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Loss of Slc12a2 specifically in pancreatic β-cells drives metabolic syndrome in mice. PLoS One 2022; 17:e0279560. [PMID: 36580474 PMCID: PMC9799326 DOI: 10.1371/journal.pone.0279560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 12/11/2022] [Indexed: 12/30/2022] Open
Abstract
The risk of type-2 diabetes and cardiovascular disease is higher in subjects with metabolic syndrome, a cluster of clinical conditions characterized by obesity, impaired glucose metabolism, hyperinsulinemia, hyperlipidemia and hypertension. Diuretics are frequently used to treat hypertension in these patients, however, their use has long been associated with poor metabolic outcomes which cannot be fully explained by their diuretic effects. Here, we show that mice lacking the diuretic-sensitive Na+K+2Cl-cotransporter-1 Nkcc1 (Slc12a2) in insulin-secreting β-cells of the pancreatic islet (Nkcc1βKO) have reduced in vitro insulin responses to glucose. This is associated with islet hypoplasia at the expense of fewer and smaller β-cells. Remarkably, Nkcc1βKO mice excessively gain weight and progressive metabolic syndrome when fed a standard chow diet ad libitum. This is characterized by impaired hepatic insulin receptor activation and altered lipid metabolism. Indeed, overweight Nkcc1βKO but not lean mice had fasting and fed hyperglycemia, hypertriglyceridemia and non-alcoholic steatohepatitis. Notably, fasting hyperinsulinemia was detected earlier than hyperglycemia, insulin resistance, glucose intolerance and increased hepatic de novo gluconeogenesis. Therefore, our data provide evidence supporting the novel hypothesis that primary β-cell defects related to Nkcc1-regulated intracellular Cl-homeostasis and β-cell growth can result in the development of metabolic syndrome shedding light into additional potential mechanisms whereby chronic diuretic use may have adverse effects on metabolic homeostasis in susceptible individuals.
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Cong S, Li Z, Yu L, Liu Y, Hu Y, Bi Y, Cheng M. Integrative proteomic and lipidomic analysis of Kaili Sour Soup-mediated attenuation of high-fat diet-induced nonalcoholic fatty liver disease in a rat model. Nutr Metab (Lond) 2021; 18:26. [PMID: 33691721 PMCID: PMC7945315 DOI: 10.1186/s12986-021-00553-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 02/22/2021] [Indexed: 12/12/2022] Open
Abstract
Background Nonalcoholic fatty liver disease (NAFLD) is the most prevalent liver disease and is characterized by excessive fat accumulation. Kaili Sour Soup, a food typical of Guizhou Province, is believed to have significant health benefits. Thus, we aimed to identify and assess the impact of Kaili Sour Soup on NAFLD and its underlying mechanism using integrative proteomic and lipidomic analysis. Methods A high-fat diet and male Wistar rats were used to construct a NAFLD rat model. Haematoxylin and eosin (HE) and Oil Red O staining analyses were used to perform the histologic examination. Proteomic analysis was utilized to systematically identify the global protein profile in NAFLD with and without Kaili Sour Soup treatment. Western blot assays were used to verify the expression of proteins screened by proteomic analysis. Lipidomic analysis was performed to screen lipid metabolism in NAFLD with and without Kaili Sour Soup treatment. Results Kaili Sour Soup alleviated high-fat diet (HFD)-induced fatty liver and had a normalizing effect on physiological and biochemical indicators of NAFLD, including body weight, liver weight, liver index, total cholesterol (TC), triglyceride (TG), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and insulin resistance level of homeostasis model assessment (HOMA-IR). Kaili Sour Soup decreased the levels of 13 proteins (Tmem44, Rnaseh2b, Gstm6l, LOC100910877, Rufy4, Slc12a2, Pcif1, P4503A1, Sult1e1, Nop53, AABR07065656.4, AABR07065789.3) that were upregulated by HFD and increased the levels of 3 proteins (Sult1c2, Sult1c2a, Snrnp48) that were downregulated by HFD. Kaili Sour Soup attenuated the HFD-induced increase in acyl carnitine (AcCa) and enhanced the HFD-induced decreases in gangliosides (GM3) and lysophosphatidylserine (LPS) in the NAFLD rat model. Conclusions Altogether, this study revealed that Kaili Sour Soup attenuated HFD-induced fatty liver and systematically identified abnormal proteins and lipids involved in the role of Kaili Sour Soup in a NAFLD rat model. Supplementary Information The online version contains supplementary material available at 10.1186/s12986-021-00553-4.
