1
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Šterk M, Zhang Y, Pohorec V, Leitgeb EP, Dolenšek J, Benninger RKP, Stožer A, Kravets V, Gosak M. Network representation of multicellular activity in pancreatic islets: Technical considerations for functional connectivity analysis. PLoS Comput Biol 2024; 20:e1012130. [PMID: 38739680 PMCID: PMC11115366 DOI: 10.1371/journal.pcbi.1012130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 05/23/2024] [Accepted: 05/02/2024] [Indexed: 05/16/2024] Open
Abstract
Within the islets of Langerhans, beta cells orchestrate synchronized insulin secretion, a pivotal aspect of metabolic homeostasis. Despite the inherent heterogeneity and multimodal activity of individual cells, intercellular coupling acts as a homogenizing force, enabling coordinated responses through the propagation of intercellular waves. Disruptions in this coordination are implicated in irregular insulin secretion, a hallmark of diabetes. Recently, innovative approaches, such as integrating multicellular calcium imaging with network analysis, have emerged for a quantitative assessment of the cellular activity in islets. However, different groups use distinct experimental preparations, microscopic techniques, apply different methods to process the measured signals and use various methods to derive functional connectivity patterns. This makes comparisons between findings and their integration into a bigger picture difficult and has led to disputes in functional connectivity interpretations. To address these issues, we present here a systematic analysis of how different approaches influence the network representation of islet activity. Our findings show that the choice of methods used to construct networks is not crucial, although care is needed when combining data from different islets. Conversely, the conclusions drawn from network analysis can be heavily affected by the pre-processing of the time series, the type of the oscillatory component in the signals, and by the experimental preparation. Our tutorial-like investigation aims to resolve interpretational issues, reconcile conflicting views, advance functional implications, and encourage researchers to adopt connectivity analysis. As we conclude, we outline challenges for future research, emphasizing the broader applicability of our conclusions to other tissues exhibiting complex multicellular dynamics.
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Affiliation(s)
- Marko Šterk
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Yaowen Zhang
- Department of Pediatrics, Department of Bioengineering, University of California, San Diego, La Jolla, California, United States of America
| | - Viljem Pohorec
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | | | - Jurij Dolenšek
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Richard K. P. Benninger
- Department of Bioengineering, Barbara Davis Center for Diabetes, Aurora, Colorado, United States of America
- Barbara Davis Center for Childhood Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Andraž Stožer
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Vira Kravets
- Department of Pediatrics, Department of Bioengineering, University of California, San Diego, La Jolla, California, United States of America
- Department of Bioengineering, Jacobs School of Engineering, University of California, San Diego, La Jolla, California, United States of America
| | - Marko Gosak
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Alma Mater Europaea, Maribor
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2
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Kabra UD, Jastroch M. Mitochondrial Dynamics and Insulin Secretion. Int J Mol Sci 2023; 24:13782. [PMID: 37762083 PMCID: PMC10530730 DOI: 10.3390/ijms241813782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Revised: 08/30/2023] [Accepted: 09/04/2023] [Indexed: 09/29/2023] Open
Abstract
Mitochondria are involved in the regulation of cellular energy metabolism, calcium homeostasis, and apoptosis. For mitochondrial quality control, dynamic processes, such as mitochondrial fission and fusion, are necessary to maintain shape and function. Disturbances of mitochondrial dynamics lead to dysfunctional mitochondria, which contribute to the development and progression of numerous diseases, including Type 2 Diabetes (T2D). Compelling evidence has been put forward that mitochondrial dynamics play a significant role in the metabolism-secretion coupling of pancreatic β cells. The disruption of mitochondrial dynamics is linked to defects in energy production and increased apoptosis, ultimately impairing insulin secretion and β cell death. This review provides an overview of molecular mechanisms controlling mitochondrial dynamics, their dysfunction in pancreatic β cells, and pharmaceutical agents targeting mitochondrial dynamic proteins, such as mitochondrial division inhibitor-1 (mdivi-1), dynasore, P110, and 15-oxospiramilactone (S3).
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Affiliation(s)
- Uma D. Kabra
- Department of Pharmaceutical Chemistry, Parul Institute of Pharmacy, Parul University, Vadodara 391760, India;
| | - Martin Jastroch
- The Arrhenius Laboratories F3, Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden
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3
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Bhatti GK, Gupta A, Pahwa P, Khullar N, Singh S, Navik U, Kumar S, Mastana SS, Reddy AP, Reddy PH, Bhatti JS. Targeting Mitochondrial bioenergetics as a promising therapeutic strategy in metabolic and neurodegenerative diseases. Biomed J 2022; 45:733-748. [PMID: 35568318 PMCID: PMC9661512 DOI: 10.1016/j.bj.2022.05.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 04/21/2022] [Accepted: 05/03/2022] [Indexed: 02/08/2023] Open
Abstract
Mitochondria are the organelles that generate energy for the cells and act as biosynthetic and bioenergetic factories, vital for normal cell functioning and human health. Mitochondrial bioenergetics is considered an important measure to assess the pathogenesis of various diseases. Dysfunctional mitochondria affect or cause several conditions involving the most energy-intensive organs, including the brain, muscles, heart, and liver. This dysfunction may be attributed to an alteration in mitochondrial enzymes, increased oxidative stress, impairment of electron transport chain and oxidative phosphorylation, or mutations in mitochondrial DNA that leads to the pathophysiology of various pathological conditions, including neurological and metabolic disorders. The drugs or compounds targeting mitochondria are considered more effective and safer for treating these diseases. In this review, we make an effort to concise the available literature on mitochondrial bioenergetics in various conditions and the therapeutic potential of various drugs/compounds targeting mitochondrial bioenergetics in metabolic and neurodegenerative diseases.
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Affiliation(s)
- Gurjit Kaur Bhatti
- Department of Medical Lab Technology, University Institute of Applied Health Sciences, Chandigarh University, Mohali Punjab, India.
| | - Anshika Gupta
- Department of Biotechnology, Sri Guru Gobind Singh College, Chandigarh, India.
| | - Paras Pahwa
- Department of Biotechnology, Sri Guru Gobind Singh College, Chandigarh, India.
| | - Naina Khullar
- Department of Zoology, Mata Gujri College, Fatehgarh Sahib, Punjab, India.
| | - Satwinder Singh
- Department of Computer Science and Technology, Central University of Punjab, Bathinda, India.
| | - Umashanker Navik
- Department of Pharmacology, Central University of Punjab, Bathinda, India.
| | - Shashank Kumar
- Department of Biochemistry, School of Basic Sciences, Central University of Punjab, Bathinda, India.
| | - Sarabjit Singh Mastana
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.
| | - Arubala P Reddy
- Department of Nutritional Sciences, Texas Tech University, Lubbock, TX, USA.
| | - P Hemachandra Reddy
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA; Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA; Department of Public Health, Graduate School of Biomedical Sciences, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA; Department of Neurology, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA; Department of Speech, Language, and Hearing Sciences, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA.
| | - Jasvinder Singh Bhatti
- Department of Human Genetics and Molecular Medicine, School of Health Sciences, Central University of Punjab, Bathinda, India.
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4
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Chhabria S, Mathur S, Vadakan S, Sahoo DK, Mishra P, Paital B. A review on phytochemical and pharmacological facets of tropical ethnomedicinal plants as reformed DPP-IV inhibitors to regulate incretin activity. Front Endocrinol (Lausanne) 2022; 13:1027237. [PMID: 36440220 PMCID: PMC9691845 DOI: 10.3389/fendo.2022.1027237] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 10/18/2022] [Indexed: 11/13/2022] Open
Abstract
Type 2 diabetes mellitus is a metabolic disorder resulting from impaired insulin secretion and resistance. Dipeptidyl peptidase (DPP)-IV is an enzyme known to trigger the catalysis of insulinotropic hormones, further abating the endogenous insulin levels and elevating the glucose levels in blood plasma. In the field of drug development, DPP-IV inhibitors have opened up numerous opportunities for leveraging this target to generate compounds as hypoglycemic agents by regulating incretin activity and subsequently decreasing blood glucose levels. However, the practice of synthetic drugs is an apparent choice but poses a great pharmacovigilance issue due to their incessant undesirable effects. The ideology was set to inventively look upon different ethnomedicinal plants for their anti-diabetic properties to address these issues. To date, myriads of phytochemicals are characterized, eliciting an anti-diabetic response by targeting various enzymes and augmenting glucose homeostasis. Antioxidants have played a crucial role in alleviating the symptoms of diabetes by scavenging free radicals or treating the underlying causes of metabolic disorders and reducing free radical formation. Plant-based DPP-IV inhibitors, including alkaloids, phenolic acid, flavonoids, quercetin, and coumarin, also possess antioxidant capabilities, providing anti-diabetic and antioxidative protection. This review article provides a new gateway for exploring the ability of plant-based DPP-IV inhibitors to withstand oxidative stress under pathological conditions related to diabetes and for reforming the strategic role of ethnomedicinal plants as potent DPP-IV inhibitors through the development of polyherbal formulations and nanophytomedicines to regulate incretin activity.
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Affiliation(s)
- Srishti Chhabria
- Department of Biochemistry and Biotechnology, St Xavier’s College, Ahmedabad, India
- Department of Biotechnology, Gujarat University, Ahmedabad, India
| | - Shivangi Mathur
- Department of Biotechnology, Gujarat University, Ahmedabad, India
- Department of Biotechnology, President Science College, Ahmedabad, India
| | - Sebastian Vadakan
- Department of Biochemistry and Biotechnology, St Xavier’s College, Ahmedabad, India
- Department of Biotechnology, Gujarat University, Ahmedabad, India
| | - Dipak Kumar Sahoo
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
- *Correspondence: Biswaranjan Paital, ; Dipak Kumar Sahoo, ;
| | - Pragnyashree Mishra
- Department of Horticulture, College of Agriculture, Odisha University of Agriculture and Technology, Chipilima, Sambalpur, India
| | - Biswaranjan Paital
- Redox Regulation Laboratory, Department of Zoology, College of Basic Science and Humanities, Odisha University of Agriculture and Technology, Bhubaneswar, India
- *Correspondence: Biswaranjan Paital, ; Dipak Kumar Sahoo, ;
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5
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Pereira APA, Fernando Figueiredo Angolini C, de Souza-Sporkens JC, da Silva TA, Coutinho Franco de Oliveira H, Pastore GM. Brazilian sunberry (Solanum oocarpum Sendtn): Alkaloid composition and improvement of mitochondrial functionality and insulin secretion of INS-1E cells. Food Res Int 2021; 148:110589. [PMID: 34507734 DOI: 10.1016/j.foodres.2021.110589] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 05/24/2021] [Accepted: 07/02/2021] [Indexed: 11/30/2022]
Abstract
Chronic high-glucose levels induce the generation of reactive oxygen species leading to mitochondrial dysfunction, which is one of the pathological triggers in the development of diabetes. This study investigated the alkaloid composition of two fruits of the genus Solanum, fruta-do-lobo (Solanum lycocarpum) and juá-açu (Solanum oocarpum), and their capacity to protect against oxidative damage and defective insulin secretion induced by chronic high-glucose levels. LC-MS and molecular network of fruit crude extracts reveals that juá-açu and fruta-do-lobo contain kukoamines and glycoalkaloids, respectively. Two purification processes were used to enrich those alkaloids. Fruta-do-lobo extract rich in glycoalkaloids showed a strong cytotoxicity effect, however the juá-açu enriched extract was able to protect mitochondrial functionality against glucotoxicity and stimulate insulin secretion even under conditions of hyperglycemia. These results are promising and suggest that juá-açu is a potential source of bioactive compounds for adjuvant/co-adjuvant therapy for diabetes.
