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Exendin-4 protects oxidative stress-induced β-cell apoptosis through reduced JNK and GSK3β activity.

Kim JY, Lim DM, Moon CI, Jo KJ, Lee SK, Baik HW, Lee KH, Lee KW, Park KY, Kim BJ - J. Korean Med. Sci. (2010)

Bottom Line: After pretreatment of Ex-4, GLP-1 receptor agonist, flow cytometric analysis shows 41.7% reduction of β-cell apoptosis.Also, Ex-4 treatment decreased GSK3β activation, JNK phosphorylation and caspase-9, -3 activation and recovered the expression of insulin2 mRNA in β-cell lines and secretion of insulin in human islet.These results suggest that Ex-4 may protect β-cell apoptosis by blocking the JNK and GSK3β mediated apoptotic pathway.

View Article: PubMed Central - PubMed

Affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Konyang University School of Medicine, Daejeon, Korea.

ABSTRACT
Oxidative stress induced by chronic hyperglycemia in type 2 diabetes plays a crucial role in progressive loss of β-cell mass through β-cell apoptosis. Glucagon like peptide-1 (GLP-1) has effects on preservation of β-cell mass and its insulin secretory function. GLP-1 possibly increases islet cell mass through stimulated proliferation from β-cell and differentiation to β-cell from progenitor cells. Also, it probably has an antiapoptotic effect on β-cell, but detailed mechanisms are not proven. Therefore, we examined the protective mechanism of GLP-1 in β-cell after induction of oxidative stress. The cell apoptosis decreased to ~50% when cells were treated with 100 µM H(2)O(2) for up to 2 hr. After pretreatment of Ex-4, GLP-1 receptor agonist, flow cytometric analysis shows 41.7% reduction of β-cell apoptosis. This data suggested that pretreatment of Ex-4 protect from oxidative stress-induced apoptosis. Also, Ex-4 treatment decreased GSK3β activation, JNK phosphorylation and caspase-9, -3 activation and recovered the expression of insulin2 mRNA in β-cell lines and secretion of insulin in human islet. These results suggest that Ex-4 may protect β-cell apoptosis by blocking the JNK and GSK3β mediated apoptotic pathway.

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Related in: MedlinePlus

Effects of the Ex-4 on insulin secretion. Human islet was pretreated with H89 (10 µM). After 30 min, HIT-T15 cells or human islet was treated Ex-4 (25 nM) and NAC (5 mM) for 1 hr before stress induction. After treatment of H2O2 (100 µM, 2 hr), (A) Expression levels of insulin2 mRNA were examined by real time RT-PCR in HIT-T15 cells. Data were expressed as the rates to the expression levels to GAPDH in the same sample. GAPDH used for loading control. (B) Insulin secretion in human islet was detected by Insulin ELISA kit. Data are shown as the means±S.E. of four independent experiments.*P<0.01 vs H2O2 alone; †P<0.01 vs Ex-4 in treated H2O2.
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Figure 4: Effects of the Ex-4 on insulin secretion. Human islet was pretreated with H89 (10 µM). After 30 min, HIT-T15 cells or human islet was treated Ex-4 (25 nM) and NAC (5 mM) for 1 hr before stress induction. After treatment of H2O2 (100 µM, 2 hr), (A) Expression levels of insulin2 mRNA were examined by real time RT-PCR in HIT-T15 cells. Data were expressed as the rates to the expression levels to GAPDH in the same sample. GAPDH used for loading control. (B) Insulin secretion in human islet was detected by Insulin ELISA kit. Data are shown as the means±S.E. of four independent experiments.*P<0.01 vs H2O2 alone; †P<0.01 vs Ex-4 in treated H2O2.

Mentions: Finally, to investigate whether Ex-4 increases the practical ability of insulin secretion, we performed change of insulin2 mRNA in β-cell line and insulin secretion in human islet. As shown in Fig. 4, under H2O2-treatment condition, expression of insulin2 mRNA and insulin secretion were decreased remarkably, but treatment of NAC or Ex-4 in oxidative stress was recovered dramatically.


