed the inhibitory influence. The latter actions might underlie the paradoxical hyperglucagonemia that aggravates hyperglycaemia in persons with diabetes.
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Affiliation(s)
- Erik Gylfe
- Department of Medical Cell Biology, Uppsala University, BMC Box 571, SE-751 23, Uppsala, Sweden.
| | - Patrick Gilon
- Pôle d'Endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium
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Jenstad M, Chaudhry FA. The Amino Acid Transporters of the Glutamate/GABA-Glutamine Cycle and Their Impact on Insulin and Glucagon Secretion. Front Endocrinol (Lausanne) 2013; 4:199. [PMID: 24427154 PMCID: PMC3876026 DOI: 10.3389/fendo.2013.00199] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 12/16/2013] [Indexed: 12/21/2022] Open
Abstract
Intercellular communication is pivotal in optimizing and synchronizing cellular responses to keep homeostasis and to respond adequately to external stimuli. In the central nervous system (CNS), glutamatergic and GABAergic signals are postulated to be dependent on the glutamate/GABA-glutamine cycle for vesicular loading of neurotransmitters, for inactivating the signal and for the replenishment of the neurotransmitters. Islets of Langerhans release the hormones insulin and glucagon, but share similarities with CNS cells in for example transcriptional control of development and differentiation, and chromatin methylation. Interestingly, CNS proteins involved in secretion of the neurotransmitters and emitting their responses as well as the regulation of these processes, are also found in islet cells. Moreover, high levels of glutamate, GABA, and glutamine and their respective vesicular and plasma membrane transporters have been shown in the islet cells and there is emerging support for these amino acids and their transporters playing important roles in the maturation and secretion of insulin and glucagon. In this review, we will discuss the feasibility of recent data in the field in relation to the biophysical properties of the transporters (Slc1, Slc17, Slc32, and Slc38) and physiology of hormone secretion in islets of Langerhans.
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Affiliation(s)
- Monica Jenstad
- Institute for Medical Informatics, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Biomedicine, University of Oslo, Oslo, Norway
- *Correspondence: Monica Jenstad, Institute for Medical Informatics, Oslo University Hospital, Radiumhospitalet, PO Box 4953 Nydalen, Oslo NO-0424, Norway e-mail:
| | - Farrukh Abbas Chaudhry
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
- The Biotechnology Centre of Oslo, University of Oslo, Oslo, Norway
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Amisten S, Salehi A, Rorsman P, Jones PM, Persaud SJ. An atlas and functional analysis of G-protein coupled receptors in human islets of Langerhans. Pharmacol Ther 2013; 139:359-91. [DOI: 10.1016/j.pharmthera.2013.05.004] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 05/03/2013] [Indexed: 12/17/2022]
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In intact islets interstitial GABA activates GABA(A) receptors that generate tonic currents in α-cells. PLoS One 2013; 8:e67228. [PMID: 23826240 PMCID: PMC3691163 DOI: 10.1371/journal.pone.0067228] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 05/15/2013] [Indexed: 11/19/2022] Open
Abstract
In the rat islets γ-aminobutyric acid (GABA) is produced by the β-cells and, at least, the α-cells express the GABAA receptors (GABAA channels). In this study, we examined in intact islets if the interstitial GABA activated the GABAA receptors. We used the patch-clamp technique to record whole-cell and single-channel currents and single-cell RT-PCR to identify the cell-type we recorded from, in the intact rat islets. We further identified which GABAA receptor subunits were expressed. We determined the cell-type of 43 cells we recorded from and of these 49%, 28% and 7% were α, β and δ-cells, respectively. In the remaining 16% of the cells, mRNA transcripts of more than one hormone gene were detected. The results show that in rat islets interstitial GABA activates tonic current in the α-cells but not in the β-cells. Seventeen different GABAA receptor subunits are expressed with high expression of α1, α2, α4, α6, β3, γ1, δ, ρ1, ρ2 and ρ3 subunits whereas no expression was detected for α5 or ε subunits. The abundance of the GABAA receptor subunits detected suggests that a number of GABAA receptor subtypes are formed in the islets. The single-channel and tonic currents were enhanced by pentobarbital and inhibited by the GABAA receptor antagonist SR-95531. The single-channel conductance ranged from 24 to 105 pS. Whether the single-channel conductance is related to subtypes of the GABAA receptor or variable interstitial GABA concentrations remains to be determined. Our results reveal that GABA is an extracellular signaling molecule in rat pancreatic islets and reaches concentration levels that activate GABAA receptors on the glucagon-releasing α-cells.