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Affiliation(s)
- Ana Paula Aparecida Pereira
- Department of Food Science, Faculty of Food Engineering, University of Campinas (UNICAMP), Rua Monteiro Lobato, 80, Campinas, São Paulo 13083-862, Brazil; Department of Food and Nutrition, Faculty of Nutrition, Federal University of Mato Grosso, Cuiabá, Mato Grosso, Brazil.
| | | | - Jane Cristina de Souza-Sporkens
- Department of Structural and Functional Biology, Biology Institute, University of Campinas, Rua Monteiro Lobato, 255, Campinas, São Paulo 13083-862, Brazil
| | - Tomaz Antonio da Silva
- Center for Natural and Human Sciences, University of ABC (UFABC), Santo André, São Paulo, Brazil
| | - Helena Coutinho Franco de Oliveira
- Department of Structural and Functional Biology, Biology Institute, University of Campinas, Rua Monteiro Lobato, 255, Campinas, São Paulo 13083-862, Brazil
| | - Glaucia Maria Pastore
- Department of Food Science, Faculty of Food Engineering, University of Campinas (UNICAMP), Rua Monteiro Lobato, 80, Campinas, São Paulo 13083-862, Brazil
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6
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Brown MR, Holmes H, Rakshit K, Javeed N, Her TK, Stiller AA, Sen S, Shull GE, Prakash YS, Romero MF, Matveyenko AV. Electrogenic sodium bicarbonate cotransporter NBCe1 regulates pancreatic β cell function in type 2 diabetes. J Clin Invest 2021; 131:142365. [PMID: 34623331 DOI: 10.1172/jci142365] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 07/22/2021] [Indexed: 12/13/2022] Open
Abstract
Pancreatic β cell failure in type 2 diabetes mellitus (T2DM) is attributed to perturbations of the β cell's transcriptional landscape resulting in impaired glucose-stimulated insulin secretion. Recent studies identified SLC4A4 (a gene encoding an electrogenic Na+-coupled HCO3- cotransporter and intracellular pH regulator, NBCe1) as one of the misexpressed genes in β cells of patients with T2DM. Thus, in the current study, we set out to test the hypothesis that misexpression of SLC4A4/NBCe1 in T2DM β cells contributes to β cell dysfunction and impaired glucose homeostasis. To address this hypothesis, we first confirmed induction of SLC4A4/NBCe1 expression in β cells of patients with T2DM and demonstrated that its expression was associated with loss of β cell transcriptional identity, intracellular alkalinization, and β cell dysfunction. In addition, we generated a β cell-selective Slc4a4/NBCe1-KO mouse model and found that these mice were protected from diet-induced metabolic stress and β cell dysfunction. Importantly, improved glucose tolerance and enhanced β cell function in Slc4a4/NBCe1-deficient mice were due to augmented mitochondrial function and increased expression of genes regulating β cell identity and function. These results suggest that increased β cell expression of SLC4A4/NBCe1 in T2DM plays a contributory role in promotion of β cell failure and should be considered as a potential therapeutic target.
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Affiliation(s)
- Matthew R Brown
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Heather Holmes
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Kuntol Rakshit
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Naureen Javeed
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Tracy K Her
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Alison A Stiller
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Satish Sen
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Gary E Shull
- Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Y S Prakash
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA.,Department of Anesthesiology
| | - Michael F Romero
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA.,Division of Nephrology and Hypertension and
| | - Aleksey V Matveyenko
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA.,Division of Endocrinology, Metabolism, Diabetes, and Nutrition, Department of Medicine, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
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7
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Xue R, Meng H, Yin J, Xia J, Hu Z, Liu H. The Role of Calmodulin vs. Synaptotagmin in Exocytosis. Front Mol Neurosci 2021; 14:691363. [PMID: 34421537 PMCID: PMC8375295 DOI: 10.3389/fnmol.2021.691363] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 07/19/2021] [Indexed: 12/04/2022] Open
Abstract
Exocytosis is a Ca2+-regulated process that requires the participation of Ca2+ sensors. In the 1980s, two classes of Ca2+-binding proteins were proposed as putative Ca2+ sensors: EF-hand protein calmodulin, and the C2 domain protein synaptotagmin. In the next few decades, numerous studies determined that in the final stage of membrane fusion triggered by a micromolar boost in the level of Ca2+, the low affinity Ca2+-binding protein synaptotagmin, especially synaptotagmin 1 and 2, acts as the primary Ca2+ sensor, whereas calmodulin is unlikely to be functional due to its high Ca2+ affinity. However, in the meantime emerging evidence has revealed that calmodulin is involved in the earlier exocytotic steps prior to fusion, such as vesicle trafficking, docking and priming by acting as a high affinity Ca2+ sensor activated at submicromolar level of Ca2+. Calmodulin directly interacts with multiple regulatory proteins involved in the regulation of exocytosis, including VAMP, myosin V, Munc13, synapsin, GAP43 and Rab3, and switches on key kinases, such as type II Ca2+/calmodulin-dependent protein kinase, to phosphorylate a series of exocytosis regulators, including syntaxin, synapsin, RIM and Ca2+ channels. Moreover, calmodulin interacts with synaptotagmin through either direct binding or indirect phosphorylation. In summary, calmodulin and synaptotagmin are Ca2+ sensors that play complementary roles throughout the process of exocytosis. In this review, we discuss the complementary roles that calmodulin and synaptotagmin play as Ca2+ sensors during exocytosis.
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Affiliation(s)
- Renhao Xue
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Hao Meng
- Guangzhou Laboratory, Guangzhou, China.,Bioland Laboratory, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
| | - Jiaxiang Yin
- Guangzhou Laboratory, Guangzhou, China.,Bioland Laboratory, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
| | - Jingyao Xia
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Zhitao Hu
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Huisheng Liu
- Guangzhou Laboratory, Guangzhou, China.,Bioland Laboratory, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
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8
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Lugo-Fabres PH, Otero-Sastre LM, Bernáldez-Sarabia J, Camacho-Villegas TA, Sánchez-Campos N, Serrano-Bello J, Medina LA, Muñiz-Hernández S, de la Cruz L, Arenas I, Barajas-Martínez A, Garcia DE, Nuñez-Garcia L, González-Canudas J, Licea-Navarro AF. Potential Therapeutic Applications of Synthetic Conotoxin s-cal14.2b, Derived from Californiconus californicus, for Treating Type 2 Diabetes. Biomedicines 2021; 9:biomedicines9080936. [PMID: 34440140 PMCID: PMC8391312 DOI: 10.3390/biomedicines9080936] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 07/25/2021] [Accepted: 07/28/2021] [Indexed: 12/25/2022] Open
Abstract
The FDA’s approval of peptide drugs such as Ziconotide or Exendin for pain relief and diabetes treatment, respectively, enhanced the interest to explore novel conotoxins from Conus species venom. In general, conotoxins can be used in pathologies where voltage-gated channels, membrane receptors, or ligands alter normal physiological functions, as in metabolic diseases such as Type 2 diabetes. In this study, the synthetic cal14.2b (s-cal14.2b) from the unusual Californiconus californicus demonstrated bioactivity on NIT-1 insulinoma cell lines stimulating insulin secretion detecting by high performance liquid chromatography (HPLC). Accordingly, s-cal14.2b increased the CaV1.2/1.3 channel-current by 35 ± 4% with a recovery τ of 10.3 ± 4 s in primary cell culture of rat pancreatic β-cells. The in vivo results indicated a similar effect of insulin secretion on mice in the glucose tolerance curve model by reducing the glucose from 500 mg/dL to 106 mg/dL in 60 min, compared to the negative control of 325 mg/dL at the same time. The PET-SCAN with radiolabeling 99mTc-s-cal14.2b demonstrated biodistribution and accumulation in rat pancreas with complete depuration in 24 h. These findings show the potential therapeutic use of s-cal14.2b in endocrinal pathologies such as early stages of Type 2 Diabetes where the pancreas’s capability to produce insulin is still effective.
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Affiliation(s)
- Pavel H. Lugo-Fabres
- CONACYT-Unidad de Biotecnología Médica y Farmacéutica, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco (CIATEJ) A. C., Av. Normalistas 800, Colinas de la Normal, Guadalajara 44270, Jalisco, Mexico; (P.H.L.-F.); (T.A.C.-V.)
- Departamento de Innovación Biomédica, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Carretera Ensenada-Tijuana No. 3918, Zona Playitas, Ensenada 22860, Baja California, Mexico; (L.M.O.-S.); (J.B.-S.); (N.S.-C.)
| | - Leslie M. Otero-Sastre
- Departamento de Innovación Biomédica, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Carretera Ensenada-Tijuana No. 3918, Zona Playitas, Ensenada 22860, Baja California, Mexico; (L.M.O.-S.); (J.B.-S.); (N.S.-C.)
| | - Johanna Bernáldez-Sarabia
- Departamento de Innovación Biomédica, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Carretera Ensenada-Tijuana No. 3918, Zona Playitas, Ensenada 22860, Baja California, Mexico; (L.M.O.-S.); (J.B.-S.); (N.S.-C.)
| | - Tanya A. Camacho-Villegas
- CONACYT-Unidad de Biotecnología Médica y Farmacéutica, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco (CIATEJ) A. C., Av. Normalistas 800, Colinas de la Normal, Guadalajara 44270, Jalisco, Mexico; (P.H.L.-F.); (T.A.C.-V.)
| | - Noemi Sánchez-Campos
- Departamento de Innovación Biomédica, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Carretera Ensenada-Tijuana No. 3918, Zona Playitas, Ensenada 22860, Baja California, Mexico; (L.M.O.-S.); (J.B.-S.); (N.S.-C.)
| | - Janeth Serrano-Bello
- Laboratorio de Bioingeniería de Tejidos, División de Estudios de Posgrado e Investigación, Facultad de Odontología, Universidad Nacional Autónoma de México, Ciudad de México 04360, Mexico;
| | - Luis A. Medina
- Laboratorio de Física Médica-Unidad de Investigación Biomédica en Cáncer-INCan, Ciudad de México 14080, Mexico;
- Instituto de Física, Universidad Nacional Autónoma de México (UNAM), Ciudad de México 04510, Mexico
| | - Saé Muñiz-Hernández
- Laboratorio de Oncología Experimental, Subdirección de Investigación Básica, Instituto Nacional de Cancerología, Ciudad de México 14080, Mexico;
| | - Lizbeth de la Cruz
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico; (L.d.l.C.); (I.A.); (A.B.-M.); (D.E.G.)
| | - Isabel Arenas
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico; (L.d.l.C.); (I.A.); (A.B.-M.); (D.E.G.)
| | - Antonio Barajas-Martínez
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico; (L.d.l.C.); (I.A.); (A.B.-M.); (D.E.G.)
| | - David E. Garcia
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico; (L.d.l.C.); (I.A.); (A.B.-M.); (D.E.G.)
| | - Linda Nuñez-Garcia
- Laboratorios Silanes S.A. de C.V., Ciudad de México 11000, Mexico; (L.N.-G.); (J.G.-C.)
| | | | - Alexei F. Licea-Navarro
- Departamento de Innovación Biomédica, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Carretera Ensenada-Tijuana No. 3918, Zona Playitas, Ensenada 22860, Baja California, Mexico; (L.M.O.-S.); (J.B.-S.); (N.S.-C.)
- Correspondence: ; Tel.: +52-6461750500 (ext. 27218)
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9
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Veluthakal R, Thurmond DC. Emerging Roles of Small GTPases in Islet β-Cell Function. Cells 2021; 10:1503. [PMID: 34203728 PMCID: PMC8232272 DOI: 10.3390/cells10061503] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/08/2021] [Accepted: 06/08/2021] [Indexed: 12/16/2022] Open
Abstract
Several small guanosine triphosphatases (GTPases) from the Ras protein superfamily regulate glucose-stimulated insulin secretion in the pancreatic islet β-cell. The Rho family GTPases Cdc42 and Rac1 are primarily involved in relaying key signals in several cellular functions, including vesicle trafficking, plasma membrane homeostasis, and cytoskeletal dynamics. They orchestrate specific changes at each spatiotemporal region within the β-cell by coordinating with signal transducers, guanine nucleotide exchange factors (GEFs), GTPase-activating factors (GAPs), and their effectors. The Arf family of small GTPases is involved in vesicular trafficking (exocytosis and endocytosis) and actin cytoskeletal dynamics. Rab-GTPases regulate pre-exocytotic and late endocytic membrane trafficking events in β-cells. Several additional functions for small GTPases include regulating transcription factor activity and mitochondrial dynamics. Importantly, defects in several of these GTPases have been found associated with type 2 diabetes (T2D) etiology. The purpose of this review is to systematically denote the identities and molecular mechanistic steps in the glucose-stimulated insulin secretion pathway that leads to the normal release of insulin. We will also note newly identified defects in these GTPases and their corresponding regulatory factors (e.g., GDP dissociation inhibitors (GDIs), GEFs, and GAPs) in the pancreatic β-cells, which contribute to the dysregulation of metabolism and the development of T2D.
