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Nguyen NT, Nguyen TT, Da Ly D, Xia JB, Qi XF, Lee IK, Cha SK, Park KS. Oxidative stress by Ca 2+ overload is critical for phosphate-induced vascular calcification. Am J Physiol Heart Circ Physiol 2020; 319:H1302-H1312. [PMID: 33095057 DOI: 10.1152/ajpheart.00305.2020] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Hyperphosphatemia is the primary risk factor for vascular calcification, which is closely associated with cardiovascular morbidity and mortality. Recent evidence showed that oxidative stress by high inorganic phosphate (Pi) mediates calcific changes in vascular smooth muscle cells (VSMCs). However, intracellular signaling responsible for Pi-induced oxidative stress remains unclear. Here, we investigated molecular mechanisms of Pi-induced oxidative stress related with intracellular Ca2+ ([Ca2+]i) disturbance, which is critical for calcification of VSMCs. VSMCs isolated from rat thoracic aorta or A7r5 cells were incubated with high Pi-containing medium. Extracellular signal-regulated kinase (ERK) and mammalian target of rapamycin were activated by high Pi that was required for vascular calcification. High Pi upregulated expressions of type III sodium-phosphate cotransporters PiT-1 and -2 and stimulated their trafficking to the plasma membrane. Interestingly, high Pi increased [Ca2+]i exclusively dependent on extracellular Na+ and Ca2+ as well as PiT-1/2 abundance. Furthermore, high-Pi induced plasma membrane depolarization mediated by PiT-1/2. Pretreatment with verapamil, as a voltage-gated Ca2+ channel (VGCC) blocker, inhibited Pi-induced [Ca2+]i elevation, oxidative stress, ERK activation, and osteogenic differentiation. These protective effects were reiterated by extracellular Ca2+-free condition, intracellular Ca2+ chelation, or suppression of oxidative stress. Mitochondrial superoxide scavenger also effectively abrogated ERK activation and osteogenic differentiation of VSMCs by high Pi. Taking all these together, we suggest that high Pi activates depolarization-triggered Ca2+ influx via VGCC, and subsequent [Ca2+]i increase elicits oxidative stress and osteogenic differentiation. PiT-1/2 mediates Pi-induced [Ca2+]i overload and oxidative stress but in turn, PiT-1/2 is upregulated by consequences of these alterations.NEW & NOTEWORTHY The novel findings of this study are type III sodium-phosphate cotransporters PiT-1 and -2-dependent depolarization by high Pi, leading to Ca2+ entry via voltage-gated Ca2+ channels in vascular smooth muscle cells. Cytosolic Ca2+ increase and subsequent oxidative stress are indispensable for osteogenic differentiation and calcification. In addition, plasmalemmal abundance of PiT-1/2 relies on Ca2+ overload and oxidative stress, establishing a positive feedback loop. Identification of mechanistic components of a vicious cycle could provide novel therapeutic strategies against vascular calcification in hyperphosphatemic patients.
