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Inhibition of Calcium Influx Reduces Dysfunction and Apoptosis in Lipotoxic Pancreatic β-Cells via Regulation of Endoplasmic Reticulum Stress.

Zhou Y, Sun P, Wang T, Chen K, Zhu W, Wang H - PLoS ONE (2015)

Bottom Line: And whether the compounds could reduce palmitic acid-induced β-cell failure and the underlying mechanism were also investigated.It was found that both nifedipine and diazoxide protected MIN6 pancreatic β-cells and primary cultured murine islets from palmitic acid-induced apoptosis.Our results verified that nifedipine and diazoxide could reduce palmitic acid-induced endoplasmic reticulum stress to generate protective effects on pancreatic β-cells.

View Article: PubMed Central - PubMed

Affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China.

ABSTRACT
Lipotoxicity plays an important role in pancreatic β-cell failure during the development of type 2 diabetes. Prolonged exposure of β-cells to elevated free fatty acids level could cause deterioration of β-cell function and induce cell apoptosis. Therefore, inhibition of fatty acids-induced β-cell dysfunction and apoptosis might provide benefit for the therapy of type 2 diabetes. The present study examined whether regulation of fatty acids-triggered calcium influx could protect pancreatic β-cells from lipotoxicity. Two small molecule compounds, L-type calcium channel blocker nifedipine and potassium channel activator diazoxide were used to inhibit palmitic acid-induced calcium influx. And whether the compounds could reduce palmitic acid-induced β-cell failure and the underlying mechanism were also investigated. It was found that both nifedipine and diazoxide protected MIN6 pancreatic β-cells and primary cultured murine islets from palmitic acid-induced apoptosis. Meanwhile, the impaired insulin secretion was also recovered to varying degrees by these two compounds. Our results verified that nifedipine and diazoxide could reduce palmitic acid-induced endoplasmic reticulum stress to generate protective effects on pancreatic β-cells. More importantly, it suggested that regulation of calcium influx by small molecule compounds might provide benefits for the prevention and therapy of type 2 diabetes.

No MeSH data available.


Related in: MedlinePlus

Nifedipine and diazoxide protects MIN6 cells from PA-induced apoptosis.(A) After 48 h incubation of nifedipine in the presence/absence of PA, the cell viability was measured by MTT assay. The cell viability was shown as inhibitory ratio (% of control), *** p<0.001 denote significant difference versus the PA-treated alone group, n = 6. (B) After 48 h incubation of diazoxide in the presence/absence of PA, the cell viability was measured by MTT assay. *** p<0.001 denote significant difference versus the PA-treated alone group, n = 6. (C) After the cells were treated with 0.5 mM PA in the presence/absence of nifedipine for 48 h, the expression of cleaved caspase-3 was detected by western blot. (D) After the cells were treated with 0.5 mM PA in the presence/absence of diazoxide for 48 h, the expression of cleaved caspase-3 was detected. (E)(F) Quantitative analysis of western blot. The optical density of each blot band was determined and adjusted by the optical density of β-actin. * p<0.05; ** p<0.01; *** p<0.001 denote significant difference versus the PA-treated alone group, n = 3.
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pone.0132411.g001: Nifedipine and diazoxide protects MIN6 cells from PA-induced apoptosis.(A) After 48 h incubation of nifedipine in the presence/absence of PA, the cell viability was measured by MTT assay. The cell viability was shown as inhibitory ratio (% of control), *** p<0.001 denote significant difference versus the PA-treated alone group, n = 6. (B) After 48 h incubation of diazoxide in the presence/absence of PA, the cell viability was measured by MTT assay. *** p<0.001 denote significant difference versus the PA-treated alone group, n = 6. (C) After the cells were treated with 0.5 mM PA in the presence/absence of nifedipine for 48 h, the expression of cleaved caspase-3 was detected by western blot. (D) After the cells were treated with 0.5 mM PA in the presence/absence of diazoxide for 48 h, the expression of cleaved caspase-3 was detected. (E)(F) Quantitative analysis of western blot. The optical density of each blot band was determined and adjusted by the optical density of β-actin. * p<0.05; ** p<0.01; *** p<0.001 denote significant difference versus the PA-treated alone group, n = 3.

Mentions: There was less effect of both nifedipine and diazoxide on MIN6 cell viability after 48 h incubation (Fig 1A and 1B). However, 48 h treatment of 0.5 mM PA significantly reduced cell viability to approximately 60% compared to control cells (Fig 1A and 1B). Co-incubated with nifedipine and diazoxide dose-dependently inhibited PA-induced decreasing in cell viability (Fig 1A and 1B). Meanwhile, western blot analysis showed that the expression of cleaved caspase-3, an apoptotic marker, was obviously increased in PA-treated cells. Similarly, nifedipine reduced cleaved caspase-3 expression since 1 μM concentration (Fig 1C and 1E). Although not as effective as nifedipine, co-incubation of 200 μM diazoxide with PA still decreased cell apoptosis (Fig 1D and 1F).


