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Role of lipid peroxidation and PPAR-δ in amplifying glucose-stimulated insulin secretion.

Cohen G, Riahi Y, Shamni O, Guichardant M, Chatgilialoglu C, Ferreri C, Kaiser N, Sasson S - Diabetes (2011)

Bottom Line: The latter mimicked the GSIS-amplifying effect of high glucose preexposure and of the PPAR-δ agonist GW501516 in INS-1E cells and isolated rat islets.Cytotoxic effects of 4-HNE were observed only above the physiologically effective concentration range.This molecule is an endogenous ligand for PPAR-δ, which amplifies insulin secretion in β-cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, School of Pharmacy, Faculty of Medicine, Institute for Drug Research, Hebrew University, Jerusalem, Israel.

ABSTRACT

Objective: Previous studies show that polyunsaturated fatty acids (PUFAs) increase the insulin secretory capacity of pancreatic β-cells. We aimed at identifying PUFA-derived mediators and their cellular targets that are involved in the amplification of insulin release from β-cells preexposed to high glucose levels.

Research design and methods: The content of fatty acids in phospholipids of INS-1E β-cells was determined by lipidomics analysis. High-performance liquid chromatography was used to identify peroxidation products in β-cell cultures. Static and dynamic glucose-stimulated insulin secretion (GSIS) assays were performed on isolated rat islets and/or INS-1E cells. The function of peroxisome proliferator-activated receptor-δ (PPAR-δ) in regulating insulin secretion was investigated using pharmacological agents and gene expression manipulations.

Results: High glucose activated cPLA(2) and, subsequently, the hydrolysis of arachidonic and linoleic acid (AA and LA, respectively) from phospholipids in INS-1E cells. Glucose also increased the level of reactive oxygen species, which promoted the peroxidation of these PUFAs to generate 4-hydroxy-2E-nonenal (4-HNE). The latter mimicked the GSIS-amplifying effect of high glucose preexposure and of the PPAR-δ agonist GW501516 in INS-1E cells and isolated rat islets. These effects were blocked with GSK0660, a selective PPAR-δ antagonist, and the antioxidant N-acetylcysteine or by silencing PPAR-δ expression. High glucose, 4-HNE, and GW501516 also induced luciferase expression in a PPAR-δ-mediated transactivation assay. Cytotoxic effects of 4-HNE were observed only above the physiologically effective concentration range.

Conclusions: Elevated glucose levels augment the release of AA and LA from phospholipids and their peroxidation to 4-HNE in β-cells. This molecule is an endogenous ligand for PPAR-δ, which amplifies insulin secretion in β-cells.

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Related in: MedlinePlus

Effect of high glucose on AA and LA content in INS-1E cells. A: INS-1E cells were incubated with the indicated glucose (Glc) levels for 16 h and processed for analysis of fatty acid residues in membrane phospholipids. The absolute content of AA and LA in phospholipids of INS-1E cells exposed to 5, 11, and 25 mmol/L glucose was calculated as follows: , where ASTD is the area of the standard reference of the fatty acid from the calibration run, CSTD is the concentration of the standard reference from the calibration run, Ax is the area of the compound (x) from the calibration run, Cx is the concentration of the compound (x) from the calibration run, Fx is the conversion factor of the compound (x), CGC is the concentration of the compound in the sample from the GC trial run, AGC is the area of the compound (x) obtained from the GC trial run, and MWx is the molecular weight of the compound (x). Results are mean ± SEM, n = 4. *P < 0.05 for the difference from the respective 5 mmol/L glucose values. B: Lysates were prepared from similarly treated INS-1E cells and taken for Western blot analysis of total cPLA2, pSer505-cPLA2 (white bars), and pSer515-cPLA2 (black bars). Representative Western blots are shown (inset). Tubulin was used for equal protein loading control. Results are mean ± SEM, n = 3. *P < 0.05 for the difference from the respective 5 mmol/L glucose control.
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Figure 1: Effect of high glucose on AA and LA content in INS-1E cells. A: INS-1E cells were incubated with the indicated glucose (Glc) levels for 16 h and processed for analysis of fatty acid residues in membrane phospholipids. The absolute content of AA and LA in phospholipids of INS-1E cells exposed to 5, 11, and 25 mmol/L glucose was calculated as follows: , where ASTD is the area of the standard reference of the fatty acid from the calibration run, CSTD is the concentration of the standard reference from the calibration run, Ax is the area of the compound (x) from the calibration run, Cx is the concentration of the compound (x) from the calibration run, Fx is the conversion factor of the compound (x), CGC is the concentration of the compound in the sample from the GC trial run, AGC is the area of the compound (x) obtained from the GC trial run, and MWx is the molecular weight of the compound (x). Results are mean ± SEM, n = 4. *P < 0.05 for the difference from the respective 5 mmol/L glucose values. B: Lysates were prepared from similarly treated INS-1E cells and taken for Western blot analysis of total cPLA2, pSer505-cPLA2 (white bars), and pSer515-cPLA2 (black bars). Representative Western blots are shown (inset). Tubulin was used for equal protein loading control. Results are mean ± SEM, n = 3. *P < 0.05 for the difference from the respective 5 mmol/L glucose control.

Mentions: These data were used to quantify the content of AA and LA. Figure 1A shows a marked decrease in their content in the phospholipid compartment of cells maintained at 11 and 25 mmol/L glucose in comparison with the 5 mmol/L glucose incubation; AA was reduced by 45 and 59% and LA by 64 and 88%, respectively. The high number of cells (>106 cells per determination) required for the lipidomic analysis precluded its application to purified islet-derived β-cells.