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Sodium/hydrogen exchanger NHA2 is critical for insulin secretion in β-cells. Proc Natl Acad Sci U S A 2013; 110:10004-9. [PMID: 23720317 DOI: 10.1073/pnas.1220009110] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
NHA2 is a sodium/hydrogen exchanger with unknown physiological function. Here we show that NHA2 is present in rodent and human β-cells, as well as β-cell lines. In vivo, two different strains of NHA2-deficient mice displayed a pathological glucose tolerance with impaired insulin secretion but normal peripheral insulin sensitivity. In vitro, islets of NHA2-deficient and heterozygous mice, NHA2-depleted Min6 cells, or islets treated with an NHA2 inhibitor exhibited reduced sulfonylurea- and secretagogue-induced insulin secretion. The secretory deficit could be rescued by overexpression of a wild-type, but not a functionally dead, NHA2 transporter. NHA2 deficiency did not affect insulin synthesis or maturation and had no impact on basal or glucose-induced intracellular Ca(2+) homeostasis in islets. Subcellular fractionation and imaging studies demonstrated that NHA2 resides in transferrin-positive endosomes and synaptic-like microvesicles but not in insulin-containing large dense core vesicles in β-cells. Loss of NHA2 inhibited clathrin-dependent, but not clathrin-independent, endocytosis in Min6 and primary β-cells, suggesting defective endo-exocytosis coupling as the underlying mechanism for the secretory deficit. Collectively, our in vitro and in vivo studies reveal the sodium/proton exchanger NHA2 as a critical player for insulin secretion in the β-cell. In addition, our study sheds light on the biological function of a member of this recently cloned family of transporters.
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Cuttitta CM, Guariglia SR, Idrissi AE, L’Amoreaux WJ. Taurine’s Effects on the Neuroendocrine Functions of Pancreatic β Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 775:299-310. [DOI: 10.1007/978-1-4614-6130-2_25] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Duncan C, Bica L, Crouch PJ, Caragounis A, Lidgerwood GE, Parker SJ, Meyerowitz J, Volitakis I, Liddell JR, Raghupathi R, Paterson BM, Duffield MD, Cappai R, Donnelly PS, Grubman A, Camakaris J, Keating DJ, White AR. Copper modulates the large dense core vesicle secretory pathway in PC12 cells. Metallomics 2013; 5:700-14. [DOI: 10.1039/c3mt20231c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
Impaired insulin secretion from pancreatic β-cells is a major factor in the pathogenesis of type 2 diabetes. The main regulator of insulin secretion is the plasma glucose concentration. Insulin secretion is modified by other nutrients, circulating hormones and the autonomic nervous system, as well as local paracrine and autocrine signals. Autocrine signalling involves diffusible molecules that bind to receptors on the same cell from which they have been released. The first transmitter to be implicated in the autocrine regulation of β-cell function was insulin itself. The importance of autocrine insulin signalling is underscored by the finding that mice lacking insulin receptors in β-cells are glucose intolerant. In addition to insulin, β-cells secrete a variety of additional substances, including peptides (e.g. amylin, chromogranin A and B and their cleavage products), neurotransmitters (ATP and γ-aminobutyric acid) and ions (e.g. zinc). Here we review the autocrine effects of substances secreted from β-cells, with a focus on acute effects in stimulus-secretion coupling, present some novel data and discuss the general significance of autocrine signals for the regulation of insulin secretion.
