1
|
Samario-Román J, Velasco M, Larqué C, Cárdenas-Vázquez R, Ortiz-Huidobro RI, Hiriart M. NGF effects promote the maturation of rat pancreatic beta cells by regulating GLUT2 levels and distribution, and glucokinase activity. PLoS One 2024; 19:e0303934. [PMID: 38875221 PMCID: PMC11178159 DOI: 10.1371/journal.pone.0303934] [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: 01/29/2024] [Accepted: 05/02/2024] [Indexed: 06/16/2024] Open
Abstract
The nerve growth factor (NGF) participates in cell survival and glucose-stimulated insulin secretion (GSIS) processes in rat adult beta cells. GSIS is a complex process in which metabolic events and ionic channel activity are finely coupled. GLUT2 and glucokinase (GK) play central roles in GSIS by regulating the rate of the glycolytic pathway. The biphasic release of insulin upon glucose stimulation characterizes mature adult beta cells. On the other hand, beta cells obtained from neonatal, suckling, and weaning rats are considered immature because they secrete low levels of insulin and do not increase insulin secretion in response to high glucose. The weaning of rats (at postnatal day 20 in laboratory conditions) involves a dietary transition from maternal milk to standard chow. It is characterized by increased basal plasma glucose levels and insulin levels, which we consider physiological insulin resistance. On the other hand, we have observed that incubating rat beta cells with NGF increases GSIS by increasing calcium currents in neonatal cells. In this work, we studied the effects of NGF on the regulation of cellular distribution and activity of GLUT2 and GK to explore its potential role in the maturation of GSIS in beta cells from P20 rats. Pancreatic islet cells from both adult and P20 rats were isolated and incubated with 5.6 mM or 15.6 mM glucose with and without NGF for 4 hours. Specific immunofluorescence assays were conducted following the incubation period to detect insulin and GLUT2. Additionally, we measured glucose uptake, glucokinase activity, and insulin secretion assays at 5.6 mM or 15.6 mM glucose concentrations. We observed an age-dependent variation in the distribution of GLUT2 in pancreatic beta cells and found that glucose plays a regulatory role in GLUT2 distribution independently of age. Moreover, NGF increases GLUT2 abundance, glucose uptake, and GSIS in P20 beta cells and GK activity in adult beta cells. Our results suggest that besides increasing calcium currents, NGF regulates metabolic components of the GSIS, thereby contributing to the maturation process of pancreatic beta cells.
Collapse
Affiliation(s)
- Jazmín Samario-Román
- Neuroscience Division, Cognitive Neuroscience Department, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Myrian Velasco
- Neuroscience Division, Cognitive Neuroscience Department, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Carlos Larqué
- Department of Embryology and Genetics, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - René Cárdenas-Vázquez
- Laboratory of Experimental Animal Biology, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Rosa Isela Ortiz-Huidobro
- Department of Genomic Medicine and Environmental Toxicology, Instituto de Investigaciones Biomédicas, Ciudad de México, Mexico
| | - Marcia Hiriart
- Neuroscience Division, Cognitive Neuroscience Department, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| |
Collapse
|
2
|
Zhang X, Zhang D, Huo L, Zhou X, Zhang J, Li M, Su D, Sun P, Chen F, Liang X. Upregulation of α-ENaC induces pancreatic β-cell dysfunction, ER stress, and SIRT2 degradation. J Biomed Res 2024; 38:241-255. [PMID: 38769731 PMCID: PMC11144933 DOI: 10.7555/jbr.37.20230128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 11/05/2023] [Accepted: 11/11/2023] [Indexed: 05/22/2024] Open
Abstract
Islet beta cells (β-cells) produce insulin in response to high blood glucose levels, which is essential for preserving glucose homeostasis. Voltage-gated ion channels in β-cells, including Na +, K +, and Ca 2+ channels, aid in the release of insulin. The epithelial sodium channel alpha subunit (α-ENaC), a voltage-independent sodium ion channel, is also expressed in human pancreatic endocrine cells. However, there is no reported study on the function of ENaC in the β-cells. In the current study, we found that α-ENaC was expressed in human pancreatic glandule and pancreatic islet β-cells. In the pancreas of db/db mice and high-fat diet-induced mice, and in mouse islet β-cells (MIN6 cells) treated with palmitate, α-ENaC expression was increased. When α-ENaC was overexpressed in MIN6 cells, insulin content and glucose-induced insulin secretion were significantly reduced. On the other hand, palmitate injured islet β-cells and suppressed insulin synthesis and secretion, but increased α-ENaC expression in MIN6 cells. However, α-ENaC knockout ( Scnn1a -/-) in MIN6 cells attenuated β-cell disorder induced by palmitate. Furthermore, α-ENaC regulated the ubiquitylation and degradation of sirtuin 2 in β-cells. α-ENaC also modulated β-cell function in correlation with the inositol-requiring enzyme 1 alpha/X-box binding protein 1 (IRE1α/XBP1) and protein kinase RNA-like endoplasmic reticulum kinase/C/EBP homologous protein (PERK/CHOP) endoplasmic reticulum stress pathways. These results suggest that α-ENaC may play a novel role in insulin synthesis and secretion in the β-cells, and the upregulation of α-ENaC promotes islet β-cell dysfunction. In conclusion, α-ENaC may be a key regulator involved in islet β-cell damage and a potential therapeutic target for type 2 diabetes mellitus.
Collapse
Affiliation(s)
- Xue Zhang
- Department of Pathophysiology, Nanjing Medical University, Nanjing, Jiangsu 211166, China
- Department of Pathology, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, Jiangsu 210009, China
| | - Dan Zhang
- Department of Pathophysiology, Nanjing Medical University, Nanjing, Jiangsu 211166, China
- Department of Pathology, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, Jiangsu 210009, China
| | - Lei Huo
- Department of Pathophysiology, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Xin Zhou
- Department of Pathophysiology, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Jia Zhang
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Min Li
- Department of Pathology, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Dongming Su
- Department of Pathology, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Peng Sun
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Fang Chen
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Xiubin Liang
- Department of Pathophysiology, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| |
Collapse
|
3
|
Quiroz-Acosta T, Bermeo K, Arenas I, Garcia DE. G-protein tonic inhibition of calcium channels in pancreatic β-cells. Am J Physiol Cell Physiol 2023; 325:C592-C598. [PMID: 37458440 DOI: 10.1152/ajpcell.00447.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 06/30/2023] [Accepted: 07/03/2023] [Indexed: 08/17/2023]
Abstract
Voltage-gated calcium channels (CaV) conduct Ca2+ influx promoting neurotransmitters and hormone release. CaV are finely regulated by voltage-dependent and independent pathways either by G-protein-coupled receptors (GPCRs) or intramembrane lipids, respectively, in neurons and glands. Interestingly, pancreatic β-cells are abundantly innervated by both sympathetic and parasympathetic neurons, while a variety of high-voltage activated (HVA) Ca2+ channels are present in these cells. Thus, autonomic system seems to exert a tonic inhibition on HVA Ca2+ channels throughout GPCRs, constitutively preventing hormone secretion. Therefore, this work aimed to investigate noradrenergic and cholinergic inhibition of HVA Ca2+ channels in pancreatic β-cells. Experiments were conducted in pancreatic β-cells of rat by using patch-clamping methods, immunocytochemistry, pharmacological probes, and biochemical reagents. A voltage-clamp protocol with a strong depolarizing prepulse was used to unmask tonic inhibition. Herein, we consistently find a basal tonic inhibition of HVA Ca2+ channels according to a GPCRs regulation. Facilitation ratio is enhanced by noradrenaline (NA) according to a voltage-dependent regulation and a membrane-delimited mechanism, while no facilitation changes are observed with carbachol or phosphatidylinositol 4,5-bisphosphate (PIP2). Furthermore, carbachol or intramembrane lipids, such as PIP2, do not change facilitation ratio according to a voltage-independent regulation. Together, HVA Ca2+ channels of pancreatic β-cells are constitutively inhibited by GPCRs, suggesting a natural brake preventing cells from exhaustive insulin secretion.NEW & NOTEWORTHY Our results support the hypothesis that GPCRs tonically inhibit HVA Ca2+ channels in pancreatic β-cells. A voltage-clamp protocol with a strong depolarizing prepulse was used to unmask voltage-dependent inhibition of Ca2+ channels. The novelty of these results strengthens the critical role of Gβγ's in Ca2+ channel regulation, highlighting kinetic slowing and increased facilitation ratio. Together, HVA Ca2+ channels of pancreatic β-cells are constitutively inhibited by GPCRs underlying fine-tuning modulation of insulin secretion.
Collapse
Affiliation(s)
- Tayde Quiroz-Acosta
- Department of Physiology, Faculty of Medicine, Universidad Nacional Autónoma de México, UNAM, Ciudad de México, Mexico
| | - Karina Bermeo
- Department of Physiology, Faculty of Medicine, Universidad Nacional Autónoma de México, UNAM, Ciudad de México, Mexico
| | - Isabel Arenas
- Department of Physiology, Faculty of Medicine, Universidad Nacional Autónoma de México, UNAM, Ciudad de México, Mexico
| | - David E Garcia
- Department of Physiology, Faculty of Medicine, Universidad Nacional Autónoma de México, UNAM, Ciudad de México, Mexico
| |
Collapse
|
4
|
Kacar AK, Aylar D, Kazdal F, Bahadori F. BuOH fraction of Salix Babylonica L. extract increases pancreatic beta-cell tumor death at lower doses without harming their function. Toxicol In Vitro 2023; 90:105609. [PMID: 37164183 DOI: 10.1016/j.tiv.2023.105609] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 04/30/2023] [Accepted: 05/02/2023] [Indexed: 05/12/2023]
Abstract
Salix babylonica L. is a species of the willow tree. Insulinoma is a tumor originating from pancreatic beta cells. This study aims to research the effect of different fractions of Salix babylonica L. leaf extract on INS-1 cells for treating pancreatic tumors. Cell death occurred at lower doses in the EtOAc fraction. The cells are functional in the BuOH fraction but not in EtOAc and H2O fractions. The EtOAc fraction has a higher percentage of necrosis and ROS. INS1, INS2, and AKT gene expressions in the H2O fraction, GLUT2, IR, HSP70 gene expressions, and WNT4 protein levels increased in the BuOH fraction. HSP90 gene expression, Beta-actin, GAPDH, insulin, HSP70, HSP90, HSF1, Beta-Catenin, and WNT7A protein levels were decreased, while IR immunolabelling intensity increased in both fractions. Ca+2, K+, Na+, and CA-19-9 in the cell, Ca+2 and K+ in secretion increased. The secondary metabolites in the EtOAc fraction cause more damage in INS-1 cells. Since the water fraction also causes the cells to die in high doses, cell function is damaged. The secondary metabolites in the BuOH fraction kill INS-1 cells with less damage. This makes the BuOH fraction of Salix babylonica L. more valuable.
Collapse
Affiliation(s)
- Ayse Karatug Kacar
- Istanbul University, Faculty of Science, Department of Biology, Istanbul, Turkey.
| | - Dilara Aylar
- Center for Immunology and Inflammation, Feinstein Institutes for Medical Research, Manhasset, NY, United States
| | - Fatma Kazdal
- Bezmialem Vakif University, Institute of Health Sciences, Department of Medicinal Biochemistry, Istanbul, Turkey
| | - Fatemeh Bahadori
- Istanbul University-Cerrahpasa, Faculty of Pharmacy, Department of Analytical Chemistry, Istanbul, Turkey
| |
Collapse
|
5
|
Rached G, Saliba Y, Maddah D, Hajal J, Smayra V, Bakhos J, Groschner K, Birnbaumer L, Fares N. TRPC3 Regulates Islet Beta-Cell Insulin Secretion. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2204846. [PMID: 36642838 PMCID: PMC9951314 DOI: 10.1002/advs.202204846] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 11/18/2022] [Indexed: 06/17/2023]
Abstract
Insulin release is tightly controlled by glucose-stimulated calcium (GSCa) through hitherto equivocal pathways. This study investigates TRPC3, a non-selective cation channel, as a critical regulator of insulin secretion and glucose control. TRPC3's involvement in glucose-stimulated insulin secretion (GSIS) is studied in human and animal islets. TRPC3-dependent in vivo insulin secretion is investigated using pharmacological tools and Trpc3-/- mice. TRPC3's involvement in islet glucose uptake and GSCa is explored using fluorescent glucose analogue 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-D-glucose and calcium imaging. TRPC3 modulation by a small-molecule activator, GSK1702934A, is evaluated in type 2 diabetic mice. TRPC3 is functionally expressed in human and mouse islet beta cells. TRPC3-controlled insulin secretion is KATP -independent and primarily mediated by diacylglycerol channel regulation of the cytosolic calcium oscillations following glucose stimulation. Conversely, glucose uptake in islets is independent of TRPC3. TRPC3 pharmacologic inhibition and knockout in mice lead to defective insulin secretion and glucose intolerance. Subsequently, TRPC3 activation through targeted small-molecule enhances insulin secretion and alleviates diabetes hallmarks in animals. This study imputes a function for TRPC3 at the onset of GSIS. These insights strengthen one's knowledge of insulin secretion physiology and set forth the TRPC3 channel as an appealing candidate for drug development in the treatment of diabetes.