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Affiliation(s)
- Shuo Cong
- School of Basic Medicine Sciences, Guizhou Medical University, Guiyang City, China.,Guizhou Cancer Hospital, Guiyang City, China
| | - Zhengchao Li
- Graduate School of Guizhou Medical University, Guiyang City, China
| | - Lei Yu
- Maternal and Child Health Hospital of Guiyang City, Guiyang City, China
| | - Yongmei Liu
- Department of Infectious Diseases, Affiliated Hospital of Guizhou Medical University, 28 Guiyi Street, Guiyang City, 550004, Guizhou Province, China
| | - Yaxin Hu
- Department of Infectious Diseases, Affiliated Hospital of Guizhou Medical University, 28 Guiyi Street, Guiyang City, 550004, Guizhou Province, China
| | - Ying Bi
- Department of Infectious Diseases, Affiliated Hospital of Guizhou Medical University, 28 Guiyi Street, Guiyang City, 550004, Guizhou Province, China
| | - Mingliang Cheng
- Department of Infectious Diseases, Affiliated Hospital of Guizhou Medical University, 28 Guiyi Street, Guiyang City, 550004, Guizhou Province, China.
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Chloride transporters and channels in β-cell physiology: revisiting a 40-year-old model. Biochem Soc Trans 2020; 47:1843-1855. [PMID: 31697318 PMCID: PMC6925527 DOI: 10.1042/bst20190513] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/14/2019] [Accepted: 10/17/2019] [Indexed: 12/13/2022]
Abstract
It is accepted that insulin-secreting β-cells release insulin in response to glucose even in the absence of functional ATP-sensitive K+ (KATP)-channels, which play a central role in a 'consensus model' of secretion broadly accepted and widely reproduced in textbooks. A major shortcoming of this consensus model is that it ignores any and all anionic mechanisms, known for more than 40 years, to modulate β-cell electrical activity and therefore insulin secretion. It is now clear that, in addition to metabolically regulated KATP-channels, β-cells are equipped with volume-regulated anion (Cl-) channels (VRAC) responsive to glucose concentrations in the range known to promote electrical activity and insulin secretion. In this context, the electrogenic efflux of Cl- through VRAC and other Cl- channels known to be expressed in β-cells results in depolarization because of an outwardly directed Cl- gradient established, maintained and regulated by the balance between Cl- transporters and channels. This review will provide a succinct historical perspective on the development of a complex hypothesis: Cl- transporters and channels modulate insulin secretion in response to nutrients.
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Kelly L, Almutairi MM, Kursan S, Pacheco R, Dias-Junior E, Castrop H, Di Fulvio M. Impaired glucose tolerance, glucagon, and insulin responses in mice lacking the loop diuretic-sensitive Nkcc2a transporter. Am J Physiol Cell Physiol 2019; 317:C843-C856. [PMID: 31365295 DOI: 10.1152/ajpcell.00144.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The Na+K+2Cl- cotransporter-2 (Nkcc2, Slc12a1) is abundantly expressed in the kidney and its inhibition with the loop-diuretics bumetanide and furosemide has been linked to transient or permanent hyperglycemia in mice and humans. Notably, Slc12a1 is expressed at low levels in hypothalamic neurons and in insulin-secreting β-cells of the endocrine pancreas. The present study was designed to determine if global elimination of one of the Slc12a1 products, i.e., Nkcc2 variant a (Nkcc2a), the main splice version of Nkcc2 found in insulin-secreting β-cells, has an impact on the insulin and glucagon secretory responses and fuel homeostasis in vivo. We have used dynamic tests of glucose homeostasis in wild-type mice and mice lacking both alleles of Nkcc2a (Nkcc2aKO) and assessed their islet secretory responses in vitro. Under basal conditions, Nkcc2aKO mice have impaired glucose homeostasis characterized by increased blood glucose, intolerance to the sugar, delayed/blunted in vivo insulin and glucagon responses to glucose, and increased glycemic responses to the gluconeogenic substrate alanine. Further, we provide evidence of conserved quantitative secretory responses of Nkcc2aKO islets within a context of increased islet size related to hyperplastic/hypertrophic glucagon- and insulin-positive cells (α-cells and β-cells, respectively), normal total islet Cl- content, and reduced β-cell expression of the Cl- extruder Kcc2.