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Affiliation(s)
- Nhung Thi Nguyen
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Korea.,Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Tuyet Thi Nguyen
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Korea.,Internal Medicine Residency Program, College of Health Sciences, VinUniversity, Hanoi, Vietnam
| | - Dat Da Ly
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Korea.,Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Jing-Bo Xia
- Key Laboratory of Regenerative Medicine, Ministry of Education, Department of Developmental and Regenerative Biology, Jinan University, Guangzhou, China
| | - Xu-Feng Qi
- Key Laboratory of Regenerative Medicine, Ministry of Education, Department of Developmental and Regenerative Biology, Jinan University, Guangzhou, China
| | - In-Kyu Lee
- Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Korea
| | - Seung-Kuy Cha
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Korea.,Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Kyu-Sang Park
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Korea.,Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Korea
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Uchida K, Nomura M, Yamamoto T, Ogawa Y, Teramoto N. Rab8a is involved in membrane trafficking of Kir6.2 in the MIN6 insulinoma cell line. Pflugers Arch 2019; 471:877-887. [PMID: 30631919 DOI: 10.1007/s00424-018-02252-1] [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: 09/12/2018] [Revised: 12/05/2018] [Accepted: 12/27/2018] [Indexed: 11/29/2022]
Abstract
Although ATP-sensitive K+ (KATP) channels play an important role in the secretion of insulin by pancreatic beta cells, the mechanisms that regulate the intracellular transport of KATP channel subunit proteins (i.e., Kir6.2 and sulfonylurea receptor 1 (SUR1)) to the plasma membrane remain uncharacterized. We investigated the possibility that an interaction between KATP channel subunit proteins and Rab8a protein, a member of the RAS superfamily, may be involved in the membrane trafficking of KATP channels. Co-immunoprecipitation and immunostaining experiments using co-expression systems with fluorescent protein-tagged Kir6.2 were carried out to identify the coupling of KATP channels and Rab8a proteins in the insulin-secreting cell line, MIN6. Rab8a protein co-localized with Kir6.2 protein, a channel pore subunit (in a granular pattern), and with insulin. Knockdown of the Rab8a gene with RNA interference using small interfering RNA systems caused reductions in the amount of total KATP and plasma membrane surface KATP channels without decreasing the messenger RNA transcription of the KATP channel subunits. Rab8a gene knockdown also enhanced glucose-induced insulin secretion. These results suggest that Rab8a may be involved in membrane trafficking of KATP channels and the maintenance of normal insulin secretion in the MIN6 pancreatic beta cell line.
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Affiliation(s)
- Keiichiro Uchida
- Department of Pharmacology, Faculty of Medicine, Saga University, Saga, 849-8501, Japan.,Department of Medicine and Bioregulatory Science, Graduate School of Medical Science, Kyushu University, Fukuoka, 812-8582, Japan
| | - Masatoshi Nomura
- Division of Endocrinology and Metabolism, Department of Internal Medicine, School of Medicine, Kurume University, Kurume, 830-0011, Japan
| | - Tadashi Yamamoto
- Department of Pharmacology, Faculty of Medicine, Saga University, Saga, 849-8501, Japan
| | - Yoshihiro Ogawa
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Science, Kyushu University, Fukuoka, 812-8582, Japan.,Department of Molecular and Cellular Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, 113-8510, Japan
| | - Noriyoshi Teramoto
- Department of Pharmacology, Faculty of Medicine, Saga University, Saga, 849-8501, Japan. .,Laboratory of Biomedical Engineering, Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan.
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Tinker A, Aziz Q, Li Y, Specterman M. ATP‐Sensitive Potassium Channels and Their Physiological and Pathophysiological Roles. Compr Physiol 2018; 8:1463-1511. [DOI: 10.1002/cphy.c170048] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Mo XD, Gao LP, Wang QJ, Yin J, Jing YH. Lipid accelerating the fibril of islet amyloid polypeptide aggravated the pancreatic islet injury in vitro and in vivo. Lipids Health Dis 2018. [PMID: 29523142 PMCID: PMC5845206 DOI: 10.1186/s12944-018-0694-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Background The fibrillation of islet amyloid polypeptide (IAPP) triggered the amyloid deposition, then enhanced the loss of the pancreatic islet mass. However, it is not clear what factor is the determinant in development of the fibril formation. The aim of this study is to investigate the effects of lipid on IAPP fibril and its injury on pancreatic islet. Methods The fibril form of human IAPP (hIAPP) was tested using thioflavin-T fluorescence assay and transmission electron microscope technology after incubated with palmitate for 5 h at 25 °C. The cytotoxicity of fibril hIAPP was evaluated in INS-1 cells through analyzing the leakage of cell membrane and cell apoptosis. Type 2 diabetes mellitus (T2DM) animal model was induced with low dose streptozotocin combined the high-fat diet feeding for two months in rats. Plasma biochemistry parameters were measured before sacrificed. Pancreatic islet was isolated to evaluate their function. Results The results showed that co-incubation of hIAPP and palmitate induced more fibril form. Fibril hIAPP induced cell lesions including cell membrane leakage and cell apoptosis accompanied insulin mRNA decrease in INS-1 cell lines. In vivo, Plasma glucose, triglyceride, rIAPP and insulin increased in T2DM rats compared with the control group. In addition, IAPP and insulin mRNA increased in pancreatic islet of T2DM rats. Furthermore, T2DM induced the reduction of insulin receptor expression and cleaved caspase-3 overexpression in pancreatic islet. Conclusions Results in vivo and in vitro suggested that lipid and IAPP plays a synergistic effect on pancreatic islet cell damage, which implicated in enhancing the IAPP expression and accelerating the fibril formation of IAPP.