Collapse
Affiliation(s)
- Gaëlle Rached
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Youakim Saliba
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Dina Maddah
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Joelle Hajal
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Viviane Smayra
- Faculty of MedicineSaint Joseph UniversitySaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Jules‐Joel Bakhos
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Klaus Groschner
- Gottfried‐Schatz‐Research‐Centre‐BiophysicsMedical University of GrazGraz8010Austria
| | - Lutz Birnbaumer
- School of Medical SciencesInstitute of Biomedical Research (BIOMED)Catholic University of ArgentinaBuenos AiresC1107AAZArgentina
- Signal Transduction LaboratoryNational Institute of Environmental Health SciencesResearch Triangle ParkDurhamNCC1107AAZUSA
| | - Nassim Fares
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| |
Collapse
|
6
|
Early Effects of Metabolic Syndrome on ATP-Sensitive Potassium Channels from Rat Pancreatic Beta Cells. Metabolites 2022; 12:metabo12040365. [PMID: 35448552 PMCID: PMC9030496 DOI: 10.3390/metabo12040365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Revised: 04/12/2022] [Accepted: 04/16/2022] [Indexed: 11/16/2022] Open
Abstract
Metabolic syndrome (MS) is a cluster of metabolic signs that increases the risk of developing type 2 two diabetes mellitus and cardiovascular diseases. MS leads to pancreatic beta cell exhaustion and decreased insulin secretion through unknown mechanisms in a time-dependent manner. ATP-sensitive potassium channels (KATP channels), common targets of anti-diabetic drugs, participate in the glucose-stimulated insulin secretion, coupling the metabolic status and electrical activity of pancreatic beta cells. We investigated the early effects of MS on the conductance, ATP and glybenclamide sensitivity of the KATP channels. We used Wistar rats fed with a high-sucrose diet (HSD) for 8 weeks as a MS model. In excised membrane patches, control and HSD channels showed similar unitary conductance and ATP sensitivity pancreatic beta cells in their KATP channels. In contrast, MS produced variability in the sensitivity to glybenclamide of KATP channels. We observed two subpopulations of pancreatic beta cells, one with similar (Gly1) and one with increased (Gly2) glybenclamide sensitivity compared to the control group. This study shows that the early effects of MS produced by consuming high-sugar beverages can affect the pharmacological properties of KATP channels to one of the drugs used for diabetes treatment.
Collapse
|
7
|
Singh A, Kukreti R, Saso L, Kukreti S. Mechanistic Insight into Oxidative Stress-Triggered Signaling Pathways and Type 2 Diabetes. Molecules 2022; 27:950. [PMID: 35164215 PMCID: PMC8840622 DOI: 10.3390/molecules27030950] [Citation(s) in RCA: 103] [Impact Index Per Article: 51.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/20/2022] [Accepted: 01/26/2022] [Indexed: 02/07/2023] Open
Abstract
Oxidative stress (OS) is a metabolic dysfunction mediated by the imbalance between the biochemical processes leading to elevated production of reactive oxygen species (ROS) and the antioxidant defense system of the body. It has a ubiquitous role in the development of numerous noncommunicable maladies including cardiovascular diseases, cancers, neurodegenerative diseases, aging and respiratory diseases. Diseases associated with metabolic dysfunction may be influenced by changes in the redox balance. Lately, there has been increasing awareness and evidence that diabetes mellitus (DM), particularly type 2 diabetes, is significantly modulated by oxidative stress. DM is a state of impaired metabolism characterized by hyperglycemia, resulting from defects in insulin secretion or action, or both. ROS such as hydrogen peroxide and the superoxide anion introduce chemical changes virtually in all cellular components, causing deleterious effects on the islets of β-cells, in turn affecting insulin production. Under hyperglycemic conditions, various signaling pathways such as nuclear factor-κβ (NF-κβ) and protein kinase C (PKC) are also activated by ROS. All of these can be linked to a hindrance in insulin signaling pathways, leading to insulin resistance. Hyperglycemia-induced oxidative stress plays a substantial role in complications including diabetic nephropathy. DM patients are more prone to microvascular as well as atherosclerotic macrovascular diseases. This systemic disease affects most countries around the world, owing to population explosion, aging, urbanization, obesity, lifestyle, etc. However, some modulators, with their free radical scavenging properties, can play a prospective role in overcoming the debilitating effects of OS. This review is a modest approach to summarizing the basics and interlinkages of oxidative stress, its modulators and diabetes mellitus. It may add to the understanding of and insight into the pathophysiology of diabetes and the crucial role of antioxidants to weaken the complications and morbidity resulting from this chronic disease.
Collapse
Affiliation(s)
- Anju Singh
- Nucleic Acids Research Lab, Department of Chemistry, University of Delhi (North Campus), Delhi 110007, India;
- Department of Chemistry, Ramjas College, University of Delhi, Delhi 110007, India
| | - Ritushree Kukreti
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology (IGIB), Mall Road, Delhi 110007, India;
| | - Luciano Saso
- Department of Physiology and Pharmacology “Vittorio Erspamer”, Sapienza University of Rome, P. le Aldo Moro 5, 00185 Rome, Italy;
| | - Shrikant Kukreti
- Nucleic Acids Research Lab, Department of Chemistry, University of Delhi (North Campus), Delhi 110007, India;
| |
Collapse
|
8
|
Pánico P, Velasco M, Salazar AM, Picones A, Ortiz-Huidobro RI, Guerrero-Palomo G, Salgado-Bernabé ME, Ostrosky-Wegman P, Hiriart M. Is Arsenic Exposure a Risk Factor for Metabolic Syndrome? A Review of the Potential Mechanisms. Front Endocrinol (Lausanne) 2022; 13:878280. [PMID: 35651975 PMCID: PMC9150370 DOI: 10.3389/fendo.2022.878280] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 04/11/2022] [Indexed: 12/14/2022] Open
Abstract
Exposure to arsenic in drinking water is a worldwide health problem. This pollutant is associated with increased risk of developing chronic diseases, including metabolic diseases. Metabolic syndrome (MS) is a complex pathology that results from the interaction between environmental and genetic factors. This condition increases the risk of developing type 2 diabetes, cardiovascular diseases, and cancer. The MS includes at least three of the following signs, central obesity, impaired fasting glucose, insulin resistance, dyslipidemias, and hypertension. Here, we summarize the existing evidence of the multiple mechanisms triggered by arsenic to developing the cardinal signs of MS, showing that this pollutant could contribute to the multifactorial origin of this pathology.
Collapse
Affiliation(s)
- Pablo Pánico
- Department of Cognitive Neurosciences, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Myrian Velasco
- Department of Cognitive Neurosciences, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Ana María Salazar
- Department of Genomic Medicine and Environmental Toxicology. Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Arturo Picones
- Department of Cognitive Neurosciences, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Rosa Isela Ortiz-Huidobro
- Department of Cognitive Neurosciences, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Gabriela Guerrero-Palomo
- Department of Genomic Medicine and Environmental Toxicology. Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Manuel Eduardo Salgado-Bernabé
- Department of Cognitive Neurosciences, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Patricia Ostrosky-Wegman
- Department of Genomic Medicine and Environmental Toxicology. Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Marcia Hiriart
- Department of Cognitive Neurosciences, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
- *Correspondence: Marcia Hiriart,
| |
Collapse
|
9
|
Ashrafuzzaman M. Artificial Intelligence, Machine Learning and Deep Learning in Ion Channel Bioinformatics. MEMBRANES 2021; 11:membranes11090672. [PMID: 34564489 PMCID: PMC8467682 DOI: 10.3390/membranes11090672] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 08/20/2021] [Accepted: 08/30/2021] [Indexed: 11/28/2022]
Abstract
Ion channels are linked to important cellular processes. For more than half a century, we have been learning various structural and functional aspects of ion channels using biological, physiological, biochemical, and biophysical principles and techniques. In recent days, bioinformaticians and biophysicists having the necessary expertise and interests in computer science techniques including versatile algorithms have started covering a multitude of physiological aspects including especially evolution, mutations, and genomics of functional channels and channel subunits. In these focused research areas, the use of artificial intelligence (AI), machine learning (ML), and deep learning (DL) algorithms and associated models have been found very popular. With the help of available articles and information, this review provide an introduction to this novel research trend. Ion channel understanding is usually made considering the structural and functional perspectives, gating mechanisms, transport properties, channel protein mutations, etc. Focused research on ion channels and related findings over many decades accumulated huge data which may be utilized in a specialized scientific manner to fast conclude pinpointed aspects of channels. AI, ML, and DL techniques and models may appear as helping tools. This review aims at explaining the ways we may use the bioinformatics techniques and thus draw a few lines across the avenue to let the ion channel features appear clearer.
Collapse
Affiliation(s)
- Md Ashrafuzzaman
- Department of Biochemistry, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
| |
Collapse
|
10
|
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; 9:936. [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] [Grants] [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.
Collapse
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.)
| |
Collapse
|
11
|
Salgado M, García-Robles MÁ, Sáez JC. Purinergic signaling in tanycytes and its contribution to nutritional sensing. Purinergic Signal 2021; 17:607-618. [PMID: 34018139 DOI: 10.1007/s11302-021-09791-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 04/19/2021] [Indexed: 10/21/2022] Open
Abstract
Tanycytes are hypothalamic radial glial-like cells with an important role in the regulation of neuroendocrine axes and energy homeostasis. These cells have been implicated in glucose, amino acids, and fatty acid sensing in the hypothalamus of rodents, where they are strategically positioned. While their cell bodies contact the cerebrospinal fluid, their extensive processes contact neurons of the arcuate and ventromedial nuclei, protagonists in the regulation of food intake. A growing body of evidence has shown that purinergic signaling plays a relevant role in this homeostatic role of tanycytes, likely regulating the release of gliotransmitters that will modify the activity of satiety-controlling hypothalamic neurons. Connexin hemichannels have proven to be particularly relevant in these mechanisms since they are responsible for the release of ATP from tanycytes in response to nutritional signals. On the other hand, either ionotropic or metabotropic ATP receptors are involved in the generation of intracellular Ca2+ waves in response to hypothalamic nutrients, which can spread between glial cells and towards neighboring neurons. This review will summarize recent evidence that supports a nutrient sensor role for tanycytes, highlighting the participation of purinergic signaling in this process.
Collapse
Affiliation(s)
- Magdiel Salgado
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.,Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - María Á García-Robles
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
| | - Juan C Sáez
- Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile.
| |
Collapse
|
12
|
Zhong B, Ma S, Wang DH. TRPV1 Mediates Glucose-induced Insulin Secretion Through Releasing Neuropeptides. In Vivo 2020; 33:1431-1437. [PMID: 31471389 DOI: 10.21873/invivo.11621] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 06/28/2019] [Accepted: 07/03/2019] [Indexed: 12/23/2022]
Abstract
BACKGROUND/AIM Transient receptor potential vanilloid 1 (TRPV1)-expressing sensory nerves innervate the pancreatic islets. Sensory neuropeptides, including calcitonin gene-related peptide (CGRP) and substance P (SP), participate in insulin secretion. This study aimed to investigate the role of TRPV1 in glucose-induced insulin secretion. MATERIALS AND METHODS TRPV1-/- and wild-type (WT) mice were fed a normal diet for 24 weeks. Glucose tolerance and insulin secretion were measured at the end of the experiments. RESULTS TRPV1-/- mice had greater impairments in glucose tolerance and higher decrease in glucose-induced insulin secretion than WT mice. Capsaicin (a TRPV1 agonist) increased insulin secretion in WT, but not in TRPV1-/- mice. Glucose-induced insulin secretion was blunted in TRPV1-/- mice, and was attenuated by AMG9810 (a TRPV1 inhibitor), CGRP8-37 (a CGRP receptor antagonist), or RP67580 (a NK-1 receptor antagonist) in WT mice. Glucose-induced SP and CGRP release from WT pancreas was higher than that from TRPV1-/- pancreas. CONCLUSION TRPV1 mediates glucose-induced insulin secretion likely through CGRP and SP release.
