1
|
Wei C, Zhang Z, Fu Q, He Y, Yang T, Sun M. The reversible effects of free fatty acids on sulfonylurea-stimulated insulin secretion are related to the expression and dynamin-mediated endocytosis of KATP channels in pancreatic β cells. Endocr Connect 2023; 12:e220221. [PMID: 36398885 PMCID: PMC9782416 DOI: 10.1530/ec-22-0221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 11/18/2022] [Indexed: 11/19/2022]
Abstract
Objective Lipotoxicity-induced pancreatic β cell-dysfunction results in decreased insulin secretion in response to multiple stimulus. In this study, we investigated the reversible effects of palmitate (PA) or oleate (OA) on insulin secretion and the relationship with pancreatic β-cell ATP-sensitive potassium (KATP) channels. Methods MIN6 cells were treated with PA and OA for 48 h and then washed out for 24 h to determine the changes in expression and endocytosis of the KATP channels and glucose-stimulated insulin secretion (GSIS) and sulfonylurea-stimulated insulin secretion (SU-SIS). Results MIN6 cells exposed to PA or OA showed both impaired GSIS and SU-SIS; the former was not restorable, while the latter was reversible with washout of PA or OA. Decreased expressions of both total and surface Kir6.2 and SUR1 and endocytosis of KATP channels were observed, which were also recoverable after washout. When MIN6 cells exposed to free fatty acids (FFAs) were cotreated with 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) or dynasore, we found that endocytosis of KATP channels did not change significantly by AICAR but was almost completely blocked by dynasore. Meanwhile, the inhibition of endocytosis of KATP channels after washout could be activated by PIP2. The recovery of SU-SIS after washout was significantly weakened by PIP2, but the decrease of SU-SIS induced by FFAs was not alleviated by dynasore. Conclusions FFAs can cause reversible impairment of SU-SIS on pancreatic β cells. The reversibility of the effects is partial because of the changes of expression and endocytosis of Kir6.2 and SUR1 which was mediated by dynamin.
Collapse
Affiliation(s)
- Chenmin Wei
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
- Department of Endocrinology, The Affiliated Jiangning Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Zichen Zhang
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Qi Fu
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yunqiang He
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Tao Yang
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Min Sun
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| |
Collapse
|
2
|
Maejima Y, Horita S, Yokota S, Yamachi M, Shimizu M, Ono T, Yu Z, Tomita H, Shimomura K. Surface translocation of Kir2.1 channel induces IL-1β secretion in microglia. Mol Cell Neurosci 2022; 120:103734. [DOI: 10.1016/j.mcn.2022.103734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 04/25/2022] [Accepted: 04/28/2022] [Indexed: 11/29/2022] Open
|
3
|
Nichols CG, York NW, Remedi MS. ATP-Sensitive Potassium Channels in Hyperinsulinism and Type 2 Diabetes: Inconvenient Paradox or New Paradigm? Diabetes 2022; 71:367-375. [PMID: 35196393 PMCID: PMC8893938 DOI: 10.2337/db21-0755] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 11/28/2021] [Indexed: 11/13/2022]
Abstract
Secretion of insulin from pancreatic β-cells is complex, but physiological glucose-dependent secretion is dominated by electrical activity, in turn controlled by ATP-sensitive potassium (KATP) channel activity. Accordingly, loss-of-function mutations of the KATP channel Kir6.2 (KCNJ11) or SUR1 (ABCC8) subunit increase electrical excitability and secretion, resulting in congenital hyperinsulinism (CHI), whereas gain-of-function mutations cause underexcitability and undersecretion, resulting in neonatal diabetes mellitus (NDM). Thus, diazoxide, which activates KATP channels, and sulfonylureas, which inhibit KATP channels, have dramatically improved therapies for CHI and NDM, respectively. However, key findings do not fit within this simple paradigm: mice with complete absence of β-cell KATP activity are not hyperinsulinemic; instead, they are paradoxically glucose intolerant and prone to diabetes, as are older human CHI patients. Critically, despite these advances, there has been little insight into any role of KATP channel activity changes in the development of type 2 diabetes (T2D). Intriguingly, the CHI progression from hypersecretion to undersecretion actually mirrors the classical response to insulin resistance in the progression of T2D. In seeking to explain the progression of CHI, multiple lines of evidence lead us to propose that underlying mechanisms are also similar and that development of T2D may involve loss of KATP activity.