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Affiliation(s)
- M Braun
- Alberta Diabetes Institute, University of Alberta, Edmonton, Canada.
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Taneera J, Jin Z, Jin Y, Muhammed SJ, Zhang E, Lang S, Salehi A, Korsgren O, Renström E, Groop L, Birnir B. γ-Aminobutyric acid (GABA) signalling in human pancreatic islets is altered in type 2 diabetes. Diabetologia 2012; 55:1985-94. [PMID: 22538358 PMCID: PMC3369140 DOI: 10.1007/s00125-012-2548-7] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 03/07/2012] [Indexed: 12/31/2022]
Abstract
AIMS/HYPOTHESIS γ-Aminobutyric acid (GABA) is a signalling molecule in the interstitial space in pancreatic islets. We examined the expression and function of the GABA signalling system components in human pancreatic islets from normoglycaemic and type 2 diabetic individuals. METHODS Expression of GABA signalling system components was studied by microarray, quantitative PCR analysis, immunohistochemistry and patch-clamp experiments on cells in intact islets. Hormone release was measured from intact islets. RESULTS The GABA signalling system was compromised in islets from type 2 diabetic individuals, where the expression of the genes encoding the α1, α2, β2 and β3 GABA(A) channel subunits was downregulated. GABA originating within the islets evoked tonic currents in the cells. The currents were enhanced by pentobarbital and inhibited by the GABA(A) receptor antagonist, SR95531. The effects of SR95531 on hormone release revealed that activation of GABA(A) channels (GABA(A) receptors) decreased both insulin and glucagon secretion. The GABA(B) receptor antagonist, CPG55845, increased insulin release in islets (16.7 mmol/l glucose) from normoglycaemic and type 2 diabetic individuals. CONCLUSIONS/INTERPRETATION Interstitial GABA activates GABA(A) channels and GABA(B) receptors and effectively modulates hormone release in islets from type 2 diabetic and normoglycaemic individuals.
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Affiliation(s)
- J. Taneera
- Lund University Diabetes Center, Department of Clinical Sciences, Diabetes & Endocrinology, University Hospital Malmö, Lund University, Malmö, Sweden
| | - Z. Jin
- Department of Neuroscience, Uppsala University, Box 593, 75124 Uppsala, Sweden
| | - Y. Jin
- Department of Neuroscience, Uppsala University, Box 593, 75124 Uppsala, Sweden
| | - S. J. Muhammed
- Department of Clinical Sciences, Islet Cell physiology, University Hospital Malmö, Lund University, Malmö, Sweden
| | - E. Zhang
- Department of Clinical Sciences, Islet Pathophysiology, University Hospital Malmö, Lund University, Malmö, 20502 Sweden
| | - S. Lang
- Department of Neuroscience, Uppsala University, Box 593, 75124 Uppsala, Sweden
- Lund University Diabetes Center, Department of Clinical Sciences, Diabetes & Endocrinology, University Hospital Malmö, Lund University, Malmö, Sweden
| | - A. Salehi
- Department of Clinical Sciences, Islet Cell physiology, University Hospital Malmö, Lund University, Malmö, Sweden
| | - O. Korsgren
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, 75185 Sweden
| | - E. Renström
- Department of Clinical Sciences, Islet Pathophysiology, University Hospital Malmö, Lund University, Malmö, 20502 Sweden
| | - L. Groop
- Lund University Diabetes Center, Department of Clinical Sciences, Diabetes & Endocrinology, University Hospital Malmö, Lund University, Malmö, Sweden
| | - B. Birnir
- Department of Neuroscience, Uppsala University, Box 593, 75124 Uppsala, Sweden
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Durst MA, Lux-Lantos VA, Hardy DB, Hill DJ, Arany EJ. Protein Restriction during Early Life in Rats Alters Pancreatic GABAA Receptor Subunit Expression and Glucagon Secretion in Adulthood. Can J Diabetes 2012. [DOI: 10.1016/j.jcjd.2012.06.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Rodriguez-Diaz R, Dando R, Huang YA, Berggren PO, Roper SD, Caicedo A. Real-time detection of acetylcholine release from the human endocrine pancreas. Nat Protoc 2012; 7:1015-23. [PMID: 22555241 DOI: 10.1038/nprot.2012.040] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Neurons, sensory cells and endocrine cells secrete neurotransmitters and hormones to communicate with other cells and to coordinate organ and system function. Validation that a substance is used as an extracellular signaling molecule by a given cell requires a direct demonstration of its secretion. In this protocol we describe the use of biosensor cells to detect neurotransmitter release from endocrine cells in real-time. Chinese hamster ovary cells expressing the muscarinic acetylcholine (ACh) receptor M3 were used as ACh biosensors to record ACh release from human pancreatic islets. We show how ACh biosensors loaded with the Ca(2+) indicator Fura-2 and pressed against isolated human pancreatic islets allow the detection of ACh release. The biosensor approach is simple; the Ca(2+) signal generated in the biosensor cell reflects the presence (release) of a neurotransmitter. The technique is versatile because biosensor cells expressing a variety of receptors can be used in many applications. The protocol takes ∼3 h.
