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McGrail C, Sears TJ, Kudtarkar P, Carter H, Gaulton K. Genetic association and machine learning improves discovery and prediction of type 1 diabetes. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.07.31.24311310. [PMID: 39132494 PMCID: PMC11312647 DOI: 10.1101/2024.07.31.24311310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/13/2024]
Abstract
Type 1 diabetes (T1D) has a large genetic component, and expanded genetic studies of T1D can lead to novel biological and therapeutic discovery and improved risk prediction. In this study, we performed genetic association and fine-mapping analyses in 817,718 European ancestry samples genome-wide and 29,746 samples at the MHC locus, which identified 165 independent risk signals for T1D of which 19 were novel. We used risk variants to train a machine learning model (named T1GRS) to predict T1D, which highly differentiated T1D from non-disease and type 2 diabetes (T2D) in Europeans as well as African Americans at or beyond the level of current standards. We identified extensive non-linear interactions between risk loci in T1GRS, for example between HLA-DQB1*57 and INS, coding and non-coding HLA alleles, and DEXI, INS and other beta cell loci, that provided mechanistic insight and improved risk prediction. T1D individuals formed distinct clusters based on genetic features from T1GRS which had significant differences in age of onset, HbA1c, and renal disease severity. Finally, we provided T1GRS in formats to enhance accessibility of risk prediction to any user and computing environment. Overall, the improved genetic discovery and prediction of T1D will have wide clinical, therapeutic, and research applications.
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Affiliation(s)
- Carolyn McGrail
- Biomedical sciences graduate program, University of California San Diego, La Jolla CA
| | - Timothy J. Sears
- Bioinformatics and Systems Biology Program, University of California San Diego, La Jolla CA
| | - Parul Kudtarkar
- Department of Pediatrics, University of California San Diego, La Jolla CA
| | - Hannah Carter
- Bioinformatics and Systems Biology Program, University of California San Diego, La Jolla CA
- Moore’s Cancer Center, University of California San Diego, La Jolla CA
- Department of Medicine, University of California San Diego, La Jolla CA
| | - Kyle Gaulton
- Department of Pediatrics, University of California San Diego, La Jolla CA
- Pediatric Diabetes Research Center, University of California San Diego, La Jolla CA
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2
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Suckert C, Zosel C, Schaefer M. Simultaneous TIRF imaging of subplasmalemmal Ca 2+ dynamics and granule fusions in insulin-secreting INS-1 cells reveals coexistent synchronized and asynchronous release. Cell Calcium 2024; 120:102883. [PMID: 38643716 DOI: 10.1016/j.ceca.2024.102883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 03/21/2024] [Accepted: 03/29/2024] [Indexed: 04/23/2024]
Abstract
The basal and glucose-induced insulin secretion from pancreatic beta cells is a tightly regulated process that is triggered in a Ca2+-dependent fashion and further positively modulated by substances that raise intracellular levels of adenosine 3',5'-cyclic monophosphate (cAMP) or by certain antidiabetic drugs. In a previous study, we have temporally resolved the subplasmalemmal [Ca2+]i dynamics in beta cells that are characterized by trains of sharply delimited spikes, reaching peak values up to 5 µM. Applying total internal reflection fluorescence (TIRF) microscopy and synaptopHluorin to visualize fusion events of individual granules, we found that several fusion events can coincide within 50 to 150 ms. To test whether subplasmalemmal [Ca2+]i microdomains around single or clustered Ca2+ channels may cause a synchronized release of insulin-containing vesicles, we applied simultaneous dual-color TIRF microscopy and monitored Ca2+ fluctuations and exocytotic events in INS-1 cells at high frame rates. The results indicate that fusions can be triggered by subplasmalemmal Ca2+ spiking. This, however, does account for a minority of fusion events. About 90 %-95 % of fusion events either happen between Ca2+ spikes or incidentally overlap with subplasmalemmal Ca2+ spikes. We conclude that only a fraction of exocytotic events in glucose-induced and tolbutamide- or forskolin-enhanced insulin release from INS-1 cells is tightly coupled to Ca2+ microdomains around voltage-gated Ca2+ channels.
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Affiliation(s)
- Charlotte Suckert
- Leipzig University, Rudolf-Boehm-Institute of Pharmacology and Toxicology, Härtelstraße 16-18, Leipzig 04107, Germany
| | - Carolin Zosel
- Leipzig University, Rudolf-Boehm-Institute of Pharmacology and Toxicology, Härtelstraße 16-18, Leipzig 04107, Germany
| | - Michael Schaefer
- Leipzig University, Rudolf-Boehm-Institute of Pharmacology and Toxicology, Härtelstraße 16-18, Leipzig 04107, Germany.
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3
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Shilleh AH, Viloria K, Broichhagen J, Campbell JE, Hodson DJ. GLP1R and GIPR expression and signaling in pancreatic alpha cells, beta cells and delta cells. Peptides 2024; 175:171179. [PMID: 38360354 DOI: 10.1016/j.peptides.2024.171179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 02/09/2024] [Accepted: 02/13/2024] [Indexed: 02/17/2024]
Abstract
Glucagon-like peptide-1 receptor (GLP1R) and glucose-dependent insulinotropic polypeptide receptor (GIPR) are transmembrane receptors involved in insulin, glucagon and somatostatin secretion from the pancreatic islet. Therapeutic targeting of GLP1R and GIPR restores blood glucose levels in part by influencing beta cell, alpha cell and delta cell function. Despite the importance of the incretin-mimetics for diabetes therapy, our understanding of GLP1R and GIPR expression patterns and signaling within the islet remain incomplete. Here, we present the evidence for GLP1R and GIPR expression in the major islet cell types, before addressing signaling pathway(s) engaged, as well as their influence on cell survival and function. While GLP1R is largely a beta cell-specific marker within the islet, GIPR is expressed in alpha cells, beta cells, and (possibly) delta cells. GLP1R and GIPR engage Gs-coupled pathways in most settings, although the exact outcome on hormone release depends on paracrine communication and promiscuous signaling. Biased agonism away from beta-arrestin is an emerging concept for improving therapeutic efficacy, and is also relevant for GLP1R/GIPR dual agonism. Lastly, dual agonists exert multiple effects on islet function through GIPR > GLP1R imbalance, increased GLP1R surface expression and cAMP signaling, as well as beneficial alpha cell-beta cell-delta cell crosstalk.
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Affiliation(s)
- Ali H Shilleh
- Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), NIHR Oxford Biomedical Research Centre, Churchill Hospital, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Katrina Viloria
- Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), NIHR Oxford Biomedical Research Centre, Churchill Hospital, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | | | - Jonathan E Campbell
- Duke Molecular Physiology Institute, USA; Department of Medicine, Division of Endocrinology, Duke University, Durham, NC, USA; Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, USA.
| | - David J Hodson
- Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), NIHR Oxford Biomedical Research Centre, Churchill Hospital, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
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Zhu H, Ding G, Huang H. FSH regulates glucose-stimulated insulin secretion: A bell-shaped curve effect. J Diabetes 2024; 16:e13546. [PMID: 38599851 PMCID: PMC11006606 DOI: 10.1111/1753-0407.13546] [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] [Received: 01/23/2024] [Accepted: 02/02/2024] [Indexed: 04/12/2024] Open
Affiliation(s)
- Hong Zhu
- Obstetrics and Gynecology HospitalInstitute of Reproduction and Development, Fudan UniversityShanghaiChina
- Research Units of Embryo Original DiseasesChinese Academy of Medical SciencesShanghaiChina
- Shanghai Key Laboratory of Reprodction and DevelopmentFudan UniversityShanghaiChina
| | - Guolian Ding
- Obstetrics and Gynecology HospitalInstitute of Reproduction and Development, Fudan UniversityShanghaiChina
- Research Units of Embryo Original DiseasesChinese Academy of Medical SciencesShanghaiChina
- Shanghai Key Laboratory of Reprodction and DevelopmentFudan UniversityShanghaiChina
| | - Hefeng Huang
- Obstetrics and Gynecology HospitalInstitute of Reproduction and Development, Fudan UniversityShanghaiChina
- Research Units of Embryo Original DiseasesChinese Academy of Medical SciencesShanghaiChina
- Shanghai Key Laboratory of Reprodction and DevelopmentFudan UniversityShanghaiChina
- Key Laboratory of Reproductive Genetics (Ministry of Education)Zhejiang University School of MedicineHangzhouChina
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Cheng Y, Zhu H, Ren J, Wu HY, Yu JE, Jin LY, Pang HY, Pan HT, Luo SS, Yan J, Dong KX, Ye LY, Zhou CL, Pan JX, Meng ZX, Yu T, Jin L, Lin XH, Wu YT, Yang HB, Liu XM, Sheng JZ, Ding GL, Huang HF. Follicle-stimulating hormone orchestrates glucose-stimulated insulin secretion of pancreatic islets. Nat Commun 2023; 14:6991. [PMID: 37914684 PMCID: PMC10620214 DOI: 10.1038/s41467-023-42801-6] [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] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Accepted: 10/20/2023] [Indexed: 11/03/2023] Open
Abstract
Follicle-stimulating hormone (FSH) is involved in mammalian reproduction via binding to FSH receptor (FSHR). However, several studies have found that FSH and FSHR play important roles in extragonadal tissue. Here, we identified the expression of FSHR in human and mouse pancreatic islet β-cells. Blocking FSH signaling by Fshr knock-out led to impaired glucose tolerance owing to decreased insulin secretion, while high FSH levels caused insufficient insulin secretion as well. In vitro, we found that FSH orchestrated glucose-stimulated insulin secretion (GSIS) in a bell curve manner. Mechanistically, FSH primarily activates Gαs via FSHR, promoting the cAMP/protein kinase A (PKA) and calcium pathways to stimulate GSIS, whereas high FSH levels could activate Gαi to inhibit the cAMP/PKA pathway and the amplified effect on GSIS. Our results reveal the role of FSH in regulating pancreatic islet insulin secretion and provide avenues for future clinical investigation and therapeutic strategies for postmenopausal diabetes.
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Affiliation(s)
- Yi Cheng
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China
- Research Units of Embryo Original Diseases, Chinese Academy of Medical Sciences, Shanghai, China
- Key Laboratory of Reproductive Genetics (Ministry of Education), Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Hong Zhu
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China
- Research Units of Embryo Original Diseases, Chinese Academy of Medical Sciences, Shanghai, China
| | - Jun Ren
- Key Laboratory of Reproductive Genetics (Ministry of Education), Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Hai-Yan Wu
- Key Laboratory of Reproductive Genetics (Ministry of Education), Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jia-En Yu
- Key Laboratory of Reproductive Genetics (Ministry of Education), Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Lu-Yang Jin
- Key Laboratory of Reproductive Genetics (Ministry of Education), Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Hai-Yan Pang
- Key Laboratory of Reproductive Genetics (Ministry of Education), Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Hai-Tao Pan
- Shaoxing Maternity and Child Health Care Hospital, Shaoxing, China
- The International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Si-Si Luo
- The International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Embryo Original Diseases, Shanghai, China
| | - Jing Yan
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China
- Research Units of Embryo Original Diseases, Chinese Academy of Medical Sciences, Shanghai, China
| | - Kai-Xuan Dong
- Research Units of Embryo Original Diseases, Chinese Academy of Medical Sciences, Shanghai, China
- Departments of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Long-Yun Ye
- Department of Pancreatic Surgery, Fudan University Shanghai Cancer Centre, Shanghai, China
| | - Cheng-Liang Zhou
- The International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Embryo Original Diseases, Shanghai, China
| | - Jie-Xue Pan
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China
- Research Units of Embryo Original Diseases, Chinese Academy of Medical Sciences, Shanghai, China
| | - Zhuo-Xian Meng
- Key Laboratory of Disease Proteomics of Zhejiang Province, Department of Pathology and Pathophysiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Ting Yu
- Key Laboratory of Disease Proteomics of Zhejiang Province, Department of Pathology and Pathophysiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Li Jin
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China
- Research Units of Embryo Original Diseases, Chinese Academy of Medical Sciences, Shanghai, China
| | - Xian-Hua Lin
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China
- Research Units of Embryo Original Diseases, Chinese Academy of Medical Sciences, Shanghai, China
| | - Yan-Ting Wu
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China
- Research Units of Embryo Original Diseases, Chinese Academy of Medical Sciences, Shanghai, China
| | - Hong-Bo Yang
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China
- Research Units of Embryo Original Diseases, Chinese Academy of Medical Sciences, Shanghai, China
| | - Xin-Mei Liu
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China
- Research Units of Embryo Original Diseases, Chinese Academy of Medical Sciences, Shanghai, China
| | - Jian-Zhong Sheng
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China.
- Research Units of Embryo Original Diseases, Chinese Academy of Medical Sciences, Shanghai, China.
- Key Laboratory of Reproductive Genetics (Ministry of Education), Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China.
- Department of Obstetrics and Gynecology, International Institutes of Medicine, the Fourth Affiliated Hospital of Zhejiang University School of Medicine, Yiwu, China.
| | - Guo-Lian Ding
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China.
- Research Units of Embryo Original Diseases, Chinese Academy of Medical Sciences, Shanghai, China.
| | - He-Feng Huang
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China.
- Research Units of Embryo Original Diseases, Chinese Academy of Medical Sciences, Shanghai, China.
- Key Laboratory of Reproductive Genetics (Ministry of Education), Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China.
- Shanghai Key Laboratory of Embryo Original Diseases, Shanghai, China.
- Department of Obstetrics and Gynecology, International Institutes of Medicine, the Fourth Affiliated Hospital of Zhejiang University School of Medicine, Yiwu, China.