Collapse
Affiliation(s)
- Beihua Zhong
- Division of Nanomedicine and Molecular Intervention, Department of Medicine, Michigan State University, East Lansing, MI, U.S.A
| | - Shuangtao Ma
- Division of Nanomedicine and Molecular Intervention, Department of Medicine, Michigan State University, East Lansing, MI, U.S.A
| | - Donna H Wang
- Division of Nanomedicine and Molecular Intervention, Department of Medicine, Michigan State University, East Lansing, MI, U.S.A. .,Neuroscience Program, Michigan State University, East Lansing, MI, U.S.A.,Cell & Molecular Biology Program, Michigan State University, East Lansing, MI, U.S.A
| |
Collapse
|
13
|
Billert M, Kołodziejski PA, Strowski MZ, Nowak KW, Skrzypski M. Phoenixin-14 stimulates proliferation and insulin secretion in insulin producing INS-1E cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:118533. [DOI: 10.1016/j.bbamcr.2019.118533] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 08/13/2019] [Accepted: 08/14/2019] [Indexed: 12/25/2022]
|
14
|
Sankar KS, Altamentova SM, Rocheleau JV. Hypoxia induction in cultured pancreatic islets enhances endothelial cell morphology and survival while maintaining beta-cell function. PLoS One 2019; 14:e0222424. [PMID: 31600313 PMCID: PMC6786522 DOI: 10.1371/journal.pone.0222424] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 08/28/2019] [Indexed: 12/23/2022] Open
Abstract
Background Pancreatic islets are heavily vascularized in vivo yet lose this vasculature after only a few days in culture. Determining how to maintain islet vascularity in culture could lead to better outcomes in transplanting this tissue for the treatment of type 1 diabetes as well as provide insight into the complex communication between beta-cells and endothelial cells (ECs). We previously showed that islet ECs die in part due to limited diffusion of serum albumin into the tissue. We now aim to determine the impact of hypoxia on islet vascularization. Methods We induced hypoxia in cultured mouse islets using the hypoxia mimetic cobalt chloride (100 μM CoCl2). We measured the impact on islet metabolism (two-photon NAD(P)H and Rh123 imaging) and function (insulin secretion and survival). We also measured the impact on hypoxia related transcripts (HIF-1α, VEGF-A, PDK-1, LDHA, COX4) and confirmed increased VEGF-A expression and secretion. Finally, we measured the vascularization of islets in static and flowing culture using PECAM-1 immunofluorescence. Results CoCl2 did not induce significant changes in beta cell metabolism (NAD(P)H and Rh123), insulin secretion, and survival. Consistent with hypoxia induction, CoCl2 stimulated HIF-1α, PDK-1, and LDHA transcripts and also stimulated VEGF expression and secretion. We observed a modest switch to the less oxidative isoform of COX4 (isoform 1 to 2) and this switch was noted in the glucose-stimulated cytoplasmic NAD(P)H responses. EC morphology and survival were greater in CoCl2 treated islets compared to exogenous VEGF-A in both static (dish) and microfluidic flow culture. Conclusions Hypoxia induction using CoCl2 had a positive effect on islet EC morphology and survival with limited impact on beta-cell metabolism, function, and survival. The EC response appears to be due to endogenous production and secretion of angiogenic factors (e.g. VEGF-A), and mechanistically independent from survival induced by serum albumin.
Collapse
Affiliation(s)
- Krishana S. Sankar
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Svetlana M. Altamentova
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Jonathan V. Rocheleau
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
| |
Collapse
|
15
|
Billert M, Sassek M, Wojciechowicz T, Jasaszwili M, Strowski MZ, Nowak KW, Skrzypski M. Neuropeptide B stimulates insulin secretion and expression but not proliferation in rat insulin‑producing INS‑1E cells. Mol Med Rep 2019; 20:2030-2038. [PMID: 31257494 DOI: 10.3892/mmr.2019.10415] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 05/24/2019] [Indexed: 11/06/2022] Open
Abstract
Neuropeptide B (NPB) regulates food intake, body weight and energy homeostasis by interacting with NPBW1/NPBW2 in humans and NPBW1 in rodents. NPB and NPBW1 are widely expressed in the central nervous system and peripheral tissues including pancreatic islets. Although previous studies have demonstrated a prominent role for NPB and NPBW1 in controlling glucose and energy homeostasis, it remains unknown as to whether NPB modulates pancreatic β‑cell functions. Therefore, the aim of the present study was to investigate the effects of NPB on insulin expression and secretion in vitro. Furthermore, the role of NPB in the modulation of INS‑1E cell growth, viability and death was examined. Gene expression was assessed by reverse transcription‑quantitative PCR. Cell proliferation and viability were determined by BrdU or MTT tests, respectively. Apoptotic cell death was evaluated by relative quantification histone‑complexed DNA fragments (mono‑and oligonucleosomes). Insulin secretion was studied using an ELISA test. Protein phosphorylation was assessed by western blot analysis. NPB and NPBW1 mRNA was expressed in INS‑1E cells and rat pancreatic islets. In INS‑1E cells, NPB enhanced insulin 1 mRNA expression via an ERK1/2‑dependent mechanism. Furthermore, NPB stimulated insulin secretion from INS‑1E cells and rat pancreatic islets. By contrast, NPB failed to affect INS‑1E cell growth or death. We conclude that NPB may regulate insulin secretion and expression in INS‑1E cells and insulin secretion in rat pancreatic islets.
Collapse
Affiliation(s)
- Maria Billert
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60‑637 Poznań, Poland
| | - Maciej Sassek
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60‑637 Poznań, Poland
| | - Tatiana Wojciechowicz
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60‑637 Poznań, Poland
| | - Mariami Jasaszwili
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60‑637 Poznań, Poland
| | - Mathias Z Strowski
- Department of Hepatology and Gastroenterology, Charité‑University Medicine Berlin, D‑13353 Berlin, Germany
| | - Krzysztof W Nowak
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60‑637 Poznań, Poland
| | - Marek Skrzypski
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60‑637 Poznań, Poland
| |
Collapse
|
16
|
Sarmiento BE, Santos Menezes LF, Schwartz EF. Insulin Release Mechanism Modulated by Toxins Isolated from Animal Venoms: From Basic Research to Drug Development Prospects. Molecules 2019; 24:E1846. [PMID: 31091684 PMCID: PMC6571724 DOI: 10.3390/molecules24101846] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 04/23/2019] [Accepted: 05/09/2019] [Indexed: 12/12/2022] Open
Abstract
Venom from mammals, amphibians, snakes, arachnids, sea anemones and insects provides diverse sources of peptides with different potential medical applications. Several of these peptides have already been converted into drugs and some are still in the clinical phase. Diabetes type 2 is one of the diseases with the highest mortality rate worldwide, requiring specific attention. Diverse drugs are available (e.g., Sulfonylureas) for effective treatment, but with several adverse secondary effects, most of them related to the low specificity of these compounds to the target. In this context, the search for specific and high-affinity compounds for the management of this metabolic disease is growing. Toxins isolated from animal venom have high specificity and affinity for different molecular targets, of which the most important are ion channels. This review will present an overview about the electrical activity of the ion channels present in pancreatic β cells that are involved in the insulin secretion process, in addition to the diversity of peptides that can interact and modulate the electrical activity of pancreatic β cells. The importance of prospecting bioactive peptides for therapeutic use is also reinforced.
Collapse
Affiliation(s)
- Beatriz Elena Sarmiento
- Departamento de Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF 70910-900, Brazil.
| | - Luis Felipe Santos Menezes
- Departamento de Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF 70910-900, Brazil.
| | - Elisabeth F Schwartz
- Departamento de Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF 70910-900, Brazil.
| |
Collapse
|
17
|
Redox TRPs in diabetes and diabetic complications: Mechanisms and pharmacological modulation. Pharmacol Res 2019; 146:104271. [PMID: 31096011 DOI: 10.1016/j.phrs.2019.104271] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 04/04/2019] [Accepted: 05/08/2019] [Indexed: 12/12/2022]
Abstract
Transient receptor potential (TRP) channels have shown to be involved in a wide variety of physiological functions and pathophysiological conditions. Modulation of TRP channels reported to play a major role in number of disorders starting from central nervous system related disorders to cardiovascular, inflammatory, cancer, gastrointestinal and metabolic diseases. Recently, a subset of TRP ion channels called redox TRPs gained importance on account of their ability to sense the cellular redox environment and respond accordingly to such redox stimuli. Diabetes, the silent epidemic of the world is increasing at an alarming rate in spite of novel therapeutic interventions. Moreover, diabetes and its associated complications are reported to arise due to a change in oxidative status of cell induced by hyperglycemia. Such a change in cellular oxidative status can modulate the activities of various redox TRP channels (TRPA1, TRPC5, TRPMs and TRPV1). Targeting redox TRPs have potential in diabetes and diabetic complications like neuropathy, cardiomyopathy, retinopathy, cystopathy, and encephalopathy. Thus in this review, we have discussed the activities of different redox sensing TRPs in diabetes and diabetic complications and how they can be modulated pharmacologically, so as to consider them a potential novel therapeutic target in treating diabetes and its comorbidity.
Collapse
|
18
|
Rey D, Miranda Sulis P, Alves Fernandes T, Gonçalves R, Silva Frederico MJ, Costa GM, Aragon M, Ospina LF, Mena Barreto Silva FR. Astragalin augments basal calcium influx and insulin secretion in rat pancreatic islets. Cell Calcium 2019; 80:56-62. [PMID: 30965223 DOI: 10.1016/j.ceca.2019.03.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/18/2019] [Accepted: 03/27/2019] [Indexed: 12/13/2022]
Abstract
Astragalin is a flavonol glycoside with several biological activities, including antidiabetic properties. The objective of this study was to investigate the effects of astragalin on glycaemia and insulin secretion, in vivo, and on calcium influx and insulin secretion in isolated rat pancreatic islets, ex vivo. Astragalin (1 and 10 mg / kg) was administered by oral gavage to fasted Wistar rats and serum glucose and plasma insulin were measured. Isolated pancreatic islets were used to measure basal insulin secretion and calcium influx. Astragalin (10 mg/ kg) decreased glycaemia and increased insulin secretion significantly at 15-180 min, respectively, in the glucose tolerance test. In isolated pancreatic cells, astragalin (100 μM) stimulated calcium influx through a mechanism involving ATP-dependent potassium channels, L-type voltage-dependent calcium channels, the sarcoendoplasmic reticulum calcium transport ATPase (SERCA), PKC and PKA. These findings highlight the dietary coadjuvant, astragalin, as a potential insulin secretagogue that may contribute to glucose homeostasis.