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Affiliation(s)
- Xiao-Dan Mo
- Institute of Anatomy and Histology & Embryology, Neuroscience, School of Basic Medical Sciences, Lanzhou University, No. 199 of Donggang West Road, Lanzhou City, Gansu Province, 730000, People's Republic of China
| | - Li-Ping Gao
- Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, No. 199 of Donggang West Road, Lanzhou City, Gansu Province, 730000, People's Republic of China
| | - Qing-Jun Wang
- Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, No. 199 of Donggang West Road, Lanzhou City, Gansu Province, 730000, People's Republic of China
| | - Jie Yin
- Institute of Anatomy and Histology & Embryology, Neuroscience, School of Basic Medical Sciences, Lanzhou University, No. 199 of Donggang West Road, Lanzhou City, Gansu Province, 730000, People's Republic of China
| | - Yu-Hong Jing
- Institute of Anatomy and Histology & Embryology, Neuroscience, School of Basic Medical Sciences, Lanzhou University, No. 199 of Donggang West Road, Lanzhou City, Gansu Province, 730000, People's Republic of China. .,Key Laboratory of Preclinical Study for New Drugs of Gansu province, Lanzhou University, No. 199 of Donggang West Road, Lanzhou City, Gansu Province, 730000, People's Republic of China.
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Khan D, Moffet CR, Flatt PR, Kelly C. Role of islet peptides in beta cell regulation and type 2 diabetes therapy. Peptides 2018; 100:212-218. [PMID: 29412821 DOI: 10.1016/j.peptides.2017.11.014] [Citation(s) in RCA: 9] [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] [Received: 10/11/2017] [Revised: 11/22/2017] [Accepted: 11/22/2017] [Indexed: 12/25/2022]
Abstract
The endocrine pancreas is composed of islets of Langerhans, which secrete a variety of peptide hormones critical for the maintenance of glucose homeostasis. Insulin is the primary regulator of glucose and its secretion from beta-cells is tightly regulated in response to physiological demands. Direct cell-cell communication within islets is essential for glucose-induced insulin secretion. Emerging data suggest that islet connectivity is also important in the regulating the release of other islet hormones including glucagon and somatostatin. Autocrine and paracrine signals exerted by secreted peptides within the islet also play a key role. A great deal of attention has focused on classical islet peptides, namely insulin, glucagon and somatostatin. Recently, it has become clear that islets also synthesise and secrete a range of non-classical peptides, which regulate beta-cell function and insulin release. The current review summarises the roles of islet cell connectivity and islet peptide-driven autocrine and paracrine signalling in beta-cell function and survival. The potential to harness the paracrine effects of non-classical islet peptides for the treatment of type 2 diabetes is also briefly discussed.
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Affiliation(s)
- Dawood Khan
- Northern Ireland Centre for Stratified Medicine, Biomedical Sciences Research Institute, University of Ulster, C-TRIC Building, Altnagelvin Area Hospital, Glenshane Road, L/Derry, BT47 6SB, Northern Ireland, UK
| | - Charlotte R Moffet
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK
| | - Peter R Flatt
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK
| | - Catriona Kelly
- Northern Ireland Centre for Stratified Medicine, Biomedical Sciences Research Institute, University of Ulster, C-TRIC Building, Altnagelvin Area Hospital, Glenshane Road, L/Derry, BT47 6SB, Northern Ireland, UK.
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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.
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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
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