Plasma Membrane Potential Oscillations in Insulin Secreting Ins-1 832/13 Cells Do Not Require Glycolysis and Are Not Initiated by Fluctuations in Mitochondrial Bioenergetics

Goehring, Isabel; Gerencser, Akos A.; Schmidt, Sara A.; Brand, Martin D.; Mulder, Hindrik; Nicholls, David G.

doi:10.1074/jbc.m111.314567

Cited by 36 publications

(41 citation statements)

References 51 publications

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“…112, 179), suggesting that the activity of ATP-dependent calcium pumps, either at the plasma membrane or on the ER, was previously restricted by the low ⌬G p . Subsequently, singlecell [Ca 2ϩ ] c tends to remain close to basal, despite partial plasma membrane depolarization, an increased ⌬ m , and elevation in cytosolic ATP/ADP ratio, until trains of action potentials are initiated (183,511). Each depolarizing spike correlates with a transient elevation in [Ca 2ϩ ] c which rapidly returns close to basal during intervening quiescent intervals, indicating that Ca 2ϩ is rapidly removed from the cytosol across a combination of the three membranes.…”

Section: ؉ ] C and Action Potentialsmentioning

confidence: 99%

“…rescence of a cationic probe such as TMRM (173,183), or the more slowly equilibrating rhodamine 123 (R123) (135,286,304). This technique is complicated by the plasma membrane potential, ⌬ p , which controls the gradient of the probe between the incubation medium and the cytosol.…”

Section: Mitochondrial Membrane Potential (⌬ M )mentioning

confidence: 99%

“…Determination of mitochondrial ⌬pH has been achieved in intact and disassociated rat islets by infecting cells with an adenovirus carrying the mitochondrial targeted yellow fluorescence protein (YFP) variant mtAlpHi (1) that responds linearly to pH over the range from 7.0 to 8.5 (536). The parallel determination of cytosolic pH, using the ratiometric fluorescent probe BCECF, has allowed ⌬pH to be quantified under differing metabolic conditions (12,536 (183).…”

Section: Mitochondrial ⌬Phmentioning

confidence: 99%

“…In studies with INS-1 832/13 cells (183), the affinity for ATP of the AT 1.03 ATeam variant was found to be too high to monitor changes in cytosolic ATP in response to glucose or pyruvate; however, the matrix-targeted probe responded sensitively to pyruvate-induced changes in matrix ATP. Addition of 1 mM pyruvate, or glucose to 16 mM increased the matrix ATP concentration 2.5-fold above that recorded for 2.8 mM glucose (183). A more recent ATeam construct, GO-ATeam, with a lower affinity for ATP, has been exploited to monitor both matrix and cytosolic ATP concentrations in both MIN6 insulinoma and mouse islets (506).…”

Section: Fret-based Atp Indicatorsmentioning

confidence: 99%

“…Similarly, there are indications that the kinetics of recovery to basal [Ca 2ϩ ] c in single islets is dependent on the cytosolic ATP achieved in elevated glucose (506). In contrast, the Na ϩ -K ϩ -ATPase may have a less stringent ⌬G p requirement, since addition of oligomycin to INS-1 832/13 cells in the presence of pyruvate or elevated glucose leads to rapid and complete repolarization of the plasma membrane as ⌬G p falls and the K ATP channel reactivates (183). This repolarization seems to be maintained, suggesting that the lowered ⌬G p does not restrict the activity of the Na ϩ -K ϩ -ATPase sufficiently to compromise ⌬ p , even with pyruvate as substrate in the apparent absence of an obvious alternative source of ATP.…”

Section: Ion Pumpsmentioning

confidence: 99%

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The Pancreatic β-Cell: A Bioenergetic Perspective

Nicholls

2016

Physiological Reviews

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123

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The pancreatic ␤-cell secretes insulin in response to elevated plasma glucose. This review applies an external bioenergetic critique to the central processes of glucose-stimulated insulin secretion, including glycolytic and mitochondrial metabolism, the cytosolic adenine nucleotide pool, and its interaction with plasma membrane ion channels. The control mechanisms responsible for the unique responsiveness of the cell to glucose availability are discussed from bioenergetic and metabolic control standpoints. The concept of coupling factor facilitation of secretion is critiqued, and an attempt is made to unravel the bioenergetic basis of the oscillatory mechanisms controlling secretion. The need to consider the physiological constraints operating in the intact cell is emphasized throughout. The aim is to provide a coherent pathway through an extensive, complex, and sometimes bewildering literature, particularly for those unfamiliar with the field.