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Affiliation(s)
- Rajakrishnan Veluthakal
- Department of Molecular and Cellular Endocrinology, Arthur Riggs Diabetes & Metabolism Research Institute, City of Hope Beckman Research Institute, Duarte, CA 91010, USA
| | - Debbie C. Thurmond
- Department of Molecular and Cellular Endocrinology, Arthur Riggs Diabetes & Metabolism Research Institute, City of Hope Beckman Research Institute, Duarte, CA 91010, USA
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10
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Yang X, Zhang M, Lu Z, Zhi L, Xue H, Liu T, Liu M, Cui L, Liu Z, He P, Liu Y, Zhang Y. Novel Small Molecule Glucagon-Like Peptide-1 Receptor Agonist S6 Stimulates Insulin Secretion From Rat Islets. Front Pharmacol 2021; 12:664802. [PMID: 33995091 PMCID: PMC8116734 DOI: 10.3389/fphar.2021.664802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 04/12/2021] [Indexed: 12/03/2022] Open
Abstract
Glucagon-like peptide-1 receptor (GLP-1R) agonist-based therapeutics for type 2 diabetes mellitus have attracted worldwide attention. However, there are challenges in the development of small molecule GLP-1R agonists owing to the complexity of ligand recognition and signal induction mechanisms. Here, we attained S6 using virtual screening and fluorescent imaging plate reader (FLIPR)-based calcium assays. The purpose of this study was to identify and characterize S6, a novel small molecule GLP-1R agonist. Data from cellular thermal shift assay (CETSA) and Bio-Layer Interferometry (BLI) indicated that S6 could bind potently with GLP-1R. Radioimmunoassay data showed that S6 potentiated insulin secretion in a glucose-dependent manner and the insulinotropic effect was mediated by GLP-1R. Calcium imaging techniques suggested that S6 elevated the intracellular calcium concentration [(Ca2+)i] by activating GLP-1R. In patch-clamp experiments, we demonstrated that S6 inhibited voltage-dependent K+ (Kv) channels in a GLP-1R-dependent fashion. Besides, S6 significantly prolonged action potential duration but had no effect on voltage-dependent Ca2+ channels. In summary, these findings indicate that S6 stimulates glucose-dependent insulin secretion mainly by acting on GLP-1R, inhibiting Kv channels, increasing (Ca2+)i. This study will provide direction for the screening and development of novel small-molecule agents targeting GLP-1R in the future.
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Affiliation(s)
- Xiaohua Yang
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Min Zhang
- Department of Pharmacy, Shanxi Medical University, Taiyuan, China
| | - Zhihong Lu
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Linping Zhi
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Huan Xue
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China.,Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan, China
| | - Tao Liu
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Mengmeng Liu
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Lijuan Cui
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China.,Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan, China
| | - Zhihong Liu
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Peifeng He
- School of Management, Shanxi Medical University, Taiyuan, China
| | - Yunfeng Liu
- Department of Endocrinology, 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
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11
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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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12
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Wang C, Liu Y, Zhu Y, Kong C. Functions of mammalian SIRT4 in cellular metabolism and research progress in human cancer. Oncol Lett 2020; 20:11. [PMID: 32774484 PMCID: PMC7405384 DOI: 10.3892/ol.2020.11872] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 05/18/2020] [Indexed: 12/11/2022] Open
Abstract
Sirtuins are mammalian homologs of yeast silent information regulator two (SIRT) and are a highly conserved family of proteins, which act as nicotinamide adenine dinucleotide (NAD+)-dependent histone deacetylases. The seven sirtuins (SIRT1-7) share a conserved catalytic core domain; however, they have different enzyme activities, biological functions, and subcellular localizations. Among them, mitochondrial SIRT4 possesses ADP-ribosyltransferase, NAD+-dependent deacetylase, lipoamidase, and long-chain deacylase activities and can modulate the function of substrate proteins via ADP-ribosylation, delipoylation, deacetylation and long-chain deacylation. SIRT4 has been shown to play a crucial role in insulin secretion, fatty acid oxidation, amino acid metabolism, ATP homeostasis, apoptosis, neurodegeneration, and cardiovascular diseases. In addition, recent studies have demonstrated that SIRT4 acts as a tumor suppressor. Here, the present review summarizes the enzymatic activities and biological functions of SIRT4, as well as its roles in cellular metabolism and human cancer, which are described in the current literature.
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Affiliation(s)
- Changming Wang
- Department of Urology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China.,Department of Urological Laboratory, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Yan Liu
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, P.R. China
| | - Yuyan Zhu
- Department of Urology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China.,Department of Urological Laboratory, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Chuize Kong
- Department of Urology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China.,Department of Urological Laboratory, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
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13
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Shrestha N, Reinert RB, Qi L. Endoplasmic Reticulum Protein Quality Control in β Cells. Semin Cell Dev Biol 2020; 103:59-67. [PMID: 32402517 PMCID: PMC7321887 DOI: 10.1016/j.semcdb.2020.04.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 03/17/2020] [Accepted: 04/10/2020] [Indexed: 12/12/2022]
Abstract
Type 1 and type 2 diabetes are associated with loss of β cell function. Optimal β cell function is linked to protein homeostasis in the endoplasmic reticulum (ER). Here, we review the roles of ER protein quality-control mechanisms, including the unfolded protein response (UPR), autophagy (specifically ER-phagy) and ER-associated degradation (ERAD), in β cells. We propose that different quality control mechanisms may control different aspects of β cell biology (i.e. function, survival, and identity), thereby contributing to disease pathogenesis.
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Affiliation(s)
- Neha Shrestha
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Rachel B Reinert
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Ling Qi
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48105, USA; Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA.
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14
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Qin WP, Cao LY, Li CH, Guo LH, Colbourne J, Ren XM. Perfluoroalkyl Substances Stimulate Insulin Secretion by Islet β Cells via G Protein-Coupled Receptor 40. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:3428-3436. [PMID: 32092270 DOI: 10.1021/acs.est.9b07295] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The potential causal relationship between exposure to environmental contaminants and diabetes is troubling. Exposure of perfluoroalkyl substances (PFASs) is found to be associated with hyperinsulinemia and the enhancement of insulin secretion by islet β cells in humans, but the underlying mechanism is still unclear. Here, by combining in vivo studies with both wild type and gene knockout mice and in vitro studies with mouse islet β cells (β-TC-6), we demonstrated clearly that 1 h exposure of perfluorooctanesulfonate (PFOS) stimulated insulin secretion and intracellular calcium level by activating G protein-coupled receptor 40 (GPR40), a vital free fatty acid regulated membrane receptor on islet β cells. We further showed that the observed effects of PFASs on the mouse model may also exist in humans by investigating the molecular binding interaction of PFASs with human GPR40. We thus provided evidence for a novel mechanism for how insulin-secretion is disrupted by PFASs in humans.
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Affiliation(s)
- Wei-Ping Qin
- State Key Laboratory of Environmental Chemistry and Eco-toxicology, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085, China
| | - Lin-Ying Cao
- State Key Laboratory of Environmental Chemistry and Eco-toxicology, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085, China
| | - Chuan-Hai Li
- State Key Laboratory of Environmental Chemistry and Eco-toxicology, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085, China
| | - Liang-Hong Guo
- Institute of Environmental and Health Sciences, China Jiliang University, Hangzhou, Zhejiang 310018, China
| | - John Colbourne
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K
| | - Xiao-Min Ren
- State Key Laboratory of Environmental Chemistry and Eco-toxicology, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085, China
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15
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Singh T, Suarez Castellanos I, Bhowmick DC, Cohen J, Jeremic A, Zderic V. Therapeutic Ultrasound-Induced Insulin Release in Vivo. ULTRASOUND IN MEDICINE & BIOLOGY 2020; 46:639-648. [PMID: 31837888 DOI: 10.1016/j.ultrasmedbio.2019.10.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 09/27/2019] [Accepted: 10/27/2019] [Indexed: 06/10/2023]
Abstract
The tolerability and efficacy of low-frequency, low-intensity therapeutic ultrasound-induced insulin release was investigated in a pre-clinical in vivo murine model. The treatment groups received a single 5-min continuous sonication at 1 MHz and 1.0 W/cm2. Insulin and glucagon levels in the serum were determined using enzyme-linked immunosorbent assay. The pancreas was excised and sectioned for histologic analysis. In terminal studies, we observed a moderate (∼50 pM) but significant increase in blood insulin concentration in vivo immediately after sonication compared with a decrease of approximately 60 pM in sham animals (n < 6, p < 0.005). No difference was observed in the change in glucose or glucagon concentrations between groups. Comparisons of hematoxylin and eosin-stained terminal and survival pancreatic tissue revealed no visible differences or evidence of damage. This study is the first step in assessing the translational potential of therapeutic ultrasound as a treatment for early stages of type 2 diabetes.
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Affiliation(s)
- Tania Singh
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA
| | - Ivan Suarez Castellanos
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA; INSERM, Laboratory of Therapeutic Applications of Ultrasound (LabTAU), Lyon, France
| | | | - Joshua Cohen
- Medical Faculty Associates, The George Washington University, Washington, DC, USA
| | - Aleksandar Jeremic
- Department of Biological Sciences, The George Washington University, Washington, DC, USA
| | - Vesna Zderic
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA.
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16
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Lv W, Wang X, Xu Q, Lu W. Mechanisms and Characteristics of Sulfonylureas and Glinides. Curr Top Med Chem 2020; 20:37-56. [PMID: 31884929 DOI: 10.2174/1568026620666191224141617] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 08/30/2019] [Accepted: 09/22/2019] [Indexed: 12/25/2022]
Abstract
BACKGROUND Type 2 diabetes mellitus is a complex progressive endocrine disease characterized by hyperglycemia and life-threatening complications. It is the most common disorder of pancreatic cell function that causes insulin deficiency. Sulfonylurea is a class of oral hypoglycemic drugs. Over the past half century, these drugs, together with the subsequent non-sulfonylureas (glinides), have been the main oral drugs for insulin secretion. OBJECTIVE Through in-depth study, the medical profession considers it as an important drug for improving blood sugar control. METHODS The mechanism, characteristics, efficacy and side effects of sulfonylureas and glinides were reviewed in detail. RESULTS Sulfonylureas and glinides not only stimulated the release of insulin from pancreatic cells, but also had many extrapanular hypoglycemic effect, such as reducing the clearance rate of insulin in liver, reducing the secretion of glucagon, and enhancing the sensitivity of peripheral tissues to insulin in type 2 diabetes mellitus. CONCLUSION Sulfonylureas and glinides are effective first-line drugs for the treatment of diabetes mellitus. Although they have the risk of hypoglycemia, weight gain and cardiovascular disease, their clinical practicability and safety can be guaranteed as long as they are reasonably used.
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Affiliation(s)
- Wei Lv
- School of Materials Science and Engineering, Shanghai University, Shanghai, China.,Shanghai Huayi Resins Co., Ltd., Shanghai, China
| | - Xianqing Wang
- Charles Institute of Dermatology, University College Dublin, Dublin D04 V1W8, Ireland
| | - Qian Xu
- Charles Institute of Dermatology, University College Dublin, Dublin D04 V1W8, Ireland
| | - Wencong Lu
- School of Materials Science and Engineering, Shanghai University, Shanghai, China
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17
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Scarl RT, Corbin KL, Vann NW, Smith HM, Satin LS, Sherman A, Nunemaker CS. Intact pancreatic islets and dispersed beta-cells both generate intracellular calcium oscillations but differ in their responsiveness to glucose. Cell Calcium 2019; 83:102081. [PMID: 31563790 DOI: 10.1016/j.ceca.2019.102081] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 09/12/2019] [Accepted: 09/14/2019] [Indexed: 01/19/2023]
Abstract
Pancreatic islets produce pulses of insulin and other hormones that maintain normal glucose homeostasis. These micro-organs possess exquisite glucose-sensing capabilities, allowing for precise changes in pulsatile insulin secretion in response to small changes in glucose. When communication among these cells is disrupted, precision glucose sensing falters. We measured intracellular calcium patterns in 6-mM-steps between 0 and 16 mM glucose, and also more finely in 2-mM-steps from 8 to 12 mM glucose, to compare glucose sensing systematically among intact islets and dispersed islet cells derived from the same mouse pancreas in vitro. The calcium activity of intact islets was uniformly low (quiescent) below 4 mM glucose and active above 8 mM glucose, whereas dispersed beta-cells displayed a broader activation range (2-to-10 mM). Intact islets exhibited calcium oscillations with 2-to-5-min periods, yet beta-cells exhibited longer 7-10 min periods. In every case, intact islets showed changes in activity with each 6-mM-glucose step, whereas dispersed islet cells displayed a continuum of calcium responses ranging from islet-like patterns to stable oscillations unaffected by changes in glucose concentration. These differences were also observed for 2-mM-glucose steps. Despite the diversity of dispersed beta-cell responses to glucose, the sum of all activity produced a glucose dose-response curve that was surprisingly similar to the curve for intact islets, arguing against the importance of "hub cells" for function. Beta-cells thus retain many of the features of islets, but some are more islet-like than others. Determining the molecular underpinnings of these variations could be valuable for future studies of stem-cell-derived beta-cell therapies.
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Affiliation(s)
- Rachel T Scarl
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, United States
| | - Kathryn L Corbin
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, United States; Diabetes Institute, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, United States
| | - Nicholas W Vann
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States
| | - Hallie M Smith
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, United States
| | - Leslie S Satin
- Brehm Diabetes Research Center, University of Michigan Medical School, Ann Arbor, MI, United States; Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Arthur Sherman
- Laboratory of Biological Modeling, NIDDK, NIH, Bethesda, MD, United States
| | - Craig S Nunemaker
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, United States; Diabetes Institute, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, United States.