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Affiliation(s)
- Lisa Kelly
- Department of Pharmacology and Toxicology, Wright State University, Dayton, Ohio
| | - Mohammed M Almutairi
- Department of Pharmacology and Toxicology, Wright State University, Dayton, Ohio
| | - Shams Kursan
- Department of Pharmacology and Toxicology, Wright State University, Dayton, Ohio
| | - Romario Pacheco
- Department of Pharmacology and Toxicology, Wright State University, Dayton, Ohio
| | - Eduardo Dias-Junior
- Department of Pharmacology and Toxicology, Wright State University, Dayton, Ohio
| | - Hayo Castrop
- Institute of Physiology, University of Regensburg, Regensburg Germany
| | - Mauricio Di Fulvio
- Department of Pharmacology and Toxicology, Wright State University, Dayton, Ohio
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5
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Rahmati N, Hoebeek FE, Peter S, De Zeeuw CI. Chloride Homeostasis in Neurons With Special Emphasis on the Olivocerebellar System: Differential Roles for Transporters and Channels. Front Cell Neurosci 2018; 12:101. [PMID: 29765304 PMCID: PMC5938380 DOI: 10.3389/fncel.2018.00101] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 03/28/2018] [Indexed: 12/14/2022] Open
Abstract
The intraneuronal ionic composition is an important determinant of brain functioning. There is growing evidence that aberrant homeostasis of the intracellular concentration of Cl- ([Cl-]i) evokes, in addition to that of Na+ and Ca2+, robust impairments of neuronal excitability and neurotransmission and thereby neurological conditions. More specifically, understanding the mechanisms underlying regulation of [Cl-]i is crucial for deciphering the variability in GABAergic and glycinergic signaling of neurons, in both health and disease. The homeostatic level of [Cl-]i is determined by various regulatory mechanisms, including those mediated by plasma membrane Cl- channels and transporters. This review focuses on the latest advances in identification, regulation and characterization of Cl- channels and transporters that modulate neuronal excitability and cell volume. By putting special emphasis on neurons of the olivocerebellar system, we establish that Cl- channels and transporters play an indispensable role in determining their [Cl-]i and thereby their function in sensorimotor coordination.