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Posner C, Mehta S, Zhang J. Fluorescent biosensor imaging meets deterministic mathematical modelling: quantitative investigation of signalling compartmentalization. J Physiol 2023; 601:4227-4241. [PMID: 37747358 PMCID: PMC10764149 DOI: 10.1113/jp282696] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 09/06/2023] [Indexed: 09/26/2023] Open
Abstract
Cells execute specific responses to diverse environmental cues by encoding information in distinctly compartmentalized biochemical signalling reactions. Genetically encoded fluorescent biosensors enable the spatial and temporal monitoring of signalling events in live cells. Temporal and spatiotemporal computational models can be used to interpret biosensor experiments in complex biochemical networks and to explore hypotheses that are difficult to test experimentally. In this review, we first provide brief discussions of the experimental toolkit of fluorescent biosensors as well as computational basics with a focus on temporal and spatiotemporal deterministic models. We then describe how we used this combined approach to identify and investigate a protein kinase A (PKA) - cAMP - Ca2+ oscillatory circuit in MIN6 β cells, a mouse pancreatic β cell system. We describe the application of this combined approach to interrogate how this oscillatory circuit is differentially regulated in a nano-compartment formed at the plasma membrane by the scaffolding protein A kinase anchoring protein 79/150. We leveraged both temporal and spatiotemporal deterministic models to identify the key regulators of this oscillatory circuit, which we confirmed with further experiments. The powerful approach of combining live-cell biosensor imaging with quantitative modelling, as discussed here, should find widespread use in the investigation of spatiotemporal regulation of cell signalling.
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Affiliation(s)
- Clara Posner
- Department of Pharmacology, University of California, San Diego, CA, USA
- Shu Chien-Gene Lay Department of Bioengineering, University of California, San Diego, CA, USA
| | - Sohum Mehta
- Department of Pharmacology, University of California, San Diego, CA, USA
| | - Jin Zhang
- Department of Pharmacology, University of California, San Diego, CA, USA
- Shu Chien-Gene Lay Department of Bioengineering, University of California, San Diego, CA, USA
- Department of Chemistry and Biochemistry, University of California, San Diego, CA, USA
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7
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Skelin Klemen M, Dolenšek J, Križančić Bombek L, Pohorec V, Gosak M, Slak Rupnik M, Stožer A. The effect of forskolin and the role of Epac2A during activation, activity, and deactivation of beta cell networks. Front Endocrinol (Lausanne) 2023; 14:1225486. [PMID: 37701894 PMCID: PMC10494243 DOI: 10.3389/fendo.2023.1225486] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 08/08/2023] [Indexed: 09/14/2023] Open
Abstract
Beta cells couple stimulation by glucose with insulin secretion and impairments in this coupling play a central role in diabetes mellitus. Cyclic adenosine monophosphate (cAMP) amplifies stimulus-secretion coupling via protein kinase A and guanine nucleotide exchange protein 2 (Epac2A). With the present research, we aimed to clarify the influence of cAMP-elevating diterpene forskolin on cytoplasmic calcium dynamics and intercellular network activity, which are two of the crucial elements of normal beta cell stimulus-secretion coupling, and the role of Epac2A under normal and stimulated conditions. To this end, we performed functional multicellular calcium imaging of beta cells in mouse pancreas tissue slices after stimulation with glucose and forskolin in wild-type and Epac2A knock-out mice. Forskolin evoked calcium signals in otherwise substimulatory glucose and beta cells from Epac2A knock-out mice displayed a faster activation. During the plateau phase, beta cells from Epac2A knock-out mice displayed a slightly higher active time in response to glucose compared with wild-type littermates, and stimulation with forskolin increased the active time via an increase in oscillation frequency and a decrease in oscillation duration in both Epac2A knock-out and wild-type mice. Functional network properties during stimulation with glucose did not differ in Epac2A knock-out mice, but the presence of Epac2A was crucial for the protective effect of stimulation with forskolin in preventing a decline in beta cell functional connectivity with time. Finally, stimulation with forskolin prolonged beta cell activity during deactivation, especially in Epac2A knock-out mice.
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Affiliation(s)
- Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | | | - Viljem Pohorec
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Alma Mater Europaea, European Center Maribor, Maribor, Slovenia
| | - Marjan Slak Rupnik
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Alma Mater Europaea, European Center Maribor, Maribor, Slovenia
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
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8
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Ramanadham S, Turk J, Bhatnagar S. Noncanonical Regulation of cAMP-Dependent Insulin Secretion and Its Implications in Type 2 Diabetes. Compr Physiol 2023; 13:5023-5049. [PMID: 37358504 PMCID: PMC10809800 DOI: 10.1002/cphy.c220031] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
Abstract
Impaired glucose tolerance (IGT) and β-cell dysfunction in insulin resistance associated with obesity lead to type 2 diabetes (T2D). Glucose-stimulated insulin secretion (GSIS) from β-cells occurs via a canonical pathway that involves glucose metabolism, ATP generation, inactivation of K ATP channels, plasma membrane depolarization, and increases in cytosolic concentrations of [Ca 2+ ] c . However, optimal insulin secretion requires amplification of GSIS by increases in cyclic adenosine monophosphate (cAMP) signaling. The cAMP effectors protein kinase A (PKA) and exchange factor activated by cyclic-AMP (Epac) regulate membrane depolarization, gene expression, and trafficking and fusion of insulin granules to the plasma membrane for amplifying GSIS. The widely recognized lipid signaling generated within β-cells by the β-isoform of Ca 2+ -independent phospholipase A 2 enzyme (iPLA 2 β) participates in cAMP-stimulated insulin secretion (cSIS). Recent work has identified the role of a G-protein coupled receptor (GPCR) activated signaling by the complement 1q like-3 (C1ql3) secreted protein in inhibiting cSIS. In the IGT state, cSIS is attenuated, and the β-cell function is reduced. Interestingly, while β-cell-specific deletion of iPLA 2 β reduces cAMP-mediated amplification of GSIS, the loss of iPLA 2 β in macrophages (MØ) confers protection against the development of glucose intolerance associated with diet-induced obesity (DIO). In this article, we discuss canonical (glucose and cAMP) and novel noncanonical (iPLA 2 β and C1ql3) pathways and how they may affect β-cell (dys)function in the context of impaired glucose intolerance associated with obesity and T2D. In conclusion, we provide a perspective that in IGT states, targeting noncanonical pathways along with canonical pathways could be a more comprehensive approach for restoring β-cell function in T2D. © 2023 American Physiological Society. Compr Physiol 13:5023-5049, 2023.
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Affiliation(s)
- Sasanka Ramanadham
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Alabama, USA
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Alabama, USA
| | - John Turk
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Sushant Bhatnagar
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Alabama, USA
- Department of Medicine, University of Alabama at Birmingham, Alabama, USA
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9
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Lee MH, Thomas JL, Lin CY, Li YCE, Lin HY. Nanoparticle-mediated CRISPR/dCas9a activation of multiple transcription factors to engineer insulin-producing cells. J Mater Chem B 2023; 11:1866-1870. [PMID: 36789698 DOI: 10.1039/d2tb02431d] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Insulin may help to control blood glucose levels in diabetes; however, the long-term release of insulin is important for therapy. In this work, four guide RNAs (gRNA) for factors that promote specification and maturation of insulin-producing cells were synthesized: pancreatic and duodenal homeobox 1 (PDX1), protoendocrine factor (neurogenin 3, NGN3), NK6 homeobox 1 (NKX6.1), and musculoaponeurotic fibrosarcoma oncogene family A (MAFA). These gRNAs were used to form ribonucleoproteins (RNPs) with tracRNA and dCas9-VPR, and were then immobilized on magnetic peptide-imprinted chitosan nanoparticles, which enhanced transfection. The production and release of insulin from transfected cells were then measured using ELISA and staining with anti-insulin antibodies. The expression of the genes was evaluated using qRT-PCR; this was also used to investigate the cascade of additional transcriptional regulators. The magnitude and duration of insulin production were evaluated for single and repeated transfections (using different transfection schedules) to identify the most promising protocol.
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Affiliation(s)
- Mei-Hwa Lee
- Department of Materials Science and Engineering, I-Shou University, Kaohsiung 84001, Taiwan
| | - James L Thomas
- Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131, USA
| | - Chien-Yu Lin
- Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan.
| | - Yi-Chen Ethan Li
- Department of Chemical Engineering, Feng Chia University, Taichung 40724, Taiwan
| | - Hung-Yin Lin
- Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan.
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10
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Rached G, Saliba Y, Maddah D, Hajal J, Smayra V, Bakhos J, Groschner K, Birnbaumer L, Fares N. TRPC3 Regulates Islet Beta-Cell Insulin Secretion. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2204846. [PMID: 36642838 PMCID: PMC9951314 DOI: 10.1002/advs.202204846] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 11/18/2022] [Indexed: 06/17/2023]
Abstract
Insulin release is tightly controlled by glucose-stimulated calcium (GSCa) through hitherto equivocal pathways. This study investigates TRPC3, a non-selective cation channel, as a critical regulator of insulin secretion and glucose control. TRPC3's involvement in glucose-stimulated insulin secretion (GSIS) is studied in human and animal islets. TRPC3-dependent in vivo insulin secretion is investigated using pharmacological tools and Trpc3-/- mice. TRPC3's involvement in islet glucose uptake and GSCa is explored using fluorescent glucose analogue 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-D-glucose and calcium imaging. TRPC3 modulation by a small-molecule activator, GSK1702934A, is evaluated in type 2 diabetic mice. TRPC3 is functionally expressed in human and mouse islet beta cells. TRPC3-controlled insulin secretion is KATP -independent and primarily mediated by diacylglycerol channel regulation of the cytosolic calcium oscillations following glucose stimulation. Conversely, glucose uptake in islets is independent of TRPC3. TRPC3 pharmacologic inhibition and knockout in mice lead to defective insulin secretion and glucose intolerance. Subsequently, TRPC3 activation through targeted small-molecule enhances insulin secretion and alleviates diabetes hallmarks in animals. This study imputes a function for TRPC3 at the onset of GSIS. These insights strengthen one's knowledge of insulin secretion physiology and set forth the TRPC3 channel as an appealing candidate for drug development in the treatment of diabetes.
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Affiliation(s)
- Gaëlle Rached
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Youakim Saliba
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Dina Maddah
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Joelle Hajal
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Viviane Smayra
- Faculty of MedicineSaint Joseph UniversitySaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Jules‐Joel Bakhos
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Klaus Groschner
- Gottfried‐Schatz‐Research‐Centre‐BiophysicsMedical University of GrazGraz8010Austria
| | - Lutz Birnbaumer
- School of Medical SciencesInstitute of Biomedical Research (BIOMED)Catholic University of ArgentinaBuenos AiresC1107AAZArgentina
- Signal Transduction LaboratoryNational Institute of Environmental Health SciencesResearch Triangle ParkDurhamNCC1107AAZUSA
| | - Nassim Fares
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
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11
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Nagao M, Lagerstedt JO, Eliasson L. Secretory granule exocytosis and its amplification by cAMP in pancreatic β-cells. Diabetol Int 2022; 13:471-479. [PMID: 35694000 PMCID: PMC9174382 DOI: 10.1007/s13340-022-00580-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/17/2022] [Indexed: 10/18/2022]
Abstract
The sequence of events for secreting insulin in response to glucose in pancreatic β-cells is termed "stimulus-secretion coupling". The core of stimulus-secretion coupling is a process which generates electrical activity in response to glucose uptake and causes Ca2+ oscillation for triggering exocytosis of insulin-containing secretory granules. Prior to exocytosis, the secretory granules are mobilized and docked to the plasma membrane and primed for fusion with the plasma membrane. Together with the final fusion with the plasma membrane, these steps are named the exocytosis process of insulin secretion. The steps involved in the exocytosis process are crucial for insulin release from β-cells and considered indispensable for glucose homeostasis. We recently confirmed a signature of defective exocytosis process in human islets and β-cells of obese donors with type 2 diabetes (T2D). Furthermore, cyclic AMP (cAMP) potentiates glucose-stimulated insulin secretion through mechanisms including accelerating the exocytosis process. In this mini-review, we aimed to organize essential knowledge of the secretory granule exocytosis and its amplification by cAMP. Then, we suggest the fatty acid translocase CD36 as a predisposition in β-cells for causing defective exocytosis, which is considered a pathogenesis of T2D in relation to obesity. Finally, we propose potential therapeutics of the defective exocytosis based on a CD36-neutralizing antibody and on Apolipoprotein A-I (ApoA-I), for improving β-cell function in T2D.
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Affiliation(s)
- Mototsugu Nagao
- Department of Endocrinology, Diabetes and Metabolism, Graduate School of Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo, 113-8603 Japan
- Department of Clinical Sciences Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, CRC 91-11, Jan Waldenströms Gata 35, 214 28 Malmö, Sweden
| | - Jens O. Lagerstedt
- Department of Clinical Sciences Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, CRC 91-11, Jan Waldenströms Gata 35, 214 28 Malmö, Sweden
- Novo Nordisk A/S, Copenhagen, Denmark
| | - Lena Eliasson
- Department of Clinical Sciences Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, CRC 91-11, Jan Waldenströms Gata 35, 214 28 Malmö, Sweden
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12
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Deng K, Thorn P. Presynaptic-like mechanisms and the control of insulin secretion in pancreatic β-cells. Cell Calcium 2022; 104:102585. [DOI: 10.1016/j.ceca.2022.102585] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 03/24/2022] [Accepted: 03/26/2022] [Indexed: 12/18/2022]
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13
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Sałówka A, Martinez-Sanchez A. Molecular Mechanisms of Nutrient-Mediated Regulation of MicroRNAs in Pancreatic β-cells. Front Endocrinol (Lausanne) 2021; 12:704824. [PMID: 34803905 PMCID: PMC8600252 DOI: 10.3389/fendo.2021.704824] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 08/02/2021] [Indexed: 12/12/2022] Open
Abstract
Pancreatic β-cells within the islets of Langerhans respond to rising blood glucose levels by secreting insulin that stimulates glucose uptake by peripheral tissues to maintain whole body energy homeostasis. To different extents, failure of β-cell function and/or β-cell loss contribute to the development of Type 1 and Type 2 diabetes. Chronically elevated glycaemia and high circulating free fatty acids, as often seen in obese diabetics, accelerate β-cell failure and the development of the disease. MiRNAs are essential for endocrine development and for mature pancreatic β-cell function and are dysregulated in diabetes. In this review, we summarize the different molecular mechanisms that control miRNA expression and function, including transcription, stability, posttranscriptional modifications, and interaction with RNA binding proteins and other non-coding RNAs. We also discuss which of these mechanisms are responsible for the nutrient-mediated regulation of the activity of β-cell miRNAs and identify some of the more important knowledge gaps in the field.