Collapse
Affiliation(s)
- Colin G Nichols
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO
| | - Nathaniel W York
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO
| | - Maria S Remedi
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO
- Division of Endocrinology Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| |
Collapse
|
4
|
Lin RJ, Yen YK, Lee CH, Hsieh SL, Chang YC, Juan YS, Long CY, Shen KP, Wu BN. Eugenosedin-A improves obesity-related hyperglycemia by regulating ATP-sensitive K + channels and insulin secretion in pancreatic β cells. Biomed Pharmacother 2021; 145:112447. [PMID: 34808553 DOI: 10.1016/j.biopha.2021.112447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/08/2021] [Accepted: 11/16/2021] [Indexed: 12/31/2022] Open
Abstract
Eugenosedin-A (Eu-A) has been shown to protect against hyperglycemia- and hyperlipidemia-induced metabolic syndrome. We investigated the relationship of KATP channel activities and insulin secretion by Eu-A in vitro in pancreatic β-cells, and examined the effect of Eu-A on streptozotocin (STZ)/nicotinamide (NA)-induced type 2 diabetes mellitus (T2DM) in vivo. We isolated pancreatic islets from adult male Wistar rats (250-350 g) and identified pancreatic β-cells by the cell size, capacitance and membrane potential. Perforated patch-clamp and inside-out recordings were used to monitor the membrane potential (current-clamp mode) and channel activity (voltage-clamp mode) of β-cells. The membrane potential of β-cells was raised by Eu-A and reversed by the KATP channel activator diazoxide. Eu-A inhibited the KATP channel activity measured at - 60 mV and increased the intracellular calcium concentration ([Ca2+]i), resulting in enhanced insulin secretion. Eu-A also reduced Kir6.2 protein on the cell membrane and scattered in the cytosol under normal glucose conditions (5.6 mM). In our animal study, rats were divided into normal and STZ/NA-induced T2DM groups. Normal rats fed with regular chow were divided into control and control+Eu-A (5 mg/kg/day, i.p.) groups. The STZ/NA-induced diabetic rats fed with a high-fat diet (HFD) were divided into three groups: T2DM, T2DM+Eu-A (5 mg/kg/day, i.p.), and T2DM+glibenclamide (0.5 mg/kg/day, i.p.; a KATP channel inhibitor). Both Eu-A and glibenclamide decreased the rats' blood glucose, prevented weight gain, and enhanced insulin secretion. We found that Eu-A blocked pancreatic β-cell KATP channels, caused membrane potential depolarization, and stimulated Ca2+ influx, thus increasing insulin secretion. Furthermore, Eu-A decreased blood glucose and increased insulin levels in T2DM rats. These results suggested that Eu-A might have clinical benefits for the control of T2DM and its complications.
Collapse
Affiliation(s)
- Rong-Jyh Lin
- Department of Parasitology, Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan; Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan
| | - Yu-Kwan Yen
- Department of Pharmacology, Graduate Institute of Medicine, College of Medicine, Drug Development and Value Creation Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Chien-Hsing Lee
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan; Department of Pharmacology, Graduate Institute of Medicine, College of Medicine, Drug Development and Value Creation Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Su-Ling Hsieh
- Department of Pharmacy, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan
| | - Yu-Chin Chang
- Department of Pharmacology, Graduate Institute of Medicine, College of Medicine, Drug Development and Value Creation Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Yung-Shun Juan
- Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Cheng-Yu Long
- Department of Obstetrics and Gynecology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Kuo-Ping Shen
- Department of Nursing, Meiho University, Pingtung 912, Taiwan.
| | - Bin-Nan Wu
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan; Department of Pharmacology, Graduate Institute of Medicine, College of Medicine, Drug Development and Value Creation Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| |
Collapse
|
5
|
Abstract
Beta cells of the pancreatic islet express many different types of ion channels. These channels reside in the β-cell plasma membrane as well as subcellular organelles and their coordinated activity and sensitivity to metabolism regulate glucose-dependent insulin secretion. Here, we review the molecular nature, expression patterns, and functional roles of many β-cell channels, with an eye toward explaining the ionic basis of glucose-induced insulin secretion. Our primary focus is on KATP and voltage-gated Ca2+ channels as these primarily regulate insulin secretion; other channels in our view primarily help to sculpt the electrical patterns generated by activated β-cells or indirectly regulate metabolism. Lastly, we discuss why understanding the physiological roles played by ion channels is important for understanding the secretory defects that occur in type 2 diabetes. © 2021 American Physiological Society. Compr Physiol 11:1-21, 2021.