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Affiliation(s)
- Negah Rahmati
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
| | - Freek E. Hoebeek
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
- NIDOD Institute, Wilhelmina Children's Hospital, University Medical Center Utrecht and Brain Center Rudolf Magnus, Utrecht, Netherlands
| | - Saša Peter
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
| | - Chris I. De Zeeuw
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
- Netherlands Institute for Neuroscience, Royal Dutch Academy for Arts and Sciences, Amsterdam, Netherlands
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Torre-Villalvazo I, Cervantes-Pérez LG, Noriega LG, Jiménez JV, Uribe N, Chávez-Canales M, Tovar-Palacio C, Marfil-Garza BA, Torres N, Bobadilla NA, Tovar AR, Gamba G. Inactivation of SPAK kinase reduces body weight gain in mice fed a high-fat diet by improving energy expenditure and insulin sensitivity. Am J Physiol Endocrinol Metab 2018; 314:E53-E65. [PMID: 29066461 DOI: 10.1152/ajpendo.00108.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The STE20/SPS1-related proline-alanine-rich protein kinase (SPAK) controls the activity of the electroneutral cation-chloride cotransporters (SLC12 family) and thus physiological processes such as modulation of cell volume, intracellular chloride concentration [Cl-]i, and transepithelial salt transport. Modulation of SPAK kinase activity may have an impact on hypertension and obesity, as STK39, the gene encoding SPAK, has been suggested as a hypertension and obesity susceptibility gene. In fact, the absence of SPAK activity in mice in which the activating threonine in the T loop was substituted by alanine (SPAK-KI mice) is associated with decreased blood pressure; however its consequences in metabolism have not been explored. Here, we fed wild-type and homozygous SPAK-KI mice a high-fat diet for 17 wk to evaluate weight gain, circulating substrates and hormones, energy expenditure, glucose tolerance, and insulin sensitivity. SPAK-KI mice exhibit resistance to HFD-induced obesity and hepatic steatosis associated with increased energy expenditure, higher thermogenic activity in brown adipose tissue, increased mitochondrial activity in skeletal muscle, and reduced white adipose tissue hypertrophy mediated by augmented whole body insulin sensitivity and glucose tolerance. Our data reveal a previously unrecognized role for the SPAK kinase in the regulation of energy balance, thermogenesis, and insulin sensitivity, suggesting that this kinase could be a new drug target for the treatment of obesity and the metabolic syndrome.
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Affiliation(s)
- Ivan Torre-Villalvazo
- Department of Nutrition Physiology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán , Mexico City, Mexico
| | | | - Lilia G Noriega
- Department of Nutrition Physiology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán , Mexico City, Mexico
| | - Jose V Jiménez
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán , Mexico City, Mexico
| | - Norma Uribe
- Department of Pathology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán , México City, Mexico
| | - María Chávez-Canales
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México , Mexico City, Mexico
| | - Claudia Tovar-Palacio
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán , Mexico City, Mexico
| | - Braulio A Marfil-Garza
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán , Mexico City, Mexico
| | - Nimbe Torres
- Department of Nutrition Physiology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán , Mexico City, Mexico
| | - Norma A Bobadilla
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán , Mexico City, Mexico
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México , Mexico City, Mexico
| | - Armando R Tovar
- Department of Nutrition Physiology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán , Mexico City, Mexico
| | - Gerardo Gamba
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán , Mexico City, Mexico
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México , Mexico City, Mexico
- Tecnologico de Monterrey, Escuela de Medicina y de Ciencias de la Salud, Monterrey, Mexico
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Kursan S, McMillen TS, Beesetty P, Dias-Junior E, Almutairi MM, Sajib AA, Kozak JA, Aguilar-Bryan L, Di Fulvio M. The neuronal K +Cl - co-transporter 2 (Slc12a5) modulates insulin secretion. Sci Rep 2017; 7:1732. [PMID: 28496181 PMCID: PMC5431760 DOI: 10.1038/s41598-017-01814-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 04/03/2017] [Indexed: 11/09/2022] Open
Abstract
Intracellular chloride concentration ([Cl-]i) in pancreatic β-cells is kept above electrochemical equilibrium due to the predominant functional presence of Cl- loaders such as the Na+K+2Cl- co-transporter 1 (Slc12a2) over Cl-extruders of unidentified nature. Using molecular cloning, RT-PCR, Western blotting, immunolocalization and in vitro functional assays, we establish that the "neuron-specific" K+Cl- co-transporter 2 (KCC2, Slc12a5) is expressed in several endocrine cells of the pancreatic islet, including glucagon secreting α-cells, but particularly in insulin-secreting β-cells, where we provide evidence for its role in the insulin secretory response. Three KCC2 splice variants were identified: the formerly described KCC2a and KCC2b along with a novel one lacking exon 25 (KCC2a-S25). This new variant is undetectable in brain or spinal cord, the only and most abundant known sources of KCC2. Inhibition of KCC2 activity in clonal MIN6 β-cells increases basal and glucose-stimulated insulin secretion and Ca2+ uptake in the presence of glibenclamide, an inhibitor of the ATP-dependent potassium (KATP)-channels, thus suggesting a possible mechanism underlying KCC2-dependent insulin release. We propose that the long-time considered "neuron-specific" KCC2 co-transporter is expressed in pancreatic islet β-cells where it modulates Ca2+-dependent insulin secretion.