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Affiliation(s)
- Rayner Rodriguez-Diaz
- Diabetes Research Institute, Miller School of Medicine, University of Miami, Miami, Florida, USA
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43
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Koh DS, Cho JH, Chen L. Paracrine interactions within islets of Langerhans. J Mol Neurosci 2012; 48:429-40. [PMID: 22528452 DOI: 10.1007/s12031-012-9752-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 03/12/2012] [Indexed: 01/05/2023]
Abstract
Glucose supply fluctuates between meal and fasting periods and its consumption by the body varies greatly depending on bodily metabolism. Pancreatic islets of Langerhans secrete various endocrine hormones including insulin and glucagon to keep blood glucose level relatively constant. Additionally, islet hormones regulate activity of neighboring cells as local autocrine or paracrine modulators. Moreover, islet cells release neurotransmitters such as glutamate and γ-aminobutyric acid (GABA) to gain more precise regulation of hormones release kinetics. Excitatory glutamate is co-released with glucagon from α-cells and activates glutamate receptors in the neighboring cells. GABA released from β-cells was shown to inhibit α-cells but to activate β-cells by acting GABA(A) receptors. This review summarizes the recent progress in understanding the paracrine/autocrine interactions in islets.
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Affiliation(s)
- Duk-Su Koh
- University of Washington, Seattle, WA, USA.
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44
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Hoppa MB, Jones E, Karanauskaite J, Ramracheya R, Braun M, Collins SC, Zhang Q, Clark A, Eliasson L, Genoud C, MacDonald PE, Monteith AG, Barg S, Galvanovskis J, Rorsman P. Multivesicular exocytosis in rat pancreatic beta cells. Diabetologia 2012; 55:1001-12. [PMID: 22189485 PMCID: PMC3296018 DOI: 10.1007/s00125-011-2400-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 11/17/2011] [Indexed: 11/04/2022]
Abstract
AIMS/HYPOTHESIS To establish the occurrence, modulation and functional significance of compound exocytosis in insulin-secreting beta cells. METHODS Exocytosis was monitored in rat beta cells by electrophysiological, biochemical and optical methods. The functional assays were complemented by three-dimensional reconstruction of confocal imaging, transmission and block face scanning electron microscopy to obtain ultrastructural evidence of compound exocytosis. RESULTS Compound exocytosis contributed marginally (<5% of events) to exocytosis elicited by glucose/membrane depolarisation alone. However, in beta cells stimulated by a combination of glucose and the muscarinic agonist carbachol, 15-20% of the release events were due to multivesicular exocytosis, but the frequency of exocytosis was not affected. The optical measurements suggest that carbachol should stimulate insulin secretion by ∼40%, similar to the observed enhancement of glucose-induced insulin secretion. The effects of carbachol were mimicked by elevating [Ca(2+)](i) from 0.2 to 2 μmol/l Ca(2+). Two-photon sulforhodamine imaging revealed exocytotic events about fivefold larger than single vesicles and that these structures, once formed, could persist for tens of seconds. Cells exposed to carbachol for 30 s contained long (1-2 μm) serpentine-like membrane structures adjacent to the plasma membrane. Three-dimensional electron microscopy confirmed the existence of fused multigranular aggregates within the beta cell, the frequency of which increased about fourfold in response to stimulation with carbachol. CONCLUSIONS/INTERPRETATION Although contributing marginally to glucose-induced insulin secretion, compound exocytosis becomes quantitatively significant under conditions associated with global elevation of cytoplasmic calcium. These findings suggest that compound exocytosis is a major contributor to the augmentation of glucose-induced insulin secretion by muscarinic receptor activation.
