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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

Hoechst33342 staining analysis in MIN6 cells.(A) After the cells were treated with 0.5 mM PA in the presence/absence of nifedipine at indicated concentrations for 48 h, Hoechst33342 staining was performed to detect apoptotic cells. Blue fluorescence indicated all nucleus, the lighter and shrinkage dots were apoptotic cells. Scale bar = 100 μm and referred to all panels. (B) After the cells were treated with 0.5 mM PA in the presence/absence of diazoxide for 48 h, Hoechst33342 staining was performed. (C)(D) The apoptotic rate was calculated as apoptotic cell number divided by total cell number. 10 random sights in each well were selected to count apoptosis, and the data from six duplicated wells were analyzed (n = 6). *** p<0.001 denote significant difference versus the PA-treated alone group.
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pone.0132411.g002: Hoechst33342 staining analysis in MIN6 cells.(A) After the cells were treated with 0.5 mM PA in the presence/absence of nifedipine at indicated concentrations for 48 h, Hoechst33342 staining was performed to detect apoptotic cells. Blue fluorescence indicated all nucleus, the lighter and shrinkage dots were apoptotic cells. Scale bar = 100 μm and referred to all panels. (B) After the cells were treated with 0.5 mM PA in the presence/absence of diazoxide for 48 h, Hoechst33342 staining was performed. (C)(D) The apoptotic rate was calculated as apoptotic cell number divided by total cell number. 10 random sights in each well were selected to count apoptosis, and the data from six duplicated wells were analyzed (n = 6). *** p<0.001 denote significant difference versus the PA-treated alone group.

Mentions: To further evaluate the protective effect of nifedipine and diazoxide on MIN6 cells, Hoechst33342 staining was performed to visualize apoptotic cells. Nuclei of apoptotic cells would display a high condensed chromatin compared with normal cells after Hoechst staining. As shown in Fig 2A and 2B, 0.5 mM PA-treated cells showed brighter nuclei with nuclei shrinkage and highly condensed DNA. However, an obviously reduced apoptotic rate was observed in co-incubation of both nifedipine and diazoxide with PA compared to PA-treated alone group in a dose-dependent manner (Fig 2A–2D).


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)

Hoechst33342 staining analysis in MIN6 cells.(A) After the cells were treated with 0.5 mM PA in the presence/absence of nifedipine at indicated concentrations for 48 h, Hoechst33342 staining was performed to detect apoptotic cells. Blue fluorescence indicated all nucleus, the lighter and shrinkage dots were apoptotic cells. Scale bar = 100 μm and referred to all panels. (B) After the cells were treated with 0.5 mM PA in the presence/absence of diazoxide for 48 h, Hoechst33342 staining was performed. (C)(D) The apoptotic rate was calculated as apoptotic cell number divided by total cell number. 10 random sights in each well were selected to count apoptosis, and the data from six duplicated wells were analyzed (n = 6). *** p<0.001 denote significant difference versus the PA-treated alone group.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0132411.g002: Hoechst33342 staining analysis in MIN6 cells.(A) After the cells were treated with 0.5 mM PA in the presence/absence of nifedipine at indicated concentrations for 48 h, Hoechst33342 staining was performed to detect apoptotic cells. Blue fluorescence indicated all nucleus, the lighter and shrinkage dots were apoptotic cells. Scale bar = 100 μm and referred to all panels. (B) After the cells were treated with 0.5 mM PA in the presence/absence of diazoxide for 48 h, Hoechst33342 staining was performed. (C)(D) The apoptotic rate was calculated as apoptotic cell number divided by total cell number. 10 random sights in each well were selected to count apoptosis, and the data from six duplicated wells were analyzed (n = 6). *** p<0.001 denote significant difference versus the PA-treated alone group.
Mentions: To further evaluate the protective effect of nifedipine and diazoxide on MIN6 cells, Hoechst33342 staining was performed to visualize apoptotic cells. Nuclei of apoptotic cells would display a high condensed chromatin compared with normal cells after Hoechst staining. As shown in Fig 2A and 2B, 0.5 mM PA-treated cells showed brighter nuclei with nuclei shrinkage and highly condensed DNA. However, an obviously reduced apoptotic rate was observed in co-incubation of both nifedipine and diazoxide with PA compared to PA-treated alone group in a dose-dependent manner (Fig 2A–2D).

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