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18
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PACAP stimulates insulin secretion by PAC1 receptor and ion channels in β-cells. Cell Signal 2019; 61:48-56. [DOI: 10.1016/j.cellsig.2019.05.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 04/28/2019] [Accepted: 05/06/2019] [Indexed: 01/02/2023]
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19
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Paseban M, Butler AE, Sahebkar A. Mechanisms of statin‐induced new‐onset diabetes. J Cell Physiol 2019; 234:12551-12561. [DOI: 10.1002/jcp.28123] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 12/20/2018] [Indexed: 08/30/2023]
Abstract
AbstractStatins, with their lipid‐lowering properties, are a first‐line therapy for the prevention of cardiovascular diseases. Recent evidence, however, suggests that statins can increase the risk of new‐onset diabetes (NOD). The molecular mechanisms of statin‐induced NOD are not precisely known, although some pathophysiologic mechanisms have been suggested. Specific to the beta cell, these mechanisms include alterations in insulin secretion, changes in ion channels, modulation of signaling pathways, and inflammation/oxidative stress. Outwith the beta cell, other suggested mechanisms involve adipocytes, including alterations in adipocyte differentiation and modulation of leptin and adiponectin, and genetic and epigenetic mechanisms, including alterations in microRNA. The evidence supporting these and other mechanisms will be discussed. Greater understanding of the underlying mechanisms linking the onset of diabetes to statin therapy is essential and clinically relevant, as it may enable novel preventative or therapeutic approaches to be instituted and guide the production of a new generation of statins lacking this side effect.
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Affiliation(s)
- Maryam Paseban
- Department of Physiology Faculty of Medicine, Mashhad University of Medical Sciences Mashhad Iran
| | | | - Amirhossein Sahebkar
- Neurogenic Inflammation Research Center, Mashhad University of Medical Sciences Mashhad Iran
- Biotechnology Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences Mashhad Iran
- School of Pharmacy, Mashhad University of Medical Sciences Mashhad Iran
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20
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Dong S, Lau H, Chavarria C, Alexander M, Cimler A, Elliott JP, Escovar S, Lewin J, Novak J, Lakey JRT. Effects of Periodic Intensive Insulin Therapy: An Updated Review. Curr Ther Res Clin Exp 2019; 90:61-67. [PMID: 31193369 PMCID: PMC6527898 DOI: 10.1016/j.curtheres.2019.04.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 04/25/2019] [Indexed: 12/15/2022] Open
Abstract
Background Traditional insulin treatment for diabetes mellitus with insulin administered subcutaneously yields nonpulsatile plasma insulin concentrations that represent a fraction of normal portal vein levels. Oral hypoglycemic medications result in the same lack of pulsatile insulin response to blood glucose levels. Intensive treatments of significant complications of diabetes are not recommended due to complicated multidrug regimens, significant weight gain, and the high risk of hypoglycemic complications. Consequently, advanced complications of diabetes do not have an effective treatment option because conventional therapy is not sufficient. Intensive insulin therapy (IIT) simulates normal pancreatic function by closely matching the periodicity and amplitude of insulin secretion in healthy subjects; however, the mechanisms involved with the observed improvement are not clearly understood. Objective The current review aims to analyze the pathophysiology of insulin secretion, discuss current therapies for the management of diabetes, provides an updates on the recent advancements of IIT, and proposes its mechanism of action. Methods A literature search on PubMed, MEDLINE, Embase, and CrossRef databases was performed on multiple key words regarding the history and current variations of pulsatile and IIT for diabetes treatment. Articles reporting the physiology of insulin secretion, advantages of pulsatile insulin delivery in patients with diabetes patients, efficacy and adverse effects of current conventional insulin therapies for the management of diabetes, benefits and shortcomings of pancreas and islet transplantation, or clinical trials on patients with diabetes treated with pulsed insulin therapy or advanced IIT were included for a qualitative analysis and categorized into the following topics: mechanism of insulin secretion in normal subjects and patients with diabetes and current therapies for the management of diabetes, including oral hypoglycemic agents, insulin therapy, pancreas and islet transplantation, pulsed insulin therapy, and advances in IIT. Results Our review of the literature shows that IIT improves the resolution of diabetic ulcers, neuropathy, and nephropathy, and reduces emergency room visits. The likely mechanism responsible for this improvement is increased insulin sensitivity from adipocytes, as well as increased insulin receptor expression. Conclusions Recent advancements show that IIT is an effective option for both type 1 diabetes mellitus and type 2 diabetes mellitus patient populations. This treatment resembles normal pancreatic function so closely that it has significantly reduced the effects of relatively common complications of diabetes in comparison to standard treatments. Thus, this new treatment is a promising advancement in the management of diabetes. (Curr Ther Res Clin Exp. 2019; 80:XXX–XXX).
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Affiliation(s)
- Shu Dong
- Department of Surgery, University of California Irvine, Orange, California
| | - Hien Lau
- Department of Surgery, University of California Irvine, Orange, California
| | - Cody Chavarria
- Department of Surgery, University of California Irvine, Orange, California
| | - Michael Alexander
- Department of Surgery, University of California Irvine, Orange, California
| | | | | | | | - Jack Lewin
- Lewin and Associates, New York, New York
| | | | - Jonathan R T Lakey
- Department of Surgery, University of California Irvine, Orange, California.,Department of Biomedical Engineering, University of California Irvine, Irvine, California
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21
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Curry L, Almukhtar H, Alahmed J, Roberts R, Smith PA. Simvastatin Inhibits L-Type Ca2+-Channel Activity Through Impairment of Mitochondrial Function. Toxicol Sci 2019; 169:543-552. [DOI: 10.1093/toxsci/kfz068] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Liam Curry
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Hani Almukhtar
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Jala Alahmed
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Richard Roberts
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Paul A Smith
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
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22
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Nanoformulation of Leonotis leonurus to improve its bioavailability as a potential antidiabetic drug. 3 Biotech 2017; 7:344. [PMID: 28955641 DOI: 10.1007/s13205-017-0986-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 09/18/2017] [Indexed: 01/06/2023] Open
Abstract
Nanostructured lipid carriers (NLCs) of Leonotis leonurus were successfully produced using high-pressure homogenisation (HPH) on a LAB 40 homogeniser. The particle size was determined for the formulation as well as short-term stability study. The formulation was exposed to Chang liver cells for a glucose uptake study and to INS-1 cells for a chronic insulin release study under normoglycaemic and hyperglycaemic conditions. The particle size of the extract NLC was 220 nm with a PdI of 0.08 after homogenisation at 800 bar. The formulation was stable at the tested temperatures. The extract NLC formulation at 1 µg/ml improved glucose uptake, relative to the control liver cells. Insulin release in INS-1 cells was also elevated under hyperglycaemic conditions when exposed to the NLCs, in comparison with the control untreated cells and the non-formulated extract. The plant extract encapsulated in NLC improved the uptake of glucose and enhanced the insulin sensitivity in vitro, compared to the extract.
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23
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Wu Y, Fortin DA, Cochrane VA, Chen PC, Shyng SL. NMDA receptors mediate leptin signaling and regulate potassium channel trafficking in pancreatic β-cells. J Biol Chem 2017; 292:15512-15524. [PMID: 28768770 DOI: 10.1074/jbc.m117.802249] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 08/01/2017] [Indexed: 12/25/2022] Open
Abstract
NMDA receptors (NMDARs) are Ca2+-permeant, ligand-gated ion channels activated by the excitatory neurotransmitter glutamate and have well-characterized roles in the nervous system. The expression and function of NMDARs in pancreatic β-cells, by contrast, are poorly understood. Here, we report a novel function of NMDARs in β-cells. Using a combination of biochemistry, electrophysiology, and imaging techniques, we now show that NMDARs have a key role in mediating the effect of leptin to modulate β-cell electrical activity by promoting AMP-activated protein kinase (AMPK)-dependent trafficking of KATP and Kv2.1 channels to the plasma membrane. Blocking NMDAR activity inhibited the ability of leptin to activate AMPK, induce KATP and Kv2.1 channel trafficking, and promote membrane hyperpolarization. Conversely, activation of NMDARs mimicked the effect of leptin, causing Ca2+ influx, AMPK activation, and increased trafficking of KATP and Kv2.1 channels to the plasma membrane, and triggered membrane hyperpolarization. Moreover, leptin potentiated NMDAR currents and triggered NMDAR-dependent Ca2+ influx. Importantly, NMDAR-mediated signaling was observed in rat insulinoma 832/13 cells and in human β-cells, indicating that this pathway is conserved across species. The ability of NMDARs to regulate potassium channel surface expression and thus, β-cell excitability provides mechanistic insight into the recently reported insulinotropic effects of NMDAR antagonists and therefore highlights the therapeutic potential of these drugs in managing type 2 diabetes.
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Affiliation(s)
- Yi Wu
- From the Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239 and
| | - Dale A Fortin
- From the Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239 and
| | - Veronica A Cochrane
- From the Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239 and
| | - Pei-Chun Chen
- the Department of Physiology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
| | - Show-Ling Shyng
- From the Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239 and
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24
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Lee JJ, Yang SY, Park J, Ferrell JE, Shin DH, Lee KJ. Calcium Ion Induced Structural Changes Promote Dimerization of Secretagogin, Which Is Required for Its Insulin Secretory Function. Sci Rep 2017; 7:6976. [PMID: 28765527 PMCID: PMC5539292 DOI: 10.1038/s41598-017-07072-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 06/16/2017] [Indexed: 11/29/2022] Open
Abstract
Secretagogin (SCGN), a hexa EF-hand calcium binding protein, plays key roles in insulin secretion in pancreatic β-cells. It is not yet understood how the binding of Ca2+ to human SCGN (hSCGN) promotes secretion. Here we have addressed this question, using mass spectrometry combined with a disulfide searching algorithm DBond. We found that the binding of Ca2+ to hSCGN promotes the dimerization of hSCGN via the formation of a Cys193-Cys193 disulfide bond. Hydrogen/deuterium exchange mass spectrometry (HDX-MS) and molecular dynamics studies revealed that Ca2+ binding to the EF-hands of hSCGN induces significant structural changes that affect the solvent exposure of N-terminal region, and hence the redox sensitivity of the Cys193 residue. These redox sensitivity changes were confirmed using biotinylated methyl-3-nitro-4-(piperidin-1-ylsulfonyl) benzoate (NPSB-B), a chemical probe that specifically labels reactive cysteine sulfhydryls. Furthermore, we found that wild type hSCGN overexpression promotes insulin secretion in pancreatic β cells, while C193S-hSCGN inhibits it. These findings suggest that insulin secretion in pancreatic cells is regulated by Ca2+ and ROS signaling through Ca2+-induced structural changes promoting dimerization of hSCGN.
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Affiliation(s)
- Jae-Jin Lee
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, 120-750, Korea
| | - Seo-Yun Yang
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, 120-750, Korea
| | - Jimin Park
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, 120-750, Korea
| | - James E Ferrell
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305-5174, USA
| | - Dong-Hae Shin
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, 120-750, Korea
| | - Kong-Joo Lee
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, 120-750, Korea.
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25
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GLP-1 receptor signalling promotes β-cell glucose metabolism via mTOR-dependent HIF-1α activation. Sci Rep 2017; 7:2661. [PMID: 28572610 PMCID: PMC5454020 DOI: 10.1038/s41598-017-02838-2] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 04/19/2017] [Indexed: 02/05/2023] Open
Abstract
Glucagon-like peptide-1 (GLP-1) promotes insulin secretion from pancreatic β-cells in a glucose dependent manner. Several pathways mediate this action by rapid, kinase phosphorylation-dependent, but gene expression-independent mechanisms. Since GLP-1-induced insulin secretion requires glucose metabolism, we aimed to address the hypothesis that GLP-1 receptor (GLP-1R) signalling can modulate glucose uptake and utilization in β-cells. We have assessed various metabolic parameters after short and long exposure of clonal BRIN-BD11 β-cells and rodent islets to the GLP-1R agonist Exendin-4 (50 nM). Here we report for the first time that prolonged stimulation of the GLP-1R for 18 hours promotes metabolic reprogramming of β-cells. This is evidenced by up-regulation of glycolytic enzyme expression, increased rates of glucose uptake and consumption, as well as augmented ATP content, insulin secretion and glycolytic flux after removal of Exendin-4. In our model, depletion of Hypoxia-Inducible Factor 1 alpha (HIF-1α) impaired the effects of Exendin-4 on glucose metabolism, while pharmacological inhibition of Phosphoinositide 3-kinase (PI3K) or mTOR completely abolished such effects. Considering the central role of glucose catabolism for stimulus-secretion coupling in β-cells, our findings suggest that chronic GLP-1 actions on insulin secretion include elevated β-cell glucose metabolism. Moreover, our data reveal novel aspects of GLP-1 stimulated insulin secretion involving de novo gene expression.