Collapse
Affiliation(s)
- Diana Rey
- Universidad Nacional de Colombia, Departamento de Farmácia, Facultad de Ciencias, Cra. 30 No. 45-03, Postal Code 111321, Bogotá, D. C., Colombia; Universidade Federal de Santa Catarina, Departamento de Bioquímica - Centro de Ciências Biológicas, Campus Universitário, BairroTrindade, Cx. Postal 5069, CEP: 88040-970, Florianópolis, SC, Brazil
| | - Paola Miranda Sulis
- Universidade Federal de Santa Catarina, Departamento de Bioquímica - Centro de Ciências Biológicas, Campus Universitário, BairroTrindade, Cx. Postal 5069, CEP: 88040-970, Florianópolis, SC, Brazil
| | - Thaís Alves Fernandes
- Universidade Federal de Santa Catarina, Departamento de Bioquímica - Centro de Ciências Biológicas, Campus Universitário, BairroTrindade, Cx. Postal 5069, CEP: 88040-970, Florianópolis, SC, Brazil
| | - Renata Gonçalves
- Universidade Federal de Santa Catarina, Departamento de Bioquímica - Centro de Ciências Biológicas, Campus Universitário, BairroTrindade, Cx. Postal 5069, CEP: 88040-970, Florianópolis, SC, Brazil
| | - Marisa Jádna Silva Frederico
- Universidade Federal de Santa Catarina, Departamento de Bioquímica - Centro de Ciências Biológicas, Campus Universitário, BairroTrindade, Cx. Postal 5069, CEP: 88040-970, Florianópolis, SC, Brazil
| | - Geison M Costa
- Pontificia Universidad Javeriana, Departamento de Química, Facultad de Ciencias, Carrera 7 No. 43-82, Edificio Carlos Ortiz (52), Oficina 617, Postal Code 110231, Bogotá, D. C., Colombia
| | - Marcela Aragon
- Universidad Nacional de Colombia, Departamento de Farmácia, Facultad de Ciencias, Cra. 30 No. 45-03, Postal Code 111321, Bogotá, D. C., Colombia
| | - Luís Fernando Ospina
- Universidad Nacional de Colombia, Departamento de Farmácia, Facultad de Ciencias, Cra. 30 No. 45-03, Postal Code 111321, Bogotá, D. C., Colombia
| | - Fátima Regina Mena Barreto Silva
- Universidade Federal de Santa Catarina, Departamento de Bioquímica - Centro de Ciências Biológicas, Campus Universitário, BairroTrindade, Cx. Postal 5069, CEP: 88040-970, Florianópolis, SC, Brazil.
| |
Collapse
|
19
|
García-Delgado N, Velasco M, Sánchez-Soto C, Díaz-García CM, Hiriart M. Calcium Channels in Postnatal Development of Rat Pancreatic Beta Cells and Their Role in Insulin Secretion. Front Endocrinol (Lausanne) 2018; 9:40. [PMID: 29556214 PMCID: PMC5845110 DOI: 10.3389/fendo.2018.00040] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 01/31/2018] [Indexed: 01/05/2023] Open
Abstract
Pancreatic beta cells during the first month of development acquire functional maturity, allowing them to respond to variations in extracellular glucose concentration by secreting insulin. Changes in ionic channel activity are important for this maturation. Within the voltage-gated calcium channels (VGCC), the most studied channels are high-voltage-activated (HVA), principally L-type; while low-voltage-activated (LVA) channels have been poorly studied in native beta cells. We analyzed the changes in the expression and activity of VGCC during the postnatal development in rat beta cells. We observed that the percentage of detection of T-type current increased with the stage of development. T-type calcium current density in adult cells was higher than in neonatal and P20 beta cells. Mean HVA current density also increased with age. Calcium current behavior in P20 beta cells was heterogeneous; almost half of the cells had HVA current densities higher than the adult cells, and this was independent of the presence of T-type current. We detected the presence of α1G, α1H, and α1I subunits of LVA channels at all ages. The Cav 3.1 subunit (α1G) was the most expressed. T-type channel blockers mibefradil and TTA-A2 significantly inhibited insulin secretion at 5.6 mM glucose, which suggests a physiological role for T-type channels at basal glucose conditions. Both, nifedipine and TTA-A2, drastically decreased the beta-cell subpopulation that secretes more insulin, in both basal and stimulating glucose conditions. We conclude that changes in expression and activity of VGCC during the development play an important role in physiological maturation of beta cells.
Collapse
Affiliation(s)
- Neivys García-Delgado
- Neuroscience Division, Cognitive Neuroscience Department, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México UNAM, Mexico City, Mexico
- Posgrado en Ciencias Biomédicas UNAM, Mexico City, Mexico
| | - Myrian Velasco
- Neuroscience Division, Cognitive Neuroscience Department, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México UNAM, Mexico City, Mexico
| | - Carmen Sánchez-Soto
- Neuroscience Division, Cognitive Neuroscience Department, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México UNAM, Mexico City, Mexico
| | - Carlos Manlio Díaz-García
- Neuroscience Division, Cognitive Neuroscience Department, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México UNAM, Mexico City, Mexico
| | - Marcia Hiriart
- Neuroscience Division, Cognitive Neuroscience Department, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México UNAM, Mexico City, Mexico
- *Correspondence: Marcia Hiriart,
| |
Collapse
|
20
|
An optimized protocol for purification of functional islets of Langerhans. J Transl Med 2017; 97:70-83. [PMID: 27892930 DOI: 10.1038/labinvest.2016.123] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 10/21/2016] [Indexed: 12/31/2022] Open
Abstract
Islets of Langerhans and β-cell isolation constitute routinely used cell models for diabetic research, and refining islet isolation protocols and cell quality assessment is a high priority. Numerous protocols have been published describing isolate of islets, but often rigorous and systematic assessment of their integrity is lacking. Herein, we propose a new protocol for optimal generation of islets. Pancreases from mice and rats were excised and digested using a low-activity collagenase solution and islets were then purified by a series of sedimentations and a Percoll gradient. Islets were maintained in culture for 5 days, during which viability, pro/antiapoptotic, and islet-specific genes, glucose-stimulated calcium entry, glucose uptake, and insulin secretion were assessed. The commonly used islet isolation technique by collagenase injection through the common bile duct (CBD) was also performed and compared with the present approach. This new protocol produced islets that retained a healthy status as demonstrated by the yield of stable living cells. Furthermore, calcium oscillation, glucose uptake, and insulin secretion remained intact in the islet cultures. This was reproducible when many rodent species were used, and neither sex nor age affected the cells behavior. When compared with the CBD technique, islet physiology was similar. Finally, this approach was used to uncover new ion channel candidates implicated in insulin secretion. In conclusion, this study outlines an efficient protocol for islet preparation that may support research into new therapeutic targets in diabetes research.
Collapse
|
21
|
de la Cruz L, Puente EI, Reyes-Vaca A, Arenas I, Garduño J, Bravo-Martínez J, Garcia DE. PIP2 in pancreatic β-cells regulates voltage-gated calcium channels by a voltage-independent pathway. Am J Physiol Cell Physiol 2016; 311:C630-C640. [PMID: 27488666 DOI: 10.1152/ajpcell.00111.2016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 07/29/2016] [Indexed: 12/21/2022]
Abstract
Phosphatidylinositol-4,5-bisphosphate (PIP2) is a membrane phosphoinositide that regulates the activity of many ion channels. Influx of calcium primarily through voltage-gated calcium (CaV) channels promotes insulin secretion in pancreatic β-cells. However, whether CaV channels are regulated by PIP2, as is the case for some non-insulin-secreting cells, is unknown. The purpose of this study was to investigate whether CaV channels are regulated by PIP2 depletion in pancreatic β-cells through activation of a muscarinic pathway induced by oxotremorine methiodide (Oxo-M). CaV channel currents were recorded by the patch-clamp technique. The CaV current amplitude was reduced by activation of the muscarinic receptor 1 (M1R) in the absence of kinetic changes. The Oxo-M-induced inhibition exhibited the hallmarks of voltage-independent regulation and did not involve PKC activation. A small fraction of the Oxo-M-induced CaV inhibition was diminished by a high concentration of Ca2+ chelator, whereas ≥50% of this inhibition was prevented by diC8-PIP2 dialysis. Localization of PIP2 in the plasma membrane was examined by transfecting INS-1 cells with PH-PLCδ1, which revealed a close temporal association between PIP2 hydrolysis and CaV channel inhibition. Furthermore, the depletion of PIP2 by a voltage-sensitive phosphatase reduced CaV currents in a way similar to that observed following M1R activation. These results indicate that activation of the M1R pathway inhibits the CaV channel via PIP2 depletion by a Ca2+-dependent mechanism in pancreatic β- and INS-1 cells and thereby support the hypothesis that membrane phospholipids regulate ion channel activity by interacting with ion channels.
Collapse
Affiliation(s)
- Lizbeth de la Cruz
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico, México
| | - Erika I Puente
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico, México
| | - Arturo Reyes-Vaca
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico, México
| | - Isabel Arenas
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico, México
| | - Julieta Garduño
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico, México
| | - Jorge Bravo-Martínez
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico, México
| | - David E Garcia
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico, México
| |
Collapse
|
22
|
Velasco M, Díaz-García CM, Larqué C, Hiriart M. Modulation of Ionic Channels and Insulin Secretion by Drugs and Hormones in Pancreatic Beta Cells. Mol Pharmacol 2016; 90:341-57. [PMID: 27436126 DOI: 10.1124/mol.116.103861] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 07/18/2016] [Indexed: 12/11/2022] Open
Abstract
Pancreatic beta cells, unique cells that secrete insulin in response to an increase in glucose levels, play a significant role in glucose homeostasis. Glucose-stimulated insulin secretion (GSIS) in pancreatic beta cells has been extensively explored. In this mechanism, glucose enters the cells and subsequently the metabolic cycle. During this process, the ATP/ADP ratio increases, leading to ATP-sensitive potassium (KATP) channel closure, which initiates depolarization that is also dependent on the activity of TRP nonselective ion channels. Depolarization leads to the opening of voltage-gated Na(+) channels (Nav) and subsequently voltage-dependent Ca(2+) channels (Cav). The increase in intracellular Ca(2+) triggers the exocytosis of insulin-containing vesicles. Thus, electrical activity of pancreatic beta cells plays a central role in GSIS. Moreover, many growth factors, incretins, neurotransmitters, and hormones can modulate GSIS, and the channels that participate in GSIS are highly regulated. In this review, we focus on the principal ionic channels (KATP, Nav, and Cav channels) involved in GSIS and how classic and new proteins, hormones, and drugs regulate it. Moreover, we also discuss advances on how metabolic disorders such as metabolic syndrome and diabetes mellitus change channel activity leading to changes in insulin secretion.
Collapse
Affiliation(s)
- Myrian Velasco
- Department of Neurodevelopment and Physiology, Neuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Carlos Manlio Díaz-García
- Department of Neurodevelopment and Physiology, Neuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Carlos Larqué
- Department of Neurodevelopment and Physiology, Neuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Marcia Hiriart
- Department of Neurodevelopment and Physiology, Neuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| |
Collapse
|
23
|
Larqué C, Velasco M, Barajas-Olmos F, García-Delgado N, Chávez-Maldonado JP, García-Morales J, Orozco L, Hiriart M. Transcriptome landmarks of the functional maturity of rat beta-cells, from lactation to adulthood. J Mol Endocrinol 2016; 57:45-59. [PMID: 27220619 DOI: 10.1530/jme-16-0052] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 05/24/2016] [Indexed: 12/22/2022]
Abstract
Research on the postnatal development of pancreatic beta-cells has become an important subject in recent years. Understanding the mechanisms that govern beta-cell postnatal maturation could bring new opportunities to therapeutic approaches for diabetes. The weaning period consists of a critical postnatal window for structural and physiologic maturation of rat beta-cells. To investigate transcriptome changes involved in the maturation of beta-cells neighboring this period, we performed microarray analysis in fluorescence-activated cell-sorted (FACS) beta-cell-enriched populations. Our results showed a variety of gene sets including those involved in the integration of metabolism, modulation of electrical activity, and regulation of the cell cycle that play important roles in the maturation process. These observations were validated using reverse hemolytic plaque assay, electrophysiological recordings, and flow cytometry analysis. Moreover, we suggest some unexplored pathways such as sphingolipid metabolism, insulin-vesicle trafficking, regulation of transcription/transduction by miRNA-30, trafficking proteins, and cell cycle proteins that could play important roles in the process mentioned above for further investigation.
Collapse
Affiliation(s)
- Carlos Larqué
- Department of Neurodevelopment and PhysiologyNeuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Myrian Velasco
- Department of Neurodevelopment and PhysiologyNeuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Francisco Barajas-Olmos
- Immunogenomics and Metabolic Disease LaboratoryInstituto Nacional de Medicina Genómica, SS, Mexico City, Mexico
| | - Neyvis García-Delgado
- Department of Neurodevelopment and PhysiologyNeuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Juan Pablo Chávez-Maldonado
- Department of Neurodevelopment and PhysiologyNeuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Jazmín García-Morales
- Department of Neurodevelopment and PhysiologyNeuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Lorena Orozco
- Immunogenomics and Metabolic Disease LaboratoryInstituto Nacional de Medicina Genómica, SS, Mexico City, Mexico
| | - Marcia Hiriart
- Department of Neurodevelopment and PhysiologyNeuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| |
Collapse
|
24
|
Zhao Y, Xue Q, Su X, Xie L, Yan Y, Wang L, Steinman AD. First Identification of the Toxicity of Microcystins on Pancreatic Islet Function in Humans and the Involved Potential Biomarkers. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:3137-3144. [PMID: 26859764 DOI: 10.1021/acs.est.5b03369] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Microcystins (MCs) produced by cyanobacteria have been recognized as a major public health threat. However, the toxicity of MCs to humans is still largely unknown. In this study, we examined the changes in pancreatic islet function in fishers exposed to ambient levels of MCs at Lake Taihu and, using a mouse model, explored the molecular mechanisms involved in toxicity. MCs content in the serum of fishers tested positive, with a range from 0.10 to 0.64 μg/L. Both lower blood insulin levels (2.26 ± 0.96 μIU/mL) and impaired fasting glucose were found in participants from the Meiliang Bay area in Lake Taihu, where MC-LR levels were substantially greater than the MC threshold established by WHO for drinking water. Animal experiments showed that glucose level increased by 27.9% in mice exposed to 5 μg/kg bw and decreased by 41.5% in mice exposed to 20 μg/kg bw. Blood insulin levels declined by 21.9% and 56.2% in mice exposed to 5 and 20 μg/kg bw MC-LR, respectively, which was consistent with the results observed in fishers. Furthermore, the diabetes gene pdx1 and several other proteins (such as Ppp3ca, Ide, Marcks, Pgk1, Suclg1, Ndufs4) involved in insulin secretion were identified for the first time in mice following MC-LR exposure; these biomarkers were considered responsible for MC-LR induced islet dysfunction. This study suggests that subchronic exposure to environmental levels of MCs may increase the risk of the occurrence of diabetes in humans.