Inhibition of Calcium Influx Reduces Dysfunction and Apoptosis in Lipotoxic Pancreatic β-Cells via Regulation of Endoplasmic Reticulum Stress.

Zhou Y, Sun P, Wang T, Chen K, Zhu W, Wang H - PLoS ONE (2015)

Nifedipine and diazoxide protects MIN6 cells from PA-induced apoptosis.(A) After 48 h incubation of nifedipine in the presence/absence of PA, the cell viability was measured by MTT assay. The cell viability was shown as inhibitory ratio (% of control), *** p<0.001 denote significant difference versus the PA-treated alone group, n = 6. (B) After 48 h incubation of diazoxide in the presence/absence of PA, the cell viability was measured by MTT assay. *** p<0.001 denote significant difference versus the PA-treated alone group, n = 6. (C) After the cells were treated with 0.5 mM PA in the presence/absence of nifedipine for 48 h, the expression of cleaved caspase-3 was detected by western blot. (D) After the cells were treated with 0.5 mM PA in the presence/absence of diazoxide for 48 h, the expression of cleaved caspase-3 was detected. (E)(F) Quantitative analysis of western blot. The optical density of each blot band was determined and adjusted by the optical density of β-actin. * p<0.05; ** p<0.01; *** p<0.001 denote significant difference versus the PA-treated alone group, n = 3.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4492560&req=5

pone.0132411.g001: Nifedipine and diazoxide protects MIN6 cells from PA-induced apoptosis.(A) After 48 h incubation of nifedipine in the presence/absence of PA, the cell viability was measured by MTT assay. The cell viability was shown as inhibitory ratio (% of control), *** p<0.001 denote significant difference versus the PA-treated alone group, n = 6. (B) After 48 h incubation of diazoxide in the presence/absence of PA, the cell viability was measured by MTT assay. *** p<0.001 denote significant difference versus the PA-treated alone group, n = 6. (C) After the cells were treated with 0.5 mM PA in the presence/absence of nifedipine for 48 h, the expression of cleaved caspase-3 was detected by western blot. (D) After the cells were treated with 0.5 mM PA in the presence/absence of diazoxide for 48 h, the expression of cleaved caspase-3 was detected. (E)(F) Quantitative analysis of western blot. The optical density of each blot band was determined and adjusted by the optical density of β-actin. * p<0.05; ** p<0.01; *** p<0.001 denote significant difference versus the PA-treated alone group, n = 3.
Mentions: There was less effect of both nifedipine and diazoxide on MIN6 cell viability after 48 h incubation (Fig 1A and 1B). However, 48 h treatment of 0.5 mM PA significantly reduced cell viability to approximately 60% compared to control cells (Fig 1A and 1B). Co-incubated with nifedipine and diazoxide dose-dependently inhibited PA-induced decreasing in cell viability (Fig 1A and 1B). Meanwhile, western blot analysis showed that the expression of cleaved caspase-3, an apoptotic marker, was obviously increased in PA-treated cells. Similarly, nifedipine reduced cleaved caspase-3 expression since 1 μM concentration (Fig 1C and 1E). Although not as effective as nifedipine, co-incubation of 200 μM diazoxide with PA still decreased cell apoptosis (Fig 1D and 1F).

Bottom Line: And whether the compounds could reduce palmitic acid-induced β-cell failure and the underlying mechanism were also investigated.It was found that both nifedipine and diazoxide protected MIN6 pancreatic β-cells and primary cultured murine islets from palmitic acid-induced apoptosis.Our results verified that nifedipine and diazoxide could reduce palmitic acid-induced endoplasmic reticulum stress to generate protective effects on pancreatic β-cells.

View Article: PubMed Central - PubMed

Affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China.

ABSTRACT
Lipotoxicity plays an important role in pancreatic β-cell failure during the development of type 2 diabetes. Prolonged exposure of β-cells to elevated free fatty acids level could cause deterioration of β-cell function and induce cell apoptosis. Therefore, inhibition of fatty acids-induced β-cell dysfunction and apoptosis might provide benefit for the therapy of type 2 diabetes. The present study examined whether regulation of fatty acids-triggered calcium influx could protect pancreatic β-cells from lipotoxicity. Two small molecule compounds, L-type calcium channel blocker nifedipine and potassium channel activator diazoxide were used to inhibit palmitic acid-induced calcium influx. And whether the compounds could reduce palmitic acid-induced β-cell failure and the underlying mechanism were also investigated. It was found that both nifedipine and diazoxide protected MIN6 pancreatic β-cells and primary cultured murine islets from palmitic acid-induced apoptosis. Meanwhile, the impaired insulin secretion was also recovered to varying degrees by these two compounds. Our results verified that nifedipine and diazoxide could reduce palmitic acid-induced endoplasmic reticulum stress to generate protective effects on pancreatic β-cells. More importantly, it suggested that regulation of calcium influx by small molecule compounds might provide benefits for the prevention and therapy of type 2 diabetes.

No MeSH data available.


Related in: MedlinePlus