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Affiliation(s)
| | - Aida Martinez-Sanchez
- Section of Cell Biology and Functional Genomics, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, United Kingdom
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14
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Acreman S, Zhang Q. Regulation of α-cell glucagon secretion: The role of second messengers. Chronic Dis Transl Med 2021; 8:7-18. [PMID: 35620162 PMCID: PMC9128566 DOI: 10.1016/j.cdtm.2021.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 06/15/2021] [Indexed: 11/30/2022] Open
Abstract
Glucagon is a potent glucose‐elevating hormone that is secreted by pancreatic α‐cells. While well‐controlled glucagon secretion plays an important role in maintaining systemic glucose homeostasis and preventing hypoglycaemia, it is increasingly apparent that defects in the regulation of glucagon secretion contribute to impaired counter‐regulation and hyperglycaemia in diabetes. It has therefore been proposed that pharmacological interventions targeting glucagon secretion/signalling can have great potential in improving glycaemic control of patients with diabetes. However, despite decades of research, a consensus on the precise mechanisms of glucose regulation of glucagon secretion is yet to be reached. Second messengers are a group of small intracellular molecules that relay extracellular signals to the intracellular signalling cascade, modulating cellular functions. There is a growing body of evidence that second messengers, such as cAMP and Ca2+, play critical roles in α‐cell glucose‐sensing and glucagon secretion. In this review, we discuss the impact of second messengers on α‐cell electrical activity, intracellular Ca2+ dynamics and cell exocytosis. We highlight the possibility that the interaction between different second messengers may play a key role in the glucose‐regulation of glucagon secretion.
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15
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Stožer A, Paradiž Leitgeb E, Pohorec V, Dolenšek J, Križančić Bombek L, Gosak M, Skelin Klemen M. The Role of cAMP in Beta Cell Stimulus-Secretion and Intercellular Coupling. Cells 2021; 10:1658. [PMID: 34359828 PMCID: PMC8304079 DOI: 10.3390/cells10071658] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 06/18/2021] [Accepted: 06/28/2021] [Indexed: 12/22/2022] Open
Abstract
Pancreatic beta cells secrete insulin in response to stimulation with glucose and other nutrients, and impaired insulin secretion plays a central role in development of diabetes mellitus. Pharmacological management of diabetes includes various antidiabetic drugs, including incretins. The incretin hormones, glucagon-like peptide-1 and gastric inhibitory polypeptide, potentiate glucose-stimulated insulin secretion by binding to G protein-coupled receptors, resulting in stimulation of adenylate cyclase and production of the secondary messenger cAMP, which exerts its intracellular effects through activation of protein kinase A or the guanine nucleotide exchange protein 2A. The molecular mechanisms behind these two downstream signaling arms are still not fully elucidated and involve many steps in the stimulus-secretion coupling cascade, ranging from the proximal regulation of ion channel activity to the central Ca2+ signal and the most distal exocytosis. In addition to modifying intracellular coupling, the effect of cAMP on insulin secretion could also be at least partly explained by the impact on intercellular coupling. In this review, we systematically describe the possible roles of cAMP at these intra- and inter-cellular signaling nodes, keeping in mind the relevance for the whole organism and translation to humans.
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Affiliation(s)
- Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
| | - Eva Paradiž Leitgeb
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
| | - Viljem Pohorec
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia
| | - Lidija Križančić Bombek
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia
| | - Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
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16
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McLean BA, Wong CK, Campbell JE, Hodson DJ, Trapp S, Drucker DJ. Revisiting the Complexity of GLP-1 Action from Sites of Synthesis to Receptor Activation. Endocr Rev 2021; 42:101-132. [PMID: 33320179 PMCID: PMC7958144 DOI: 10.1210/endrev/bnaa032] [Citation(s) in RCA: 112] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Indexed: 02/06/2023]
Abstract
Glucagon-like peptide-1 (GLP-1) is produced in gut endocrine cells and in the brain, and acts through hormonal and neural pathways to regulate islet function, satiety, and gut motility, supporting development of GLP-1 receptor (GLP-1R) agonists for the treatment of diabetes and obesity. Classic notions of GLP-1 acting as a meal-stimulated hormone from the distal gut are challenged by data supporting production of GLP-1 in the endocrine pancreas, and by the importance of brain-derived GLP-1 in the control of neural activity. Moreover, attribution of direct vs indirect actions of GLP-1 is difficult, as many tissue and cellular targets of GLP-1 action do not exhibit robust or detectable GLP-1R expression. Furthermore, reliable detection of the GLP-1R is technically challenging, highly method dependent, and subject to misinterpretation. Here we revisit the actions of GLP-1, scrutinizing key concepts supporting gut vs extra-intestinal GLP-1 synthesis and secretion. We discuss new insights refining cellular localization of GLP-1R expression and integrate recent data to refine our understanding of how and where GLP-1 acts to control inflammation, cardiovascular function, islet hormone secretion, gastric emptying, appetite, and body weight. These findings update our knowledge of cell types and mechanisms linking endogenous vs pharmacological GLP-1 action to activation of the canonical GLP-1R, and the control of metabolic activity in multiple organs.
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Affiliation(s)
- Brent A McLean
- Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Ontario, Canada
| | - Chi Kin Wong
- Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Ontario, Canada
| | - Jonathan E Campbell
- The Department of Medicine, Division of Endocrinology, Department of Pharmacology and Cancer Biology, Duke Molecular Physiology Institute, Duke University, Durham, NC, USA
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, and Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Stefan Trapp
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology & Pharmacology, UCL, London, UK
| | - Daniel J Drucker
- Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Ontario, Canada
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17
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Gil-Rivera M, Medina-Gali RM, Martínez-Pinna J, Soriano S. Physiology of pancreatic β-cells: Ion channels and molecular mechanisms implicated in stimulus-secretion coupling. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 359:287-323. [PMID: 33832651 DOI: 10.1016/bs.ircmb.2021.02.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The human and mouse islet of Langerhans is an endocrine organ composed of five different cells types; insulin-secreting β-cells, glucagon-producing α-cells, somatostatin-producing δ-cells, pancreatic polypeptide-secreting PP cells and ɛ-cells that secretes ghrelin. The most important cells are the pancreatic β-cells that comprise around 45-50% of human islets and 75-80% in the mouse. Pancreatic β-cells secrete insulin at high glucose concentration, thereby finely regulating glycaemia by the hypoglycaemic effects of this hormone. Different ion channels are implicated in the stimulus-secretion coupling of insulin. An increase in the intracellular ATP concentration leads to closure KATP channels, depolarizing the cell and opening voltage-gated calcium channels. The increase of intracellular calcium concentration induced by calcium entry through voltage-gated calcium channels promotes insulin secretion. Here, we briefly describe the diversity of ion channels present in pancreatic β-cells and the different mechanisms that are responsible to induce insulin secretion in human and mouse cells. Moreover, we described the pathophysiology due to alterations in the physiology of the main ion channels present in pancreatic β-cell and its implication to predispose metabolic disorders as type 2 diabetes mellitus.
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Affiliation(s)
- Minerva Gil-Rivera
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Alicante, Spain.
| | - Regla M Medina-Gali
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universidad Miguel Hernández, Elche, Spain
| | - Juan Martínez-Pinna
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Alicante, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universidad Miguel Hernández, Elche, Spain
| | - Sergi Soriano
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Alicante, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universidad Miguel Hernández, Elche, Spain.
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18
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A Practical Guide to Rodent Islet Isolation and Assessment Revisited. Biol Proced Online 2021; 23:7. [PMID: 33641671 PMCID: PMC7919091 DOI: 10.1186/s12575-021-00143-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 01/26/2021] [Indexed: 02/06/2023] Open
Abstract
Insufficient insulin secretion is a key component of both type 1 and type 2 diabetes. Since insulin is released by the islets of Langerhans, obtaining viable and functional islets is critical for research and transplantation. The effective and efficient isolation of these small islands of endocrine cells from the sea of exocrine tissue that is the rest of the pancreas is not necessarily simple or quick. Choosing and administering the digestive enzyme, separation of the islets from acinar tissue, and culture of islets are all things that must be considered. The purpose of this review is to provide a history of the development of islet isolation procedures and to serve as a practical guide to rodent islet research for newcomers to islet biology. We discuss key elements of mouse islet isolation including choosing collagenase, the digestion process, purification of islets using a density gradient, and islet culture conditions. In addition, this paper reviews techniques for assessing islet viability and function such as visual assessment, glucose-stimulated insulin secretion and intracellular calcium measurements. A detailed protocol is provided that describes a common method our laboratory uses to obtain viable and functional mouse islets for in vitro study. This review thus provides a strong foundation for successful procurement and purification of high-quality mouse islets for research purposes.
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19
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Huey J, Keutler K, Schultz C. Chemical Biology Toolbox for Studying Pancreatic Islet Function - A Perspective. Cell Chem Biol 2020; 27:1015-1031. [PMID: 32822616 DOI: 10.1016/j.chembiol.2020.07.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 07/10/2020] [Accepted: 07/28/2020] [Indexed: 01/14/2023]
Abstract
The islets of Langerhans represent one of the many complex endocrine organs in mammals. Traditionally, islet function is studied by a mixture of physiological, cell biological, and molecular biological methods. Recently, novel techniques stemming from the ever-increasing toolbox provided by chemical laboratories have been added to the repertoire. Many emerging techniques will soon be available to manipulate and monitor islet function at the single-cell level and potentially in intact model animals, as well as in isolated human islets. Here, we review the most current small-molecule-based and genetically encoded molecular tool sets available to study islet function. We provide an outlook regarding future tool developments that will impact islet research, with a special focus on the interplay between different islet cell types.
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Affiliation(s)
- Julia Huey
- Program in Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97210, USA; Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97210, USA
| | - Kaya Keutler
- Program in Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97210, USA; Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97210, USA
| | - Carsten Schultz
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97210, USA.
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20
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Denwood G, Tarasov A, Salehi A, Vergari E, Ramracheya R, Takahashi H, Nikolaev VO, Seino S, Gribble F, Reimann F, Rorsman P, Zhang Q. Glucose stimulates somatostatin secretion in pancreatic δ-cells by cAMP-dependent intracellular Ca 2+ release. J Gen Physiol 2019; 151:1094-1115. [PMID: 31358556 PMCID: PMC6719402 DOI: 10.1085/jgp.201912351] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 05/11/2019] [Accepted: 07/09/2019] [Indexed: 12/12/2022] Open
Abstract
Somatostatin secretion from pancreatic islet δ-cells is stimulated by elevated glucose levels, but the underlying mechanisms have only partially been elucidated. Here we show that glucose-induced somatostatin secretion (GISS) involves both membrane potential-dependent and -independent pathways. Although glucose-induced electrical activity triggers somatostatin release, the sugar also stimulates GISS via a cAMP-dependent stimulation of CICR and exocytosis of somatostatin. The latter effect is more quantitatively important and in mouse islets depolarized by 70 mM extracellular K+ , increasing glucose from 1 mM to 20 mM produced an ∼3.5-fold stimulation of somatostatin secretion, an effect that was mimicked by the application of the adenylyl cyclase activator forskolin. Inhibiting cAMP-dependent pathways with PKI or ESI-05, which inhibit PKA and exchange protein directly activated by cAMP 2 (Epac2), respectively, reduced glucose/forskolin-induced somatostatin secretion. Ryanodine produced a similar effect that was not additive to that of the PKA or Epac2 inhibitors. Intracellular application of cAMP produced a concentration-dependent stimulation of somatostatin exocytosis and elevation of cytoplasmic Ca2+ ([Ca2+]i). Both effects were inhibited by ESI-05 and thapsigargin (an inhibitor of SERCA). By contrast, inhibition of PKA suppressed δ-cell exocytosis without affecting [Ca2+]i Simultaneous recordings of electrical activity and [Ca2+]i in δ-cells expressing the genetically encoded Ca2+ indicator GCaMP3 revealed that the majority of glucose-induced [Ca2+]i spikes did not correlate with δ-cell electrical activity but instead reflected Ca2+ release from the ER. These spontaneous [Ca2+]i spikes are resistant to PKI but sensitive to ESI-05 or thapsigargin. We propose that cAMP links an increase in plasma glucose to stimulation of somatostatin secretion by promoting CICR, thus evoking exocytosis of somatostatin-containing secretory vesicles in the δ-cell.
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Affiliation(s)
- Geoffrey Denwood
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Andrei Tarasov
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, UK
| | - Albert Salehi
- Institute of Neuroscience and Physiology, Department of Physiology, Metabolic Research Unit, University of Goteborg, Göteborg, Sweden
| | - Elisa Vergari
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Reshma Ramracheya
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Harumi Takahashi
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Viacheslav O Nikolaev
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Susumo Seino
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Fiona Gribble
- Institute of Metabolic Science, University of Cambridge, Addenbrook's Hospital, Cambridge, UK
| | - Frank Reimann
- Institute of Metabolic Science, University of Cambridge, Addenbrook's Hospital, Cambridge, UK
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
- Institute of Neuroscience and Physiology, Department of Physiology, Metabolic Research Unit, University of Goteborg, Göteborg, Sweden
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
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21
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Tomas A, Jones B, Leech C. New Insights into Beta-Cell GLP-1 Receptor and cAMP Signaling. J Mol Biol 2019; 432:1347-1366. [PMID: 31446075 DOI: 10.1016/j.jmb.2019.08.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Revised: 08/06/2019] [Accepted: 08/13/2019] [Indexed: 12/14/2022]
Abstract
Harnessing the translational potential of the GLP-1/GLP-1R system in pancreatic beta cells has led to the development of established GLP-1R-based therapies for the long-term preservation of beta cell function. In this review, we discuss recent advances in the current research on the GLP-1/GLP-1R system in beta cells, including the regulation of signaling by endocytic trafficking as well as the application of concepts such as signal bias, allosteric modulation, dual agonism, polymorphic receptor variants, spatial compartmentalization of cAMP signaling and new downstream signaling targets involved in the control of beta cell function.