Collapse
Affiliation(s)
- Benjamin Thompson
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
- Brehm Diabetes Research Center, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | | |
Collapse
|
6
|
Role of cAMP in Double Switch of Glucagon Secretion. Cells 2021; 10:cells10040896. [PMID: 33919776 PMCID: PMC8070687 DOI: 10.3390/cells10040896] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/12/2021] [Accepted: 04/12/2021] [Indexed: 01/03/2023] Open
Abstract
Glucose metabolism plays a crucial role in modulating glucagon secretion in pancreatic alpha cells. However, the downstream effects of glucose metabolism and the activated signaling pathways influencing glucagon granule exocytosis are still obscure. We developed a computational alpha cell model, implementing metabolic pathways of glucose and free fatty acids (FFA) catabolism and an intrinsically activated cAMP signaling pathway. According to the model predictions, increased catabolic activity is able to suppress the cAMP signaling pathway, reducing exocytosis in a Ca2+-dependent and Ca2+ independent manner. The effect is synergistic to the pathway involving ATP-dependent closure of KATP channels and consequent reduction of Ca2+. We analyze the contribution of each pathway to glucagon secretion and show that both play decisive roles, providing a kind of "secure double switch". The cAMP-driven signaling switch plays a dominant role, while the ATP-driven metabolic switch is less favored. The ratio is approximately 60:40, according to the most recent experimental evidence.
Collapse
|
7
|
Nichols CG, York NW, Remedi MS. Preferential Gq signaling in diabetes: an electrical switch in incretin action and in diabetes progression? J Clin Invest 2021; 130:6235-6237. [PMID: 33196460 DOI: 10.1172/jci143199] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Patients with type 2 diabetes (T2D) fail to secrete insulin in response to increased glucose levels that occur with eating. Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are two incretins secreted from gastrointestinal cells that amplify insulin secretion when glucose is high. In this issue of the JCI, Oduori et al. explore the role of ATP-sensitive K+ (KATP) channels in maintaining glucose homeostasis. In persistently depolarized β cells from KATP channel knockout (KO) mice, the researchers revealed a shift in G protein signaling from the Gs family to the Gq family. This shift explains why GLP-1, which signals via Gq, but not GIP, which signals preferentially via Gs, can effectively potentiate secretion in islets from the KATP channel-deficient mice and in other models of KATP deficiency, including diabetic KK-Ay mice. Their results provide one explanation for differential insulinotropic potential of incretins in human T2D and point to a potentially unifying model for T2D progression itself.
Collapse
Affiliation(s)
- Colin G Nichols
- Center for the Investigation of Membrane Excitability Diseases.,Department of Cell Biology and Physiology
| | - Nathaniel W York
- Center for the Investigation of Membrane Excitability Diseases.,Department of Cell Biology and Physiology
| | - Maria S Remedi
- Center for the Investigation of Membrane Excitability Diseases.,Division of Endocrinology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| |
Collapse
|
8
|
Grubelnik V, Zmazek J, Markovič R, Gosak M, Marhl M. Mitochondrial Dysfunction in Pancreatic Alpha and Beta Cells Associated with Type 2 Diabetes Mellitus. Life (Basel) 2020; 10:E348. [PMID: 33327428 PMCID: PMC7764865 DOI: 10.3390/life10120348] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/04/2020] [Accepted: 12/10/2020] [Indexed: 12/16/2022] Open
Abstract
Type 2 diabetes mellitus is a complex multifactorial disease of epidemic proportions. It involves genetic and lifestyle factors that lead to dysregulations in hormone secretion and metabolic homeostasis. Accumulating evidence indicates that altered mitochondrial structure, function, and particularly bioenergetics of cells in different tissues have a central role in the pathogenesis of type 2 diabetes mellitus. In the present study, we explore how mitochondrial dysfunction impairs the coupling between metabolism and exocytosis in the pancreatic alpha and beta cells. We demonstrate that reduced mitochondrial ATP production is linked with the observed defects in insulin and glucagon secretion by utilizing computational modeling approach. Specifically, a 30-40% reduction in alpha cells' mitochondrial function leads to a pathological shift of glucagon secretion, characterized by oversecretion at high glucose concentrations and insufficient secretion in hypoglycemia. In beta cells, the impaired mitochondrial energy metabolism is accompanied by reduced insulin secretion at all glucose levels, but the differences, compared to a normal beta cell, are the most pronounced in hyperglycemia. These findings improve our understanding of metabolic pathways and mitochondrial bioenergetics in the pathology of type 2 diabetes mellitus and might help drive the development of innovative therapies to treat various metabolic diseases.
