Acute nutrient regulation of the mitochondrial glutathione redox state in pancreatic β-cells

2014 ◽  
Vol 460 (3) ◽  
pp. 411-423 ◽  
Author(s):  
Hilton K. Takahashi ◽  
Laila R. B. Santos ◽  
Letícia P. Roma ◽  
Jessica Duprez ◽  
Christophe Broca ◽  
...  
Keyword(s):  
Redox Potential ◽  
Redox State ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Nutrient Regulation ◽  
Mitochondrial Glutathione ◽  
Glutathione Redox

Nutrient stimulation acutely reduces mitochondrial, but not cytosolic/nuclear, glutathione redox potential (EGSH) in insulin-secreting β-cells under control conditions. These changes are negatively correlated with NAD(P)H autofluorescence, but independent from changes in intracellular Ca2+ or mitochondrial pH.

Dynamic measurements of mitochondrial hydrogen peroxide concentration and glutathione redox state in rat pancreatic β-cells using ratiometric fluorescent proteins: confounding effects of pH with HyPer but not roGFP1

2012 ◽  
Vol 441 (3) ◽  
pp. 971-978 ◽  
Author(s):  
Leticia P. Roma ◽  
Jessica Duprez ◽  
Hilton K. Takahashi ◽  
Patrick Gilon ◽  
Andreas Wiederkehr ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Redox State ◽  
Fluorescent Dyes ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Ph Sensitivity ◽  
Fluorescence Ratio ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Glutathione Redox

Using the ROS (reactive oxygen species)-sensitive fluorescent dyes dichlorodihydrofluorescein and dihydroethidine, previous studies yielded opposite results about the glucose regulation of oxidative stress in insulin-secreting pancreatic β-cells. In the present paper, we used the ratiometric fluorescent proteins HyPer and roGFP1 (redox-sensitive green fluorescent protein 1) targeted to mitochondria [mt-HyPer (mitochondrial HyPer)/mt-roGFP1 (mitochondrial roGFP1)] to monitor glucose-induced changes in mitochondrial hydrogen peroxide concentration and glutathione redox state in adenovirus-infected rat islet cell clusters. Because of the reported pH sensitivity of HyPer, the results were compared with those obtained with the mitochondrial pH sensors mt-AlpHi and mt-SypHer. The fluorescence ratio of the mitochondrial probes slowly decreased (mt-HyPer) or increased (mt-roGFP1) in the presence of 10 mmol/l glucose. Besides its expected sensitivity to H2O2, mt-HyPer was also highly pH sensitive. In agreement, changes in mitochondrial metabolism similarly affected mt-HyPer, mt-AlpHi and mt-SypHer fluorescence signals. In contrast, the mt-roGFP1 fluorescence ratio was only slightly affected by pH and reversibly increased when glucose was lowered from 10 to 2 mmol/l. This increase was abrogated by the catalytic antioxidant Mn(III) tetrakis (4-benzoic acid) porphyrin but not by N-acetyl-L-cysteine. In conclusion, due to its pH sensitivity, mt-HyPer is not a reliable indicator of mitochondrial H2O2 in β-cells. In contrast, the mt-roGFP1 fluorescence ratio monitors changes in β-cell mitochondrial glutathione redox state with little interference from pH changes. Our results also show that glucose acutely decreases rather than increases mitochondrial thiol oxidation in rat β-cells.

scholarly journals NNT reverse mode of operation mediates glucose control of mitochondrial NADPH and glutathione redox state in mouse pancreatic β-cells

2017 ◽  
Vol 6 (6) ◽  
pp. 535-547 ◽  
Author(s):  
Laila R.B. Santos ◽  
Carole Muller ◽  
Arnaldo H. de Souza ◽  
Hilton K. Takahashi ◽  
Peter Spégel ◽  
...  
Keyword(s):  
Glucose Control ◽  
Redox State ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Reverse Mode ◽  
Mode Of Operation ◽  
Glutathione Redox

scholarly journals Temperature and redox state dependence of native Kv2.1 currents in rat pancreatic β‐cells

2003 ◽  
Vol 546 (3) ◽  
pp. 647-653 ◽  
Author(s):  
Patrick E. MacDonald ◽  
Anne Marie F. Salapatek ◽  
Michael B. Wheeler
Keyword(s):  
Redox State ◽  
State Dependence ◽  
Β Cells ◽  
Pancreatic Β Cells

scholarly journals Glutathione redox potential in the mitochondrial intermembrane space is linked to the cytosol and impacts the Mia40 redox state