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26
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Kabra UD, Pfuhlmann K, Migliorini A, Keipert S, Lamp D, Korsgren O, Gegg M, Woods SC, Pfluger PT, Lickert H, Affourtit C, Tschöp MH, Jastroch M. Direct Substrate Delivery Into Mitochondrial Fission-Deficient Pancreatic Islets Rescues Insulin Secretion. Diabetes 2017; 66:1247-1257. [PMID: 28174288 DOI: 10.2337/db16-1088] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 01/29/2017] [Indexed: 11/13/2022]
Abstract
In pancreatic β-cells, mitochondrial bioenergetics control glucose-stimulated insulin secretion. Mitochondrial dynamics are generally associated with quality control, maintaining the functionality of bioenergetics. By acute pharmacological inhibition of mitochondrial fission protein Drp1, we demonstrate in this study that mitochondrial fission is necessary for glucose-stimulated insulin secretion in mouse and human islets. We confirm that genetic silencing of Drp1 increases mitochondrial proton leak in MIN6 cells. However, our comprehensive analysis of pancreatic islet bioenergetics reveals that Drp1 does not control insulin secretion via its effect on proton leak but instead via modulation of glucose-fueled respiration. Notably, pyruvate fully rescues the impaired insulin secretion of fission-deficient β-cells, demonstrating that defective mitochondrial dynamics solely affect substrate supply upstream of oxidative phosphorylation. The present findings provide novel insights into how mitochondrial dysfunction may cause pancreatic β-cell failure. In addition, the results will stimulate new thinking in the intersecting fields of mitochondrial dynamics and bioenergetics, as treatment of defective dynamics in mitochondrial diseases appears to be possible by improving metabolism upstream of mitochondria.
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Affiliation(s)
- Uma D Kabra
- Helmholtz Diabetes Center, Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research, Helmholtz Zentrum München, Neuherberg, Germany
- Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - Katrin Pfuhlmann
- Helmholtz Diabetes Center, Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research, Helmholtz Zentrum München, Neuherberg, Germany
- Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - Adriana Migliorini
- Helmholtz Diabetes Center, Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research, Helmholtz Zentrum München, Neuherberg, Germany
| | - Susanne Keipert
- Helmholtz Diabetes Center, Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research, Helmholtz Zentrum München, Neuherberg, Germany
| | - Daniel Lamp
- Helmholtz Diabetes Center, Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research, Helmholtz Zentrum München, Neuherberg, Germany
- Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - Olle Korsgren
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Moritz Gegg
- Helmholtz Diabetes Center, Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research, Helmholtz Zentrum München, Neuherberg, Germany
- Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - Stephen C Woods
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH
| | - Paul T Pfluger
- Helmholtz Diabetes Center, Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research, Helmholtz Zentrum München, Neuherberg, Germany
| | - Heiko Lickert
- Helmholtz Diabetes Center, Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research, Helmholtz Zentrum München, Neuherberg, Germany
- Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - Charles Affourtit
- School of Biomedical and Healthcare Sciences, Plymouth University, Plymouth, U.K
| | - Matthias H Tschöp
- Helmholtz Diabetes Center, Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research, Helmholtz Zentrum München, Neuherberg, Germany
- Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - Martin Jastroch
- Helmholtz Diabetes Center, Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research, Helmholtz Zentrum München, Neuherberg, Germany
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27
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Félix-Martínez GJ, Godínez-Fernández JR. Modeling the spatiotemporal distribution of Ca
2+
during action potential firing in human pancreatic
β
-cells. Biomed Phys Eng Express 2017. [DOI: 10.1088/2057-1976/aa669f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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28
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Briant LJB, Zhang Q, Vergari E, Kellard JA, Rodriguez B, Ashcroft FM, Rorsman P. Functional identification of islet cell types by electrophysiological fingerprinting. J R Soc Interface 2017; 14:20160999. [PMID: 28275121 PMCID: PMC5378133 DOI: 10.1098/rsif.2016.0999] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 02/15/2017] [Indexed: 01/18/2023] Open
Abstract
The α-, β- and δ-cells of the pancreatic islet exhibit different electrophysiological features. We used a large dataset of whole-cell patch-clamp recordings from cells in intact mouse islets (N = 288 recordings) to investigate whether it is possible to reliably identify cell type (α, β or δ) based on their electrophysiological characteristics. We quantified 15 electrophysiological variables in each recorded cell. Individually, none of the variables could reliably distinguish the cell types. We therefore constructed a logistic regression model that included all quantified variables, to determine whether they could together identify cell type. The model identified cell type with 94% accuracy. This model was applied to a dataset of cells recorded from hyperglycaemic βV59M mice; it correctly identified cell type in all cells and was able to distinguish cells that co-expressed insulin and glucagon. Based on this revised functional identification, we were able to improve conductance-based models of the electrical activity in α-cells and generate a model of δ-cell electrical activity. These new models could faithfully emulate α- and δ-cell electrical activity recorded experimentally.
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Affiliation(s)
- Linford J B Briant
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, Radcliffe Department of Medicine, University of Oxford, Churchill Hospital, Oxford OX3 7LE, UK
- Department of Computer Science, University of Oxford, Oxford OX1 3QD, UK
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, Radcliffe Department of Medicine, University of Oxford, Churchill Hospital, Oxford OX3 7LE, UK
| | - Elisa Vergari
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, Radcliffe Department of Medicine, University of Oxford, Churchill Hospital, Oxford OX3 7LE, UK
| | - Joely A Kellard
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, Radcliffe Department of Medicine, University of Oxford, Churchill Hospital, Oxford OX3 7LE, UK
| | - Blanca Rodriguez
- Department of Computer Science, University of Oxford, Oxford OX1 3QD, UK
| | - Frances M Ashcroft
- Department of Physiology, Anatomy, and Genetics, University of Oxford, South Parks Road, Oxford OX1 3PT, UK
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, Radcliffe Department of Medicine, University of Oxford, Churchill Hospital, Oxford OX3 7LE, UK
- Metabolic Research, Department of Physiology, Institute of Neuroscience and Physiology, University of Göteborg, SE-405 30 Göteborg, Sweden
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29
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Noto D, Arca M, Tarugi P, Cefalù AB, Barbagallo CM, Averna MR. Association between familial hypobetalipoproteinemia and the risk of diabetes. Is this the other side of the cholesterol-diabetes connection? A systematic review of literature. Acta Diabetol 2017; 54:111-122. [PMID: 27804036 DOI: 10.1007/s00592-016-0931-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 10/09/2016] [Indexed: 02/03/2023]
Abstract
Statin therapy is beneficial in reducing LDL cholesterol (LDL-C) levels and cardiovascular events, but it is associated with the risk of incident diabetes mellitus (DM). Familial hypercholesterolemia (FH) is characterized by genetically determined high levels of plasma LDL-C and a low prevalence of DM. LDL-C levels seem then inversely correlated with prevalence of DM. Familial hypobetalipoproteinemia (FHBL) represents the genetic mirror of FH in terms of LDL-C levels, very low in subjects carrying mutations of APOB, PCSK9 (FHBL1) or ANGPTL3 (FHBL2). This review explores the hypothesis that FHBL might represent also the genetic mirror of FH in terms of prevalence of DM and that it is expected to be increased in FHBL in comparison with the general population. A systematic review of published literature on FHBL was made by searching PubMed (1980-2016) for articles presenting clinical data on FHBL probands and relatives. The standardized prevalence rates of DM in FHBL1 were similar to those of the reference population, with a prevalence rate of 8.2 and 9.2%, respectively, while FHBL2 showed a 4.9% prevalence of DM. In conclusion, low LDL-C levels of FHBL do not seem connected to DM as it happens in subjects undergoing statin therapy and the diabetogenic effect of statins has to be explained by mechanisms that do not rely exclusively on the reduced levels of LDL-C. The review also summarizes the published data on the effects of FHBL on insulin sensitivity and the relationships between FH, statin therapy, FHBL1 and intracellular cholesterol metabolism, evaluating possible diabetogenic pathways.
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Affiliation(s)
- Davide Noto
- Department of Biomedicine, Internal Medicine and Medical Specialties (DIBIMIS), University of Palermo, Palermo, Italy.
- Department of Internal Medicine, Policlinico "Paolo Giaccone", Via del Vespro 141, 90127, Palermo, Italy.
| | - Marcello Arca
- Department of Internal Medicine and Allied Sciences, Unit of Atherosclerosis and Lipid Disorders, Sapienza University of Rome, Rome, Italy
| | - Patrizia Tarugi
- Department of Biomedical Sciences, University of Modena-Reggio, Modena, Italy
| | - Angelo B Cefalù
- Department of Biomedicine, Internal Medicine and Medical Specialties (DIBIMIS), University of Palermo, Palermo, Italy
| | - Carlo M Barbagallo
- Department of Biomedicine, Internal Medicine and Medical Specialties (DIBIMIS), University of Palermo, Palermo, Italy
| | - Maurizio R Averna
- Department of Biomedicine, Internal Medicine and Medical Specialties (DIBIMIS), University of Palermo, Palermo, Italy.
- Department of Internal Medicine, Policlinico "Paolo Giaccone", Via del Vespro 141, 90127, Palermo, Italy.
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30
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Osteopontin Affects Insulin Vesicle Localization and Ca2+ Homeostasis in Pancreatic Beta Cells from Female Mice. PLoS One 2017; 12:e0170498. [PMID: 28107503 PMCID: PMC5249066 DOI: 10.1371/journal.pone.0170498] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 12/15/2016] [Indexed: 02/06/2023] Open
Abstract
Type 2 diabetic patients suffer from insulin resistance and reduced insulin secretion. Osteopontin (OPN), a versatile protein expressed in several tissues throughout the body including the islets of Langerhans, has previously been implicated in the development of insulin resistance. Here we have investigated the role of OPN in insulin secretion using an OPN knock out mouse model (OPN-/-). Ultra-structural analyzes of islets from OPN-/- and WT mice indicated weaker cell-cell connections between the islet cells in the OPN-/- mouse compared to WT. Analysis of the insulin granule distribution in the beta cells showed that although OPN-/- and WT beta cells have the same number of insulin granules OPN-/- beta cells have significantly fewer docked granules. Both OPN-/- and WT islets displayed synchronized Ca2+ oscillations indicative of an intact beta cell communication. OPN-/- islets displayed higher intracellular Ca2+ concentrations when stimulated with 16.7 mM glucose than WT islets and the initial dip upon elevated glucose concentrations (which is associated with Ca2+ uptake into ER) was significantly lower in these islets. Glucose-induced insulin secretion was similar in OPN-/- and WT islets. Likewise, non-fasted blood glucose levels were the same in both groups. In summary, deletion of OPN results in several minor beta-cell defects that can be compensated for in a healthy system.
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31
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Frank JA, Yushchenko DA, Hodson DJ, Lipstein N, Nagpal J, Rutter GA, Rhee JS, Gottschalk A, Brose N, Schultz C, Trauner D. Photoswitchable diacylglycerols enable optical control of protein kinase C. Nat Chem Biol 2016; 12:755-62. [PMID: 27454932 PMCID: PMC6101201 DOI: 10.1038/nchembio.2141] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 05/16/2016] [Indexed: 01/02/2023]
Abstract
Increased levels of the second messenger lipid diacylglycerol (DAG) induce downstream signaling events including the translocation of C1-domain-containing proteins toward the plasma membrane. Here, we introduce three light-sensitive DAGs, termed PhoDAGs, which feature a photoswitchable acyl chain. The PhoDAGs are inactive in the dark and promote the translocation of proteins that feature C1 domains toward the plasma membrane upon a flash of UV-A light. This effect is quickly reversed after the termination of photostimulation or by irradiation with blue light, permitting the generation of oscillation patterns. Both protein kinase C and Munc13 can thus be put under optical control. PhoDAGs control vesicle release in excitable cells, such as mouse pancreatic islets and hippocampal neurons, and modulate synaptic transmission in Caenorhabditis elegans. As such, the PhoDAGs afford an unprecedented degree of spatiotemporal control and are broadly applicable tools to study DAG signaling.