Collapse
Affiliation(s)
- Vladimir Grubelnik
- Faculty of Electrical Engineering and Computer Science, University of Maribor, SI-2000 Maribor, Slovenia; (V.G.); (R.M.)
| | - Jan Zmazek
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia; (J.Z.); (M.G.)
| | - Rene Markovič
- Faculty of Electrical Engineering and Computer Science, University of Maribor, SI-2000 Maribor, Slovenia; (V.G.); (R.M.)
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia; (J.Z.); (M.G.)
| | - Marko Gosak
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia; (J.Z.); (M.G.)
- Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia
| | - Marko Marhl
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia; (J.Z.); (M.G.)
- Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia
- Faculty of Education, University of Maribor, SI-2000 Maribor, Slovenia
| |
Collapse
|
9
|
Sohn JW, Ho WK. Cellular and systemic mechanisms for glucose sensing and homeostasis. Pflugers Arch 2020; 472:1547-1561. [PMID: 32960363 DOI: 10.1007/s00424-020-02466-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 08/14/2020] [Accepted: 09/14/2020] [Indexed: 12/25/2022]
Abstract
Glucose is a major source of energy in animals. Maintaining blood glucose levels within a physiological range is important for facilitating glucose uptake by cells, as required for optimal functioning. Glucose homeostasis relies on multiple glucose-sensing cells in the body that constantly monitor blood glucose levels and respond accordingly to adjust its glycemia. These include not only pancreatic β-cells and α-cells that secrete insulin and glucagon, but also central and peripheral neurons regulating pancreatic endocrine function. Different types of cells respond distinctively to changes in blood glucose levels, and the mechanisms involved in glucose sensing are diverse. Notably, recent studies have challenged the currently held views regarding glucose-sensing mechanisms. Furthermore, peripheral and central glucose-sensing cells appear to work in concert to control blood glucose level and maintain glucose and energy homeostasis in organisms. In this review, we summarize the established concepts and recent advances in the understanding of cellular and systemic mechanisms that regulate glucose sensing and its homeostasis.
Collapse
Affiliation(s)
- Jong-Woo Sohn
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, South Korea.
| | - Won-Kyung Ho
- Department of Physiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongro-gu, Seoul, 03080, South Korea.
- Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, South Korea.
| |
Collapse
|
10
|
Grubelnik V, Zmazek J, Markovič R, Gosak M, Marhl M. Modelling of energy-driven switch for glucagon and insulin secretion. J Theor Biol 2020; 493:110213. [PMID: 32109481 DOI: 10.1016/j.jtbi.2020.110213] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 02/19/2020] [Accepted: 02/24/2020] [Indexed: 12/14/2022]
Abstract
We present a mathematical model of the energy-driven metabolic switch for glucagon and insulin secretion from pancreatic alpha and beta cells, respectively. The energy status related to hormone secretion is studied for various glucose concentrations. Additionally, the physiological response is studied with regards to the presence of other metabolites, particularly the free-fatty acids. At low glucose, the ATP production in alpha cells is high due to free-fatty acids oxidation in mitochondria, which enables glucagon secretion. When the glucose concentration is elevated above the threshold value, the glucagon secretion is switched off due to the contribution of glycolytic ATP production, representing an "anaerobic switch". On the other hand, during hypoglycemia, the ATP production in beta cells is low, reflecting a "waiting state" for glucose as the main metabolite. When glucose is elevated above the threshold value, the oxidative fate of glucose in mitochondria is the main source of energy required for effective insulin secretion, i.e. the "aerobic switch". Our results show the importance of well-regulated and fine-tuned energetic processes in pancreatic alpha and beta cells required for efficient hormone secretion and hence effective blood glucose regulation. These energetic processes have to be appropriately switched on and off based on the sensing of different metabolites by alpha and beta cells. Our computational results indicate that disturbances in cell energetics (e.g. mitochondrial dysfunction), and dysfunctional metabolite sensing and distribution throughout the cell might be related to pathologies such as metabolic syndrome and diabetes.