Exendin-4 protects oxidative stress-induced β-cell apoptosis through reduced JNK and GSK3β activity.

Kim JY, Lim DM, Moon CI, Jo KJ, Lee SK, Baik HW, Lee KH, Lee KW, Park KY, Kim BJ - J. Korean Med. Sci. (2010)

Effects of the Ex-4 on insulin secretion. Human islet was pretreated with H89 (10 µM). After 30 min, HIT-T15 cells or human islet was treated Ex-4 (25 nM) and NAC (5 mM) for 1 hr before stress induction. After treatment of H2O2 (100 µM, 2 hr), (A) Expression levels of insulin2 mRNA were examined by real time RT-PCR in HIT-T15 cells. Data were expressed as the rates to the expression levels to GAPDH in the same sample. GAPDH used for loading control. (B) Insulin secretion in human islet was detected by Insulin ELISA kit. Data are shown as the means±S.E. of four independent experiments.*P<0.01 vs H2O2 alone; †P<0.01 vs Ex-4 in treated H2O2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2967000&req=5

Figure 4: Effects of the Ex-4 on insulin secretion. Human islet was pretreated with H89 (10 µM). After 30 min, HIT-T15 cells or human islet was treated Ex-4 (25 nM) and NAC (5 mM) for 1 hr before stress induction. After treatment of H2O2 (100 µM, 2 hr), (A) Expression levels of insulin2 mRNA were examined by real time RT-PCR in HIT-T15 cells. Data were expressed as the rates to the expression levels to GAPDH in the same sample. GAPDH used for loading control. (B) Insulin secretion in human islet was detected by Insulin ELISA kit. Data are shown as the means±S.E. of four independent experiments.*P<0.01 vs H2O2 alone; †P<0.01 vs Ex-4 in treated H2O2.
Mentions: Finally, to investigate whether Ex-4 increases the practical ability of insulin secretion, we performed change of insulin2 mRNA in β-cell line and insulin secretion in human islet. As shown in Fig. 4, under H2O2-treatment condition, expression of insulin2 mRNA and insulin secretion were decreased remarkably, but treatment of NAC or Ex-4 in oxidative stress was recovered dramatically.

Bottom Line: After pretreatment of Ex-4, GLP-1 receptor agonist, flow cytometric analysis shows 41.7% reduction of β-cell apoptosis.Also, Ex-4 treatment decreased GSK3β activation, JNK phosphorylation and caspase-9, -3 activation and recovered the expression of insulin2 mRNA in β-cell lines and secretion of insulin in human islet.These results suggest that Ex-4 may protect β-cell apoptosis by blocking the JNK and GSK3β mediated apoptotic pathway.

View Article: PubMed Central - PubMed

Affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Konyang University School of Medicine, Daejeon, Korea.

ABSTRACT
Oxidative stress induced by chronic hyperglycemia in type 2 diabetes plays a crucial role in progressive loss of β-cell mass through β-cell apoptosis. Glucagon like peptide-1 (GLP-1) has effects on preservation of β-cell mass and its insulin secretory function. GLP-1 possibly increases islet cell mass through stimulated proliferation from β-cell and differentiation to β-cell from progenitor cells. Also, it probably has an antiapoptotic effect on β-cell, but detailed mechanisms are not proven. Therefore, we examined the protective mechanism of GLP-1 in β-cell after induction of oxidative stress. The cell apoptosis decreased to ~50% when cells were treated with 100 µM H(2)O(2) for up to 2 hr. After pretreatment of Ex-4, GLP-1 receptor agonist, flow cytometric analysis shows 41.7% reduction of β-cell apoptosis. This data suggested that pretreatment of Ex-4 protect from oxidative stress-induced apoptosis. Also, Ex-4 treatment decreased GSK3β activation, JNK phosphorylation and caspase-9, -3 activation and recovered the expression of insulin2 mRNA in β-cell lines and secretion of insulin in human islet. These results suggest that Ex-4 may protect β-cell apoptosis by blocking the JNK and GSK3β mediated apoptotic pathway.

Show MeSH
Related in: MedlinePlus