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Affiliation(s)
- Alejandra Tomas
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 0NN, UK.
| | - Ben Jones
- Section of Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 0NN, UK
| | - Colin Leech
- Department of Surgery, State University of New York, Upstate Medical University, Syracuse, NY, 13210, USA
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22
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Hameed A, Hafizur RM, Khan MI, Jawed A, Wang H, Zhao M, Matsunaga K, Izumi T, Siddiqui S, Khan F, Adhikari A, Sharma KR. Coixol amplifies glucose-stimulated insulin secretion via cAMP mediated signaling pathway. Eur J Pharmacol 2019; 858:172514. [PMID: 31265841 DOI: 10.1016/j.ejphar.2019.172514] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 06/25/2019] [Accepted: 06/28/2019] [Indexed: 12/20/2022]
Abstract
Recently, we reported the role of coixol (6-methoxy-2(3H)-benzoxazolone), an alkaloid from Scoparia dulcis, in glucose-dependent insulin secretion; however, its insulin secretory mechanism(s) remained unknown. Here, we explored the insulinotropic mechanism(s) of coixol in vitro and in vivo. Mice islets were batch incubated, perifused with coixol in the presence of agonists/antagonists, and insulin secretion was measured by ELISA. Intracellular cAMP levels were measured using enzyme immunoassay. K+- and Ca2+-currents were recorded in MIN6 cells using whole-cell patch-clamp technique. The in vivo glucose tolerance and the insulinogenic index were evaluated in diabetic rats treated with coixol at 25 and 50 mg/kg, respectively. Coixol, unlike sulfonylurea, enhanced insulin secretion in batch incubated and perifused islets at high glucose, with no effect at basal glucose concentrations. Coixol showed no pronounced effect on the inward rectifying K+- and Ca2+-currents in whole-cell patch recordings. Moreover, coixol-induced insulin secretion was further amplified in the depolarized islets. Coixol showed an additive effect with forskolin (10 μM)-induced cAMP level, and in insulin secretion; however, no additive effect was observed with isobutylmethylxanthine (IBMX, 100 μM)-induced cAMP level, nor in insulin secretion. The PKA inhibitor H-89 (50 μM), and Epac2 inhibitor MAY0132 (50 μM) significantly inhibited the coixol-induced insulin secretion (P < 0.01). Furthermore, insulin secretory kinetics revealed that coixol potentiates insulin secretion in both early and late phases of insulin secretion. In diabetic animals, coixol showed significant improvement in glucose tolerance and on fasting blood glucose levels. These data suggest that coixol amplifies glucose-stimulated insulin secretion by cAMP-mediated signaling pathways.
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Affiliation(s)
- Abdul Hameed
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences (ICCBS), University of Karachi, Karachi, 75270, Pakistan; Centre for Advanced Drug Research (CADR), COMSATS University Islamabad (CUI), Abbottabad, 22060, Pakistan
| | - Rahman M Hafizur
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences (ICCBS), University of Karachi, Karachi, 75270, Pakistan.
| | - M Israr Khan
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences (ICCBS), University of Karachi, Karachi, 75270, Pakistan
| | - Abira Jawed
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences (ICCBS), University of Karachi, Karachi, 75270, Pakistan
| | - Hao Wang
- Laboratory of Molecular Endocrinology and Metabolism, Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Miaomiao Zhao
- Laboratory of Molecular Endocrinology and Metabolism, Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Kohichi Matsunaga
- Laboratory of Molecular Endocrinology and Metabolism, Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Tetsuro Izumi
- Laboratory of Molecular Endocrinology and Metabolism, Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Sonia Siddiqui
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences (ICCBS), University of Karachi, Karachi, 75270, Pakistan
| | - Faisal Khan
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences (ICCBS), University of Karachi, Karachi, 75270, Pakistan
| | - Achyut Adhikari
- H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan; Central Department of Chemistry, Tribhuvan University, Kirtipur, Kathmandu, Nepal
| | - Khaga Raj Sharma
- Central Department of Chemistry, Tribhuvan University, Kirtipur, Kathmandu, Nepal
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23
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Salem V, Silva LD, Suba K, Georgiadou E, Neda Mousavy Gharavy S, Akhtar N, Martin-Alonso A, Gaboriau DCA, Rothery SM, Stylianides T, Carrat G, Pullen TJ, Singh SP, Hodson DJ, Leclerc I, Shapiro AMJ, Marchetti P, Briant LJB, Distaso W, Ninov N, Rutter GA. Leader β-cells coordinate Ca 2+ dynamics across pancreatic islets in vivo. Nat Metab 2019; 1:615-629. [PMID: 32694805 DOI: 10.1038/s42255-019-0075-2] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 05/08/2019] [Indexed: 02/06/2023]
Abstract
Pancreatic β-cells form highly connected networks within isolated islets. Whether this behaviour pertains to the situation in vivo, after innervation and during continuous perfusion with blood, is unclear. In the present study, we used the recombinant Ca2+ sensor GCaMP6 to assess glucose-regulated connectivity in living zebrafish Danio rerio, and in murine or human islets transplanted into the anterior eye chamber. In each setting, Ca2+ waves emanated from temporally defined leader β-cells, and three-dimensional connectivity across the islet increased with glucose stimulation. Photoablation of zebrafish leader cells disrupted pan-islet signalling, identifying these as likely pacemakers. Correspondingly, in engrafted mouse islets, connectivity was sustained during prolonged glucose exposure, and super-connected 'hub' cells were identified. Granger causality analysis revealed a controlling role for temporally defined leaders, and transcriptomic analyses revealed a discrete hub cell fingerprint. We thus define a population of regulatory β-cells within coordinated islet networks in vivo. This population may drive Ca2+ dynamics and pulsatile insulin secretion.
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Affiliation(s)
- Victoria Salem
- Department of Medicine, Imperial College London, London, UK.
| | - Luis Delgadillo Silva
- Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany
| | - Kinga Suba
- Department of Medicine, Imperial College London, London, UK
| | | | | | - Nadeem Akhtar
- Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany
| | | | - David C A Gaboriau
- Facility for Imaging by Light Microscopy, Imperial College London, London, UK
| | - Stephen M Rothery
- Facility for Imaging by Light Microscopy, Imperial College London, London, UK
| | | | - Gaelle Carrat
- Department of Medicine, Imperial College London, London, UK
| | - Timothy J Pullen
- Department of Diabetes, Faculty of Life Science and Medicine, King's College London, London, UK
| | - Sumeet Pal Singh
- Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany
| | - David J Hodson
- Institute of Metabolism and Systems Research, University of Birmingham, Edgbaston, UK
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
- Centre of Membrane Proteins and Receptors, University of Birmingham and University of Nottingham, Nottingham, UK
| | | | - A M James Shapiro
- Clinical Islet Laboratory and Clinical Islet Transplant Program, University of Alberta, Edmonton, Alberta, Canada
| | | | | | | | - Nikolay Ninov
- Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany.
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the University Hospital Carl Gustav Carus of TU Dresden, German Center for Diabetes Research, Dresden, Germany.
| | - Guy A Rutter
- Department of Medicine, Imperial College London, London, UK.
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24
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Shigeto H, Ono T, Ikeda T, Hirota R, Ishida T, Kuroda A, Funabashi H. Insulin sensor cells for the analysis of insulin secretion responses in single living pancreatic β cells. Analyst 2019; 144:3765-3772. [PMID: 31089611 DOI: 10.1039/c9an00405j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Investigation of the functions of insulin-secreting cells in response to glucose in single-living cells is essential for improving our knowledge on the pathogenesis of diabetes. Therefore, it is desired to develop a new convenient method that enables the direct detection of insulin secreted from single-living cells. Here, insulin-sensor-cells expressing a protein-based insulin-detecting probe immobilized on the extracellular membrane were developed to evaluate the insulin-secretion response in single-living pancreatic β cells. The protein-based insulin-detecting probe (NαLY) was composed of a bioluminescent protein (nano-luc), the αCT segment of the insulin receptor, L1 and CR domains of the insulin receptor, and a fluorescent protein (YPet). NαLY exhibited a bioluminescence resonance energy transfer (BRET) signal in response to insulin; thus, cells of Hepa1-6 line were genetically engineered to express NαLY on the extracellular membrane. The cells were found to act as insulin-sensor-cells, exhibiting a BRET signal in response to insulin. When the insulin-sensor-cells and pancreatic β cells (MIN6 cell line) were cocultured and stimulated with glucose, insulin-sensor-cells nearby pancreatic β cells showed the spike-shaped BRET signal response, whereas the insulin-sensor-cells close to one pancreatic β cell did not exhibit such signal response. However, all the insulin-sensor-cells showed a gradual increase in BRET signals, which were presumably attributed to the increase in insulin concentrations in the culture dish, confirming the function of these insulin-sensor-cells. Therefore, we demonstrated that heterogenetic insulin secretion in single-living pancreatic β cells could be measured directly using the insulin sensor cells.
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Affiliation(s)
- Hajime Shigeto
- Institute for Sustainable Sciences and Development, Hiroshima University, Higashihiroshima, Hiroshima 739-8511, Japan. and Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashihiroshima, Hiroshima 739-8530, Japan and Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14 Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan
| | - Takuto Ono
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashihiroshima, Hiroshima 739-8530, Japan
| | - Takeshi Ikeda
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashihiroshima, Hiroshima 739-8530, Japan
| | - Ryuichi Hirota
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashihiroshima, Hiroshima 739-8530, Japan
| | - Takenori Ishida
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashihiroshima, Hiroshima 739-8530, Japan
| | - Akio Kuroda
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashihiroshima, Hiroshima 739-8530, Japan
| | - Hisakage Funabashi
- Institute for Sustainable Sciences and Development, Hiroshima University, Higashihiroshima, Hiroshima 739-8511, Japan. and Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashihiroshima, Hiroshima 739-8530, Japan
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25
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Szczoczarz A, Marchwińska A, Dyś A, Boblewski K, Lehmann A, Lewko B, Rybczyńska A. Verapamil prevents the effect of calcium-sensing receptor activation on the blood glucose and insulin levels in rats. Pharmacol Rep 2019; 71:478-484. [PMID: 31003161 DOI: 10.1016/j.pharep.2019.01.004] [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: 09/27/2018] [Revised: 12/14/2018] [Accepted: 01/04/2019] [Indexed: 10/27/2022]
Abstract
BACKGROUND The Ca2+ triggered insulin exocytosis in β cells of the pancreatic islets may be the result of Ca2+ influx through L-type voltage dependent calcium channels (VDCC) localized in the plasma membrane, as well as of liberation of Ca2+ from intracellular storages, induced by activation of the calcium receptor (CaR) coupled with the PLC enzyme present in the pancreatic islets. The present study was designated to determine, in in vivo experiments, the effects of CaR activation by R-568 and inhibition of the receptor by NPS 2143 on the plasma glucose and insulin levels in the presence of verapamil, a calcium channel blocker. METHODS Wistar rats, after fasting for 14 h before the experiment, were anesthetized with inactin and loaded ip with 1 g/kg glucose. RESULTS In comparison to the control group, the verapamil-induced blockade of the calcium channels in glucose loaded animals increased the blood glucose level and decreased the insulin level, whereas CaR activation with R-568 induced opposite effects. However, in the presence of verapamil, R-568 did not change the concentration of glucose or insulin versus the control animals. Verapamil infusion did not alter elevated glucose concentration in the NPS 2143 animals. At the same time, verapamil reduced the plasma insulin level and potentiated the drop of insulin concentration induced by NPS 2143. CONCLUSION The observations suggest that under the in vivo conditions, calcium channel blockade may prevent changes in the blood glucose and insulin concentrations induced by the CaR activation.
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Affiliation(s)
- Anna Szczoczarz
- Department of Pathophysiology, Faculty of Pharmacy, Medical University of Gdańsk, Gdańsk, Poland
| | - Aleksandra Marchwińska
- Department of Pathophysiology, Faculty of Pharmacy, Medical University of Gdańsk, Gdańsk, Poland
| | - Aleksandra Dyś
- Department of Laboratory Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | - Konrad Boblewski
- Department of Pathophysiology, Faculty of Pharmacy, Medical University of Gdańsk, Gdańsk, Poland
| | - Artur Lehmann
- Department of Pathophysiology, Faculty of Pharmacy, Medical University of Gdańsk, Gdańsk, Poland
| | - Barbara Lewko
- Department of Pathophysiology, Faculty of Pharmacy, Medical University of Gdańsk, Gdańsk, Poland
| | - Apolonia Rybczyńska
- Department of Pathophysiology, Faculty of Pharmacy, Medical University of Gdańsk, Gdańsk, Poland.