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Affiliation(s)
- Shams Kursan
- Department of Pharmacology and Toxicology, Wright State University, School of Medicine, Dayton, OH, 45435, USA
| | | | - Pavani Beesetty
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, School of Medicine, Dayton, OH, 45435, USA
| | - Eduardo Dias-Junior
- Department of Pharmacology and Toxicology, Wright State University, School of Medicine, Dayton, OH, 45435, USA
| | - Mohammed M Almutairi
- Department of Pharmacology and Toxicology, Wright State University, School of Medicine, Dayton, OH, 45435, USA
| | - Abu A Sajib
- Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka, Bangladesh
| | - J Ashot Kozak
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, School of Medicine, Dayton, OH, 45435, USA
| | | | - Mauricio Di Fulvio
- Department of Pharmacology and Toxicology, Wright State University, School of Medicine, Dayton, OH, 45435, USA.
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8
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Singh R, Kursan S, Almiahoub MY, Almutairi MM, Garzón-Muvdi T, Alvarez-Leefmans FJ, Di Fulvio M. Plasma Membrane Targeting of Endogenous NKCC2 in COS7 Cells Bypasses Functional Golgi Cisternae and Complex N-Glycosylation. Front Cell Dev Biol 2017; 4:150. [PMID: 28101499 PMCID: PMC5209364 DOI: 10.3389/fcell.2016.00150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 12/14/2016] [Indexed: 12/04/2022] Open
Abstract
Na+K+2Cl− co-transporters (NKCCs) effect the electroneutral movement of Na+-K+ and 2Cl− ions across the plasma membrane of vertebrate cells. There are two known NKCC isoforms, NKCC1 (Slc12a2) and NKCC2 (Slc12a1). NKCC1 is a ubiquitously expressed transporter involved in cell volume regulation, Cl− homeostasis and epithelial salt secretion, whereas NKCC2 is abundantly expressed in kidney epithelial cells of the thick ascending loop of Henle, where it plays key roles in NaCl reabsorption and electrolyte homeostasis. Although NKCC1 and NKCC2 co-transport the same ions with identical stoichiometry, NKCC1 actively co-transports water whereas NKCC2 does not. There is growing evidence showing that NKCC2 is expressed outside the kidney, but its function in extra-renal tissues remains unknown. The present study shows molecular and functional evidence of endogenous NKCC2 expression in COS7 cells, a widely used mammalian cell model. Endogenous NKCC2 is primarily found in recycling endosomes, Golgi cisternae, Golgi-derived vesicles, and to a lesser extent in the endoplasmic reticulum. Unlike NKCC1, NKCC2 is minimally hybrid/complex N-glycosylated under basal conditions and yet it is trafficked to the plasma membrane region of hyper-osmotically challenged cells through mechanisms that require minimal complex N-glycosylation or functional Golgi cisternae. Control COS7 cells exposed to slightly hyperosmotic (~6.7%) solutions for 16 h were not shrunken, suggesting that either one or both NKCC1 and NKCC2 may participate in cell volume recovery. However, NKCC2 targeted to the plasma membrane region or transient over-expression of NKCC2 failed to rescue NKCC1 in COS7 cells where NKCC1 had been silenced. Further, COS7 cells in which NKCC1, but not NKCC2, was silenced exhibited reduced cell size compared to control cells. Altogether, these results suggest that NKCC2 does not participate in cell volume recovery and therefore, NKCC1 and NKCC2 are functionally different Na+K+2Cl− co-transporters.