Collapse
Affiliation(s)
- Yanyan Zhao
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences , 73 East Beijing Road, Nanjing 210008, P. R. China
| | - Qingju Xue
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences , 73 East Beijing Road, Nanjing 210008, P. R. China
| | - Xiaomei Su
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences , 73 East Beijing Road, Nanjing 210008, P. R. China
| | - Liqiang Xie
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences , 73 East Beijing Road, Nanjing 210008, P. R. China
| | - Yunjun Yan
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology , 1037 Luoyu Road, Wuhan 430074, P. R. China
| | - Lixiao Wang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology , 1037 Luoyu Road, Wuhan 430074, P. R. China
| | - Alan D Steinman
- Annis Water Resources Institute, Grand Valley State University , 740 West Shoreline Drive, Muskegon, Michigan 49441, United States
| |
Collapse
|
25
|
Félix-Martínez GJ, Godínez-Fernández JR. Modeling Ca(2+) currents and buffered diffusion of Ca(2+) in human β-cells during voltage clamp experiments. Math Biosci 2015; 270:66-80. [PMID: 26476144 DOI: 10.1016/j.mbs.2015.09.009] [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: 10/09/2014] [Revised: 09/03/2015] [Accepted: 09/28/2015] [Indexed: 11/27/2022]
Abstract
Macroscopic Ca(2+) currents of the human β-cells were characterized using the Hodgkin-Huxley formalism. Expressions describing the Ca(2+)-dependent inactivation process of the L-type Ca(2+) channels in terms of the concentration of Ca(2+) were obtained. By coupling the modeled Ca(2+) currents to a three-dimensional model of buffered diffusion of Ca(2+), we simulated the Ca(2+) transients formed in the immediate vicinity of the cell membrane during voltage clamp experiments performed in high buffering conditions. Our modeling approach allowed us to consider the distribution of the Ca(2+) sources over the cell membrane. The effect of exogenous (EGTA) and endogenous Ca(2+) buffers on the temporal course of the Ca(2+) transients was evaluated. We show that despite the high Ca(2+) buffering capacity, nanodomains are formed in the submembrane space, where a peak Ca(2+) concentration between ∼76 and 143 µM was estimated from our simulations. In addition, the contribution of each Ca(2+) current to the formation of the Ca(2+) nanodomains was also addressed. Here we provide a general framework to incorporate the spatial aspects to the models of the pancreatic β-cell, such as a more detailed and realistic description of Ca(2+) dynamics in response to electrical activity in physiological conditions can be provided by future models.
Collapse
Affiliation(s)
- Gerardo J Félix-Martínez
- Department of Electrical Engineering, Universidad Autónoma Metropolitana Iztapalapa, México, D.F., Mexico .
| | - J Rafael Godínez-Fernández
- Department of Electrical Engineering, Universidad Autónoma Metropolitana Iztapalapa, México, D.F., Mexico
| |
Collapse
|
26
|
Battocchio M, Zatelli MC, Chiarelli S, Trento M, Ambrosio MR, Pasquali C, De Carlo E, Dassie F, Mioni R, Rebellato A, Fallo F, Degli Uberti E, Martini C, Vettor R, Maffei P. Ovarian tumors secreting insulin. Endocrine 2015; 49:611-9. [PMID: 25896552 DOI: 10.1007/s12020-015-0605-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 04/13/2015] [Indexed: 10/23/2022]
Abstract
Combined ovarian germ cell and neuroendocrine tumors are rare. Only few cases of hyperinsulinism due to ovarian ectopic secretion have been hypothesized in the literature. An ovarian tumor was diagnosed in a 76-year-old woman, referred to our department for recurrent hypoglycemia with hyperinsulinism. In vivo tests, in particular fasting test, rapid calcium infusion test, and Octreotide test were performed. Ectopic hyperinsulinemic hypoglycemia was demonstrated in vivo and hypoglycemia disappeared after hysteroadnexectomy. Histological exam revealed an ovarian germ cell tumor with neuroendocrine and Yolk sac differentiation, while immunostaining showed insulin positivity in neuroendocrine cells. A cell culture was obtained by tumoral cells, testing Everolimus, and Pasireotide. Insulin was detected in cell culture medium and Everolimus and Pasireotide demonstrated their potentiality in reducing insulin secretion, more than controlling cell viability. Nine cases of hyperinsulinism due to ovarian ectopic secretion reported in literature have been reviewed. These data confirm the ovarian tissue potentiality to induce hyperinsulinemic hypoglycemic syndrome after neoplastic transformation.
Collapse
Affiliation(s)
- Marialberta Battocchio
- Internal Medicine 3, Department of Medicine, University of Padua, Via Giustiniani 2, 35100, Padua, Italy,
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Elizondo-Vega R, Cortes-Campos C, Barahona MJ, Oyarce KA, Carril CA, García-Robles MA. The role of tanycytes in hypothalamic glucosensing. J Cell Mol Med 2015; 19:1471-82. [PMID: 26081217 PMCID: PMC4511346 DOI: 10.1111/jcmm.12590] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 03/03/2015] [Indexed: 12/23/2022] Open
Abstract
Tanycytes are elongated hypothalamic glial cells that cover the basal walls of the third ventricle; their apical regions contact the cerebrospinal fluid (CSF), and their processes reach hypothalamic neuronal nuclei that control the energy status of an organism. These nuclei maintain the balance between energy expenditure and intake, integrating several peripheral signals and triggering cellular responses that modify the feeding behaviour and peripheral glucose homeostasis. One of the most important and well-studied signals that control this process is glucose; however, the mechanism by which this molecule is sensed remains unknown. We along with others have proposed that tanycytes play a key role in this process, transducing changes in CSF glucose concentration to the neurons that control energy status. Recent studies have demonstrated the expression and function of monocarboxylate transporters and canonical pancreatic β cell glucose sensing molecules, including glucose transporter 2 and glucokinase, in tanycytes. These and other data, which will be discussed in this review, suggest that hypothalamic glucosensing is mediated through a metabolic interaction between tanycytes and neurons through lactate. This article will summarize the recent evidence that supports the importance of tanycytes in hypothalamic glucosensing, and discuss the possible mechanisms involved in this process. Finally, it is important to highlight that a detailed analysis of this mechanism could represent an opportunity to understand the evolution of associated pathologies, including diabetes and obesity, and identify new candidates for therapeutic intervention.
Collapse
Affiliation(s)
- Roberto Elizondo-Vega
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | | | - Maria J Barahona
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Karina A Oyarce
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Claudio A Carril
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Maria A García-Robles
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| |
Collapse
|
28
|
Murovets VO, Bachmanov AA, Travnikov SV, Churikova AA, Zolotarev VA. The Involvement of the T1R3 Receptor Protein in the Control of Glucose Metabolism in Mice at Different Levels of Glycemia. J EVOL BIOCHEM PHYS+ 2014; 50:334-344. [PMID: 25983343 DOI: 10.1134/s0022093014040061] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The heterodimeric protein T1R2/T1R3 is a chemoreceptor mediating taste perception of sugars, several amino acids, and non-caloric sweeteners in humans and many other vertebrate species. The T1R2 and T1R3 proteins are expressed not only in the oral cavity, but also in the intestine, pancreas, liver, adipose tissue, and in structures of the central nervous system, which suggests their involvement in functions other than gustatory perception. In this study, we analyzed the role of the T1R3 protein in regulation of glucose metabolism in experiments with the gene-knockout mouse strain C57BL/6J-Tas1r3tm1Rfm (Tas1r3-/-), with a deletion of the Tas1r3 gene encoding T1R3, and the control strain C57BL/6ByJ with the intact gene. Glucose tolerance was measured in euglycemic or food-deprived mice after intraperitoneal or intragastric glucose administration. We have shown that in the Tas1r3-/- strain, in addition to the disappearance of taste preference for sucrose, glucose tolerance is also substantially reduced, and insulin resistance is observed. The effect of the Tas1r3 gene knockout on glucose utilization was more pronounced in the euglycemic state than after food deprivation. The baseline glucose level after food deprivation was lower in the Tas1r3-/- strain than in the control strain, which suggests that T1R3 is involved in regulation of endogenous glucose production. These data suggest that the T1R3-mediated glucoreception interacts with the KATP-dependent mechanisms of regulation of the glucose metabolism, and that the main role is likely played by T1R3 expressed in the pancreas and possibly in the central nervous system, but not in the intestinal mucosa, as it was suggested earlier.
Collapse
Affiliation(s)
- V O Murovets
- Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia
| | | | - S V Travnikov
- Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia
| | - A A Churikova
- Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia
| | - V A Zolotarev
- Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia
| |
Collapse
|
29
|
Uchida K, Tominaga M. The role of TRPM2 in pancreatic β-cells and the development of diabetes. Cell Calcium 2014; 56:332-9. [PMID: 25084624 DOI: 10.1016/j.ceca.2014.07.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 06/30/2014] [Accepted: 07/02/2014] [Indexed: 12/29/2022]
Abstract
TRPM2 is a Ca(2+)-permeable non-selective cation channel that can be activated by adenosine dinucleotides, hydrogen peroxide, or intracellular Ca(2+). The protein is expressed in a wide variety of cells, including neurons in the brain, immune cells, endocrine cells, and endothelial cells. This channel is also well expressed in β-cells in the pancreas. Insulin secretion from pancreatic β-cells is the primary mechanism by which the concentration of blood glucose is reduced. Thus, impairment of insulin secretion leads to hyperglycemia and eventually causes diabetes. Glucose is the principal stimulator of insulin secretion. The primary pathway involved in glucose-stimulated insulin secretion is the ATP-sensitive K(+) (KATP) channel to voltage-gated Ca(2+) channel (VGCC)-mediated pathway. Increases in the intracellular Ca(2+) concentration are necessary for insulin secretion, but VGCC is not sufficient to explain [Ca(2+)]i increases in pancreatic β-cells and the resultant secretion of insulin. In this review, we focus on TRPM2 as a candidate for a [Ca(2+)]i modulator in pancreatic β-cells and its involvement in insulin secretion and development of diabetes. Although further analyses are needed to clarify the mechanism underlying TRPM2-mediated insulin secretion, TRPM2 could be a key player in the regulation of insulin secretion and could represent a new target for diabetes therapy.
Collapse
Affiliation(s)
- Kunitoshi Uchida
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan; Department of Physiological Sciences, The University of Advanced Studies, Okazaki, Aichi 444-8585, Japan.
| | - Makoto Tominaga
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan; Department of Physiological Sciences, The University of Advanced Studies, Okazaki, Aichi 444-8585, Japan.
| |
Collapse
|
30
|
Hoeijmakers JGJ, Faber CG, Merkies ISJ, Waxman SG. Channelopathies, painful neuropathy, and diabetes: which way does the causal arrow point? Trends Mol Med 2014; 20:544-50. [PMID: 25008557 DOI: 10.1016/j.molmed.2014.06.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 06/09/2014] [Accepted: 06/12/2014] [Indexed: 12/13/2022]
Abstract
Diabetes mellitus, a major global health problem, is commonly associated with painful peripheral neuropathy, which can substantially erode quality of life. Despite its clinical importance, the pathophysiology of painful diabetic neuropathy is incompletely understood. It has traditionally been thought that diabetes may cause neuropathy in patients with appropriate genetic makeup. Here, we propose a hypothesis whereby painful neuropathy is not a complication of diabetes, but rather occurs as a result of mutations that, in parallel, confer vulnerability to injury in pancreatic β cells and pain-signaling dorsal root ganglion (DRG) neurons. We suggest that mutations of sodium channel NaV1.7, which is present in both cell types, may increase susceptibility for development of diabetes via β cell injury and produce painful neuropathy via a distinct effect on DRG neurons.