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26
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Hwang HJ, Jang HJ, Cocco L, Suh PG. The regulation of insulin secretion via phosphoinositide-specific phospholipase Cβ signaling. Adv Biol Regul 2019; 71:10-18. [PMID: 30293894 DOI: 10.1016/j.jbior.2018.09.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 09/17/2018] [Accepted: 09/17/2018] [Indexed: 06/08/2023]
Abstract
Phospholipase Cβ (PLCβ) is a membrane-associated enzyme activated by membrane receptors, especially G-protein coupled receptors (GPCRs). It propagates intracellular signaling by mediating phospholipid metabolism and generating key second messengers, such as inositol triphosphate and diacylglycerol, leading to intracellular Ca2+ mobilization and activation of kinases, such as protein kinases C. In pancreatic β-cells, PLCβ-mediated signaling activated by various factors, such as free fatty acids and neuronal and hormonal ligands, has been confirmed as being involved in the regulation of insulin secretion, and PLCβs have been regarded as essential mediators for augmenting insulin secretion. In this review, we describe the physiological function of PLCβs in the regulation of glucose-stimulated insulin secretion and discuss emerging data on GPCR/PLCβ signaling that is being developed as a target for the treatment of diabetes mellitus.
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Affiliation(s)
- Hyeon-Jeong Hwang
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Hyun-Jun Jang
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Lucio Cocco
- Cellular Signaling Laboratory, Department of Biomedical Sciences, University of Bologna, Via Irnerio, 48, I-40126, Bologna, Italy
| | - Pann-Ghill Suh
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea.
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27
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Loh K, Shi YC, Bensellam M, Lee K, Laybutt DR, Herzog H. Y1 receptor deficiency in β-cells leads to increased adiposity and impaired glucose metabolism. Sci Rep 2018; 8:11835. [PMID: 30177746 PMCID: PMC6120893 DOI: 10.1038/s41598-018-30140-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 07/24/2018] [Indexed: 01/12/2023] Open
Abstract
Insulin secretion from pancreatic β-cells is critical for maintaining glucose homeostasis and deregulation of circulating insulin levels is associated with the development of metabolic diseases. While many factors have been implicated in the stimulation of insulin secretion, the mechanisms that subsequently reduce insulin secretion remain largely unexplored. Here we demonstrate that mice with β-cell specific ablation of the Y1 receptor exhibit significantly upregulated serum insulin levels associated with increased body weight and adiposity. Interestingly, when challenged with a high fat diet these β-cell specific Y1-deficient mice also develop hyperglycaemia and impaired glucose tolerance. This is most likely due to enhanced hepatic lipid synthesis, resulting in an increase of lipid accumulation in the liver. Together, our study demonstrates that Y1 receptor signaling negatively regulates insulin release, and pharmacological inhibition of Y1 receptor signalling for the treatment of non-insulin dependent diabetes should be taken into careful consideration.
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Affiliation(s)
- Kim Loh
- Neuroscience Division, Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, 2010, Australia. .,Faculty of Medicine, UNSW Australia, Sydney, 2052, Australia. .,St. Vincent's Institute of Medical Research, Fitzroy, VIC, 3065, Australia.
| | - Yan-Chuan Shi
- Neuroscience Division, Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, 2010, Australia.,Faculty of Medicine, UNSW Australia, Sydney, 2052, Australia
| | - Mohammed Bensellam
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, 2010, Australia
| | - Kailun Lee
- Neuroscience Division, Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, 2010, Australia.,Diabetes and Metabolism Division, Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, 2010, Australia.,Faculty of Medicine, UNSW Australia, Sydney, 2052, Australia
| | - D Ross Laybutt
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, 2010, Australia.,Faculty of Medicine, UNSW Australia, Sydney, 2052, Australia
| | - Herbert Herzog
- Neuroscience Division, Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, 2010, Australia. .,Faculty of Medicine, UNSW Australia, Sydney, 2052, Australia.
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28
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Huang C, Walker EM, Dadi PK, Hu R, Xu Y, Zhang W, Sanavia T, Mun J, Liu J, Nair GG, Tan HYA, Wang S, Magnuson MA, Stoeckert CJ, Hebrok M, Gannon M, Han W, Stein R, Jacobson DA, Gu G. Synaptotagmin 4 Regulates Pancreatic β Cell Maturation by Modulating the Ca 2+ Sensitivity of Insulin Secretion Vesicles. Dev Cell 2018; 45:347-361.e5. [PMID: 29656931 PMCID: PMC5962294 DOI: 10.1016/j.devcel.2018.03.013] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 02/12/2018] [Accepted: 03/19/2018] [Indexed: 12/14/2022]
Abstract
Islet β cells from newborn mammals exhibit high basal insulin secretion and poor glucose-stimulated insulin secretion (GSIS). Here we show that β cells of newborns secrete more insulin than adults in response to similar intracellular Ca2+ concentrations, suggesting differences in the Ca2+ sensitivity of insulin secretion. Synaptotagmin 4 (Syt4), a non-Ca2+ binding paralog of the β cell Ca2+ sensor Syt7, increased by ∼8-fold during β cell maturation. Syt4 ablation increased basal insulin secretion and compromised GSIS. Precocious Syt4 expression repressed basal insulin secretion but also impaired islet morphogenesis and GSIS. Syt4 was localized on insulin granules and Syt4 levels inversely related to the number of readily releasable vesicles. Thus, transcriptional regulation of Syt4 affects insulin secretion; Syt4 expression is regulated in part by Myt transcription factors, which repress Syt4 transcription. Finally, human SYT4 regulated GSIS in EndoC-βH1 cells, a human β cell line. These findings reveal the role that altered Ca2+ sensing plays in regulating β cell maturation.
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Affiliation(s)
- Chen Huang
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Center for Stem Cell Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; The Program of Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - Emily M Walker
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - Ruiying Hu
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Center for Stem Cell Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; The Program of Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - Yanwen Xu
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Center for Stem Cell Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; The Program of Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - Wenjian Zhang
- China-Japan Friendship Hospital, Beijing 100029, P. R. China
| | - Tiziana Sanavia
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
| | - Jisoo Mun
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - Jennifer Liu
- Diabetes Center, UCSF, San Francisco, CA 94143, USA
| | | | - Hwee Yim Angeline Tan
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, Singapore, Singapore
| | - Sui Wang
- Department of Ophthalmology, Mary M. and Sash A. Spencer Center for Vision Research, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Mark A Magnuson
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Center for Stem Cell Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - Christian J Stoeckert
- Institute for Biomedical Informatics and Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | | | - Maureen Gannon
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Center for Stem Cell Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; The Program of Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Department of Medicine, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - Weiping Han
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, Singapore, Singapore
| | - Roland Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA.
| | - Guoqiang Gu
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Center for Stem Cell Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; The Program of Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA.
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29
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Treatments for diabetes mellitus type II: New perspectives regarding the possible role of calcium and cAMP interaction. Eur J Pharmacol 2018; 830:9-16. [PMID: 29679542 DOI: 10.1016/j.ejphar.2018.04.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/29/2018] [Accepted: 04/03/2018] [Indexed: 12/18/2022]
Abstract
Diabetes mellitus (DM) is among the top ten causes of death worldwide. It is considered to be one of the major global epidemics of the 21st century, with a significant impact on public health budgets. DM is a metabolic disorder with multiple etiologies. Its pathophysiology is marked by dysfunction of pancreatic β-cells which compromises the synthesis and secretion of insulin along with resistance to insulin action in peripheral tissues (muscle and adipose). Subjects presenting insulin resistance in DM type 2 often also exhibit increased insulin secretion and hyperinsulinemia. Insulin secretion is controlled by several factors such as nutrients, hormones, and neural factors. Exocytosis of insulin granules has, as its main stimulus, increased intracellular calcium ([Ca+2]i) and it is further amplified by cyclic AMP (cAMP). In the event of this hyperfunction, it is very common for β-cells to go into exhaustion leading to failure or death. Several animal studies have demonstrated pleiotropic effects of L-type Ca2+ channel blockers (CCBs). In animal models of obesity and diabetes, treatment with CCBs promoted restoration of insulin secretion, glycemic control, and reduction of pancreatic β-cell apoptosis. In addition, hypertensive individuals treated with CCBs presented a lower incidence of DM when compared with other antihypertensive agents. In this review, we propose that pharmacological manipulation of the Ca2+/cAMP interaction system could lead to important targets for pharmacological improvement of insulin secretion in DM type 2.
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30
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Kukushkin NV. Taking memory beyond the brain: Does tobacco dream of the mosaic virus? Neurobiol Learn Mem 2018; 153:111-116. [PMID: 29396326 DOI: 10.1016/j.nlm.2018.01.003] [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: 10/06/2017] [Revised: 01/05/2018] [Accepted: 01/21/2018] [Indexed: 10/18/2022]
Abstract
Memory is typically defined through animal behavior, but this point of view may limit our understanding of many related processes in diverse biological systems. The concept of memory can be broadened meaningfully by considering it from the perspective of time and homeostasis. On the one hand, this theoretical angle can help explain and predict the behavior of various non-neural systems such as insulin-secreting cells, plants, or signaling cascades. On the other hand, it emphasizes biological continuity between neural phenomena, such as synaptic plasticity, and their evolutionary precursors in cellular signaling.
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Affiliation(s)
- Nikolay V Kukushkin
- Center for Neural Science, New York University, 4 Washington Pl, New York, NY 10003, USA.
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31
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Fine NHF, Doig CL, Elhassan YS, Vierra NC, Marchetti P, Bugliani M, Nano R, Piemonti L, Rutter GA, Jacobson DA, Lavery GG, Hodson DJ. Glucocorticoids Reprogram β-Cell Signaling to Preserve Insulin Secretion. Diabetes 2018; 67:278-290. [PMID: 29203512 PMCID: PMC5780059 DOI: 10.2337/db16-1356] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 11/16/2017] [Indexed: 12/19/2022]
Abstract
Excessive glucocorticoid exposure has been shown to be deleterious for pancreatic β-cell function and insulin release. However, glucocorticoids at physiological levels are essential for many homeostatic processes, including glycemic control. We show that corticosterone and cortisol and their less active precursors 11-dehydrocorticosterone (11-DHC) and cortisone suppress voltage-dependent Ca2+ channel function and Ca2+ fluxes in rodent as well as in human β-cells. However, insulin secretion, maximal ATP/ADP responses to glucose, and β-cell identity were all unaffected. Further examination revealed the upregulation of parallel amplifying cAMP signals and an increase in the number of membrane-docked insulin secretory granules. Effects of 11-DHC could be prevented by lipotoxicity and were associated with paracrine regulation of glucocorticoid activity because global deletion of 11β-hydroxysteroid dehydrogenase type 1 normalized Ca2+ and cAMP responses. Thus, we have identified an enzymatically amplified feedback loop whereby glucocorticoids boost cAMP to maintain insulin secretion in the face of perturbed ionic signals. Failure of this protective mechanism may contribute to diabetes in states of glucocorticoid excess, such as Cushing syndrome, which are associated with frank dyslipidemia.
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Affiliation(s)
- Nicholas H F Fine
- Institute of Metabolism and Systems Research, University of Birmingham, Edgbaston, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - Craig L Doig
- Institute of Metabolism and Systems Research, University of Birmingham, Edgbaston, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - Yasir S Elhassan
- Institute of Metabolism and Systems Research, University of Birmingham, Edgbaston, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - Nicholas C Vierra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Piero Marchetti
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Marco Bugliani
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Rita Nano
- Diabetes Research Institute, San Raffaele Scientific Institute, Milan, Italy
| | - Lorenzo Piemonti
- Diabetes Research Institute, San Raffaele Scientific Institute, Milan, Italy
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Department of Medicine, Imperial College London, London, U.K
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Gareth G Lavery
- Institute of Metabolism and Systems Research, University of Birmingham, Edgbaston, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - David J Hodson
- Institute of Metabolism and Systems Research, University of Birmingham, Edgbaston, U.K.
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
- Centre of Membrane Proteins and Receptors, University of Birmingham and University of Nottingham, Midlands, U.K
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32
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Altieri B, Grant WB, Della Casa S, Orio F, Pontecorvi A, Colao A, Sarno G, Muscogiuri G. Vitamin D and pancreas: The role of sunshine vitamin in the pathogenesis of diabetes mellitus and pancreatic cancer. Crit Rev Food Sci Nutr 2018; 57:3472-3488. [PMID: 27030935 DOI: 10.1080/10408398.2015.1136922] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Increasing evidence suggests that vitamin D exerts multiple effects beyond bone and calcium metabolism. Vitamin D seems to play a role in pancreatic disease, including type 1 and type 2 diabetes mellitus as well as pancreatic cancer. Vitamin D's immune-modulatory action suggests that it could help prevent type 1 diabetes. In type 2 diabetes, vitamin D may influence β-cell function, insulin sensitivity, and systematic inflammation-all characteristic pathways of that disease. Data from observational studies correlated vitamin D deficiency with risk of type 1 and type 2 diabetes. Prospective and ecological studies of pancreatic cancer incidence generally support a beneficial effect of higher 25-hydroxyvitamin D concentration as well as inverse correlations between UVB dose or exposure and incidence and/or mortality rate of pancreatic cancer. This review discusses the literature regarding vitamin D's role in risk of diabetes and pancreatic cancer. The results to date generally satisfy Hill's criteria for causality regarding vitamin D and incidence of these pancreatic diseases. However, large randomized, blinded, prospective studies are required to more fully evaluate the potential therapeutic role of vitamin D in preventing pancreatic diseases.
