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Barker CJ, Tessaro FHG, Ferreira SDS, Simas R, Ayala TS, Köhler M, Rajasekaran SS, Martins JO, Darè E, Berggren PO. XPR1 Mediates the Pancreatic β-Cell Phosphate Flush. Diabetes 2021; 70:111-118. [PMID: 32826297 PMCID: PMC7881847 DOI: 10.2337/db19-0633] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 08/17/2020] [Indexed: 11/13/2022]
Abstract
Glucose-stimulated insulin secretion is the hallmark of the pancreatic β-cell, a critical player in the regulation of blood glucose concentration. In 1974, the remarkable observation was made that an efflux of intracellular inorganic phosphate (Pi) accompanied the events of stimulated insulin secretion. The mechanism behind this "phosphate flush," its association with insulin secretion, and its regulation have since then remained a mystery. We recapitulated the phosphate flush in the MIN6m9 β-cell line and pseudoislets. We demonstrated that knockdown of XPR1, a phosphate transporter present in MIN6m9 cells and pancreatic islets, prevented this flush. Concomitantly, XPR1 silencing led to intracellular Pi accumulation and a potential impact on Ca2+ signaling. XPR1 knockdown slightly blunted first-phase glucose-stimulated insulin secretion in MIN6m9 cells, but had no significant impact on pseudoislet secretion. In keeping with other cell types, basal Pi efflux was stimulated by inositol pyrophosphates, and basal intracellular Pi accumulated following knockdown of inositol hexakisphosphate kinases. However, the glucose-driven phosphate flush occurred despite inositol pyrophosphate depletion. Finally, while it is unlikely that XPR1 directly affects exocytosis, it may protect Ca2+ signaling. Thus, we have revealed XPR1 as the missing mediator of the phosphate flush, shedding light on a 45-year-old mystery.
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Affiliation(s)
- Christopher J Barker
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Fernando Henrique Galvão Tessaro
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
- Laboratory of Immunoendocrinology, Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University São Paulo, São Paulo, Brazil
| | - Sabrina de Souza Ferreira
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
- Laboratory of Immunoendocrinology, Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University São Paulo, São Paulo, Brazil
| | - Rafael Simas
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Thais S Ayala
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
- Laboratory of Immunoendocrinology, Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University São Paulo, São Paulo, Brazil
| | - Martin Köhler
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | | | - Joilson O Martins
- Laboratory of Immunoendocrinology, Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University São Paulo, São Paulo, Brazil
| | - Elisabetta Darè
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
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Erecińska M, Bryła J, Michalik M, Meglasson MD, Nelson D. Energy metabolism in islets of Langerhans. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1101:273-95. [PMID: 1643073 DOI: 10.1016/0005-2728(92)90084-f] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- M Erecińska
- Department of Pharmacology, University of Pennsylvania, School of Medicine, Philadelphia 19104-6084
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Corkey BE, Deeney JT, Glennon MC, Matschinsky FM, Prentki M. Regulation of steady-state free Ca2+ levels by the ATP/ADP ratio and orthophosphate in permeabilized RINm5F insulinoma cells. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68916-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Meglasson MD, Matschinsky FM. Pancreatic islet glucose metabolism and regulation of insulin secretion. DIABETES/METABOLISM REVIEWS 1986; 2:163-214. [PMID: 2943567 DOI: 10.1002/dmr.5610020301] [Citation(s) in RCA: 371] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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5
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Meglasson MD, Matschinsky FM. New perspectives on pancreatic islet glucokinase. THE AMERICAN JOURNAL OF PHYSIOLOGY 1984; 246:E1-13. [PMID: 6364828 DOI: 10.1152/ajpendo.1984.246.1.e1] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Control of blood sugar involves the complex interaction of the pancreatic glucose-sensing beta-cells with the liver, which serves as the primary site of glucose disposal after a meal. Glucokinase occupies an important role in controlling glucose phosphorylation and metabolism both in the liver and in pancreatic islets. In the beta-cells, glucokinase functions as pacemaker of glycolysis at physiological glucose levels. It determines the unique characteristics of islet hexose usage, that is, the rate, affinity, cooperativity, and anomeric discrimination of glucose metabolism. Because glycolysis controls hexose-induced insulin release, glucokinase is considered the best-qualified candidate for the elusive glucose sensor of beta-cells. A deficiency of glucokinase would disturb glucose homeostasis. Decreased islet glucokinase would diminish islet glycolysis and would result in a higher set point of beta-cells for glucose-induced insulin release. Decreased liver glucokinase would cause less efficient hepatic glucose disposal. Human maturity-onset diabetes (type II diabetes) has these characteristics. It is thus conceivable that certain forms of type II diabetes are due to a glucokinase deficiency.