Collapse
Affiliation(s)
- Janneke G J Hoeijmakers
- Department of Neurology, Maastricht University Medical Center, Maastricht, 6202 AZ, The Netherlands
| | - Catharina G Faber
- Department of Neurology, Maastricht University Medical Center, Maastricht, 6202 AZ, The Netherlands
| | - Ingemar S J Merkies
- Department of Neurology, Maastricht University Medical Center, Maastricht, 6202 AZ, The Netherlands; Department of Neurology, Spaarne Hospital, Hoofddorp, 2130 AT, The Netherlands
| | - Stephen G Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06515, USA; Center for Neuroscience and Regeneration Research, Veterans Affairs Medical Center, West Haven, CT 06515, USA.
| |
Collapse
|
31
|
McIntosh CH, Widenmaier S, Kim SJ. Glucose-dependent insulinotropic polypeptide signaling in pancreatic β-cells and adipocytes. J Diabetes Investig 2014; 3:96-106. [PMID: 24843552 PMCID: PMC4020726 DOI: 10.1111/j.2040-1124.2012.00196.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Glucose‐dependent insulinotropic polypeptide (GIP) was the first incretin to be identified. In addition to stimulating insulin secretion, GIP plays regulatory roles in the maintenance, growth and survival of pancreatic islets, as well as impacting on adipocyte function. The current review focuses on the intracellular signaling pathways by which GIP contributes to the regulation of β‐cell secretion and survival, and adipocyte differentiation and lipogenesis. Studies on signaling underlying the insulinotropic actions of the incretin hormones have largely been carried out with glucagon‐like peptide‐1. They have provided evidence for contributions by both protein kinase A (PKA) and exchange protein directly activated by cyclic adenosine monophosphate (EPAC2), and their probable role in GIP signaling is discussed. Recent studies have shown that inhibition of the kinase apoptosis signal‐regulating kinase 1 (ASK1) by GIP plays a key role in reducing mitochondria‐induced apoptosis in β‐cells through protein kinase B (PKB)‐mediated pathways, and that GIP‐induced post‐translational modification of voltage‐ dependent K+ (Kv) channels also contributes to its prosurvival role. Through regulation of gene expression, GIP tips the balance between pro‐ and anti‐apoptotic members of the B‐cell lymphoma‐2 (Bcl‐2) protein family towards β‐cell survival. GIP also plays important roles in the differentiation of pre‐adipocytes to adipocytes, and in the regulation of lipoprotein lipase expression and lipogenesis. These events involve interactions between GIP, insulin and resistin signaling pathways. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00196.x, 2012)
Collapse
Affiliation(s)
- Christopher Hs McIntosh
- Department of Cellular and Physiological Sciences and the Diabetes Research Group, Life Sciences Institute University of British Columbia, Vancouver, BC, Canada
| | - Scott Widenmaier
- Department of Cellular and Physiological Sciences and the Diabetes Research Group, Life Sciences Institute University of British Columbia, Vancouver, BC, Canada
| | - Su-Jin Kim
- Department of Cellular and Physiological Sciences and the Diabetes Research Group, Life Sciences Institute University of British Columbia, Vancouver, BC, Canada
| |
Collapse
|
32
|
Nita II, Hershfinkel M, Kantor C, Rutter GA, Lewis EC, Sekler I. Pancreatic β-cell Na+ channels control global Ca2+ signaling and oxidative metabolism by inducing Na+ and Ca2+ responses that are propagated into mitochondria. FASEB J 2014; 28:3301-12. [PMID: 24719357 DOI: 10.1096/fj.13-248161] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Communication between the plasma membrane and mitochondria is essential for initiating the Ca(2+) and metabolic signals required for secretion in β cells. Although voltage-dependent Na(+) channels are abundantly expressed in β cells and activated by glucose, their role in communicating with mitochondria is unresolved. Here, we combined fluorescent Na(+), Ca(2+), and ATP imaging, electrophysiological analysis with tetrodotoxin (TTX)-dependent block of the Na(+) channel, and molecular manipulation of mitochondrial Ca(2+) transporters to study the communication between Na(+) channels and mitochondria. We show that TTX inhibits glucose-dependent depolarization and blocks cytosolic Na(+) and Ca(2+) responses and their propagation into mitochondria. TTX-sensitive mitochondrial Ca(2+) influx was largely blocked by knockdown of the mitochondrial Ca(2+) uniporter (MCU) expression. Knockdown of the mitochondrial Na(+)/Ca(2+) exchanger (NCLX) and Na(+) dose response analysis demonstrated that NCLX mediates the mitochondrial Na(+) influx and is tuned to sense the TTX-sensitive cytosolic Na(+) responses. Finally, TTX blocked glucose-dependent mitochondrial Ca(2+) rise, mitochondrial metabolic activity, and ATP production. Our results show that communication of the Na(+) channels with mitochondria shape both global Ca(2+) and metabolism signals linked to insulin secretion in β cells.- Nita, I. I., Hershfinkel, M., Kantor, C., Rutter, G. A., Lewis, E. C., Sekler, I. Pancreatic β-cell Na(+) channels control global Ca(2+) signaling and oxidative metabolism by inducing Na(+) and Ca(2+) responses that are propagated into mitochondria.
Collapse
Affiliation(s)
| | | | - Chase Kantor
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Imperial College London, London, UK
| | - Guy A Rutter
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Imperial College London, London, UK
| | - Eli C Lewis
- Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel; and
| | | |
Collapse
|
33
|
Role for the TRPV1 channel in insulin secretion from pancreatic beta cells. J Membr Biol 2014; 247:479-91. [PMID: 24676478 DOI: 10.1007/s00232-014-9658-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 03/10/2014] [Indexed: 02/04/2023]
Abstract
Transient receptor potential channels have been put forward as regulators of insulin secretion. A role for the TRPV1 ion channel in insulin secretion has been suggested in pancreatic beta cell lines. We explored whether TRPV1 is functionally expressed in RINm5F and primary beta cells from neonate and adult rats. We examined if capsaicin could activate cationic non-selective currents. Our results show that TRPV1 channels are not functional in insulin-secreting cells, since capsaicin did not produce current activation, not even under culture conditions known to induce the expression of other ion channels in these cells. Although TRPV1 channels seem to be irrelevant for the physiology of isolated beta cells, they may play a role in glucose homeostasis acting through the nerve fibers that regulate islet function. At the physiological level, we observed that Trpv1 (-/-) mice presented lower fasting insulin levels than their wild-type littermates, however, we did not find differences between these experimental groups nor in the glucose tolerance test or in the insulin secretion. However, we did find that the Trpv1 (-/-) mice exhibited a higher insulin sensitivity compared to their wild-type counterparts. Our results demonstrate that TRPV1 does not contribute to glucose-induced insulin secretion in beta cells as was previously thought, but it is possible that it may control insulin sensitivity.
Collapse
|
34
|
Abstract
Mathematical modeling of the electrical activity of the pancreatic β-cell has been extremely important for understanding the cellular mechanisms involved in glucose-stimulated insulin secretion. Several models have been proposed over the last 30 y, growing in complexity as experimental evidence of the cellular mechanisms involved has become available. Almost all the models have been developed based on experimental data from rodents. However, given the many important differences between species, models of human β-cells have recently been developed. This review summarizes how modeling of β-cells has evolved, highlighting the proposed physiological mechanisms underlying β-cell electrical activity.
Collapse
Key Words
- ADP, adenosine diphosphate
- ATP, adenosine triphosphate
- CK, Chay-Keizer
- CRAC, calcium release-activated current
- Ca2+, calcium ions
- DOM, dual oscillator model
- ER, endoplasmic reticulum
- F6P, fructose-6-phosphate
- FBP, fructose-1,6-bisphosphate
- GLUT, glucose transporter
- GSIS, glucose-stimulated insulin secretion
- HERG, human eter à-go-go related gene
- IP3R, inositol-1,4,5-trisphosphate receptors
- KATP, ATP-sensitive K+ channels
- KCa, Ca2+-dependent K+ channels
- Kv, voltage-dependent K+ channels
- MCU, mitochondrial Ca2+ uniporter
- NCX, Na+/Ca2+ exchanger
- PFK, phosphofructokinase
- PMCA, plasma membrane Ca2+-ATPase
- ROS, reactive oxygen species
- RyR, ryanodine receptors
- SERCA, sarco-endoplasmic reticulum Ca2+-ATPase
- T2D, Type 2 Diabetes
- TCA, trycarboxylic acid cycle
- TRP, transient receptor potential
- VDCC, voltage-dependent Ca2+ channels
- Vm, membrane potential
- [ATP]i, cytosolic ATP
- [Ca2+]i, intracellular calcium concentration
- [Ca2+]m, mitochondrial calcium
- [Na+], Na+ concentration
- action potentials
- bursting
- cAMP, cyclic AMP
- calcium
- electrical activity
- ion channels
- mNCX, mitochondrial Na+/Ca2+ exchanger
- mathematical model
- β-cell
Collapse
Affiliation(s)
- Gerardo J Félix-Martínez
- Department of Electrical Engineering; Universidad
Autónoma Metropolitana-Iztapalapa; México, DF,
México
- Correspondence to: Gerardo J
Félix-Martínez;
| | | |
Collapse
|
35
|
Hiriart M, Velasco M, Larqué C, Diaz-Garcia CM. Metabolic Syndrome and Ionic Channels in Pancreatic Beta Cells. THE PANCREATIC BETA CELL 2014; 95:87-114. [DOI: 10.1016/b978-0-12-800174-5.00004-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
36
|
Pérez-Armendariz EM. Connexin 36, a key element in pancreatic beta cell function. Neuropharmacology 2013; 75:557-66. [PMID: 23973309 DOI: 10.1016/j.neuropharm.2013.08.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 08/05/2013] [Accepted: 08/07/2013] [Indexed: 12/01/2022]
Abstract
The prevalence of diabetes at a global scale has markedly increased during the last three decades. Diabetes is a chronic disease that includes a group of metabolic disorders, in which high serum glucose levels is a common factor. Insulin is the only hormone that decreases serum glucose levels. Therefore, it is relevant to deepen our understanding of cell mechanisms that regulate insulin production and release. Insulin is produced in pancreatic islet beta cells. They are excitable cells and most of them are electrically coupled through gap junction channels. Connexin 36 (Cx36) has been identified at junctional membranes of islet beta cells in both rodents and humans. Co-localization of Cx36 with Cx30.2 has been recently identified. Functional studies in Cx36 deficient mice have provided direct evidence that Cx36 gap junction channels are necessary for the synchronization of [Ca(2+)]i oscillations in islet beta cells. The latter allows for the generation of insulin pulses in a single perfused islet. Moreover, Cx36 deficient mice were found to have altered serum insulin pulse dynamics and to be glucose intolerant. In addition, Cx36 has been recently identified as an early gene that is specifically expressed in embryonic beta cells, whose transcript and protein are upregulated in unison with the main wave of beta cell differentiation. In conclusion, Cx36 is critical for endocrine pancreatic function and may represent a molecular target for future prevention and treatment of diabetes. This article is part of the Special Issue Section entitled 'Current Pharmacology of Gap Junction Channels and Hemichannels'.