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Section: ؉ ] C and Action Potentialsmentioning

confidence: 99%

Section: Mitochondrial Membrane Potential (⌬ M )mentioning

confidence: 99%

Section: Mitochondrial ⌬Phmentioning

confidence: 99%

Section: Fret-based Atp Indicatorsmentioning

confidence: 99%

Section: Ion Pumpsmentioning

confidence: 99%

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The Pancreatic β-Cell: A Bioenergetic Perspective

Nicholls

2016

Physiological Reviews

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123

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Oscillations of sub-membrane ATP in glucose-stimulated beta cells depend on negative feedback from Ca2+

et al. 2013

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Aims/hypothesisATP links changes in glucose metabolism to electrical activity, Ca2+ signalling and insulin secretion in pancreatic beta cells. There is evidence that beta cell metabolism oscillates, but little is known about ATP dynamics at the plasma membrane, where regulation of ion channels and exocytosis occur.MethodsThe sub-plasma-membrane ATP concentration ([ATP]pm) was recorded in beta cells in intact mouse and human islets using total internal reflection microscopy and the fluorescent reporter Perceval.ResultsGlucose dose-dependently increased [ATP]pm with half-maximal and maximal effects at 5.2 and 9 mmol/l, respectively. Additional elevations of glucose to 11 to 20 mmol/l promoted pronounced [ATP]pm oscillations that were synchronised between neighbouring beta cells. [ATP]pm increased further and the oscillations disappeared when voltage-dependent Ca2+ influx was prevented. In contrast, K+-depolarisation induced prompt lowering of [ATP]pm. Simultaneous recordings of [ATP]pm and the sub-plasma-membrane Ca2+ concentration ([Ca2+]pm) during the early glucose-induced response revealed that the initial [ATP]pm elevation preceded, and was temporarily interrupted by the rise of [Ca2+]pm. During subsequent glucose-induced oscillations, the increases of [Ca2+]pm correlated with lowering of [ATP]pm.Conclusions/interpretationIn beta cells, glucose promotes pronounced oscillations of [ATP]pm, which depend on negative feedback from Ca2+. The bidirectional interplay between these messengers in the sub-membrane space generates the metabolic and ionic oscillations that underlie pulsatile insulin secretion.Electronic supplementary materialThe online version of this article (doi:10.1007/s00125-013-2894-0) contains peer-reviewed but unedited supplementary material, which is available to authorised users.

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RNA sequencing unravels novel L cell constituents and mechanisms of GLP-1 secretion in human gastric bypass-operated intestine

Miskelly,

Lindqvist,

Piccinin

et al. 2023

Diabetologia

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Aims/hypothesis Roux-en-Y gastric bypass surgery (RYGB) frequently results in remission of type 2 diabetes as well as exaggerated secretion of glucagon-like peptide-1 (GLP-1). Here, we assessed RYGB-induced transcriptomic alterations in the small intestine and investigated how they were related to the regulation of GLP-1 production and secretion in vitro and in vivo. Methods Human jejunal samples taken perisurgically and 1 year post RYGB (n=13) were analysed by RNA-seq. Guided by bioinformatics analysis we targeted four genes involved in cholesterol biosynthesis, which we confirmed to be expressed in human L cells, for potential involvement in GLP-1 regulation using siRNAs in GLUTag and STC-1 cells. Gene expression analyses, GLP-1 secretion measurements, intracellular calcium imaging and RNA-seq were performed in vitro. OGTTs were performed in C57BL/6j and iScd1−/− mice and immunohistochemistry and gene expression analyses were performed ex vivo. Results Gene Ontology (GO) analysis identified cholesterol biosynthesis as being most affected by RYGB. Silencing or chemical inhibition of stearoyl-CoA desaturase 1 (SCD1), a key enzyme in the synthesis of monounsaturated fatty acids, was found to reduce Gcg expression and secretion of GLP-1 by GLUTag and STC-1 cells. Scd1 knockdown also reduced intracellular Ca2+ signalling and membrane depolarisation. Furthermore, Scd1 mRNA expression was found to be regulated by NEFAs but not glucose. RNA-seq of SCD1 inhibitor-treated GLUTag cells identified altered expression of genes implicated in ATP generation and glycolysis. Finally, gene expression and immunohistochemical analysis of the jejunum of the intestine-specific Scd1 knockout mouse model, iScd1−/−, revealed a twofold higher L cell density and a twofold increase in Gcg mRNA expression. Conclusions/interpretation RYGB caused robust alterations in the jejunal transcriptome, with genes involved in cholesterol biosynthesis being most affected. Our data highlight SCD as an RYGB-regulated L cell constituent that regulates the production and secretion of GLP-1. Graphical Abstract

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Plasma Membrane Potential Oscillations in Insulin Secreting Ins-1 832/13 Cells Do Not Require Glycolysis and Are Not Initiated by Fluctuations in Mitochondrial Bioenergetics

Cited by 36 publications

References 51 publications

The Pancreatic β-Cell: A Bioenergetic Perspective

The Pancreatic β-Cell: A Bioenergetic Perspective

Oscillations of sub-membrane ATP in glucose-stimulated beta cells depend on negative feedback from Ca2+

RNA sequencing unravels novel L cell constituents and mechanisms of GLP-1 secretion in human gastric bypass-operated intestine

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