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Bauer BA, Younathan ES. Gas chromatographic determination of the anomers of blood glucose in normal and diabetic rats. BIOCHEMICAL MEDICINE 1980; 24:293-9. [PMID: 7283985 DOI: 10.1016/0006-2944(80)90023-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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8
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Carpinelli AR, Malaisse WJ. The stimulus-secretion coupling in glucose-induced insulin release xliv. A possible link between glucose metabolism and phosphate flush. Diabetologia 1980; 19:458-64. [PMID: 7004965 DOI: 10.1007/bf00281826] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Above a threshold of 3.0-4.2 mmol/l, D-glucose provoked a transient increase in 32P fractional outflow rate from rat pancreatic islets prelabelled with 32P-orthophosphate. Nutrients which stimulate insulin release in the absence of glucose, alpha-ketoisocaproate and L-leucine, also provoked a phosphate flush. No flush occurred in islets exposed to non-insulinotropic nutrients (L-glutamine and and L-lactate) or non-nutriet secretagogues (arginine, tolbutamide, theophylline). A late increase in 32P fractional outflow rate was observed in Ca2+ deprived islets stimulated with BaCl2 and theophylline. The occurrence of a phosphate flush did not appear to be attributable to changes in insulin release, cyclic AMP content, membrane polarisation, K+ conductance, or reduced pyridine nucleotide content. The 32P response to glucose was slightly decreased in the absence of extracellular Ca2+ or HCO3-, markedly impaired in the absence of K4, and virtually abolished in the presence of menadione (10 mumol/l). It is proposed that the occurrence of a phosphate flush is linked to the metabolism of nutrient secretagogues, possibly via an increase in O2 uptake and the production rate of NAD(P)H and ATP.
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9
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Campillo JE, Luyckx AS, Lefebvre PJ. Effect of phosphate on the arginine-induced insulin release by the isolated perfused rat pancreas. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1980; 128:229-37. [PMID: 6999854 DOI: 10.1007/978-1-4615-9167-2_28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The isolated perfused rat pancreas was used to investigate the effect of extracellular phosphate on the arginine-induced insulin release. In the absence of any metabolic substrate, the insulin response to arginine was monophasic. In the absence of phosphate in the medium, the insulin release as unaffected until the 15th minute of the stimulation period, but was significantly augmented from that time onward. In the presence of oleic acid in the perfusate, the insulin response to arginine was also monophasic but occurred earlier than in controls. In this conditin, phosphate omission resulted in an increase of the insulin response to arginine from the 3rd minute of the stimulatory period onward. In the presence of glucose 5.5 mM in the medium the insulin response to argnine was biphasic and was not affected by extracellular phosphate omission.
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Campillo JE, Castillo M, Valdivia MM, Rodriguez E. Effect of phosphate omission on glucose-induced insulin release in vitro. EXPERIENTIA 1979; 35:1260-1. [PMID: 488302 DOI: 10.1007/bf01963326] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In the isolated perfused rat pancreas, omission of extracellular phosphate (H2PO-4) significantly reduces the insulin secretion in response to 16.7 mM glucose.