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Affiliation(s)
- M. B. Hoppa
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ UK
| | - E. Jones
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ UK
| | - J. Karanauskaite
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ UK
| | - R. Ramracheya
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ UK
| | - M. Braun
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ UK
| | - S. C. Collins
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ UK
| | - Q. Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ UK
| | - A. Clark
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ UK
| | - L. Eliasson
- Lund University Diabetes Centre, Clinical Research Centre, Malmo, Sweden
| | - C. Genoud
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - P. E. MacDonald
- Department of Pharmacology, University of Alberta, Edmonton, Canada
| | | | - S. Barg
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - J. Galvanovskis
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ UK
| | - P. Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ UK
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Bonaventura MM, Crivello M, Ferreira ML, Repetto M, Cymeryng C, Libertun C, Lux-Lantos VA. Effects of GABAB receptor agonists and antagonists on glycemia regulation in mice. Eur J Pharmacol 2011; 677:188-96. [PMID: 22210053 DOI: 10.1016/j.ejphar.2011.12.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 12/02/2011] [Accepted: 12/09/2011] [Indexed: 11/30/2022]
Abstract
γ-Aminobutyric acid (GABA) inhibits insulin secretion through GABA(B) receptors in pancreatic β-cells. We investigated whether GABA(B) receptors participated in the regulation of glucose homeostasis in vivo. BALB/c mice acutely pre-injected with the GABA(B) receptor agonist baclofen (7.5mg/kg, i.p.) presented glucose intolerance and diminished insulin secretion during a glucose tolerance test (GTT, 2g/kg body weight, i.p.). The GABA(B) receptor antagonist 2-hydroxysaclofen (15 mg/kg, i.p.) improved the GTT and reversed the baclofen effect. Also a slight increase in insulin secretion was observed with 2-hydroxysaclofen. In incubated islets 1.10(-5)M baclofen inhibited 20mM glucose-induced insulin secretion and this effect was reversed by coincubation with 1.10(-5)M 2-hydroxysaclofen. In chronically-treated animals (18 days) both the receptor agonist (5mg/kg/day i.p.) and the receptor antagonist (10mg/kg/day i.p.) induced impaired GTTs; the receptor antagonist, but not the agonist, also induced a decrease in insulin secretion. No alterations in insulin tolerance tests, body weight and food intake were observed with the treatments. In addition glucagon, insulin-like growth factor I, prolactin, corticosterone and growth hormone, other hormones involved in glucose metabolism regulation, were not affected by chronic baclofen or 2-hydroxysaclofen. In islets obtained from chronically injected animals with baclofen, 2-hydroxysaclofen or saline (as above), GABA(B2) mRNA expression was not altered. Results demonstrate that GABA(B) receptors are involved in the regulation of glucose homeostasis in vivo. Treatment with receptor agonists or antagonists, given acutely or chronically, altered glucose homeostasis and insulin secretion alerting to the need to evaluate glucose metabolism during the clinical use of these drugs.