Collapse
Affiliation(s)
- E Martha Pérez-Armendariz
- Unidad de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Torre de Investigación 5to piso, Avenida Universidad 3000, Circuito Interior, Ciudad Universitaria, UNAM, México D.F. 04510, Mexico; Hospital General de México, Hospital General de México/Unidad de Medicina Experimental, Facultad de Medicina, UNAM, Dr Balmis 148, Colonia Doctores, Delegación Cuahutémoc, CP 06726 Ciudad de México, Mexico; Departamento of Biología Celular yTisular, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Circuito Interior, Ciudad Universitaria, UNAM, Mexico D.F. 04510, Mexico.
| |
Collapse
|
37
|
Hinke SA, Navedo MF, Ulman A, Whiting JL, Nygren PJ, Tian G, Jimenez-Caliani AJ, Langeberg LK, Cirulli V, Tengholm A, Dell'Acqua ML, Santana LF, Scott JD. Anchored phosphatases modulate glucose homeostasis. EMBO J 2012; 31:3991-4004. [PMID: 22940692 PMCID: PMC3474922 DOI: 10.1038/emboj.2012.244] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 07/23/2012] [Indexed: 02/07/2023] Open
Abstract
AKAP150 knockout- and mutant knock-in alleles reveal an unexpected role of the adaptor in anchoring phosphatase 2B for efficient insulin secretion from pancreatic β-cells and thus glucose homeostasis. Endocrine release of insulin principally controls glucose homeostasis. Nutrient-induced exocytosis of insulin granules from pancreatic β-cells involves ion channels and mobilization of Ca2+ and cyclic AMP (cAMP) signalling pathways. Whole-animal physiology, islet studies and live-β-cell imaging approaches reveal that ablation of the kinase/phosphatase anchoring protein AKAP150 impairs insulin secretion in mice. Loss of AKAP150 impacts L-type Ca2+ currents, and attenuates cytoplasmic accumulation of Ca2+ and cAMP in β-cells. Yet surprisingly AKAP150 null animals display improved glucose handling and heightened insulin sensitivity in skeletal muscle. More refined analyses of AKAP150 knock-in mice unable to anchor protein kinase A or protein phosphatase 2B uncover an unexpected observation that tethering of phosphatases to a seven-residue sequence of the anchoring protein is the predominant molecular event underlying these metabolic phenotypes. Thus anchored signalling events that facilitate insulin secretion and glucose homeostasis may be set by AKAP150 associated phosphatase activity.
Collapse
Affiliation(s)
- Simon A Hinke
- Department of Pharmacology, Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Effects of biotin supplementation in the diet on insulin secretion, islet gene expression, glucose homeostasis and beta-cell proportion. J Nutr Biochem 2012; 24:169-77. [PMID: 22841397 DOI: 10.1016/j.jnutbio.2012.03.020] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2011] [Revised: 03/24/2012] [Accepted: 03/28/2012] [Indexed: 12/14/2022]
Abstract
Besides its role as a carboxylase cofactor, biotin has a wide repertoire of effects on gene expression, development and metabolism. Pharmacological concentrations of biotin enhance insulin secretion and the expression of genes and signaling pathways that favor islet function in vitro. However, the in vivo effects of biotin supplementation on pancreatic islet function are largely unknown. In the present study, we investigated whether in vivo biotin supplementation in the diet has positive effects in rodent pancreatic islets. Male BALB/cAnN Hsd mice were fed a control or a biotin-supplemented diet over 8 weeks postweaning and tested for glucose homeostasis, insulin secretion, islet gene expression and pancreatic morphometry. Insulin secretion increased from the islets of biotin-supplemented mice, together with the messenger RNA (mRNA) expression of several transcription factors regulating insulin expression and secretion, including forkhead box A2, pancreatic and duodenal homeobox 1 and hepatocyte nuclear factor 4α. The mRNA abundance of glucokinase, Cacna1d, acetyl-CoA carboxylase, and insulin also increased. Consistent with these effects, glucose tolerance improved, and glucose-stimulated serum insulin levels increased in biotin-supplemented mice, without changes in fasting glucose levels or insulin tolerance. Biotin supplementation augmented the proportion of beta cells by enlarging islet size and, unexpectedly, also increased the percentage of islets with alpha cells at the islet core. mRNA expression of neural cell adhesion molecule 1, an adhesion protein participating in the maintenance of islet architecture, decreased in biotin-supplemented islets. These findings provide, for the first time, insight into how biotin supplementation exerts its effects on function and proportion of beta cells, suggesting a role for biotin in the prevention and treatment of diabetes.
Collapse
|
39
|
Velasco M, Larqué C, Gutiérrez-Reyes G, Arredondo R, Sanchez-Soto C, Hiriart M. Metabolic syndrome induces changes in KATP-channels and calcium currents in pancreatic β-cells. Islets 2012; 4:302-11. [PMID: 22885660 PMCID: PMC3496655 DOI: 10.4161/isl.21374] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Metabolic syndrome (MS) can be defined as a group of signs that increases the risk of developing type 2 diabetes mellitus (DM2). These signs include obesity, hyperinsulinemia and insulin resistance. We are interested in the mechanisms that trigger hyperinsulinemia as a step to understand how β cells fail in DM2. Pancreatic β cells secrete insulin in response to glucose variations in the extracellular medium. When they are chronically over-stimulated, hyperinsulinemia is observed; but then, with time, they become incapable of maintaining normal glucose levels, giving rise to DM2. A chronic high sucrose diet for two months induces MS in adult male Wistar rats. In the present article, we analyzed the effect of the internal environment of rats with MS, on the activity of ATP-sensitive potassium channels (KATP) and calcium currents of pancreatic β cells. After 24 weeks of treatment with 20% sucrose in their drinking water, rats showed central obesity, hyperinsulinemia and insulin resistance, and their systolic blood pressure and triglycerides plasma levels increased. These signs indicate the onset of MS. KATP channels in isolated patches of β cells from MS rats, had an increased sensitivity to ATP with respect to controls. Moreover, the macroscopic calcium currents, show increased variability compared with cells from control individuals. These results demonstrate that regardless of genetic background, a high sucrose diet leads to the development of MS. The observed changes in ionic channels can partially explain the increase in insulin secretion in MS rats. However, some β cells showed smaller calcium currents. These cells may represent a β cell subpopulation as it becomes exhausted by the long-term high sucrose diet.
Collapse
Affiliation(s)
- Myrian Velasco
- Neuroscience Division, Department of Neural Development and Physiology; Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Coyoacán, México.
| | | | | | | | | | | |
Collapse
|
40
|
Finol-Urdaneta RK, Remedi MS, Raasch W, Becker S, Clark RB, Strüver N, Pavlov E, Nichols CG, French RJ, Terlau H. Block of Kv1.7 potassium currents increases glucose-stimulated insulin secretion. EMBO Mol Med 2012; 4:424-34. [PMID: 22438204 PMCID: PMC3403299 DOI: 10.1002/emmm.201200218] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 01/12/2012] [Accepted: 01/13/2012] [Indexed: 01/26/2023] Open
Abstract
Glucose-stimulated insulin secretion (GSIS) relies on repetitive, electrical spiking activity of the beta cell membrane. Cyclic activation of voltage-gated potassium channels (Kv) generates an outward, ‘delayed rectifier’ potassium current, which drives the repolarizing phase of each spike and modulates insulin release. Although several Kv channels are expressed in pancreatic islets, their individual contributions to GSIS remain incompletely understood. We take advantage of a naturally occurring cone-snail peptide toxin, Conkunitzin-S1 (Conk-S1), which selectively blocks Kv1.7 channels to provide an intrinsically limited, finely graded control of total beta cell delayed rectifier current and hence of GSIS. Conk-S1 increases GSIS in isolated rat islets, likely by reducing Kv1.7-mediated delayed rectifier currents in beta cells, which yields increases in action potential firing and cytoplasmic free calcium. In rats, Conk-S1 increases glucose-dependent insulin secretion without decreasing basal glucose. Thus, we conclude that Kv1.7 contributes to the membrane-repolarizing current of beta cells during GSIS and that block of this specific component of beta cell Kv current offers a potential strategy for enhancing GSIS with minimal risk of hypoglycaemia during metabolic disorders such as Type 2 diabetes.
Collapse
Affiliation(s)
- Rocio K Finol-Urdaneta
- Department of Physiology and Pharmacology, and HBI, University of Calgary, Calgary, AB, Canada
| | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Abstract
The pancreas is characterized by a major component, an exocrine and ductal system involved in digestion, and a minor component, the endocrine islets represented by islet micro-organs that tightly regulate glucose homoeostasis. Pancreatic organogenesis is strictly co-ordinated by transcription factors that are expressed sequentially to yield functional islets capable of maintaining glucose homoeostasis. Angiogenesis and innervation complete islet development, equipping islets to respond to metabolic demands. Proper regulation of this triad of processes during development is critical for establishing functional islets.
Collapse
|
42
|
Raoux M, Bornat Y, Quotb A, Catargi B, Renaud S, Lang J. Non-invasive long-term and real-time analysis of endocrine cells on micro-electrode arrays. J Physiol 2011; 590:1085-91. [PMID: 22199167 DOI: 10.1113/jphysiol.2011.220038] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Non-invasive high-throughput and long-term monitoring of endocrine cells is important for drug research, phenotyping, tissue engineering and pre-transplantation quality control. Here we report a novel approach to obtain simultaneous long-term electrical recordings of different islet cell types using multi-electrode arrays. We implemented wavelet transforms to resolve the low signal/noise ratio inherent to these measurements and extracted on-line a signature specific of cell activity. The architecture employed allows multiplexing a large number of electrodes for high-throughput screening. This method should be of considerable advantage in endocrine research and may be extended to other excitable cells previously not accessible to the technique.
Collapse
Affiliation(s)
- Matthieu Raoux
- Université de Bordeaux, CBMN, UMR 5248, F-33600 Pessac, France
| | | | | | | | | | | |
Collapse
|
43
|
Low molecular weight compounds from Zoanthus sociatus impair insulin secretion via Ca(+2) influx blockade and cause glucose intolerance in vivo. Toxicon 2011; 59:306-14. [PMID: 22155304 DOI: 10.1016/j.toxicon.2011.11.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 11/17/2011] [Accepted: 11/23/2011] [Indexed: 11/24/2022]
Abstract
Cnidarians comprise a taxon with a high biodiversity of cytolitic, neurotoxic and cardiotoxic compounds, which have not been studied on insulin release. We tested the effect of a crude extract of Zoanthus sociatus (Ellis, 1767) and the low molecular weight fraction of this extract on insulin secretion in isolated rat β-cells and also in a glucose tolerance test in vivo. We observed that the extract inhibited insulin release by reducing the amount secreted by individual β-cells and also by silencing a fraction of the secreting population. This effect coincided with a diminished rise of intracellular Ca(+2) in response to high glucose and high K+ -induced depolarization. Moreover intraperitoneal administration of the low molecular weight fraction produced glucose intolerance in adult rats. The active fraction exhibited molecular weights similar to the neurotoxins described in the phylum. Our results broaden the toxic effects of cnidarian venoms and show evidence of potential modulators of voltage-gated Ca(+2) channels in this group.
Collapse
|
44
|
Larqué C, Velasco M, Navarro-Tableros V, Duhne M, Aguirre J, Gutiérrez-Reyes G, Moreno J, Robles-Diaz G, Hong E, Hiriart M. Early endocrine and molecular changes in metabolic syndrome models. IUBMB Life 2011; 63:831-9. [PMID: 21905198 DOI: 10.1002/iub.544] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 07/02/2011] [Indexed: 12/12/2022]
Abstract
The twenty-first century arrived in the middle of a global epidemic of metabolic syndrome (MS) and type 2 diabetes mellitus (DM2). It is generally accepted that an excess of nutrients linked to a low physical activity triggers the problem. However, the molecular features that interact to develop the MS are not clear. In an effort to understand and control them, they have been extensively studied, but this goal has not been achieved yet. Nonhuman animal models have been used to explore diet and genetic factors in which experimental conditions are controlled. For example, only one factor in the diet, such as fats or carbohydrates can be modified to better understand a single change that would be impossible in humans. Most of the studies have been done in rodents. However, it is difficult to directly compare them, because experiments are different in more than one variable; genetic strains, amount, and the type of fat used in the diet and sex. Thus, the only possible criteria of comparison are the relevance of the observed changes. We review different animal models and add some original observations on short-term changes in metabolism and beta cells in our own model of adult Wistar rats that are not especially prone to get fat or develop DM2, treated with 20% sucrose in drinking water. One early change observed in pancreatic beta cells is the increase in GLUT2 expression that is located to the membrane of the cells. This change could partially explain the presence of insulin hypersecretion and hyperinsulinemia in these rats. Understanding early changes that lead to MS and in time to pancreatic islet exhaustion is an important biomedical problem that may contribute to learn how to prevent or even reverse MS, before developing DM2.