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Affiliation(s)
- James Allen Frank
- Department of Chemistry and Center for Integrated Protein Science, Ludwig Maximilians University Munich, Munich, Germany
| | - Dmytro A Yushchenko
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - David J Hodson
- Section of Cell Biology and Functional Genomics, Department of Medicine, Imperial College London, ICTEM, Hammersmith Hospital, London, UK
- Institute of Metabolism and Systems Research (IMSR) and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK
- Centre for Endocrinology, Diabetes and Metabolism (CEDAM), Birmingham Health Partners, Birmingham, UK
| | - Noa Lipstein
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Jatin Nagpal
- Buchmann Institute for Molecular Life Sciences, Goethe University, Frankfurt, Germany
- Institute of Biochemistry, Department for Biochemistry, Chemistry and Pharmacy, Goethe University, Frankfurt, Germany
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Department of Medicine, Imperial College London, ICTEM, Hammersmith Hospital, London, UK
| | - Jeong-Seop Rhee
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Alexander Gottschalk
- Buchmann Institute for Molecular Life Sciences, Goethe University, Frankfurt, Germany
- Institute of Biochemistry, Department for Biochemistry, Chemistry and Pharmacy, Goethe University, Frankfurt, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Carsten Schultz
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Dirk Trauner
- Department of Chemistry and Center for Integrated Protein Science, Ludwig Maximilians University Munich, Munich, Germany
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32
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Rorsman P. Review: Insulin secretion: function and therapy of pancreatic beta-cells in diabetes. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/14746514050050040201] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
nsulin is secreted from the beta-cells of the pancreatic islets in response to an elevation of blood glucose concentration. This review describes a current view of the metabolic control of insulin secretion and the molecular mechanisms involved, including the role played by the beta-cell to ensure correct release of insulin as a result of electrical signals. It then considers what goes wrong in type 2 diabetes, a disease resulting from insufficient insulin secretion. It focuses on the influence of genetics exploring the theory of a genetic predisposition to type 2 diabetes, as well as the roles played by age and obesity. Finally, the mode of action of the hypoglycaemic sulphonylureas is discussed and the potential implications for the beta-cell associated with a sulphonylurea-based therapy.
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Affiliation(s)
- Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology; and Metabolism, Churchill Hospital, University of Oxford, Oxford, OX3 7LJ, UK,
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33
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McCommis KS, Hodges WT, Bricker DK, Wisidagama DR, Compan V, Remedi MS, Thummel CS, Finck BN. An ancestral role for the mitochondrial pyruvate carrier in glucose-stimulated insulin secretion. Mol Metab 2016; 5:602-614. [PMID: 27656398 PMCID: PMC5021712 DOI: 10.1016/j.molmet.2016.06.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 06/24/2016] [Accepted: 06/30/2016] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE Transport of pyruvate into the mitochondrial matrix by the Mitochondrial Pyruvate Carrier (MPC) is an important and rate-limiting step in its metabolism. In pancreatic β-cells, mitochondrial pyruvate metabolism is thought to be important for glucose sensing and glucose-stimulated insulin secretion. METHODS To evaluate the role that the MPC plays in maintaining systemic glucose homeostasis, we used genetically-engineered Drosophila and mice with loss of MPC activity in insulin-producing cells. RESULTS In both species, MPC deficiency results in elevated blood sugar concentrations and glucose intolerance accompanied by impaired glucose-stimulated insulin secretion. In mouse islets, β-cell MPC-deficiency resulted in decreased respiration with glucose, ATP-sensitive potassium (KATP) channel hyperactivity, and impaired insulin release. Moreover, treatment of pancreas-specific MPC knockout mice with glibenclamide, a sulfonylurea KATP channel inhibitor, improved defects in islet insulin secretion and abnormalities in glucose homeostasis in vivo. Finally, using a recently-developed biosensor for MPC activity, we show that the MPC is rapidly stimulated by glucose treatment in INS-1 insulinoma cells suggesting that glucose sensing is coupled to mitochondrial pyruvate carrier activity. CONCLUSIONS Altogether, these studies suggest that the MPC plays an important and ancestral role in insulin-secreting cells in mediating glucose sensing, regulating insulin secretion, and controlling systemic glycemia.
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Key Words
- DILP2, Drosophila insulin-like peptide 2
- Diabetes
- Drosophila
- GSIS, glucose-stimulated insulin secretion
- GTT, glucose tolerance test
- IMM, inner mitochondrial membrane
- IPCs, Insulin-producing Cells
- ITT, insulin tolerance test
- Insulin
- MPC1 and MPC2, Mitochondrial Pyruvate Carrier 1 and 2
- Mitochondria
- OCR, oxygen consumption rates
- Pdx1, pancreatic and duodenal homeobox 1
- Pyruvate
- RESPYR, REporter Sensitive to PYRuvate
- Stimulus-coupled secretion
- β-Cell
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Affiliation(s)
- Kyle S McCommis
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Wesley T Hodges
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Daniel K Bricker
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Dona R Wisidagama
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Vincent Compan
- Institute of Functional Genomics, Labex ICST; INSERM U1191, CNRS UMR5203; University of Montpellier, Montpellier, France
| | - Maria S Remedi
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Carl S Thummel
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
| | - Brian N Finck
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Kolic J, Manning Fox JE, Chepurny OG, Spigelman AF, Ferdaoussi M, Schwede F, Holz GG, MacDonald PE. PI3 kinases p110α and PI3K-C2β negatively regulate cAMP via PDE3/8 to control insulin secretion in mouse and human islets. Mol Metab 2016; 5:459-471. [PMID: 27408772 PMCID: PMC4921792 DOI: 10.1016/j.molmet.2016.05.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Revised: 04/26/2016] [Accepted: 05/04/2016] [Indexed: 01/09/2023] Open
Abstract
OBJECTIVES Phosphatidylinositol-3-OH kinase (PI3K) signalling in the endocrine pancreas contributes to glycaemic control. However, the mechanism by which PI3K modulates insulin secretion from the pancreatic beta cell is poorly understood. Thus, our objective was two-fold; to determine the signalling pathway by which acute PI3K inhibition enhances glucose-stimulated insulin secretion (GSIS) and to examine the role of this pathway in islets from type-2 diabetic (T2D) donors. METHODS Isolated islets from mice and non-diabetic or T2D human donors, or INS 832/13 cells, were treated with inhibitors of PI3K and/or phosphodiesterases (PDEs). The expression of PI3K-C2β was knocked down using siRNA. We measured insulin release, single-cell exocytosis, intracellular Ca(2+) responses ([Ca(2+)]i) and Ca(2+) channel currents, intracellular cAMP concentrations ([cAMP]i), and activation of cAMP-dependent protein kinase A (PKA) and protein kinase B (PKB/AKT). RESULTS The non-specific PI3K inhibitor wortmannin amplifies GSIS, raises [cAMP]i and activates PKA, but is without effect in T2D islets. Direct inhibition of specific PDE isoforms demonstrates a role for PDE3 (in humans and mice) and PDE8 (in mice) downstream of PI3K, and restores glucose-responsiveness of T2D islets. We implicate a role for the Class II PI3K catalytic isoform PI3K-C2β in this effect by limiting beta cell exocytosis. CONCLUSIONS PI3K limits GSIS via PDE3 in human islets. While inhibition of p110α or PIK-C2β signalling per se, may promote nutrient-stimulated insulin release, we now suggest that this signalling pathway is perturbed in islets from T2D donors.
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Affiliation(s)
- Jelena Kolic
- Department of Pharmacology, and the Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada.
| | - Jocelyn E Manning Fox
- Department of Pharmacology, and the Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - Oleg G Chepurny
- Department of Medicine, State University of New York, Upstate Medical University, Syracuse, NY 13210, USA
| | - Aliya F Spigelman
- Department of Pharmacology, and the Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - Mourad Ferdaoussi
- Department of Pharmacology, and the Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - Frank Schwede
- BIOLOG Life Science Institute, 28199 Bremen, Germany
| | - George G Holz
- Department of Medicine, State University of New York, Upstate Medical University, Syracuse, NY 13210, USA; Department of Pharmacology, State University of New York, Upstate Medical University, Syracuse, NY 13210, USA
| | - Patrick E MacDonald
- Department of Pharmacology, and the Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
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Secretagogin affects insulin secretion in pancreatic β-cells by regulating actin dynamics and focal adhesion. Biochem J 2016; 473:1791-803. [PMID: 27095850 PMCID: PMC4901359 DOI: 10.1042/bcj20160137] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 04/18/2016] [Indexed: 01/03/2023]
Abstract
Secretagogin (SCGN), a Ca2+-binding protein having six EF-hands, is selectively expressed in pancreatic β-cells and neuroendocrine cells. Previous studies suggested that SCGN enhances insulin secretion by functioning as a Ca2+-sensor protein, but the underlying mechanism has not been elucidated. The present study explored the mechanism by which SCGN enhances glucose-induced insulin secretion in NIT-1 insulinoma cells. To determine whether SCGN influences the first or second phase of insulin secretion, we examined how SCGN affects the kinetics of insulin secretion in NIT-1 cells. We found that silencing SCGN suppressed the second phase of insulin secretion induced by glucose and H2O2, but not the first phase induced by KCl stimulation. Recruitment of insulin granules in the second phase of insulin secretion was significantly impaired by knocking down SCGN in NIT-1 cells. In addition, we found that SCGN interacts with the actin cytoskeleton in the plasma membrane and regulates actin remodelling in a glucose-dependent manner. Since actin dynamics are known to regulate focal adhesion, a critical step in the second phase of insulin secretion, we examined the effect of silencing SCGN on focal adhesion molecules, including FAK (focal adhesion kinase) and paxillin, and the cell survival molecules ERK1/2 (extracellular-signal-regulated kinase 1/2) and Akt. We found that glucose- and H2O2-induced activation of FAK, paxillin, ERK1/2 and Akt was significantly blocked by silencing SCGN. We conclude that SCGN controls glucose-stimulated insulin secretion and thus may be useful in the therapy of Type 2 diabetes.
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Röder PV, Wu B, Liu Y, Han W. Pancreatic regulation of glucose homeostasis. Exp Mol Med 2016; 48:e219. [PMID: 26964835 PMCID: PMC4892884 DOI: 10.1038/emm.2016.6] [Citation(s) in RCA: 442] [Impact Index Per Article: 55.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 12/03/2015] [Accepted: 12/06/2015] [Indexed: 12/11/2022] Open
Abstract
In order to ensure normal body function, the human body is dependent on a tight control of its blood glucose levels. This is accomplished by a highly sophisticated network of various hormones and neuropeptides released mainly from the brain, pancreas, liver, intestine as well as adipose and muscle tissue. Within this network, the pancreas represents a key player by secreting the blood sugar-lowering hormone insulin and its opponent glucagon. However, disturbances in the interplay of the hormones and peptides involved may lead to metabolic disorders such as type 2 diabetes mellitus (T2DM) whose prevalence, comorbidities and medical costs take on a dramatic scale. Therefore, it is of utmost importance to uncover and understand the mechanisms underlying the various interactions to improve existing anti-diabetic therapies and drugs on the one hand and to develop new therapeutic approaches on the other. This review summarizes the interplay of the pancreas with various other organs and tissues that maintain glucose homeostasis. Furthermore, anti-diabetic drugs and their impact on signaling pathways underlying the network will be discussed.
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Affiliation(s)
- Pia V Röder
- Metabolism in Human Diseases Unit, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- Metabolism in Human Diseases Unit, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore 138673, Singapore. E-mail: or
| | - Bingbing Wu
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, A*STAR, Singapore, Singapore
| | - Yixian Liu
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, A*STAR, Singapore, Singapore
| | - Weiping Han
- Metabolism in Human Diseases Unit, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, A*STAR, Singapore, Singapore
- Metabolism in Human Diseases Unit, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore 138673, Singapore. E-mail: or
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Han YE, Ryu SY, Park SH, Lee KH, Lee SH, Ho WK. Ca(2+) clearance by plasmalemmal NCLX, Li(+)-permeable Na(+)/Ca(2+) exchanger, is required for the sustained exocytosis in rat insulinoma INS-1 cells. Pflugers Arch 2015; 467:2461-72. [PMID: 26100674 DOI: 10.1007/s00424-015-1715-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 06/03/2015] [Accepted: 06/11/2015] [Indexed: 11/29/2022]
Abstract
Na(+)/Ca(2+) exchangers are key players for Ca(2+) clearance in pancreatic β-cells, but their molecular determinants and roles in insulin secretion are not fully understood. In the present study, we newly discovered that the Li(+)-permeable Na(+)/Ca(2+) exchangers (NCLX), which were known as mitochondrial Na(+)/Ca(2+) exchangers, contributed to the Na(+)-dependent Ca(2+) movement across the plasma membrane in rat INS-1 insulinoma cells. Na(+)/Ca(2+) exchange activity by NCLX was comparable to that by the Na(+)/Ca(2+) exchanger, NCX. We also confirmed the presence of NCLX proteins on the plasma membrane using immunocytochemistry and cell surface biotinylation experiments. We further investigated the role of NCLX on exocytosis function by measuring the capacitance increase in response to repetitive depolarization. Small interfering (si)RNA-mediated downregulation of NCLX did not affect the initial exocytosis, but significantly suppressed sustained exocytosis and recovery of exocytosis. XIP (NCX inhibitory peptide) or Na(+) replacement for inhibiting Na(+)-dependent Ca(2+) clearance also selectively suppressed sustained exocytosis. Consistent with the idea that sustained exocytosis requires ATP-dependent vesicle recruitment, mitochondrial function, assessed by mitochondrial membrane potential (ΔΨ), was impaired by siNCLX or XIP. However, depolarization-induced exocytosis was hardly affected by changes in intracellular Na(+) concentration, suggesting a negligible contribution of mitochondrial Na(+)/Ca(2+) exchanger. Taken together, our data indicate that Na(+)/Ca(2+) exchanger-mediated Ca(2+) clearance mediated by NCLX and NCX is crucial for optimizing mitochondrial function, which in turn contributes to vesicle recruitment for sustained exocytosis in pancreatic β-cells.