Collapse
Affiliation(s)
- Vladimir Grubelnik
- Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor SI-2000, Slovenia
| | - Jan Zmazek
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor SI-2000, Slovenia
| | - Rene Markovič
- Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor SI-2000, Slovenia; Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor SI-2000, Slovenia
| | - Marko Gosak
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor SI-2000, Slovenia; Faculty of Medicine, University of Maribor, Maribor SI-2000, Slovenia
| | - Marko Marhl
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor SI-2000, Slovenia; Faculty of Medicine, University of Maribor, Maribor SI-2000, Slovenia; Faculty of Education, University of Maribor, Maribor SI-2000, Slovenia.
| |
Collapse
|
11
|
Gómez-Elías MD, Fissore RA, Cuasnicú PS, Cohen DJ. Compensatory endocytosis occurs after cortical granule exocytosis in mouse eggs. J Cell Physiol 2019; 235:4351-4360. [PMID: 31612508 DOI: 10.1002/jcp.29311] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 09/30/2019] [Indexed: 12/31/2022]
Abstract
Compensatory endocytosis (CE) is one of the primary mechanisms through which cells maintain their surface area after exocytosis. Considering that in eggs massive exocytosis of cortical granules (CG) takes place after fertilization, the aim of this study was to evaluate the occurrence of CE following cortical exocytosis in mouse eggs. For this purpose, we developed a pulse-chase assay to detect CG membrane internalization. Results showed internalized labeling in SrCl2 -activated and fertilized eggs when chasing at 37°C, but not at a nonpermissive temperature (4°C). The use of kinase and calcineurin inhibitors led us to conclude that this internal labeling corresponded to CE. Further experiments showed that CE in mouse eggs is dependent on actin dynamics and dynamin activity, and could be associated with a transient exposure of phosphatidylserine. Finally, CE was impaired in A23187 ionophore-activated eggs, highlighting once again the mechanistic differences between the activation methods. Altogether, these results demonstrate for the first time that egg activation triggers CE in mouse eggs after exocytosis of CG, probably as a plasma membrane homeostasis mechanism.
Collapse
Affiliation(s)
- Matías D Gómez-Elías
- Laboratorio de Mecanismos Moleculares de la Fertilización, Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científico y Técnicas (IBYME-CONICET), Buenos Aires, Argentina
| | - Rafael A Fissore
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, 661 North Pleasant Street, Amherst, Massachusetts
| | - Patricia S Cuasnicú
- Laboratorio de Mecanismos Moleculares de la Fertilización, Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científico y Técnicas (IBYME-CONICET), Buenos Aires, Argentina
| | - Débora J Cohen
- Laboratorio de Mecanismos Moleculares de la Fertilización, Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científico y Técnicas (IBYME-CONICET), Buenos Aires, Argentina
| |
Collapse
|
12
|
Leptin-induced Trafficking of K ATP Channels: A Mechanism to Regulate Pancreatic β-cell Excitability and Insulin Secretion. Int J Mol Sci 2019; 20:ijms20112660. [PMID: 31151172 PMCID: PMC6600549 DOI: 10.3390/ijms20112660] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Revised: 05/25/2019] [Accepted: 05/27/2019] [Indexed: 11/17/2022] Open
Abstract
The adipocyte hormone leptin was first recognized for its actions in the central nervous system to regulate energy homeostasis but has since been shown to have direct actions on peripheral tissues. In pancreatic β-cells leptin suppresses insulin secretion by increasing KATP channel conductance, which causes membrane hyperpolarization and renders β-cells electrically silent. However, the mechanism by which leptin increases KATP channel conductance had remained unresolved for many years following the initial observation. Recent studies have revealed that leptin increases surface abundance of KATP channels by promoting channel trafficking to the β-cell membrane. Thus, KATP channel trafficking regulation has emerged as a mechanism by which leptin increases KATP channel conductance to regulate β-cell electrical activity and insulin secretion. This review will discuss the leptin signaling pathway that underlies KATP channel trafficking regulation in β-cells.