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Affiliation(s)
- María M Bonaventura
- Instituto de Biología y Medicina Experimental-CONICET, Buenos Aires, Argentina
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46
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Hinke SA. Inverse vaccination with islet autoantigens to halt progression of autoimmune diabetes. Drug Dev Res 2011. [DOI: 10.1002/ddr.20488] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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47
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Kim KJ, Pearl PL, Jensen K, Snead OC, Malaspina P, Jakobs C, Gibson KM. Succinic semialdehyde dehydrogenase: biochemical-molecular-clinical disease mechanisms, redox regulation, and functional significance. Antioxid Redox Signal 2011; 15:691-718. [PMID: 20973619 PMCID: PMC3125545 DOI: 10.1089/ars.2010.3470] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Succinic semialdehyde dehydrogenase (SSADH; aldehyde dehydrogenase 5a1, ALDH5A1; E.C. 1.2.1.24; OMIM 610045, 271980) deficiency is a rare heritable disorder that disrupts the metabolism of the inhibitory neurotransmitter 4-aminobutyric acid (GABA). Identified in conjunction with increased urinary excretion of the GABA analog gamma-hydroxybutyric acid (GHB), numerous patients have been identified worldwide and the autosomal-recessive disorder has been modeled in mice. The phenotype is one of nonprogressive neurological dysfunction in which seizures may be prominently displayed. The murine model is a reasonable phenocopy of the human disorder, yet the severity of the seizure disorder in the mouse exceeds that observed in SSADH-deficient patients. Abnormalities in GABAergic and GHBergic neurotransmission, documented in patients and mice, form a component of disease pathophysiology, although numerous other disturbances (metabolite accumulations, myelin abnormalities, oxidant stress, neurosteroid depletion, altered bioenergetics, etc.) are also likely to be involved in developing the disease phenotype. Most recently, the demonstration of a redox control system in the SSADH protein active site has provided new insights into the regulation of SSADH by the cellular oxidation/reduction potential. The current review summarizes some 30 years of research on this protein and disease, addressing pathological mechanisms in human and mouse at the protein, metabolic, molecular, and whole-animal level.
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Affiliation(s)
- Kyung-Jin Kim
- Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang, Republic of Korea
| | - Phillip L. Pearl
- Department of Neurology, Children's National Medical Center, Washington, District of Columbia
| | - Kimmo Jensen
- Synaptic Physiology Laboratory, Department of Physiology and Biophysics, Aarhus University, Aarhus, Denmark
- Center for Psychiatric Research, Aarhus University Hospital, Risskov, Denmark
| | - O. Carter Snead
- Department of Neurology, Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada
| | | | - Cornelis Jakobs
- Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands
| | - K. Michael Gibson
- Department of Biological Sciences, Michigan Technological University, Houghton, Michigan
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48
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Galvanovskis J, Braun M, Rorsman P. Exocytosis from pancreatic β-cells: mathematical modelling of the exit of low-molecular-weight granule content. Interface Focus 2010; 1:143-52. [PMID: 22419980 DOI: 10.1098/rsfs.2010.0006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 11/11/2010] [Indexed: 11/12/2022] Open
Abstract
Pancreatic β-cells use Ca(2+)-dependent exocytosis of large dense core vesicles to release insulin. Exocytosis in β-cells has been studied biochemically, biophysically and optically. We have previously developed a biophysical method to monitor release of endogenous intragranular constituents that are co-released with insulin. This technique involves the expression of ionotropic membrane receptors in the β-cell plasma membrane and enables measurements of exocytosis of individual vesicles with sub-millisecond resolution. Like carbon fibre amperometry, this method allows fine details of the release process, like the expansion of the fusion pore (the narrow connection between the granule lumen and the extracellular space), to be monitored. Here, we discuss experimental data obtained with this method within the framework of a simple mathematical model that describes the release of low-molecular constituents during exocytosis of the insulin granules. Our findings suggest that the fusion pore functions as a molecular sieve, allowing differential release of low- and high-molecular-weight granule constituents.