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Affiliation(s)
- Young-Eun Han
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Shin-Young Ryu
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Sun-Hyun Park
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Kyu-Hee Lee
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Suk-Ho Lee
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Won-Kyung Ho
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea.
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Boland BB, Alarcón C, Ali A, Rhodes CJ. Monomethylated-adenines potentiate glucose-induced insulin production and secretion via inhibition of phosphodiesterase activity in rat pancreatic islets. Islets 2015; 7:e1073435. [PMID: 26404841 PMCID: PMC4878263 DOI: 10.1080/19382014.2015.1073435] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Monomethyladenines have effects on DNA repair, G-protein-coupled receptor antagonism and autophagy. In islet ß-cells, 3-methyladenine (3-MA) has been implicated in DNA-repair and autophagy, but its mechanism of action is unclear. Here, the effect of monomethylated adenines was examined in rat islets. 3-MA, N6-methyladenine (N6-MA) and 9-methyladenine (9-MA), but not 1- or 7-monomethylated adenines, specifically potentiated glucose-induced insulin secretion (3-4 fold; p ≤ 0.05) and proinsulin biosynthesis (∼2-fold; p ≤ 0.05). Using 3-MA as a 'model' monomethyladenine, it was found that 3-MA augmented [cAMP]i accumulation (2-3 fold; p ≤ 0.05) in islets within 5 minutes. The 3-, N6- and 9-MA also enhanced glucose-induced phosphorylation of the cAMP/protein kinase-A (PKA) substrate cAMP-response element binding protein (CREB). Treatment of islets with pertussis or cholera toxin indicated 3-MA mediated elevation of [cAMP]i was not mediated via G-protein-coupled receptors. Also, 3-MA did not compete with 9-cyclopentyladenine (9-CPA) for adenylate cyclase inhibition, but did for the pan-inhibitor of phosphodiesterase (PDE), 3-isobutyl-1-methylxanthine (IBMX). Competitive inhibition experiments with PDE-isoform specific inhibitors suggested 3-MA to have a preference for PDE4 in islet ß-cells, but this was likely reflective of PDE4 being the most abundant PDE isoform in ß-cells. In vitro enzyme assays indicated that 3-, N6- and 9-MA were capable of inhibiting most PDE isoforms found in ß-cells. Thus, in addition to known inhibition of phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3'K)/m Target of Rapamycin (mTOR) signaling, 3-MA also acts as a pan-phosphodiesterase inhibitor in pancreatic ß-cells to elevate [cAMP]i and then potentiate glucose-induced insulin secretion and production in parallel.
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Affiliation(s)
- Brandon B Boland
- The Kovler Diabetes Center; Department of Medicine; Section on Endocrinology, Diabetes & Metabolism; The University of Chicago; Chicago, IL USA
| | - Cristina Alarcón
- The Kovler Diabetes Center; Department of Medicine; Section on Endocrinology, Diabetes & Metabolism; The University of Chicago; Chicago, IL USA
| | - Almas Ali
- The Kovler Diabetes Center; Department of Medicine; Section on Endocrinology, Diabetes & Metabolism; The University of Chicago; Chicago, IL USA
| | - Christopher J Rhodes
- The Kovler Diabetes Center; Department of Medicine; Section on Endocrinology, Diabetes & Metabolism; The University of Chicago; Chicago, IL USA
- Correspondence to: Christopher J Rhodes PhD;
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The L-type voltage-gated calcium channel modulates microglial pro-inflammatory activity. Mol Cell Neurosci 2014; 64:104-15. [PMID: 25497271 DOI: 10.1016/j.mcn.2014.12.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 11/06/2014] [Accepted: 12/11/2014] [Indexed: 02/02/2023] Open
Abstract
Under pathological conditions, microglia, the resident CNS immune cells, become reactive and release pro-inflammatory cytokines and neurotoxic factors. We investigated whether this phenotypic switch includes changes in the expression of the L-type voltage-gated calcium channel (VGCC) in a rat model of N-methyl-D-aspartate-induced hippocampal neurodegeneration. Double immunohistochemistry and confocal microscopy evidenced that activated microglia express the L-type VGCC. We then analyzed whether BV2 microglia express functional L-type VGCC, and investigated the latter's role in microglial cytokine release and phagocytic capacity. Activated BV2 microglia express the CaV1.2 and CaV1.3 subunits of the L-type VGCC determined by reverse transcription-polymerase chain reaction, Western blot and immunocytochemistry. Depolarization with KCl induced a Ca2+ entry facilitated by Bay k8644 and partially blocked with nifedipine, which also reduced TNF-α and NO release by 40%. However, no nifedipine effect on BV2 microglia viability or phagocytic capacity was observed. Our results suggest that in CNS inflammatory processes, the L-type VGCC plays a specific role in the control of microglial secretory activity.
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40
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Leiss V, Flockerzie K, Novakovic A, Rath M, Schönsiegel A, Birnbaumer L, Schürmann A, Harteneck C, Nürnberg B. Insulin secretion stimulated by L-arginine and its metabolite L-ornithine depends on Gα(i2). Am J Physiol Endocrinol Metab 2014; 307:E800-12. [PMID: 25205820 PMCID: PMC4216945 DOI: 10.1152/ajpendo.00337.2014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Bordetella pertussis toxin (PTx), also known as islet-activating protein, induces insulin secretion by ADP-ribosylation of inhibitory G proteins. PTx-induced insulin secretion may result either from inactivation of Gα(o) proteins or from combined inactivation of Gα(o), Gα(i1), Gα(i2), and Gα(i3) isoforms. However, the specific role of Gα(i2) in pancreatic β-cells still remains unknown. In global (Gα(i2)(-/-)) and β-cell-specific (Gα(i2)(βcko)) gene-targeted Gα(i2) mouse models, we studied glucose homeostasis and islet functions. Insulin secretion experiments and intracellular Ca²⁺ measurements were used to characterize Gα(i2) function in vitro. Gα(i2)(-/-) and Gα(i2)(βcko) mice showed an unexpected metabolic phenotype, i.e., significantly lower plasma insulin levels upon intraperitoneal glucose challenge in Gα(i2)(-/-) and Gα(i2)(βcko) mice, whereas plasma glucose concentrations were unchanged in Gα(i2)(-/-) but significantly increased in Gα(i2)(βcko) mice. These findings indicate a novel albeit unexpected role for Gα(i2) in the expression, turnover, and/or release of insulin from islets. Detection of insulin secretion in isolated islets did not show differences in response to high (16 mM) glucose concentrations between control and β-cell-specific Gα(i2)-deficient mice. In contrast, the two- to threefold increase in insulin secretion evoked by L-arginine or L-ornithine (in the presence of 16 mM glucose) was significantly reduced in islets lacking Gα(i2). In accord with a reduced level of insulin secretion, intracellular calcium concentrations induced by the agonistic amino acid L-arginine did not reach control levels in β-cells. The presented analysis of gene-targeted mice provides novel insights in the role of β-cell Gα(i2) showing that amino acid-induced insulin-release depends on Gα(i2).
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MESH Headings
- Animals
- Arginine/metabolism
- Blood Glucose/analysis
- Calcium Signaling
- Crosses, Genetic
- Down-Regulation
- Fluorescent Antibody Technique
- GTP-Binding Protein alpha Subunit, Gi2/agonists
- GTP-Binding Protein alpha Subunit, Gi2/genetics
- GTP-Binding Protein alpha Subunit, Gi2/metabolism
- GTP-Binding Protein alpha Subunits, Gi-Go/agonists
- GTP-Binding Protein alpha Subunits, Gi-Go/genetics
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- Hyperglycemia/blood
- Hyperglycemia/metabolism
- Hyperglycemia/prevention & control
- Hypoglycemia/blood
- Hypoglycemia/metabolism
- Hypoglycemia/prevention & control
- Insulin/blood
- Insulin/metabolism
- Insulin Secretion
- Islets of Langerhans/cytology
- Islets of Langerhans/metabolism
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Ornithine/blood
- Ornithine/metabolism
- Specific Pathogen-Free Organisms
- Tissue Culture Techniques
- Up-Regulation
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Affiliation(s)
- Veronika Leiss
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany
| | - Katarina Flockerzie
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany
| | - Ana Novakovic
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany
| | - Michaela Rath
- Department of Experimental Diabetology, German Institute of Human Nutrition, Potsdam-Rehbrücke, Nuthetal, Germany
| | - Annika Schönsiegel
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany
| | - Lutz Birnbaumer
- Laboratory of Neurobiology, National Institute of Environmental Health Sciences, National Institutes of Health/Department of Health and Human Services, Durham, North Carolina
| | - Annette Schürmann
- Department of Experimental Diabetology, German Institute of Human Nutrition, Potsdam-Rehbrücke, Nuthetal, Germany
| | - Christian Harteneck
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany
| | - Bernd Nürnberg
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany;
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41
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Zhang D, Leung PS. Potential roles of GPR120 and its agonists in the management of diabetes. DRUG DESIGN DEVELOPMENT AND THERAPY 2014; 8:1013-27. [PMID: 25114508 PMCID: PMC4122337 DOI: 10.2147/dddt.s53892] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Free fatty acids (FFAs) serve not only as nutrients that provide energy but also as extracellular signaling molecules that manipulate intracellular physiological events through FFA receptors (FFARs) such as FFAR4. FFAR4 is also known as G-protein coupled receptor 120 (GPR120). The main role of GPR120 is to elicit FFA regulation on metabolism homeostasis. GPR120 agonism correlates with prevention of the occurrence and development of metabolic disorders such as obesity and diabetes. GPR120 activation directly or indirectly inhibits inflammation, modulates hormone secretion from the gastrointestinal tract and pancreas, and regulates lipid and/or glucose metabolism in adipose, liver, and muscle tissues, which may help prevent obesity and diabetes. This review summarizes recent advances in physiological roles of GPR120 in preventing insulin resistance and protecting pancreatic islet function, and examines how resident GPR120 in the pancreas may be involved in modulating pancreatic islet function.
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Affiliation(s)
- Dan Zhang
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
| | - Po Sing Leung
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
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Abstract
The oversupply of calories and sedentary lifestyle has resulted in a rapid increase of diabetes prevalence worldwide. During the past two decades, lines of evidence suggest that mitochondrial dysfunction plays a key role in the pathophysiology of diabetes. Mitochondria are vital to most of the eukaryotic cells as they provide energy in the form of adenosine triphosphate by oxidative phosphorylation. In addition, mitochondrial function is an integral part of glucose-stimulated insulin secretion in pancreatic β-cells. In the present article, we will briefly review the major functions of mitochondria in regard to energy metabolism, and discuss the genetic and environmental factors causing mitochondrial dysfunction in diabetes. In addition, the pathophysiological role of mitochondrial dysfunction in insulin resistance and β-cell dysfunction are discussed. We argue that mitochondrial dysfunction could be the central defect causing the abnormal glucose metabolism in the diabetic state. A deeper understanding of the role of mitochondria in diabetes will provide us with novel insights in the pathophysiology of diabetes. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2010.00047.x, 2010).