Collapse
|
13
|
Hwang HJ, Jang HJ, Cocco L, Suh PG. The regulation of insulin secretion via phosphoinositide-specific phospholipase Cβ signaling. Adv Biol Regul 2019; 71:10-18. [PMID: 30293894 DOI: 10.1016/j.jbior.2018.09.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 09/17/2018] [Accepted: 09/17/2018] [Indexed: 06/08/2023]
Abstract
Phospholipase Cβ (PLCβ) is a membrane-associated enzyme activated by membrane receptors, especially G-protein coupled receptors (GPCRs). It propagates intracellular signaling by mediating phospholipid metabolism and generating key second messengers, such as inositol triphosphate and diacylglycerol, leading to intracellular Ca2+ mobilization and activation of kinases, such as protein kinases C. In pancreatic β-cells, PLCβ-mediated signaling activated by various factors, such as free fatty acids and neuronal and hormonal ligands, has been confirmed as being involved in the regulation of insulin secretion, and PLCβs have been regarded as essential mediators for augmenting insulin secretion. In this review, we describe the physiological function of PLCβs in the regulation of glucose-stimulated insulin secretion and discuss emerging data on GPCR/PLCβ signaling that is being developed as a target for the treatment of diabetes mellitus.
Collapse
Affiliation(s)
- Hyeon-Jeong Hwang
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Hyun-Jun Jang
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Lucio Cocco
- Cellular Signaling Laboratory, Department of Biomedical Sciences, University of Bologna, Via Irnerio, 48, I-40126, Bologna, Italy
| | - Pann-Ghill Suh
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea.
| |
Collapse
|
14
|
Yan Z, Shyr ZA, Fortunato M, Welscher A, Alisio M, Martino M, Finck BN, Conway H, Remedi MS. High-fat-diet-induced remission of diabetes in a subset of K ATP -GOF insulin-secretory-deficient mice. Diabetes Obes Metab 2018; 20:2574-2584. [PMID: 29896801 PMCID: PMC6407888 DOI: 10.1111/dom.13423] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 06/04/2018] [Accepted: 06/09/2018] [Indexed: 02/06/2023]
Abstract
AIMS To examine the effects of a high-fat-diet (HFD) on monogenic neonatal diabetes, without the confounding effects of compensatory hyperinsulinaemia. METHODS Mice expressing KATP channel gain-of-function (KATP -GOF) mutations, which models human neonatal diabetes, were fed an HFD. RESULTS Surprisingly, KATP -GOF mice exhibited resistance to HFD-induced obesity, accompanied by markedly divergent blood glucose control, with some KATP -GOF mice showing persistent diabetes (KATP -GOF-non-remitter [NR] mice) and others showing remission of diabetes (KATP -GOF-remitter [R] mice). Compared with the severely diabetic and insulin-resistant KATP -GOF-NR mice, HFD-fed KATP -GOF-R mice had lower blood glucose, improved insulin sensitivity, and increased circulating plasma insulin and glucagon-like peptide-1 concentrations. Strikingly, while HFD-fed KATP -GOF-NR mice showed increased food intake and decreased physical activity, reduced whole body fat mass and increased plasma lipids, KATP -GOF-R mice showed similar features to those of control littermates. Importantly, KATP -GOF-R mice had restored insulin content and β-cell mass compared with the marked loss observed in both HFD-fed KATP -GOF-NR and chow-fed KATP -GOF mice. CONCLUSION Together, our results suggest that restriction of dietary carbohydrates and caloric replacement by fat can induce metabolic changes that are beneficial in reducing glucotoxicity and secondary consequences of diabetes in a mouse model of insulin-secretory deficiency.
Collapse
Affiliation(s)
- Zihan Yan
- Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA
| | - Zeenat A. Shyr
- Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA
| | - Manuela Fortunato
- Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA
| | - Alecia Welscher
- Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA
| | - Mariana Alisio
- Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA
| | - Michael Martino
- Department of Medicine, Division of Geriatrics and Nutritional Science, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA
| | - Brian N. Finck
- Department of Medicine, Division of Geriatrics and Nutritional Science, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA
| | - Hannah Conway
- Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA
| | - Maria S. Remedi
- Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA
- Address all correspondence and reprint requests to MSR: Ph: (314) 362-6636,
| |
Collapse
|