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Affiliation(s)
- Juris Galvanovskis
- Department of Physiology, Anatomy and Genetics, University of Oxford, Henry Wellcome Building, Parks Road, Oxford OX1 3PT , UK
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49
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Mendu SK, Akesson L, Jin Z, Edlund A, Cilio C, Lernmark A, Birnir B. Increased GABA(A) channel subunits expression in CD8(+) but not in CD4(+) T cells in BB rats developing diabetes compared to their congenic littermates. Mol Immunol 2010; 48:399-407. [PMID: 21112637 DOI: 10.1016/j.molimm.2010.08.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 08/04/2010] [Accepted: 08/09/2010] [Indexed: 11/30/2022]
Abstract
GABA (γ-aminobutyric acid), the main inhibitory neurotransmitter in the central nervous system is also present in the pancreatic islet β cells where it may function as a paracrine molecule and perhaps as an immunomodulator of lymphocytes infiltrating the pancreatic islet. We examined CD4(+) and CD8(+) T cells from diabetes prone (DR(lyp/lyp)) or resistant (DR(+/+)) congenic biobreeding (BB) rats for expression of GABA(A) channels. Our results show that BB rat CD4(+) and CD8(+) T cells express α1, α2, α3, α4, α6, β3, γ1, δ, ρ1 and ρ2 GABA(A) channel subunits. In CD8(+) T cells from DR(lyp/lyp) animals the subunits were significantly upregulated relative to expression levels in the CD8(+) T cells from DR(+/+) rats as well as from CD4(+) T cells from both DR(lyp/lyp) and DR(+/+) rats. Functional channels were formed in the T cells and physiological concentrations of GABA (100 nM) decreased T cell proliferation. Our results are consistent with the hypothesis that GABA in the islets of Langerhans may diminish inflammation by inhibition of activated T lymphocytes.
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50
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Suckow AT, Craige B, Faundez V, Cain WJ, Chessler SD. An AP-3-dependent mechanism drives synaptic-like microvesicle biogenesis in pancreatic islet beta-cells. Am J Physiol Endocrinol Metab 2010; 299:E23-32. [PMID: 20442321 PMCID: PMC2904044 DOI: 10.1152/ajpendo.00664.2009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Accepted: 04/29/2010] [Indexed: 11/22/2022]
Abstract
Pancreatic islet beta-cells contain synaptic-like microvesicles (SLMVs). The origin, trafficking, and role of these SLMVs are poorly understood. In neurons, synaptic vesicle (SV) biogenesis is mediated by two different cytosolic adaptor protein complexes, a ubiquitous AP-2 complex and the neuron-specific AP-3B complex. Mice lacking AP-3B subunits exhibit impaired GABAergic (inhibitory) neurotransmission and reduced neuronal vesicular GABA transporter (VGAT) content. Since beta-cell maturation and exocytotic function seem to parallel that of the inhibitory synapse, we predicted that AP-3B-associated vesicles would be present in beta-cells. Here, we test the hypothesis that AP-3B is expressed in islets and mediates beta-cell SLMV biogenesis. A secondary aim was to test whether the sedimentation properties of INS-1 beta-cell microvesicles are identical to those of bona fide SLMVs isolated from PC12 cells. Our results show that the two neuron-specific AP-3 subunits beta3B and mu3B are expressed in beta-cells, the first time these proteins have been found to be expressed outside the nervous system. We found that beta-cell SLMVs share the same sedimentation properties as PC12 SLMVs and contain SV proteins that sort specifically to AP-3B-associated vesicles in the brain. Brefeldin A, a drug that interferes with AP-3-mediated SV biogenesis, inhibits the delivery of AP-3 cargoes to beta-cell SLMVs. Consistent with a role for AP-3 in the biogenesis of GABAergic SLMV in beta-cells, INS-1 cell VGAT content decreases upon inhibition of AP-3 delta-subunit expression. Our findings suggest that beta-cells and neurons share molecules and mechanisms important for mediating the neuron-specific membrane trafficking pathways that underlie synaptic vesicle formation.
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Affiliation(s)
- Arthur T Suckow
- 1Department of Medicine and Pediatric Diabetes Research Center, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0983, USA
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