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Affiliation(s)
| | - Kyong Soo Park
- Departments of Internal Medicine ; Molecular Medicine and Biopharmaceutical Sciences, Seoul National University College of Medicine
| | - Ki-Up Lee
- Department of Internal Medicine, University of Ulsan College of Medicine
| | - Hong Kyu Lee
- Department of Internal Medicine, Eulji University College of Medicine, Seoul, Korea
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43
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Brault M, Ray J, Gomez YH, Mantzoros CS, Daskalopoulou SS. Statin treatment and new-onset diabetes: a review of proposed mechanisms. Metabolism 2014; 63:735-45. [PMID: 24641882 DOI: 10.1016/j.metabol.2014.02.014] [Citation(s) in RCA: 158] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 02/09/2014] [Accepted: 02/18/2014] [Indexed: 12/13/2022]
Abstract
New-onset diabetes has been observed in clinical trials and meta-analyses involving statin therapy. To explain this association, three major mechanisms have been proposed and discussed in the literature. First, certain statins affect insulin secretion through direct, indirect or combined effects on calcium channels in pancreatic β-cells. Second, reduced translocation of glucose transporter 4 in response to treatment results in hyperglycemia and hyperinsulinemia. Third, statin therapy decreases other important downstream products, such as coenzyme Q10, farnesyl pyrophosphate, geranylgeranyl pyrophosphate, and dolichol; their depletion leads to reduced intracellular signaling. Other possible mechanisms implicated in the effect of statins on new-onset diabetes are: statin interference with intracellular insulin signal transduction pathways via inhibition of necessary phosphorylation events and reduction of small GTPase action; inhibition of adipocyte differentiation leading to decreased peroxisome proliferator activated receptor gamma and CCAAT/enhancer-binding protein which are important pathways for glucose homeostasis; decreased leptin causing inhibition of β-cells proliferation and insulin secretion; and diminished adiponectin levels. Given that the magnitude of the risk of new-onset diabetes following statin use remains to be fully clarified and the well-established beneficial effect of statins in reducing cardiovascular risk, statins remain the first-choice treatment for prevention of CVD. Elucidation of the mechanisms underlying the development of diabetes in association with statin use may help identify novel preventative or therapeutic approaches to this problem and/or help design a new generation statin without such side-effects.
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Affiliation(s)
- Marilyne Brault
- Department of Medicine, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
| | - Jessica Ray
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
| | - Yessica-Haydee Gomez
- Division of Internal Medicine, Department of Medicine, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
| | - Christos S Mantzoros
- Endocrinology Section, VA Boston Healthcare System and Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Stella S Daskalopoulou
- Division of Internal Medicine, Department of Medicine, Faculty of Medicine, McGill University, Montreal, Quebec, Canada; Division of Experimental Medicine, Department of Medicine, Faculty of Medicine, McGill University, Montreal, Quebec, Canada.
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Tanaka T, Nagashima K, Inagaki N, Kioka H, Takashima S, Fukuoka H, Noji H, Kakizuka A, Imamura H. Glucose-stimulated single pancreatic islets sustain increased cytosolic ATP levels during initial Ca2+ influx and subsequent Ca2+ oscillations. J Biol Chem 2013; 289:2205-16. [PMID: 24302735 DOI: 10.1074/jbc.m113.499111] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In pancreatic islets, insulin secretion occurs via synchronous elevation of Ca(2+) levels throughout the islets during high glucose conditions. This Ca(2+) elevation has two phases: a quick increase, observed after the glucose stimulus, followed by prolonged oscillations. In these processes, the elevation of intracellular ATP levels generated from glucose is assumed to inhibit ATP-sensitive K(+) channels, leading to the depolarization of membranes, which in turn induces Ca(2+) elevation in the islets. However, little is known about the dynamics of intracellular ATP levels and their correlation with Ca(2+) levels in the islets in response to changing glucose levels. In this study, a genetically encoded fluorescent biosensor for ATP and a fluorescent Ca(2+) dye were employed to simultaneously monitor the dynamics of intracellular ATP and Ca(2+) levels, respectively, inside single isolated islets. We observed rapid increases in cytosolic and mitochondrial ATP levels after stimulation with glucose, as well as with methyl pyruvate or leucine/glutamine. High ATP levels were sustained as long as high glucose levels persisted. Inhibition of ATP production suppressed the initial Ca(2+) increase, suggesting that enhanced energy metabolism triggers the initial phase of Ca(2+) influx. On the other hand, cytosolic ATP levels did not fluctuate significantly with the Ca(2+) level in the subsequent oscillation phases. Importantly, Ca(2+) oscillations stopped immediately before ATP levels decreased significantly. These results might explain how food or glucose intake evokes insulin secretion and how the resulting decrease in plasma glucose levels leads to cessation of secretion.
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45
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Karbalaei N, Ghasemi A, Hedayati M, Godini A, Zahediasl S. The possible mechanisms by which maternal hypothyroidism impairs insulin secretion in adult male offspring in rats. Exp Physiol 2013; 99:701-14. [DOI: 10.1113/expphysiol.2013.073825] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Narges Karbalaei
- Department of Physiology; Faculty of Medicine; Shiraz University of Medical Sciences; Shiraz Iran
| | | | - Mehdi Hedayati
- Cellular & Molecular Endocrine Research Center; Research Institute for Endocrine Sciences; Shahid Beheshti University of Medical Sciences; Tehran Iran
| | - Aliashraf Godini
- Department of Physiology; Faculty of Medicine; Shahid Beheshti University of Medical Sciences; Tehran Iran
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Down-regulation of voltage-gated Ca2+ channels in Ca2+ store-depleted rat insulinoma RINm5F cells. Biomedicine (Taipei) 2013. [DOI: 10.1016/j.biomed.2012.11.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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Zhao YF, Wang L, Zha D, Qiao L, Lu L, Yu J, Qu P, Sun Q, Qiu J, Chen C. GW9508 inhibits insulin secretion by activating ATP-sensitive potassium channels in rat pancreatic β-cells. J Mol Endocrinol 2013; 51:69-77. [PMID: 23628491 DOI: 10.1530/jme-13-0019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
GW9508 is an agonist of G protein-coupled receptor 40 (GPR40) that is expressed in pancreatic β-cells and is reported to regulate insulin secretion. However, the effects of GW9508 on pancreatic β-cells in primary culture have not been well investigated. This study measured the acute effects of GW9508 on insulin secretion from rat pancreatic islets in primary culture, and the insulin secretion-related events such as the changes in membrane potential, ATP-sensitive potassium currents (KATP currents), and intracellular Ca(2+) concentrations ([Ca(2+)]i) of rat islet β-cells were also recorded. GW9508 (10-40 μM) did not influence basal insulin levels at 2 mM glucose, but it (above 20 μM) significantly inhibited 5 and 15 mM glucose-stimulated insulin secretion (GSIS). GW9508 did not inhibit insulin secretion stimulated by tolbutamide, the closer of KATP channels. GW9508 activated KATP channels and blocked the membrane depolarization and the increase in [Ca(2+)]i that were stimulated by glucose. GW9508 itself stimulated a transient increase in [Ca(2+)]i, which was fully blocked by depletion of intracellular Ca(2+) stores with thapsigargin or by inhibition of phospholipase C (PLC) activity with U73122. GW9508-induced activation of KATP channels was only partly inhibited by U73122 treatment. In conclusion, although it stimulates a transient release of Ca(2+) from intracellular Ca(2+) stores via activation of PLC, GW9508 inhibits GSIS by activating KATP channels probably in a distal step to GPR40 activation in rat β-cells.
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Affiliation(s)
- Yu-Feng Zhao
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
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Guo-Parke H, McCluskey JT, Kelly C, Hamid M, McClenaghan NH, Flatt PR. Configuration of electrofusion-derived human insulin-secreting cell line as pseudoislets enhances functionality and therapeutic utility. J Endocrinol 2012; 214:257-65. [PMID: 22685334 DOI: 10.1530/joe-12-0188] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Formation of pseudoislets from rodent cell lines has provided a particularly useful model to study homotypic islet cell interactions and insulin secretion. This study aimed to extend this research to generate and characterize, for the first time, functional human pseudoislets comprising the recently described electrofusion-derived insulin-secreting 1.1B4 human β-cell line. Structural pseudoislets formed readily over 3-7 days in culture using ultra-low-attachment plastic, attaining a static size of 100-200 μm in diameter, corresponding to ~6000 β cells. This was achieved by decreases in cell proliferation and integrity as assessed by BrdU ELISA, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide, and lactate dehydrogenase assays. Insulin content was comparable between monolayers and pseudoislets. However, pseudoislet formation enhanced insulin secretion by 1·7- to 12·5-fold in response to acute stimulation with glucose, amino acids, incretin hormones, or drugs compared with equivalent cell monolayers. Western blot and RT-PCR showed expression of key genes involved in cell communication and the stimulus-secretion pathway. Expression of E-Cadherin and connexin 36 and 43 was greatly enhanced in pseudoislets with no appreciable connexin 43 protein expression in monolayers. Comparable levels of insulin, glucokinase, and GLUT1 were found in both cell populations. The improved secretory function of human 1.1B4 cell pseudoislets over monolayers results from improved cellular interactions mediated through gap junction communication. Pseudoislets comprising engineered electrofusion-derived human β cells provide an attractive model for islet research and drug testing as well as offering novel therapeutic application through transplantation.
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Affiliation(s)
- Hong Guo-Parke
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
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Javorsky M, Klimcakova L, Schroner Z, Zidzik J, Babjakova E, Fabianova M, Kozarova M, Tkacova R, Salagovic J, Tkac I. KCNJ11 gene E23K variant and therapeutic response to sulfonylureas. Eur J Intern Med 2012; 23:245-9. [PMID: 22385882 DOI: 10.1016/j.ejim.2011.10.018] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 09/26/2011] [Accepted: 10/22/2011] [Indexed: 12/25/2022]
Abstract
AIMS Potassium inwardly rectifier 6.2 subunit (Kir6.2) of the ATP-sensitive potassium (K(ATP)) channel encoded by KCNJ11 gene is a therapeutical target for sulfonylureas. KCNJ11 E23K polymorphism was associated with type 2 diabetes in genetic association studies. The aim of the present pharmacogenetic study was to examine the effect of sulfonylurea treatment on glycemic control in relationship to KCNJ11 E23K variant. PATIENTS AND METHODS One hundred and one patients with type 2 diabetes who failed to achieve HbA1c<7% on previous metformin monotherapy were included to the study. Sulfonylurea drug was given in addition to metformin. The main outcome of the study was reduction in HbA1c level (ΔHbA1c) after 6-month sulfonylurea therapy. KCNJ11 genotypes were determined by real-time PCR with melting curve analysis. RESULTS After 6-month treatment, KCNJ11 K-allele carriers had higher decrease in HbA1c compared with EE homozygotes in the dominant genetic model (1.04±0.10 vs. 0.79±0.12%, p=0.036). In the log-additive model, greater mean reduction in HbA1c by 0.16% (95% CI 0.01-0.32, p=0.038) per each K-allele was observed. The relationship of treatment response with KCNJ11 genotype was also significant in the biggest subgroup of patients treated with gliclazide (n=55). CONCLUSIONS Carriers of the KCNJ11 K-allele have better therapeutic response to gliclazide. This observation might help to identify patients who will have the highest benefit from sulfonylurea treatment.
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Affiliation(s)
- Martin Javorsky
- Department of Internal Medicine 4, Faculty of Medicine, Safarik University, Kosice, Slovakia
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Goehring I, Gerencser AA, Schmidt S, Brand MD, Mulder H, Nicholls DG. Plasma membrane potential oscillations in insulin secreting Ins-1 832/13 cells do not require glycolysis and are not initiated by fluctuations in mitochondrial bioenergetics. J Biol Chem 2012; 287:15706-17. [PMID: 22418435 DOI: 10.1074/jbc.m111.314567] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Oscillations in plasma membrane potential play a central role in glucose-induced insulin secretion from pancreatic β-cells and related insulinoma cell lines. We have employed a novel fluorescent plasma membrane potential (Δψ(p)) indicator in combination with indicators of cytoplasmic free Ca(2+) ([Ca(2+)](c)), mitochondrial membrane potential (Δψ(m)), matrix ATP concentration, and NAD(P)H fluorescence to investigate the role of mitochondria in the generation of plasma membrane potential oscillations in clonal INS-1 832/13 β-cells. Elevated glucose caused oscillations in plasma membrane potential and cytoplasmic free Ca(2+) concentration over the same concentration range required for insulin release, although considerable cell-to-cell heterogeneity was observed. Exogenous pyruvate was as effective as glucose in inducing oscillations, both in the presence and absence of 2.8 mM glucose. Increased glucose and pyruvate each produced a concentration-dependent mitochondrial hyperpolarization. The causal relationships between pairs of parameters (Δψ(p) and [Ca(2+)](c), Δψ(p) and NAD(P)H, matrix ATP and [Ca(2+)](c), and Δψ(m) and [Ca(2+)](c)) were investigated at single cell level. It is concluded that, in these β-cells, depolarizing oscillations in Δψ(p) are not initiated by mitochondrial bioenergetic changes. Instead, regardless of substrate, it appears that the mitochondria may simply be required to exceed a critical bioenergetic threshold to allow release of insulin. Once this threshold is exceeded, an autonomous Δψ(p) oscillatory mechanism is initiated.
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