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11
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Larson BA, Williams TL, Showers MO, VanderLaan WP. Effect of 2-deoxyglucose on [32P] phosphate and insulin release from perifused rat pancreatic islets. Diabetologia 1979; 17:117-20. [PMID: 385404 DOI: 10.1007/bf01222212] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The effect of 2-deoxyglucose on glucose mediated insulin and [32P]phosphate release was studied by perifusion of isolated rat pancreatic islets. When islets were perifused with media containing 2.8 mmol/l glucose and 20 mmol/l 2-deoxyglucose for 60 minutes and then exposed to media containing 8.3 or 16.7 mmol/l glucose and 20 mmol/l 2-deoxyglucose for the next 15 minutes, insulin release at either glucose concentration was prompt but blunted. Similarly, islets preincubated (90 min) with [32P] orthophosphate, then perifused with 20 mmol/l 2-deoxyglucose for 75 min and stimulated by either 8.3 or 16.7 mmol/l glucose for the final 15 minutes or 2-deoxyglucose exposure demonstrated obtundation of [32P]phosphate release. Perifusion of islets with 20 mmol/l 2-deoxyglucose alone induced no heightened 32P efflux. These studies suggest that 2-deoxyglucose affects initial events in stimulus-secretion coupling of glucose mediated insulin release.
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12
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Bukowiecki L, Trus M, Matschinsky FM, Freinkel N. Alterations in pancreatic islet phosphate content during secretory stimulation with glucose. BIOCHIMICA ET BIOPHYSICA ACTA 1979; 583:370-7. [PMID: 375990 DOI: 10.1016/0304-4165(79)90461-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Isolated rat pancreatic islets were perifused and analyzed for phosphate content immediately following the transient increase in the efflux of orthophosphate which occurs when insulin secretion is stimulated by glucose. In some instances, islets were perifused directly following isolation to minimize preparative delay; in others, islets were prelabeled during incubation with [32P]orthophosphate for 90 min prior to perifusion. In both experimental situations, total islet phosphate content declined 40--50% following exposure to stimulating concentrations of glucose and initiation of enhanced insulin release. In the experiments with prelabeled islets, tissue content of [32P]orthophosphate fell to a similar extent so that the specific radioactivity of islet orthophosphate was unaffected. Inhibited of heightened insulin release with Ni2+ did not modify the decrements in total or radioactive tissue orthophosphate, thus indicating that these responses to islet stimulation reflect events which are proximal to activated exocytosis. Simultaneous analyses for tissue ATP and ADP demonstrated that the efflux in orthophosphate and reduction in tissue orthophosphate content were not mediated via net changes in islet adenine nucleotides. The observations represent the first documentation that a net reduction of tissue inorganic phosphate is one of the early components of stimulus-secretion coupling in isolated pancreatic islets.
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Freinkel N. Phosphate translocations during secretory stimulation of pancreatic islets. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1979; 119:71-7. [PMID: 386733 DOI: 10.1007/978-1-4615-9110-8_12] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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14
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Freinkel N, Pedley KC, Wooding P, Dawson RM. Localization of inorganic phosphate in the pancreatic B cell and its loss on glucose stimulation. Science 1978; 201:1124-6. [PMID: 356269 DOI: 10.1126/science.356269] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Perifusion experiments have shown that there is a discharge of inorganic phosphate into the medium when insulin secretion from isolated islets is stimulated by glucose. Histochemical and microprobe examination of resting pancreatic islets in the electron microscope shows a specific accumulation of inorganic phosphate adjacent to the plasmalemma and nucleolus of the B (beta) cells. This phossphate is lost from the cells during secretory stimulation of islets with high concentrations of glucose.