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Affiliation(s)
- Barbara Altieri
- a Institute of Medical Pathology, Division of Endocrinology and Metabolic Diseases, Catholic University of the Sacred Heart , Rome , Italy
| | - William B Grant
- b Sunlight , Nutrition, and Health Research Center , San Francisco , California , USA
| | - Silvia Della Casa
- a Institute of Medical Pathology, Division of Endocrinology and Metabolic Diseases, Catholic University of the Sacred Heart , Rome , Italy
| | - Francesco Orio
- c Endocrinology, Department of Sports Science and Wellness , Parthenope University , Naples , Italy.,d Fertility Techniques SSD , San Giovanni di Dio e Ruggi D'Aragona University Hospital , Salerno , Italy
| | - Alfredo Pontecorvi
- a Institute of Medical Pathology, Division of Endocrinology and Metabolic Diseases, Catholic University of the Sacred Heart , Rome , Italy
| | - Annamaria Colao
- e Department of Clinical Medicine and Surgery, Section of Endocrinology , University "Federico II," Naples , Italy
| | - Gerardo Sarno
- f Department of General Surgery and Transplantation Unit , San Giovanni di Dio e Ruggi D'Aragona University Hospital, Scuola Medica Salernitana , Salerno , Italy
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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: 456] [Impact Index Per Article: 76.0] [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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34
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Hameed A, Hafizur RM, Hussain N, Raza SA, Rehman M, Ashraf S, Ul-Haq Z, Khan F, Abbas G, Choudhary MI. Eriodictyol stimulates insulin secretion through cAMP/PKA signaling pathway in mice islets. Eur J Pharmacol 2017; 820:245-255. [PMID: 29229531 DOI: 10.1016/j.ejphar.2017.12.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 11/21/2017] [Accepted: 12/06/2017] [Indexed: 12/21/2022]
Abstract
Eriodictyol, a flavonoid isolated from Lyonia ovalifolia, was found to be the most potent insulin secretagogue in our preliminary studies. Here, we explored mechanism(s) of insulin secretory activity of eriodictyol in vitro and in vivo. Mice islets and MIN6 cells were incubated in basal and stimulatory glucose containing eriodictyol with or without agonist/antagonist. Secreted insulin and cAMP contents were measured using ELISA kits. K+- and Ca2+-channels currents were recorded with patch-clamp technique. Oral glucose tolerance test and plasma insulin was evaluated in non-diabetic and diabetic rats. Eriodictyol stimulated insulin secretion from mice islets and MIN6 cells only at stimulatory glucose concentrations with maximum effect at 200μM. Eriodictyol showed no pronounced effect on inward rectifying K+ and Ca2+ currents. Furthermore, in KCl depolarized islets, in the presence of diazoxide, insulin secretory ability of eriodictyol was enhanced. IBMX, a phosphodiesterase inhibitor, significantly (P<0.001) enhanced eriodictyol-induced insulin secretion at 16.7mM glucose in comparison to eriodictyol or IBMX alone. The cAMP content after eriodictyol exposure was also increased. Eriodictyol-induced insulin secretion was partially inhibited by adenylate cyclase inhibitor (SQ22536) and completely inhibited by PKA inhibitor (H-89), suggesting that the eriodictyol effect is more on PKA. Molecular docking studies showed the best binding affinities of eriodictyol with PKA. Eriodictyol improved glucose tolerance and enhanced plasma insulin in non-diabetic and diabetic rats. Eriodictyol also lowered blood glucose in diabetic rats upon chronic treatment. Taken together, it can be concluded that eriodictyol, a novel insulin secretagogue, exerts an exclusive glucose-dependent insulinotropic effect through cAMP/PKA pathway.
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Affiliation(s)
- Abdul Hameed
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi-75270, Pakistan
| | - Rahman M Hafizur
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi-75270, Pakistan.
| | - Nusrat Hussain
- H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences (ICCBS), University of Karachi, Karachi-75270, Pakistan
| | - Sayed Ali Raza
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi-75270, Pakistan
| | - Mujeeb Rehman
- H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences (ICCBS), University of Karachi, Karachi-75270, Pakistan
| | - Sajda Ashraf
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi-75270, Pakistan
| | - Zaheer Ul-Haq
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi-75270, Pakistan
| | - Faisal Khan
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi-75270, Pakistan
| | - Ghulam Abbas
- H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences (ICCBS), University of Karachi, Karachi-75270, Pakistan
| | - M Iqbal Choudhary
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi-75270, Pakistan; H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences (ICCBS), University of Karachi, Karachi-75270, Pakistan; Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah-21412, Saudi Arabia
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Zhu M, Wei Y, Geißler C, Abschlag K, Corbalán Campos J, Hristov M, Möllmann J, Lehrke M, Karshovska E, Schober A. Hyperlipidemia-Induced MicroRNA-155-5p Improves β-Cell Function by Targeting Mafb. Diabetes 2017; 66:3072-3084. [PMID: 28970282 DOI: 10.2337/db17-0313] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 09/19/2017] [Indexed: 11/13/2022]
Abstract
A high-fat diet increases bacterial lipopolysaccharide (LPS) in the circulation and thereby stimulates glucagon-like peptide 1 (GLP-1)-mediated insulin secretion by upregulating interleukin-6 (IL-6). Although microRNA-155-5p (miR-155-5p), which increases IL-6 expression, is upregulated by LPS and hyperlipidemia and patients with familial hypercholesterolemia less frequently develop diabetes, the role of miR-155-5p in the islet stress response to hyperlipidemia is unclear. In this study, we demonstrate that hyperlipidemia-associated endotoxemia upregulates miR-155-5p in murine pancreatic β-cells, which improved glucose metabolism and the adaptation of β-cells to obesity-induced insulin resistance. This effect of miR-155-5p is because of suppression of v-maf musculoaponeurotic fibrosarcoma oncogene family, protein B, which promotes β-cell function through IL-6-induced GLP-1 production in α-cells. Moreover, reduced GLP-1 levels are associated with increased obesity progression, dyslipidemia, and atherosclerosis in hyperlipidemic Mir155 knockout mice. Hence, induction of miR-155-5p expression in β-cells by hyperlipidemia-associated endotoxemia improves the adaptation of β-cells to insulin resistance and represents a protective mechanism in the islet stress response.
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Affiliation(s)
- Mengyu Zhu
- Institute for Cardiovascular Prevention, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Yuanyuan Wei
- Institute for Cardiovascular Prevention, Ludwig-Maximilians-Universität München, Munich, Germany
- German Centre for Cardiovascular Research, Partner Site Munich Heart Alliance, Munich, Germany
| | - Claudia Geißler
- Institute for Cardiovascular Prevention, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Kathrin Abschlag
- Institute for Cardiovascular Prevention, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Judit Corbalán Campos
- Institute for Cardiovascular Prevention, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Michael Hristov
- Institute for Cardiovascular Prevention, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Julia Möllmann
- Department of Internal Medicine I, University Hospital Aachen, Aachen, Germany
| | - Michael Lehrke
- Department of Internal Medicine I, University Hospital Aachen, Aachen, Germany
| | - Ela Karshovska
- Institute for Cardiovascular Prevention, Ludwig-Maximilians-Universität München, Munich, Germany
- German Centre for Cardiovascular Research, Partner Site Munich Heart Alliance, Munich, Germany
| | - Andreas Schober
- Institute for Cardiovascular Prevention, Ludwig-Maximilians-Universität München, Munich, Germany
- German Centre for Cardiovascular Research, Partner Site Munich Heart Alliance, Munich, Germany
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36
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Saliani N, Montazersaheb S, Montasser Kouhsari S. Micromanaging Glucose Tolerance and Diabetes. Adv Pharm Bull 2017; 7:547-556. [PMID: 29399544 PMCID: PMC5788209 DOI: 10.15171/apb.2017.066] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 12/05/2017] [Accepted: 12/12/2017] [Indexed: 12/12/2022] Open
Abstract
MicroRNAs (miRNAs) are endogenous non-coding RNAs that have significant roles in biological processes such as glucose homoeostasis. MiRNAs fine-tune target genes expression via sequence-specific binding of their seed sequence to the untranslated region of mRNAs and degrade target mRNAs. MicroRNAs in islet β-cells regulate β-cell differentiation, proliferation, insulin transcription and glucose-stimulated insulin secretion. Furthermore, miRNAs play key roles in the regulation of glucose and lipid metabolisms and modify insulin sensitivity by controlling metabolic functions in main target organs of insulin such as skeletal muscle, liver and adipose tissue. Moreover, since circulating miRNAs are detectable and stable in serum, levels of certain miRNAs seem to be novel biomarkers for prediction of diabetes mellitus. In this article, due to the prominent impact of miRNAs on diabetes, we overviewed the microRNAs regulatory functions in organs related to insulin resistance and diabetes and shed light on their potential as diagnostic and therapeutic markers for diabetes.
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Affiliation(s)
- Negar Saliani
- Department of Cellular and Molecular Biology, School of Biology, College of Sciences, University of Tehran, Tehran, Iran
| | | | - Shideh Montasser Kouhsari
- Department of Cellular and Molecular Biology, School of Biology, College of Sciences, University of Tehran, Tehran, Iran
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37
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Inhibition of Y1 receptor signaling improves islet transplant outcome. Nat Commun 2017; 8:490. [PMID: 28887564 PMCID: PMC5591241 DOI: 10.1038/s41467-017-00624-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 07/13/2017] [Indexed: 02/08/2023] Open
Abstract
Failure to secrete sufficient quantities of insulin is a pathological feature of type-1 and type-2 diabetes, and also reduces the success of islet cell transplantation. Here we demonstrate that Y1 receptor signaling inhibits insulin release in β-cells, and show that this can be pharmacologically exploited to boost insulin secretion. Transplanting islets with Y1 receptor deficiency accelerates the normalization of hyperglycemia in chemically induced diabetic recipient mice, which can also be achieved by short-term pharmacological blockade of Y1 receptors in transplanted mouse and human islets. Furthermore, treatment of non-obese diabetic mice with a Y1 receptor antagonist delays the onset of diabetes. Mechanistically, Y1 receptor signaling inhibits the production of cAMP in islets, which via CREB mediated pathways results in the down-regulation of several key enzymes in glycolysis and ATP production. Thus, manipulating Y1 receptor signaling in β-cells offers a unique therapeutic opportunity for correcting insulin deficiency as it occurs in the pathological state of type-1 diabetes as well as during islet transplantation.Islet transplantation is considered one of the potential treatments for T1DM but limited islet survival and their impaired function pose limitations to this approach. Here Loh et al. show that the Y1 receptor is expressed in β- cells and inhibition of its signalling, both genetic and pharmacological, improves mouse and human islet function.
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38
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Rutter GA, Hodson DJ, Chabosseau P, Haythorne E, Pullen TJ, Leclerc I. Local and regional control of calcium dynamics in the pancreatic islet. Diabetes Obes Metab 2017; 19 Suppl 1:30-41. [PMID: 28466490 DOI: 10.1111/dom.12990] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 04/19/2017] [Accepted: 04/24/2017] [Indexed: 12/31/2022]
Abstract
Ca2+ is the key intracellular regulator of insulin secretion, acting in the β-cell as the ultimate trigger for exocytosis. In response to high glucose, ATP-sensitive K+ channel closure and plasma membrane depolarization engage a sophisticated machinery to drive pulsatile cytosolic Ca2+ changes. Voltage-gated Ca2+ channels, Ca2+ -activated K+ channels and Na+ /Ca2+ exchange all play important roles. The use of targeted Ca2+ probes has revealed that during each cytosolic Ca2+ pulse, uptake of Ca2+ by mitochondria, endoplasmic reticulum (ER), secretory granules and lysosomes fine-tune cytosolic Ca2+ dynamics and control organellar function. For example, changes in the expression of the Ca2+ -binding protein Sorcin appear to provide a link between ER Ca2+ levels and ER stress, affecting β-cell function and survival. Across the islet, intercellular communication between highly interconnected "hubs," which act as pacemaker β-cells, and subservient "followers," ensures efficient insulin secretion. Loss of connectivity is seen after the deletion of genes associated with type 2 diabetes (T2D) and follows metabolic and inflammatory insults that characterize this disease. Hubs, which typically comprise ~1%-10% of total β-cells, are repurposed for their specialized role by expression of high glucokinase (Gck) but lower Pdx1 and Nkx6.1 levels. Single cell-omics are poised to provide a deeper understanding of the nature of these cells and of the networks through which they communicate. New insights into the control of both the intra- and intercellular Ca2+ dynamics may thus shed light on T2D pathology and provide novel opportunities for therapy.
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Affiliation(s)
- Guy A Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, and the Imperial Pancreatic Islet Biology and Diabetes Consortium, Hammersmith Hospital, Imperial College London, London, UK
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Edgbaston, UK
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, COMPARE University of Birmingham and University of Nottingham Midlands, Birmingham, UK
| | - Pauline Chabosseau
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, and the Imperial Pancreatic Islet Biology and Diabetes Consortium, Hammersmith Hospital, Imperial College London, London, UK
| | - Elizabeth Haythorne
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, and the Imperial Pancreatic Islet Biology and Diabetes Consortium, Hammersmith Hospital, Imperial College London, London, UK
| | - Timothy J Pullen
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, and the Imperial Pancreatic Islet Biology and Diabetes Consortium, Hammersmith Hospital, Imperial College London, London, UK
| | - Isabelle Leclerc
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, and the Imperial Pancreatic Islet Biology and Diabetes Consortium, Hammersmith Hospital, Imperial College London, London, UK
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Nuñez-Durán E, Chanclón B, Sütt S, Real J, Marschall HU, Wernstedt Asterholm I, Cansby E, Mahlapuu M. Protein kinase STK25 aggravates the severity of non-alcoholic fatty pancreas disease in mice. J Endocrinol 2017; 234:15-27. [PMID: 28442507 PMCID: PMC5510597 DOI: 10.1530/joe-17-0018] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 04/25/2017] [Indexed: 12/18/2022]
Abstract
Characterising the molecular networks that negatively regulate pancreatic β-cell function is essential for understanding the underlying pathogenesis and developing new treatment strategies for type 2 diabetes. We recently identified serine/threonine protein kinase 25 (STK25) as a critical regulator of ectopic fat storage, meta-inflammation, and fibrosis in liver and skeletal muscle. Here, we assessed the role of STK25 in control of progression of non-alcoholic fatty pancreas disease in the context of chronic exposure to dietary lipids in mice. We found that overexpression of STK25 in high-fat-fed transgenic mice aggravated diet-induced lipid storage in the pancreas compared with that of wild-type controls, which was accompanied by exacerbated pancreatic inflammatory cell infiltration, stellate cell activation, fibrosis and apoptosis. Pancreas of Stk25 transgenic mice also displayed a marked decrease in islet β/α-cell ratio and alteration in the islet architecture with an increased presence of α-cells within the islet core, whereas islet size remained similar between genotypes. After a continued challenge with a high-fat diet, lower levels of fasting plasma insulin and C-peptide, and higher levels of plasma leptin, were detected in Stk25 transgenic vs wild-type mice. Furthermore, the glucose-stimulated insulin secretion was impaired in high-fat-fed Stk25 transgenic mice during glucose tolerance test, in spite of higher net change in blood glucose concentrations compared with wild-type controls, suggesting islet β-cell dysfunction. In summary, this study unravels a role for STK25 in determining the susceptibility to diet-induced non-alcoholic fatty pancreas disease in mice in connection to obesity. Our findings highlight STK25 as a potential drug target for metabolic disease.
