Sangguayin preparation prevents palmitate-induced apoptosis by suppressing endoplasmic reticulum stress and autophagy in db/db mice and MIN6 pancreatic β-cells / 中国天然药物

Sangguayin preparation (SGY-P) is refined from the traditional Chinese medicinal compound Sangguayin, which "clears heat and promotes fluid" and "tonifies kidney and spleen" for "Xiaoke", commonly known as 'Diabetes mellitus' in clinics. Previous studies have shown that SGY-P could reduce insulin resistance and repair damaged pancreas in db/db mice, but the underlying mechanisms were unclear. Here, we investigated whether treatment with SGY-P could protect pancreatic β-cells from apoptosis and uncovered the underlying mechanisms. db/db mice were used to observe the hypoglycemic and islet protective effect in vivo. Apoptosis was induced in mouse insulinoma 6 (MIN6) cells by palmitate, following which the cells were treated with SGY-P for elucidating the anti-apoptotic mechanism in vitro. Cell viability and nuclear morphology were detected by CCK-8 assay and Hoechst 33258 staining. The expression levels of apoptosis-, endoplasmic reticulum (ER) stress-, and autophagy-related proteins were measured by western blot. The results showed that SGY-P reduced fasting blood glucose, pancreatic pathological changes, and islet β-cell apoptosis in db/db mice. Palmitate-induced apoptosis in MIN6 cells was decreased by SGY-P treatment. Hence, SGY-P therapy exhibited a protective effect on pancreatic β-cells by decreasing the expression of cleaved caspase-3, cleaved PARP and Bax, and increasing Bcl-2 by suppressing ER stress (Bip/XBP1/IRE1α/CHOP/Caspase-12) and autophagy (LC3/p62/Atg5) pathways.2/Atg5) pathways.

The protective effect of 1,25-dihydroxyvitamin-d3 on hydrogen peroxide-induced min6 cell apoptosis / 中国药理学通报

Aim To investigate the role and mechanism of VitD in protecting apoptosis of mouse islet (3 cell line MIN6 cells induced by H202. Methods MIN6 cells were treated with H202 after the pretreat-ment of VitD. The proliferation, morphological changes and apoptotic percentage of MIN6 cells were determined by CCK-8, Hoechst 33258 fluorescence staining and flow cytometry respectively. The expressions of ap-optosis-related genes Bel-2, Bax, Caspase-3 and Cleaved caspase-3 were detected by Western blot. Results H202 inhibited proliferation and induced apop-tosis of MIN6 cells through up-regulation of Bax and cleaved caspase-3, down-regulation of Bcl-2, decrease of Bcl-2/Bax ratio,and increase of cleaved caspase-3/caspase-3 ratio. After pretreatment of VitD, MIN6 cell viability was restored by increasing Bcl-2 expression, decreasing Bax and cleaved caspase-3 expression, increasing Bcl-2/Bax ratio, and decreasing cleaved caspase-3/caspase-3 ratio. Conclusions VitD protects MIN6 against H202-induced apoptosis through decreasing pro-apoptotic gene Bax and cleaved caspase-3,and increasing anti-apoptotic gene Bcl-2 expression.

Effects of advanced glycation end products on cell viability and level of reactive oxygen species(ROS)in MIN6 cells / 中华内分泌代谢杂志

To explore the effect of advanced glycation end-products(AGEs)on cell viability and level of reactive oxygen species(ROS)in MIN6 cells. After intervention of various concentrations(100,200, and 400 mg/L)of AGEs for some time, cell viability was detected by MTT assay. 2', 7'-dichlorofluorescein diacetate(DCFH-DA)was used as a reactive oxygen species capture agent. The fluorescent intensity of 2', 7'-dichlorofluorescein(DCF), which was the product of cellular oxidation of DCFH-DA, was detected by flow cytometry. The level of ROS and insulin secretion was thus measured. Viability of MIN6 cells was inhibited by AGEs in a dose and time dependent manner(P＜0.05).Intracellular fluorescent intensity of DCF was markedly elevated in the AGEs groups as compared with that in the control group(P＜0.05).Insulin secretion was decreased in the AGEs groups than that in the control group(P＞0.05). The results suggest that AGEs inhibit the viability and induce oxidative stress in MIN6 cells by overproduction of ROS.

Mechanism of lipotoxicity-associated apoptosis mediated by mitochondrial dysfunction in pancreatic β-cells / 中国病理生理杂志

AIM:To investigate the mechanism of lipotoxicity-associated apoptosis mediated by mitochondrial pathway in pancreatic β-cells. METHODS:The pancreatic β-cell line MIN6 cells were incubated respectively in serum-free DMEM medium with or without palmitate (0.1-0.5 mmol/L) for 24 h,followed by Hoechst 33258 staining. The activity of caspase 3 was assayed for determining apoptosis,transmission electron microscope was used for observing mitochondrial structure,and RT-PCR analysis was applied for detection of mRNA expression of bcl-2-associated X protein (bax),B-cell lymphoma 2 (bcl-2),sterol regulatory element binding transcription factor 1c (SREBP1c) and DNA-damage inducible transcript 3 (chop-10). RESULTS:Palmitate induced apoptosis of MIN6 cells and swelling of mitochondria. Palmitate also inhibited mRNA expression of bcl-2,whereas enhanced mRNA expression of bax,SREBP1c and chop-10. CONCLUSION:Palmitate induces apoptosis of pancreatic β-cells by promoting mitochondrial dysfunction,which is associated with abnormal expressions of bax,bcl-2,SREBP1c and chop-10.

Palmitate induces cell apoptosis in insulinoma MIN6 cell / 基础医学与临床

Objective To investigate the effect of protein kinase B and its phosphorylation on the apoptosis of MIN6 induced by palmitate.Methods Incubated with different level of palmitate concentration (0 ～ 0.5 mmol/L),MIN6 cells were cultured in high glucose DMEM with or without LY294002 ; the apoptosis of MIN6 cells was detec-ted and quantified with TUNEL technology.Then we inspected the cell ultrastructure through electron microscopy and determined the expression of protein kinase B and its phosphorylation p-PKB (Ser473) by Western blot,fol-lowed by an RT-PCR detection of BAX and BCL-2 expression.Results Apoptosis of MIN6 cells was induced by palmitate in a concentration-dependent correlation and enhanced by LY294002.Palmitate also inhibited phospho-rylation of protein kinase B on Ser473.Finally,we detected a downregulation of BCL-2 mRNA expression and up-regulation of BAX mRNA expression under palmitate-incubated state.Conclusion Palmitate may induce apoptosis of pancreatic β-cells through inhibiting activation of PKB phosphorylation in diabetes.

Visfatin inhibits pancreatic β-cell line MIN6 apoptosis via PI3K-Akt and MAPK-ERK1/2 signaling pathways / 中华内分泌代谢杂志

To investigate the effects and the mechanism of visfatin on MIN6 cell signaling pathway and apoptosis induced by palmitate.Human recombinant visfatin promotes protein kinase B (Akt) and extracellularsignal regulating kinase (ERK)1/2 phosphorylation in dose-and time-dependent manner,and prevents MIN6 cell from apoptosis induced by palmitate (P<0.05 or P<0.01).The activation of Akt and ERK1/2 signaling pathway may be one of the molecular mechanisms of visfatin.