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Affiliation(s)
- Richa Singh
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Shams Kursan
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Mohamed Y Almiahoub
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Mohammed M Almutairi
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Tomás Garzón-Muvdi
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Francisco J Alvarez-Leefmans
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Mauricio Di Fulvio
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
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9
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Alshahrani S, Almutairi MM, Kursan S, Dias-Junior E, Almiahuob MM, Aguilar-Bryan L, Di Fulvio M. Increased Slc12a1 expression in β-cells and improved glucose disposal in Slc12a2 heterozygous mice. J Endocrinol 2015; 227:153-65. [PMID: 26400961 PMCID: PMC4623298 DOI: 10.1530/joe-15-0327] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/23/2015] [Indexed: 12/26/2022]
Abstract
The products of the Slc12a1 and Slc12a2 genes, commonly known as Na(+)-dependent K(+)2Cl(-) co-transporters NKCC2 and NKCC1, respectively, are the targets for the diuretic bumetanide. NKCCs are implicated in the regulation of intracellular chloride concentration ([Cl(-)]i) in pancreatic β-cells, and as such, they may play a role in glucose-stimulated plasma membrane depolarization and insulin secretion. Unexpectedly, permanent elimination of NKCC1 does not preclude insulin secretion, an event potentially linked to the homeostatic regulation of additional Cl(-) transporters expressed in β-cells. In this report we provide evidence for such a mechanism. Mice lacking a single allele of Slc12a2 exhibit lower fasting glycemia, increased acute insulin response (AIR) and lower blood glucose levels 15-30 min after a glucose load when compared to mice harboring both alleles of the gene. Furthermore, heterozygous expression or complete absence of Slc12a2 associates with increased NKCC2 protein expression in rodent pancreatic β-cells. This has been confirmed by using chronic pharmacological down-regulation of NKCC1 with bumetanide in the mouse MIN6 β-cell line or permanent molecular silencing of NKCC1 in COS7 cells, which results in increased NKCC2 expression. Furthermore, MIN6 cells chronically pretreated with bumetanide exhibit increased initial rates of Cl(-) uptake while preserving glucose-stimulated insulin secretion. Together, our results suggest that NKCCs are involved in insulin secretion and that a single Slc12a2 allele may protect β-cells from failure due to increased homeostatic expression of Slc12a1.
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Affiliation(s)
- Saeed Alshahrani
- Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA
| | - Mohammed Mashari Almutairi
- Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA
| | - Shams Kursan
- Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA
| | - Eduardo Dias-Junior
- Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA
| | - Mohamed Mahmoud Almiahuob
- Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA
| | - Lydia Aguilar-Bryan
- Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA
| | - Mauricio Di Fulvio
- Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA
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10
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Impact of Hybrid and Complex N-Glycans on Cell Surface Targeting of the Endogenous Chloride Cotransporter Slc12a2. Int J Cell Biol 2015; 2015:505294. [PMID: 26351455 PMCID: PMC4553341 DOI: 10.1155/2015/505294] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 06/29/2015] [Accepted: 07/07/2015] [Indexed: 11/21/2022] Open
Abstract
The Na+K+2Cl− cotransporter-1 (Slc12a2, NKCC1) is widely distributed and involved in cell volume/ion regulation. Functional NKCC1 locates in the plasma membrane of all cells studied, particularly in the basolateral membrane of most polarized cells. Although the mechanisms involved in plasma membrane sorting of NKCC1 are poorly understood, it is assumed that N-glycosylation is necessary. Here, we characterize expression, N-glycosylation, and distribution of NKCC1 in COS7 cells. We show that ~25% of NKCC1 is complex N-glycosylated whereas the rest of it corresponds to core/high-mannose and hybrid-type N-glycosylated forms. Further, ~10% of NKCC1 reaches the plasma membrane, mostly as core/high-mannose type, whereas ~90% of NKCC1 is distributed in defined intracellular compartments. In addition, inhibition of the first step of N-glycan biosynthesis with tunicamycin decreases total and plasma membrane located NKCC1 resulting in almost undetectable cotransport function. Moreover, inhibition of N-glycan maturation with swainsonine or kifunensine increased core/hybrid-type NKCC1 expression but eliminated plasma membrane complex N-glycosylated NKCC1 and transport function. Together, these results suggest that (i) NKCC1 is delivered to the plasma membrane of COS7 cells independently of its N-glycan nature, (ii) most of NKCC1 in the plasma membrane is core/hybrid-type N-glycosylated, and (iii) the minimal proportion of complex N-glycosylated NKCC1 is functionally active.