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Affiliation(s)
- Esther Nuñez-Durán
- Department of Molecular and Clinical MedicineLundberg Laboratory for Diabetes Research, Institute of Medicine, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Belén Chanclón
- Department of Molecular and Clinical MedicineLundberg Laboratory for Diabetes Research, Institute of Medicine, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden
- Department of Metabolic PhysiologyInstitute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
| | - Silva Sütt
- Department of Molecular and Clinical MedicineLundberg Laboratory for Diabetes Research, Institute of Medicine, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Joana Real
- Department of Metabolic PhysiologyInstitute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
| | - Hanns-Ulrich Marschall
- Department of Molecular and Clinical MedicineWallenberg Laboratory, Institute of Medicine, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Ingrid Wernstedt Asterholm
- Department of Metabolic PhysiologyInstitute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
| | - Emmelie Cansby
- Department of Molecular and Clinical MedicineLundberg Laboratory for Diabetes Research, Institute of Medicine, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Margit Mahlapuu
- Department of Molecular and Clinical MedicineLundberg Laboratory for Diabetes Research, Institute of Medicine, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden
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Kursan S, McMillen TS, Beesetty P, Dias-Junior E, Almutairi MM, Sajib AA, Kozak JA, Aguilar-Bryan L, Di Fulvio M. The neuronal K +Cl - co-transporter 2 (Slc12a5) modulates insulin secretion. Sci Rep 2017; 7:1732. [PMID: 28496181 PMCID: PMC5431760 DOI: 10.1038/s41598-017-01814-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 04/03/2017] [Indexed: 11/09/2022] Open
Abstract
Intracellular chloride concentration ([Cl-]i) in pancreatic β-cells is kept above electrochemical equilibrium due to the predominant functional presence of Cl- loaders such as the Na+K+2Cl- co-transporter 1 (Slc12a2) over Cl-extruders of unidentified nature. Using molecular cloning, RT-PCR, Western blotting, immunolocalization and in vitro functional assays, we establish that the "neuron-specific" K+Cl- co-transporter 2 (KCC2, Slc12a5) is expressed in several endocrine cells of the pancreatic islet, including glucagon secreting α-cells, but particularly in insulin-secreting β-cells, where we provide evidence for its role in the insulin secretory response. Three KCC2 splice variants were identified: the formerly described KCC2a and KCC2b along with a novel one lacking exon 25 (KCC2a-S25). This new variant is undetectable in brain or spinal cord, the only and most abundant known sources of KCC2. Inhibition of KCC2 activity in clonal MIN6 β-cells increases basal and glucose-stimulated insulin secretion and Ca2+ uptake in the presence of glibenclamide, an inhibitor of the ATP-dependent potassium (KATP)-channels, thus suggesting a possible mechanism underlying KCC2-dependent insulin release. We propose that the long-time considered "neuron-specific" KCC2 co-transporter is expressed in pancreatic islet β-cells where it modulates Ca2+-dependent insulin secretion.
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Affiliation(s)
- Shams Kursan
- Department of Pharmacology and Toxicology, Wright State University, School of Medicine, Dayton, OH, 45435, USA
| | | | - Pavani Beesetty
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, School of Medicine, Dayton, OH, 45435, USA
| | - Eduardo Dias-Junior
- Department of Pharmacology and Toxicology, Wright State University, School of Medicine, Dayton, OH, 45435, USA
| | - Mohammed M Almutairi
- Department of Pharmacology and Toxicology, Wright State University, School of Medicine, Dayton, OH, 45435, USA
| | - Abu A Sajib
- Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka, Bangladesh
| | - J Ashot Kozak
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, School of Medicine, Dayton, OH, 45435, USA
| | | | - Mauricio Di Fulvio
- Department of Pharmacology and Toxicology, Wright State University, School of Medicine, Dayton, OH, 45435, USA.
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41
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Schifferer M, Yushchenko DA, Stein F, Bolbat A, Schultz C. A Ratiometric Sensor for Imaging Insulin Secretion in Single β Cells. Cell Chem Biol 2017; 24:525-531.e4. [PMID: 28366620 PMCID: PMC5404835 DOI: 10.1016/j.chembiol.2017.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 12/14/2016] [Accepted: 03/02/2017] [Indexed: 01/03/2023]
Abstract
Despite the urgent need for assays to visualize insulin secretion there is to date no reliable method available for measuring insulin release from single cells. To address this need, we developed a genetically encoded reporter termed RINS1 based on proinsulin superfolder GFP (sfGFP) and mCherry fusions for monitoring insulin secretion. RINS1 expression in MIN6 β cells resulted in proper processing yielding single-labeled insulin species. Unexpectedly, glucose or drug stimulation of insulin secretion in β cells led to the preferential release of the insulin-sfGFP construct, while the mCherry-fused C-peptide remained trapped in exocytic granules. This physical separation was used to monitor glucose-stimulated insulin secretion ratiometrically by total internal reflection fluorescence microscopy in single MIN6 and primary mouse β cells. Further, RINS1 enabled parallel monitoring of pulsatile insulin release in tolbutamide-treated β cells, demonstrating the potential of RINS1 for investigations of antidiabetic drug candidates at the single-cell level.
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Affiliation(s)
- Martina Schifferer
- Interdisciplinary Chemistry Group, Cell Biology & Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Dmytro A Yushchenko
- Interdisciplinary Chemistry Group, Cell Biology & Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany; Group of Chemical Biology, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo namesti 2, 16610 Prague 6, Czech Republic
| | - Frank Stein
- Interdisciplinary Chemistry Group, Cell Biology & Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Andrey Bolbat
- Interdisciplinary Chemistry Group, Cell Biology & Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Carsten Schultz
- Interdisciplinary Chemistry Group, Cell Biology & Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany; Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97237, USA.
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42
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Liu Y, Zhong X, Ding Y, Ren L, Bai T, Liu M, Liu Z, Guo Y, Guo Q, Zhang Y, Yang J, Zhang Y. Inhibition of voltage-dependent potassium channels mediates cAMP-potentiated insulin secretion in rat pancreatic β cells. Islets 2017; 9:11-18. [PMID: 28103136 PMCID: PMC5345751 DOI: 10.1080/19382014.2017.1280644] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Insulin secretion is essential for maintenance of glucose homeostasis. An important intracellular signal regulating insulin secretion is cAMP. In this report, we showed that an increase of cAMP induced by adenylyl cyclase (AC) activator forskolin or by cAMP analog db-cAMP not only potentiated insulin secretion but also inhibited Kv channels, and these effects were reversed by AC inhibitor SQ22536. The cAMP-mediated Kv channel inhibition resulted in prolongation of action potential duration, which partly accounts for the elevation of intracellular Ca2+ induced by activation of cAMP signaling. Taken together, the results suggest that Kv channels are involved in cAMP-potentiated insulin secretion in pancreatic β cells.
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Affiliation(s)
- Yunfeng Liu
- Department of Endocrinology, the First Hospital of Shanxi Medical University, Shanxi Medical University, Taiyuan, China
- CONTACT Yunfeng Liu Department of Endocrinology, The first Hospital of Shanxi Medical University, Taiyuan 030001, China; Yi Zhang , Department of Pharmacology, Shanxi Medical University, Taiyuan 030001, China
| | - Xiangqin Zhong
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Yaqin Ding
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Lele Ren
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Tao Bai
- Department of Endocrinology, the First Hospital of Shanxi Medical University, Shanxi Medical University, Taiyuan, China
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
- Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan, China
| | - Mengmeng Liu
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Zhihong Liu
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
- Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan, China
| | - Yangyan Guo
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Qing Guo
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Yu Zhang
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Jing Yang
- Department of Endocrinology, the First Hospital of Shanxi Medical University, Shanxi Medical University, Taiyuan, China
| | - Yi Zhang
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
- Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan, China
- CONTACT Yunfeng Liu Department of Endocrinology, The first Hospital of Shanxi Medical University, Taiyuan 030001, China; Yi Zhang , Department of Pharmacology, Shanxi Medical University, Taiyuan 030001, China
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Chen C, Chmelova H, Cohrs CM, Chouinard JA, Jahn SR, Stertmann J, Uphues I, Speier S. Alterations in β-Cell Calcium Dynamics and Efficacy Outweigh Islet Mass Adaptation in Compensation of Insulin Resistance and Prediabetes Onset. Diabetes 2016; 65:2676-85. [PMID: 27207518 DOI: 10.2337/db15-1718] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 04/05/2016] [Indexed: 11/13/2022]
Abstract
Emerging insulin resistance is normally compensated by increased insulin production of pancreatic β-cells, thereby maintaining normoglycemia. However, it is unclear whether this is achieved by adaptation of β-cell function, mass, or both. Most importantly, it is still unknown which of these adaptive mechanisms fail when type 2 diabetes develops. We performed longitudinal in vivo imaging of β-cell calcium dynamics and islet mass of transplanted islets of Langerhans throughout diet-induced progression from normal glucose homeostasis, through compensation of insulin resistance, to prediabetes. The results show that compensation of insulin resistance is predominated by alterations of β-cell function, while islet mass only gradually expands. Hereby, functional adaptation is mediated by increased calcium efficacy, which involves Epac signaling. Prior to prediabetes, β-cell function displays decreased stimulated calcium dynamics, whereas islet mass continues to increase through prediabetes onset. Thus, our data reveal a predominant role of islet function with distinct contributions of triggering and amplifying pathway in the in vivo processes preceding diabetes onset. These findings support protection and recovery of β-cell function as primary goals for prevention and treatment of diabetes and provide insight into potential therapeutic targets.
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Affiliation(s)
- Chunguang Chen
- Paul Langerhans Institute Dresden, Helmholtz Center Munich, University Clinic Carl Gustav Carus, Technische Universität Dresden, Helmholtz Zentrum München, Neuherberg, Germany German Research Foundation-Center for Regenerative Therapies Dresden (CRTD), Faculty of Medicine, Technische Universität Dresden, Dresden, Germany German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Helena Chmelova
- Paul Langerhans Institute Dresden, Helmholtz Center Munich, University Clinic Carl Gustav Carus, Technische Universität Dresden, Helmholtz Zentrum München, Neuherberg, Germany German Research Foundation-Center for Regenerative Therapies Dresden (CRTD), Faculty of Medicine, Technische Universität Dresden, Dresden, Germany German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Christian M Cohrs
- Paul Langerhans Institute Dresden, Helmholtz Center Munich, University Clinic Carl Gustav Carus, Technische Universität Dresden, Helmholtz Zentrum München, Neuherberg, Germany German Research Foundation-Center for Regenerative Therapies Dresden (CRTD), Faculty of Medicine, Technische Universität Dresden, Dresden, Germany German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Julie A Chouinard
- Paul Langerhans Institute Dresden, Helmholtz Center Munich, University Clinic Carl Gustav Carus, Technische Universität Dresden, Helmholtz Zentrum München, Neuherberg, Germany German Research Foundation-Center for Regenerative Therapies Dresden (CRTD), Faculty of Medicine, Technische Universität Dresden, Dresden, Germany German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Stephan R Jahn
- Paul Langerhans Institute Dresden, Helmholtz Center Munich, University Clinic Carl Gustav Carus, Technische Universität Dresden, Helmholtz Zentrum München, Neuherberg, Germany German Research Foundation-Center for Regenerative Therapies Dresden (CRTD), Faculty of Medicine, Technische Universität Dresden, Dresden, Germany German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Julia Stertmann
- Paul Langerhans Institute Dresden, Helmholtz Center Munich, University Clinic Carl Gustav Carus, Technische Universität Dresden, Helmholtz Zentrum München, Neuherberg, Germany German Research Foundation-Center for Regenerative Therapies Dresden (CRTD), Faculty of Medicine, Technische Universität Dresden, Dresden, Germany German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Ingo Uphues
- Boehringer Ingelheim Pharma GmbH & Co. KG, Ingelheim, Germany
| | - Stephan Speier
- Paul Langerhans Institute Dresden, Helmholtz Center Munich, University Clinic Carl Gustav Carus, Technische Universität Dresden, Helmholtz Zentrum München, Neuherberg, Germany German Research Foundation-Center for Regenerative Therapies Dresden (CRTD), Faculty of Medicine, Technische Universität Dresden, Dresden, Germany German Center for Diabetes Research (DZD), München-Neuherberg, Germany
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Yang H, Yang L. Targeting cAMP/PKA pathway for glycemic control and type 2 diabetes therapy. J Mol Endocrinol 2016; 57:R93-R108. [PMID: 27194812 DOI: 10.1530/jme-15-0316] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 05/18/2016] [Indexed: 12/11/2022]
Abstract
In mammals, cyclic adenosine monophosphate (cAMP) is an intracellular second messenger that is usually elicited by binding of hormones and neurotransmitters to G protein-coupled receptors (GPCRs). cAMP exerts many of its physiological effects by activating cAMP-dependent protein kinase (PKA), which in turn phosphorylates and regulates the functions of downstream protein targets including ion channels, enzymes, and transcription factors. cAMP/PKA signaling pathway regulates glucose homeostasis at multiple levels including insulin and glucagon secretion, glucose uptake, glycogen synthesis and breakdown, gluconeogenesis, and neural control of glucose homeostasis. This review summarizes recent genetic and pharmacological studies concerning the regulation of glucose homeostasis by cAMP/PKA in pancreas, liver, skeletal muscle, adipose tissues, and brain. We also discuss the strategies for targeting cAMP/PKA pathway for research and potential therapeutic treatment of type 2 diabetes mellitus (T2D).