2012 ◽  
Vol 31 (14) ◽  
pp. 3169-3182 ◽  
Author(s):  
Kerstin Kojer ◽  
Melanie Bien ◽  
Heike Gangel ◽  
Bruce Morgan ◽  
Tobias P Dick ◽  
...  
Keyword(s):  
Redox Potential ◽  
Redox State ◽  
Intermembrane Space ◽  
Mitochondrial Intermembrane Space ◽  
Glutathione Redox

scholarly journals Regulation of pancreatic β-cell mitochondrial metabolism: influence of Ca2+, substrate and ADP

1996 ◽  
Vol 318 (2) ◽  
pp. 615-621 ◽  
Author(s):  
Vildan N CIVELEK ◽  
Jude T DEENEY ◽  
Nicholas J SHALOSKY ◽  
Keith TORNHEIM ◽  
Richard G. HANSFORD ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Pyruvate Dehydrogenase ◽  
Redox State ◽  
Co2 Production ◽  
Pancreatic Β Cell ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Mitochondrial Redox State ◽  
Malonyl Coa

To gain insight into the regulation of pancreatic β-cell mitochondrial metabolism, the direct effects on respiration of different mitochondrial substrates, variations in the ATP/ADP ratio and free Ca2+ were examined using isolated mitochondria and permeabilized clonal pancreatic β-cells (HIT). Respiration from pyruvate was high and not influenced by Ca2+ in State 3 or under various redox states and fixed values of the ATP/ADP ratio; nevertheless, high Ca2+ elevated pyridine nucleotide fluorescence, indicating activation of pyruvate dehydrogenase by Ca2+. Furthermore, in the presence of pyruvate, elevated Ca2+ stimulated CO2 production from pyruvate, increased citrate production and efflux from the mitochondria and inhibited CO2 production from palmitate. The latter observation suggests that β-cell fatty acid oxidation is not regulated exclusively by malonyl-CoA but also by the mitochondrial redox state. α-Glycerophosphate (α-GP) oxidation was Ca2+-dependent with a half-maximal rate observed at around 300 nM Ca2+. We have recently demonstrated that increases in respiration precede increases in Ca2+ in glucose-stimulated clonal pancreatic β-cells (HIT), indicating that Ca2+ is not responsible for the initial stimulation of respiration [Civelek, Deeney, Kubik, Schultz, Tornheim and Corkey (1996) Biochem. J. 315, 1015–1019]. It is suggested that respiration is stimulated by increased substrate (α-GP and pyruvate) supply together with oscillatory increases in ADP [Nilsson, Schultz, Berggren, Corkey and Tornheim (1996) Biochem. J. 314, 91–94]. The rise in Ca2+, which in itself may not significantly increase net respiration, could have the important functions of (1) activating the α-GP shuttle, to maintain an oxidized cytosol and high glycolytic flux; (2) activating pyruvate dehydrogenase, and indirectly pyruvate carboxylase, to sustain production of citrate and hence the putative signal coupling factors, malonyl-CoA and acyl-CoA; and (3) increasing mitochondrial redox state to implement the switch from fatty acid to pyruvate oxidation.

MICROCHEMICAL ASSAYS OF GLUCOSE AND GLUCOSE-6-PHOSPHATE IN MAMMALIAN PANCREATIC β-CELLS

1968 ◽  
Vol 59 (3) ◽  
pp. 479-486 ◽  
Author(s):  
Lars-Ake Idahl ◽  
Bo Hellman
Keyword(s):  
Glucose Level ◽  
Exocrine Pancreas ◽  
The Other ◽  
Wide Concentration Range ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Enzymatic Cycling ◽  
Glucose Diffusion ◽  
Significant Barrier ◽  
The Brain

ABSTRACT The combination of enzymatic cycling and fluorometry was used for measuring glucose and glucose-6-phosphate in pancreatic β-cells from obese-hyperglycaemic mice. The glucose level of the β-cells corresponded to that of serum over a wide concentration range. In the exocrine pancreas, on the other hand, a significant barrier to glucose diffusion across the cell membranes was demonstrated. During 5 min of ischaemia, the glucose level remained practically unchanged in the β-cells while it increased in the liver and decreased in the brain. The observation that the pancreatic β-cells are characterized by a relatively low ratio of glucose-6-phosphate to glucose may be attributed to the presence of a specific glucose-6-phosphatase.

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