Collapse
Affiliation(s)
- Carlos Larqué
- Neuroscience Division, Department of Neural Development and Physiology, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico DF, Mexico
| | | | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Sankar KS, Green BJ, Crocker AR, Verity JE, Altamentova SM, Rocheleau JV. Culturing pancreatic islets in microfluidic flow enhances morphology of the associated endothelial cells. PLoS One 2011; 6:e24904. [PMID: 21961048 PMCID: PMC3178551 DOI: 10.1371/journal.pone.0024904] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 08/19/2011] [Indexed: 11/24/2022] Open
Abstract
Pancreatic islets are heavily vascularized in vivo with each insulin secreting beta-cell associated with at least one endothelial cell (EC). This structure is maintained immediately post-isolation; however, in culture the ECs slowly deteriorate, losing density and branched morphology. We postulate that this deterioration occurs in the absence of blood flow due to limited diffusion of media inside the tissue. To improve exchange of media inside the tissue, we created a microfluidic device to culture islets in a range of flow-rates. Culturing the islets from C57BL6 mice in this device with media flowing between 1 and 7 ml/24 hr resulted in twice the EC-density and -connected length compared to classically cultured islets. Media containing fluorescent dextran reached the center of islets in the device in a flow-rate-dependant manner consistent with improved penetration. We also observed deterioration of EC morphology using serum free media that was rescued by addition of bovine serum albumin, a known anti-apoptotic signal with limited diffusion in tissue. We further examined the effect of flow on beta-cells showing dampened glucose-stimulated Ca2+-response from cells at the periphery of the islet where fluid shear-stress is greatest. However, we observed normal two-photon NAD(P)H response and insulin secretion from the remainder of the islet. These data reveal the deterioration of islet EC-morphology is in part due to restricted diffusion of serum albumin within the tissue. These data further reveal microfluidic devices as unique platforms to optimize islet culture by introducing intercellular flow to overcome the restricted diffusion of media components.
Collapse
Affiliation(s)
- Krishana S. Sankar
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Brenda J. Green
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Alana R. Crocker
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Jocelyne E. Verity
- Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
| | | | - Jonathan V. Rocheleau
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
- * E-mail:
| |
Collapse
|
46
|
Klassen T, Davis C, Goldman A, Burgess D, Chen T, Wheeler D, McPherson J, Bourquin T, Lewis L, Villasana D, Morgan M, Muzny D, Gibbs R, Noebels J. Exome sequencing of ion channel genes reveals complex profiles confounding personal risk assessment in epilepsy. Cell 2011; 145:1036-48. [PMID: 21703448 DOI: 10.1016/j.cell.2011.05.025] [Citation(s) in RCA: 234] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 04/21/2011] [Accepted: 05/20/2011] [Indexed: 11/25/2022]
Abstract
Ion channel mutations are an important cause of rare Mendelian disorders affecting brain, heart, and other tissues. We performed parallel exome sequencing of 237 channel genes in a well-characterized human sample, comparing variant profiles of unaffected individuals to those with the most common neuronal excitability disorder, sporadic idiopathic epilepsy. Rare missense variation in known Mendelian disease genes is prevalent in both groups at similar complexity, revealing that even deleterious ion channel mutations confer uncertain risk to an individual depending on the other variants with which they are combined. Our findings indicate that variant discovery via large scale sequencing efforts is only a first step in illuminating the complex allelic architecture underlying personal disease risk. We propose that in silico modeling of channel variation in realistic cell and network models will be crucial to future strategies assessing mutation profile pathogenicity and drug response in individuals with a broad spectrum of excitability disorders.
Collapse
Affiliation(s)
- Tara Klassen
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Gandini MA, Sandoval A, González-Ramírez R, Mori Y, de Waard M, Felix R. Functional coupling of Rab3-interacting molecule 1 (RIM1) and L-type Ca2+ channels in insulin release. J Biol Chem 2011; 286:15757-65. [PMID: 21402706 DOI: 10.1074/jbc.m110.187757] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Insulin release by pancreatic β-cells is regulated by diverse intracellular signals, including changes in Ca(2+) concentration resulting from Ca(2+) entry through voltage-gated (Ca(V)) channels. It has been reported that the Rab3 effector RIM1 acts as a functional link between neuronal Ca(V) channels and the machinery for exocytosis. Here, we investigated whether RIM1 regulates recombinant and native L-type Ca(V) channels (that play a key role in hormone secretion) and whether this regulation affects insulin release. Whole-cell patch clamp currents were recorded from HEK-293 and insulinoma RIN-m5F cells. RIM1 and Ca(V) channel expression was identified by RT-PCR and Western blot. RIM1-Ca(V) channel interaction was determined by co-immunoprecipitation. Knockdown of RIM1 and Ca(V) channel subunit expression were performed using small interference RNAs. Insulin release was assessed by ELISA. Co-expression of Ca(V)1.2 and Ca(V)1.3 L-type channels with RIM1 in HEK-293 cells revealed that RIM1 may not determine the availability of L-type Ca(V) channels but decreases the rate of inactivation of the whole cell currents. Co-immunoprecipitation experiments showed association of the Ca(V)β auxiliary subunit with RIM1. The lack of Ca(V)β expression suppressed channel regulation by RIM1. Similar to the heterologous system, an increase of current inactivation was observed upon knockdown of endogenous RIM1. Co-immunoprecipitation showed association of Ca(V)β and RIM1 in insulin-secreting RIN-m5F cells. Knockdown of RIM1 notably impaired high K(+)-stimulated insulin secretion in the RIN-m5F cells. These data unveil a novel functional coupling between RIM1 and the L-type Ca(V) channels via the Ca(V)β auxiliary subunit that contribute to determine insulin secretion.
Collapse
Affiliation(s)
- María A Gandini
- Department of Cell Biology, Center for Research and Advanced Studies, National Polytechnic Institute (Cinvestav-IPN), Colonia Zacatenco, México DF, México
| | | | | | | | | | | |
Collapse
|
48
|
Choi KJ, Cho DS, Kim JY, Kim BJ, Lee KM, Kim SH, Kim DK, Kim SH, Park HS. Ca-induced Ca Release from Internal Stores in INS-1 Rat Insulinoma Cells. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2011; 15:53-9. [PMID: 21461241 DOI: 10.4196/kjpp.2011.15.1.53] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 02/14/2011] [Accepted: 02/16/2011] [Indexed: 12/23/2022]
Abstract
The secretion of insulin from pancreatic β-cells is triggered by the influx of Ca(2+) through voltage-dependent Ca(2+) channels. The resulting elevation of intracellular calcium ([Ca(2+)](i)) triggers additional Ca(2+) release from internal stores. Less well understood are the mechanisms involved in Ca(2+) mobilization from internal stores after activation of Ca(2+) influx. The mobilization process is known as calcium-induced calcium release (CICR). In this study, our goal was to investigate the existence of and the role of caffeine-sensitive ryanodine receptors (RyRs) in a rat pancreatic β-cell line, INS-1 cells. To measure cytosolic and stored Ca(2+), respectively, cultured INS-1 cells were loaded with fura-2/AM or furaptra/AM. [Ca(2+)](i) was repetitively increased by caffeine stimulation in normal Ca(2+) buffer. However, peak [Ca(2+)](i) was only observed after the first caffeine stimulation in Ca(2+) free buffer and this increase was markedly blocked by ruthenium red, a RyR blocker. KCl-induced elevations in [Ca(2+)](i) were reduced by pretreatment with ruthenium red, as well as by depletion of internal Ca(2+) stores using cyclopiazonic acid (CPA) or caffeine. Caffeine-induced Ca(2+) mobilization ceased after the internal stores were depleted by carbamylcholine (CCh) or CPA. In permeabilized INS-1 cells, Ca(2+) release from internal stores was activated by caffeine, Ca(2+), or ryanodine. Furthermore, ruthenium red completely blocked the CICR response in permeabilized cells. RyRs were widely distributed throughout the intracellular compartment of INS-1 cells. These results suggest that caffeine-sensitive RyRs exist and modulate the CICR response from internal stores in INS-1 pancreatic β-cells.
Collapse
Affiliation(s)
- Kyung Jin Choi
- Department of Physiology, College of Medicine, Konyang University, Daejeon 302-718, Korea
| | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Stepien M, Gaudichon C, Fromentin G, Even P, Tomé D, Azzout-Marniche D. Increasing protein at the expense of carbohydrate in the diet down-regulates glucose utilization as glucose sparing effect in rats. PLoS One 2011; 6:e14664. [PMID: 21326875 PMCID: PMC3034717 DOI: 10.1371/journal.pone.0014664] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2010] [Accepted: 01/11/2011] [Indexed: 12/22/2022] Open
Abstract
High protein (HP) diet could serve as a good strategy against obesity, provoking the changes in energy metabolic pathways. However, those modifications differ during a dietary adaptation. To better understand the mechanisms involved in effect of high protein diet (HP) on limiting adiposity in rats we studied in parallel the gene expression of enzymes involved in protein and energy metabolism and the profiles of nutrients oxidation. Eighty male Wistar rats were fed a normal protein diet (NP, 14% of protein) for one week, then either maintained on NP diet or assigned to a HP diet (50% of protein) for 1, 3, 6 and 14 days. mRNA levels of genes involved in carbohydrate and lipid metabolism were measured in liver, adipose tissues, kidney and muscles by real time PCR. Energy expenditure (EE) and substrate oxidation were measured by indirect calorimetry. Liver glycogen and plasma glucose and hormones were assayed. In liver, HP feeding 1) decreased mRNA encoding glycolysis enzymes (GK, L-PK) and lipogenesis enzymes(ACC, FAS), 2) increased mRNA encoding gluconeogenesis enzymes (PEPCK), 3) first lowered, then restored mRNA encoding glycogen synthesis enzyme (GS), 4) did not change mRNA encoding β-oxidation enzymes (CPT1, ACOX1, βHAD). Few changes were seen in other organs. In parallel, indirect calorimetry confirmed that following HP feeding, glucose oxidation was reduced and fat oxidation was stable, except during the 1(st) day of adaptation where lipid oxidation was increased. Finally, this study showed that plasma insulin was lowered and hepatic glucose uptake was decreased. Taken together, these results demonstrate that following HP feeding, CHO utilization was increased above the increase in carbohydrate intake while lipogenesis was decreased thus giving a potential explanation for the fat lowering effect of HP diets.
Collapse
Affiliation(s)
- Magdalena Stepien
- INRA/AgroParisTech, CNRH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
- INRA,CNRH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
| | - Claire Gaudichon
- INRA/AgroParisTech, CNRH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
- INRA,CNRH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
| | - Gilles Fromentin
- INRA/AgroParisTech, CNRH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
- INRA,CNRH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
| | - Patrick Even
- INRA/AgroParisTech, CNRH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
- INRA,CNRH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
| | - Daniel Tomé
- INRA/AgroParisTech, CNRH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
- INRA,CNRH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
| | - Dalila Azzout-Marniche
- INRA/AgroParisTech, CNRH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
- INRA,CNRH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
- * E-mail:
| |
Collapse
|
50
|
Uchida K, Tominaga M. The role of thermosensitive TRP (transient receptor potential) channels in insulin secretion. Endocr J 2011; 58:1021-8. [PMID: 21785227 DOI: 10.1507/endocrj.ej11-0130] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Insulin secretion from pancreatic β-cells is the only efficient means to decrease blood glucose concentrations. Glucose is the principal stimulator of insulin secretion with the ATP-sensitive K+ channel-voltage-gated Ca2+ channel-mediated pathway being the primary one involved in glucose-stimulated insulin secretion. Recently, several reports demonstrated that some transient receptor potential (TRP) channels are expressed in pancreatic β-cells and contribute to pancreatic β-cell functions. Interestingly, six of them (TRPM2, TRPM4, TRPM5, TRPV1, TRPV2 and TRPV4) are thermosensitive TRP channels. Thermosensitive TRP channels in pancreatic β-cells can function as multimodal receptors and cause Ca2+ influx and membrane depolarization at physiological body temperature. TRPM channels (TRPM2, TRPM4 and TRPM5) control insulin secretion levels by sensing intracellular Ca2+ increase, NAD metabolites, or hormone receptor activation. TRPV2 is involved not only in insulin secretion but also cell proliferation, and is regulated by the autocrine effects of insulin. TRPV1 expressed in sensory neurons is involved in β-cell stress and islet inflammation by controlling neuropeptide release levels. It is thus clear that thermosensitive TRP channels play important roles in pancreatic β-cell functions, and future analyses of TRP channel function will lead to better understanding of the complicated mechanisms involved in insulin secretion and diabetes pathogenesis.
Collapse
Affiliation(s)
- Kunitoshi Uchida
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Aichi 444-8787 Japan.
| | | |
Collapse
|