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15
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Campillo JE, Luyckx AS, Torres MD, Lefèbvre PJ. Effect of phosphate omission on arginine-induced insulin and glucagon release by the isolated perfused rat pancreas. FEBS Lett 1977; 84:141-3. [PMID: 338357 DOI: 10.1016/0014-5793(77)81074-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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16
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Malaisse WJ, Sener A, Koser M, Herchuelz A. Stimulus-secretion coupling of glucose-induced insulin release. Metabolism of alpha- and beta-D-glucose in isolated islets. J Biol Chem 1976. [DOI: 10.1016/s0021-9258(17)33042-9] [Citation(s) in RCA: 75] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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17
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Freinkel N, Younsi CE, Dawson RM. Insulin release and phosphate ion efflux from rat pancreatic islets induced by L-leucine and its nonmetabolizable analogue, 2-aminobicyclo[2.2.1]heptane-2-carboxylic acid. Proc Natl Acad Sci U S A 1976; 73:3403-7. [PMID: 790384 PMCID: PMC431123 DOI: 10.1073/pnas.73.10.3403] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
When isolated rat pancreatic islets that had been labeled with 32P were exposed to 10mM L-leucine in a microperifusion system, there was a transitory, immediate heightened efflux of [32P]phosphate ions. Commencement of the phosphate flush coincided with the first release of insulin, and it occurred in the absence or presence of nonstimulatory levels of glucose (0.5 mg/ml). The effects of leucine upon phosphate efflux were not inhibited by D-mannoheptulose, whereas glucose-induced stimulations were suppressed. The phosphate flush could be induced also by the nonmetabolizable analogue of leucine, 2-aminobicyclo[2.2.1]heptane-2-carboxylic acid. Like insulin release, the effect was stereospecific, with only one of the four stereoisomers, (-)-b-aminobicycloheptane carboxylic acid, being active. Analogue-induced phosphate and insulin release were totally suppressed in a medium containing D2O, but on reversion to H2O the efflux of both hormone and anion occured. It is concluded that insulin secretion from islet beta cells and the release of phosphate ions showed the same specificity for nutrient secretagogues and that both can be triggered even in the absence of exogenous oxidizable fuels. However, the partial dissociation of the dose-response curves for the two phenomena lends support to the contention that the phosphate flush reflects an earlier event in the sequence of stimulus-secretion coupling.
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Bukowiecki L, Freinkel N. Relationship between efflux of ionic calcium and phosphorus during excitation of pancreatic islets with glucose. BIOCHIMICA ET BIOPHYSICA ACTA 1976; 436:190-8. [PMID: 776228 DOI: 10.1016/0005-2736(76)90230-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Simultaneous rates of [32P]orthophosphate and 45Ca2+ efflux from prelabeled rat pancreatic islets have been evaluated to assess whether these ions move in concert throughout all phases of "stimulus-secretion coupling". Perifusion with stimulatory concentrations of glucose elicited immediate but transitory increases in 32P outflow accompanied by initial retardations and subsequent augmentations in net 45Ca2+ outflows. These monophasic 32P and biphasic 45Ca2+ responses to secretory stimulation were abolished completely by membrane stabilization with tetracaine. However, certain manipulations enabled individual components to be modified separately. During stimulation with glucose, inhibition of insulin release by Ni2+ abolished the late increases in 45Ca2+ outflow without affecting the initial retentions of 45Ca2+ or the increased releases of 32P. Under basal conditions, the ionophore A23187 "triggered" increased releases of 45Ca2+ and insulin without prior retentions of 45Ca2+ or enhancements of 32P efflux. Thus, the immediate retardations of 45Ca2+ outflow and heightened efflux of 32P may reflect early events in stimulus-secretion coupling which can be dissociated from the augmented release of 45Ca2+ accompanying activated emiocytosis.
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Malaisse WJ, Sener A, Koser M, Herchuelz A. Identification of the alpha-stereospecific glucosensor in the pancreatic B-cell. FEBS Lett 1976; 65:131-4. [PMID: 776691 DOI: 10.1016/0014-5793(76)80463-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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