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11
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Blackman SM, Commander CW, Watson C, Arcara KM, Strug LJ, Stonebraker JR, Wright FA, Rommens JM, Sun L, Pace RG, Norris SA, Durie PR, Drumm ML, Knowles MR, Cutting GR. Genetic modifiers of cystic fibrosis-related diabetes. Diabetes 2013; 62:3627-35. [PMID: 23670970 PMCID: PMC3781476 DOI: 10.2337/db13-0510] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Diabetes is a common age-dependent complication of cystic fibrosis (CF) that is strongly influenced by modifier genes. We conducted a genome-wide association study in 3,059 individuals with CF (644 with CF-related diabetes [CFRD]) and identified single nucleotide polymorphisms (SNPs) within and 5' to the SLC26A9 gene that associated with CFRD (hazard ratio [HR] 1.38; P = 3.6 × 10(-8)). Replication was demonstrated in 694 individuals (124 with CFRD) (HR, 1.47; P = 0.007), with combined analysis significant at P = 9.8 × 10(-10). SLC26A9 is an epithelial chloride/bicarbonate channel that can interact with the CF transmembrane regulator (CFTR), the protein mutated in CF. We also hypothesized that common SNPs associated with type 2 diabetes also might affect risk for CFRD. A previous association of CFRD with SNPs in TCF7L2 was replicated in this study (P = 0.004; combined analysis P = 3.8 × 10(-6)), and type 2 diabetes SNPs at or near CDKAL1, CDKN2A/B, and IGF2BP2 were associated with CFRD (P < 0.004). These five loci accounted for 8.3% of the phenotypic variance in CFRD onset and had a combined population-attributable risk of 68%. Diabetes is a highly prevalent complication of CF, for which susceptibility is determined in part by variants at SLC26A9 (which mediates processes proximate to the CF disease-causing gene) and at four susceptibility loci for type 2 diabetes in the general population.
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Affiliation(s)
- Scott M. Blackman
- Division of Pediatric Endocrinology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Corresponding author: Scott M. Blackman,
| | - Clayton W. Commander
- Cystic Fibrosis–Pulmonary Research and Treatment Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Christopher Watson
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Kristin M. Arcara
- Division of Pediatric Endocrinology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Lisa J. Strug
- Division of Biostatistics, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
- Program in Child Health Evaluative Sciences, the Hospital for Sick Children, Toronto, Ontario, Canada
| | - Jaclyn R. Stonebraker
- Cystic Fibrosis–Pulmonary Research and Treatment Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Fred A. Wright
- Cystic Fibrosis–Pulmonary Research and Treatment Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Johanna M. Rommens
- Program in Genetics and Genome Biology, the Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Lei Sun
- Division of Biostatistics, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
- Department of Statistical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Rhonda G. Pace
- Cystic Fibrosis–Pulmonary Research and Treatment Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Sarah A. Norris
- Cystic Fibrosis–Pulmonary Research and Treatment Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Peter R. Durie
- Program in Physiology and Experimental Medicine, the Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Pediatrics, University of Toronto, Toronto, Ontario, Canada
| | - Mitchell L. Drumm
- Departments of Pediatrics and Genetics, Case Western Reserve University, Cleveland, Ohio
| | - Michael R. Knowles
- Cystic Fibrosis–Pulmonary Research and Treatment Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Garry R. Cutting
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
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