Role of lipid peroxidation and PPAR-δ in amplifying glucose-stimulated insulin secretion.

Cohen G, Riahi Y, Shamni O, Guichardant M, Chatgilialoglu C, Ferreri C, Kaiser N, Sasson S - Diabetes (2011)

Effect of high glucose on AA and LA content in INS-1E cells. A: INS-1E cells were incubated with the indicated glucose (Glc) levels for 16 h and processed for analysis of fatty acid residues in membrane phospholipids. The absolute content of AA and LA in phospholipids of INS-1E cells exposed to 5, 11, and 25 mmol/L glucose was calculated as follows: , where ASTD is the area of the standard reference of the fatty acid from the calibration run, CSTD is the concentration of the standard reference from the calibration run, Ax is the area of the compound (x) from the calibration run, Cx is the concentration of the compound (x) from the calibration run, Fx is the conversion factor of the compound (x), CGC is the concentration of the compound in the sample from the GC trial run, AGC is the area of the compound (x) obtained from the GC trial run, and MWx is the molecular weight of the compound (x). Results are mean ± SEM, n = 4. *P < 0.05 for the difference from the respective 5 mmol/L glucose values. B: Lysates were prepared from similarly treated INS-1E cells and taken for Western blot analysis of total cPLA2, pSer505-cPLA2 (white bars), and pSer515-cPLA2 (black bars). Representative Western blots are shown (inset). Tubulin was used for equal protein loading control. Results are mean ± SEM, n = 3. *P < 0.05 for the difference from the respective 5 mmol/L glucose control.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3198069&req=5

Figure 1: Effect of high glucose on AA and LA content in INS-1E cells. A: INS-1E cells were incubated with the indicated glucose (Glc) levels for 16 h and processed for analysis of fatty acid residues in membrane phospholipids. The absolute content of AA and LA in phospholipids of INS-1E cells exposed to 5, 11, and 25 mmol/L glucose was calculated as follows: , where ASTD is the area of the standard reference of the fatty acid from the calibration run, CSTD is the concentration of the standard reference from the calibration run, Ax is the area of the compound (x) from the calibration run, Cx is the concentration of the compound (x) from the calibration run, Fx is the conversion factor of the compound (x), CGC is the concentration of the compound in the sample from the GC trial run, AGC is the area of the compound (x) obtained from the GC trial run, and MWx is the molecular weight of the compound (x). Results are mean ± SEM, n = 4. *P < 0.05 for the difference from the respective 5 mmol/L glucose values. B: Lysates were prepared from similarly treated INS-1E cells and taken for Western blot analysis of total cPLA2, pSer505-cPLA2 (white bars), and pSer515-cPLA2 (black bars). Representative Western blots are shown (inset). Tubulin was used for equal protein loading control. Results are mean ± SEM, n = 3. *P < 0.05 for the difference from the respective 5 mmol/L glucose control.
Mentions: These data were used to quantify the content of AA and LA. Figure 1A shows a marked decrease in their content in the phospholipid compartment of cells maintained at 11 and 25 mmol/L glucose in comparison with the 5 mmol/L glucose incubation; AA was reduced by 45 and 59% and LA by 64 and 88%, respectively. The high number of cells (>106 cells per determination) required for the lipidomic analysis precluded its application to purified islet-derived β-cells.

Bottom Line: The latter mimicked the GSIS-amplifying effect of high glucose preexposure and of the PPAR-δ agonist GW501516 in INS-1E cells and isolated rat islets.Cytotoxic effects of 4-HNE were observed only above the physiologically effective concentration range.This molecule is an endogenous ligand for PPAR-δ, which amplifies insulin secretion in β-cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, School of Pharmacy, Faculty of Medicine, Institute for Drug Research, Hebrew University, Jerusalem, Israel.

ABSTRACT

Objective: Previous studies show that polyunsaturated fatty acids (PUFAs) increase the insulin secretory capacity of pancreatic β-cells. We aimed at identifying PUFA-derived mediators and their cellular targets that are involved in the amplification of insulin release from β-cells preexposed to high glucose levels.

Research design and methods: The content of fatty acids in phospholipids of INS-1E β-cells was determined by lipidomics analysis. High-performance liquid chromatography was used to identify peroxidation products in β-cell cultures. Static and dynamic glucose-stimulated insulin secretion (GSIS) assays were performed on isolated rat islets and/or INS-1E cells. The function of peroxisome proliferator-activated receptor-δ (PPAR-δ) in regulating insulin secretion was investigated using pharmacological agents and gene expression manipulations.

Results: High glucose activated cPLA(2) and, subsequently, the hydrolysis of arachidonic and linoleic acid (AA and LA, respectively) from phospholipids in INS-1E cells. Glucose also increased the level of reactive oxygen species, which promoted the peroxidation of these PUFAs to generate 4-hydroxy-2E-nonenal (4-HNE). The latter mimicked the GSIS-amplifying effect of high glucose preexposure and of the PPAR-δ agonist GW501516 in INS-1E cells and isolated rat islets. These effects were blocked with GSK0660, a selective PPAR-δ antagonist, and the antioxidant N-acetylcysteine or by silencing PPAR-δ expression. High glucose, 4-HNE, and GW501516 also induced luciferase expression in a PPAR-δ-mediated transactivation assay. Cytotoxic effects of 4-HNE were observed only above the physiologically effective concentration range.

Conclusions: Elevated glucose levels augment the release of AA and LA from phospholipids and their peroxidation to 4-HNE in β-cells. This molecule is an endogenous ligand for PPAR-δ, which amplifies insulin secretion in β-cells.

Show MeSH
Related in: MedlinePlus