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Affiliation(s)
- Haihua Yang
- Division of EndocrinologyZhengzhou Children's Hospital, Zhengzhou, Henan, China
| | - Linghai Yang
- Department of PharmacologyUniversity of Washington, Seattle, Washington, USA
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Ravnskjaer K, Madiraju A, Montminy M. Role of the cAMP Pathway in Glucose and Lipid Metabolism. Handb Exp Pharmacol 2016; 233:29-49. [PMID: 26721678 DOI: 10.1007/164_2015_32] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
3'-5'-Cyclic adenosine monophosphate (cyclic AMP or cAMP) was first described in 1957 as an intracellular second messenger mediating the effects of glucagon and epinephrine on hepatic glycogenolysis (Berthet et al., J Biol Chem 224(1):463-475, 1957). Since this initial characterization, cAMP has been firmly established as a versatile molecular signal involved in both central and peripheral regulation of energy homeostasis and nutrient partitioning. Many of these effects appear to be mediated at the transcriptional level, in part through the activation of the transcription factor CREB and its coactivators. Here we review current understanding of the mechanisms by which the cAMP signaling pathway triggers metabolic programs in insulin-responsive tissues.
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Malm HA, Mollet IG, Berggreen C, Orho-Melander M, Esguerra JLS, Göransson O, Eliasson L. Transcriptional regulation of the miR-212/miR-132 cluster in insulin-secreting β-cells by cAMP-regulated transcriptional co-activator 1 and salt-inducible kinases. Mol Cell Endocrinol 2016; 424:23-33. [PMID: 26797246 DOI: 10.1016/j.mce.2016.01.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 12/15/2015] [Accepted: 01/11/2016] [Indexed: 12/25/2022]
Abstract
MicroRNAs are central players in the control of insulin secretion, but their transcriptional regulation is poorly understood. Our aim was to investigate cAMP-mediated transcriptional regulation of the miR-212/miR-132 cluster and involvement of further upstream proteins in insulin secreting β-cells. cAMP induced by forskolin+IBMX or GLP-1 caused increased expression of miR-212/miR-132, and elevated phosphorylation of cAMP-response-element-binding-protein (CREB)/Activating-transcription-factor-1 (ATF1) and Salt-Inducible-Kinases (SIKs). CyclicAMP-Regulated Transcriptional Co-activator-1 (CRTC1) was concomitantly dephosphorylated and translocated to the nucleus. Silencing of miR-212/miR-132 reduced, and overexpression of miR-212 increased, glucose-stimulated insulin secretion. Silencing of CRTC1 expression resulted in decreased insulin secretion and miR-212/miR-132 expression, while silencing or inhibition of SIKs was associated with increased expression of the microRNAs and dephosphorylation of CRTC1. CRTC1 protein levels were reduced after silencing of miR-132, suggesting feed-back regulation. Our data propose cAMP-dependent co-regulation of miR-212/miR-132, in part mediated through SIK-regulated CRTC1, as an important factor for fine-tuned regulation of insulin secretion.
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Affiliation(s)
- Helena Anna Malm
- Lund University Diabetes Centre, Lund University, Unit of Islet Cell Exocytosis, Dept. Clinical Sciences in Malmö, 205 02 Malmö, Sweden; Lund University Diabetes Centre, Lund University, Unit of Diabetes and Cardiovascular Disease, Genetic Epidemiology, Dept. Clinical Sciences in Malmö, 205 02 Malmö, Sweden
| | - Inês G Mollet
- Lund University Diabetes Centre, Lund University, Unit of Islet Cell Exocytosis, Dept. Clinical Sciences in Malmö, 205 02 Malmö, Sweden; Lund University Diabetes Centre, Lund University, Unit of Diabetes and Cardiovascular Disease, Genetic Epidemiology, Dept. Clinical Sciences in Malmö, 205 02 Malmö, Sweden
| | - Christine Berggreen
- Lund University Diabetes Centre, Lund University, Protein Phosphorylation Research Unit, Dept. Experimental Medical Science, 221 84 Lund, Sweden
| | - Marju Orho-Melander
- Lund University Diabetes Centre, Lund University, Unit of Diabetes and Cardiovascular Disease, Genetic Epidemiology, Dept. Clinical Sciences in Malmö, 205 02 Malmö, Sweden
| | - Jonathan Lou S Esguerra
- Lund University Diabetes Centre, Lund University, Unit of Islet Cell Exocytosis, Dept. Clinical Sciences in Malmö, 205 02 Malmö, Sweden
| | - Olga Göransson
- Lund University Diabetes Centre, Lund University, Protein Phosphorylation Research Unit, Dept. Experimental Medical Science, 221 84 Lund, Sweden
| | - Lena Eliasson
- Lund University Diabetes Centre, Lund University, Unit of Islet Cell Exocytosis, Dept. Clinical Sciences in Malmö, 205 02 Malmö, Sweden.
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Type II PKAs are anchored to mature insulin secretory granules in INS-1 β-cells and required for cAMP-dependent potentiation of exocytosis. Biochimie 2016; 125:32-41. [PMID: 26898328 DOI: 10.1016/j.biochi.2016.02.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 02/13/2016] [Indexed: 11/23/2022]
Abstract
Specificity of the cAMP-dependent protein kinase (PKA) pathway relies on an extremely sophisticated compartmentalization mechanism of the kinase within a given cell, based on high-affinity binding of PKA tetramer pools to different A-Kinase Anchoring Proteins (AKAPs). We and others have previously shown that AKAPs-dependent PKA subcellular targeting is a requisite for optimal cAMP-dependent potentiation of insulin exocytosis. We thus hypothesized that a PKA pool may directly anchor to the secretory compartment to potentiate insulin exocytosis. Here, using immunofluorescence analyses combined to subcellular fractionations and purification of insulin secretory granules (ISGs), we identified discrete subpools of type II PKAs, RIIα and RIIβ PKAs, along with the catalytic subunit, physically associated with ISGs within pancreatic insulin-secreting β-cells. Ultrastructural analysis of native rodent β-cells confirmed in vivo the occurrence of PKA on dense-core ISGs. Isoform-selective disruption of binding of PKAs to AKAPs reinforced the requirement of type II PKA isoforms for cAMP potentiation of insulin exocytosis. This granular localization of PKA was of critical importance since siRNA-mediated depletion of either RIIα or RIIβ PKAs resulted in a significant reduction of cAMP-dependent potentiation of insulin release. The present work provides evidence for a previously unrecognized pool of type II PKAs physically anchored to the β-cell ISGs compartment and supports a non-redundant function for type II PKAs during cAMP potentiation of exocytosis.
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48
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Liang Y, Li Z, Liang S, Li Y, Yang L, Lu M, Gu HF, Xia N. Hepatic adenylate cyclase 3 is upregulated by Liraglutide and subsequently plays a protective role in insulin resistance and obesity. Nutr Diabetes 2016; 6:e191. [PMID: 26807509 PMCID: PMC4742720 DOI: 10.1038/nutd.2015.37] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 09/29/2015] [Accepted: 11/10/2015] [Indexed: 12/16/2022] Open
Abstract
OBJECTIVE Recent studies have demonstrated that adenylate cyclase 3 (AC3) has a protective role in obesity. This gene resides at the pathway with glucagon-like peptide (GLP)-1. Liraglutide is a GLP-1 analog and has independent glucose and body weight (BW)-reducing effects. In the present study, we aimed to examine whether hepatic AC3 activity was regulated by Liraglutide and to further understand the effect of AC3 in reduction of BW and insulin resistance. SUBJECTS The diabesity and obese mice were induced from db/db and C57BL/6 J mice, respectively, by high-fat diet. Liraglutide (0.1 mg kg(-1) per 12 h) was given to the mice twice daily for 12 weeks. C57BL/6 J mice fed with chow diet and obese or diabesity mice treated with saline were used as the controls. Hepatic AC3 gene expression at mRNA and protein levels was analyzed with real-time reverse transcription-PCR and western blot. Fasting blood glucose and serum insulin levels were measured and followed insulin resistance index (HOMA-IR) was evaluated according to the homeostasis model assessment. RESULTS After administration of Liraglutide, BW and HOMA-IR in obese and diabesity mice were decreased, whereas hepatic AC3 mRNA and protein expression levels were upregulated. The AC3 gene expression was negatively correlated with BW, HOMA-IR and the area ratio of hepatic fat deposition in the liver. CONCLUSIONS The present study thus provides the evidence that hepatic AC3 gene expression is upregulated by Liraglutide. The reduction of BW and improvement of insulin resistance with Liraglutide may be partially explained by AC3 activation.
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Affiliation(s)
- Y Liang
- Department of Endocrinology and Metabolism, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Z Li
- Department of Endocrinology and Metabolism, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - S Liang
- Department of Endocrinology and Metabolism, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Y Li
- Department of Endocrinology and Metabolism, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - L Yang
- Department of Endocrinology and Metabolism, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - M Lu
- Department of Endocrinology and Metabolism, First Affiliated Hospital of Guangxi Medical University, Nanning, China.,Department of Oncology-Pathology, Karolinska University Hospital, Karolinska Institute, Stockholm, Sweden
| | - H F Gu
- Rolf Luft Research Center for Diabetes and Endocrinology, Department of Molecular Medicine and Surgery, Karolinska University Hospital, Karolinska Institute, Stockholm, Sweden
| | - N Xia
- Department of Endocrinology and Metabolism, First Affiliated Hospital of Guangxi Medical University, Nanning, China
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Shigeto M, Ramracheya R, Tarasov AI, Cha CY, Chibalina MV, Hastoy B, Philippaert K, Reinbothe T, Rorsman N, Salehi A, Sones WR, Vergari E, Weston C, Gorelik J, Katsura M, Nikolaev VO, Vennekens R, Zaccolo M, Galione A, Johnson PRV, Kaku K, Ladds G, Rorsman P. GLP-1 stimulates insulin secretion by PKC-dependent TRPM4 and TRPM5 activation. J Clin Invest 2015; 125:4714-28. [PMID: 26571400 DOI: 10.1172/jci81975] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 10/01/2015] [Indexed: 01/11/2023] Open
Abstract
Strategies aimed at mimicking or enhancing the action of the incretin hormone glucagon-like peptide 1 (GLP-1) therapeutically improve glucose-stimulated insulin secretion (GSIS); however, it is not clear whether GLP-1 directly drives insulin secretion in pancreatic islets. Here, we examined the mechanisms by which GLP-1 stimulates insulin secretion in mouse and human islets. We found that GLP-1 enhances GSIS at a half-maximal effective concentration of 0.4 pM. Moreover, we determined that GLP-1 activates PLC, which increases submembrane diacylglycerol and thereby activates PKC, resulting in membrane depolarization and increased action potential firing and subsequent stimulation of insulin secretion. The depolarizing effect of GLP-1 on electrical activity was mimicked by the PKC activator PMA, occurred without activation of PKA, and persisted in the presence of PKA inhibitors, the KATP channel blocker tolbutamide, and the L-type Ca(2+) channel blocker isradipine; however, depolarization was abolished by lowering extracellular Na(+). The PKC-dependent effect of GLP-1 on membrane potential and electrical activity was mediated by activation of Na(+)-permeable TRPM4 and TRPM5 channels by mobilization of intracellular Ca(2+) from thapsigargin-sensitive Ca(2+) stores. Concordantly, GLP-1 effects were negligible in Trpm4 or Trpm5 KO islets. These data provide important insight into the therapeutic action of GLP-1 and suggest that circulating levels of this hormone directly stimulate insulin secretion by β cells.
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Simvastatin Impairs Insulin Secretion by Multiple Mechanisms in MIN6 Cells. PLoS One 2015; 10:e0142902. [PMID: 26561346 PMCID: PMC4641640 DOI: 10.1371/journal.pone.0142902] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 10/28/2015] [Indexed: 01/17/2023] Open
Abstract
Statins are widely used in the treatment of hypercholesterolemia and are efficient in the prevention of cardiovascular disease. Molecular mechanisms explaining statin-induced impairment in insulin secretion remain largely unknown. In the current study, we show that simvastatin decreased glucose-stimulated insulin secretion in mouse pancreatic MIN6 β-cells by 59% and 79% (p<0.01) at glucose concentration of 5.5 mmol/l and 16.7 mmol/l, respectively, compared to control, whereas pravastatin did not impair insulin secretion. Simvastatin induced decrease in insulin secretion occurred through multiple targets. In addition to its established effects on ATP-sensitive potassium channels (p = 0.004) and voltage-gated calcium channels (p = 0.004), simvastatin suppressed insulin secretion stimulated by muscarinic M3 or GPR40 receptor agonists (Tak875 by 33%, p = 0.002; GW9508 by 77%, p = 0.01) at glucose level of 5.5 mmol/l, and inhibited calcium release from the endoplasmic reticulum. Impaired insulin secretion caused by simvastatin treatment were efficiently restored by GPR119 or GLP-1 receptor stimulation and by direct activation of cAMP-dependent signaling pathways with forskolin. The effects of simvastatin treatment on insulin secretion were not affected by the presence of hyperglycemia. Our observation of the opposite effects of simvastatin and pravastatin on glucose-stimulated insulin secretion is in agreement with previous reports showing that simvastatin, but not pravastatin, was associated with increased risk of incident diabetes.
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