Glucose-6-phosphatase catalytic subunit 2 negatively regulates glucose oxidation and insulin secretion in pancreatic β-cells
Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved..
Elevated fasting blood glucose (FBG) is associated with increased risks of developing type 2 diabetes (T2D) and cardiovascular-associated mortality. G6PC2 is predominantly expressed in islets, encodes a glucose-6-phosphatase catalytic subunit that converts glucose-6-phosphate (G6P) to glucose, and has been linked with variations in FBG in genome-wide association studies. Deletion of G6pc2 in mice has been shown to lower FBG without affecting fasting plasma insulin levels in vivo. At 5 mM glucose, pancreatic islets from G6pc2 knockout (KO) mice exhibit no glucose cycling, increased glycolytic flux, and enhanced glucose-stimulated insulin secretion (GSIS). However, the broader effects of G6pc2 KO on β-cell metabolism and redox regulation are unknown. Here we used CRISPR/Cas9 gene editing and metabolic flux analysis in βTC3 cells, a murine pancreatic β-cell line, to examine the role of G6pc2 in regulating glycolytic and mitochondrial fluxes. We found that deletion of G6pc2 led to ∼60% increases in glycolytic and citric acid cycle (CAC) fluxes at both 5 and 11 mM glucose concentrations. Furthermore, intracellular insulin content and GSIS were enhanced by approximately two-fold, along with increased cytosolic redox potential and reductive carboxylation flux. Normalization of fluxes relative to net glucose uptake revealed upregulation in two NADPH-producing pathways in the CAC. These results demonstrate that G6pc2 regulates GSIS by modulating not only glycolysis but also, independently, citric acid cycle activity in β-cells. Overall, our findings implicate G6PC2 as a potential therapeutic target for enhancing insulin secretion and lowering FBG, which could benefit individuals with prediabetes, T2D, and obesity.
| Medienart: |
E-Artikel |
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| Erscheinungsjahr: |
2022 |
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| Erschienen: |
2022 |
| Enthalten in: |
Zur Gesamtaufnahme - volume:298 |
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| Enthalten in: |
The Journal of biological chemistry - 298(2022), 4 vom: 15. Apr., Seite 101729 |
| Sprache: |
Englisch |
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| Beteiligte Personen: |
Rahim, Mohsin [VerfasserIn] |
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| Links: |
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| Anmerkungen: |
Date Completed 26.04.2022 Date Revised 31.05.2022 published: Print-Electronic Citation Status MEDLINE |
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| doi: |
10.1016/j.jbc.2022.101729 |
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| Förderinstitution / Projekttitel: |
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| 520 | |a Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved. | ||
| 520 | |a Elevated fasting blood glucose (FBG) is associated with increased risks of developing type 2 diabetes (T2D) and cardiovascular-associated mortality. G6PC2 is predominantly expressed in islets, encodes a glucose-6-phosphatase catalytic subunit that converts glucose-6-phosphate (G6P) to glucose, and has been linked with variations in FBG in genome-wide association studies. Deletion of G6pc2 in mice has been shown to lower FBG without affecting fasting plasma insulin levels in vivo. At 5 mM glucose, pancreatic islets from G6pc2 knockout (KO) mice exhibit no glucose cycling, increased glycolytic flux, and enhanced glucose-stimulated insulin secretion (GSIS). However, the broader effects of G6pc2 KO on β-cell metabolism and redox regulation are unknown. Here we used CRISPR/Cas9 gene editing and metabolic flux analysis in βTC3 cells, a murine pancreatic β-cell line, to examine the role of G6pc2 in regulating glycolytic and mitochondrial fluxes. We found that deletion of G6pc2 led to ∼60% increases in glycolytic and citric acid cycle (CAC) fluxes at both 5 and 11 mM glucose concentrations. Furthermore, intracellular insulin content and GSIS were enhanced by approximately two-fold, along with increased cytosolic redox potential and reductive carboxylation flux. Normalization of fluxes relative to net glucose uptake revealed upregulation in two NADPH-producing pathways in the CAC. These results demonstrate that G6pc2 regulates GSIS by modulating not only glycolysis but also, independently, citric acid cycle activity in β-cells. Overall, our findings implicate G6PC2 as a potential therapeutic target for enhancing insulin secretion and lowering FBG, which could benefit individuals with prediabetes, T2D, and obesity | ||
| 650 | 4 | |a Journal Article | |
| 650 | 4 | |a G6PC2 | |
| 650 | 4 | |a glucose uptake | |
| 650 | 4 | |a glycolysis | |
| 650 | 4 | |a insulin secretion | |
| 650 | 4 | |a metabolic flux analysis | |
| 650 | 4 | |a systems biology | |
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| 700 | 1 | |a Nakhe, Arya Y |e verfasserin |4 aut | |
| 700 | 1 | |a Banerjee, Deveena R |e verfasserin |4 aut | |
| 700 | 1 | |a Overway, Emily M |e verfasserin |4 aut | |
| 700 | 1 | |a Bosma, Karin J |e verfasserin |4 aut | |
| 700 | 1 | |a Rosch, Jonah C |e verfasserin |4 aut | |
| 700 | 1 | |a Oeser, James K |e verfasserin |4 aut | |
| 700 | 1 | |a Wang, Bo |e verfasserin |4 aut | |
| 700 | 1 | |a Lippmann, Ethan S |e verfasserin |4 aut | |
| 700 | 1 | |a Jacobson, David A |e verfasserin |4 aut | |
| 700 | 1 | |a O'Brien, Richard M |e verfasserin |4 aut | |
| 700 | 1 | |a Young, Jamey D |e verfasserin |4 aut | |
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