Buteau J, El-Assaad W, Rhodes C J, Rosenberg L, Joly E, Prentki M
Molecular Nutrition Unit, Department of Nutrition, University of Montreal, CR-CHUM, Pavillon de Sève, Montreal, PQ, Canada.
Diabetologia. 2004 May;47(5):806-15. doi: 10.1007/s00125-004-1379-6. Epub 2004 Apr 17.
AIMS/HYPOTHESIS: We have provided evidence that glucagon-like peptide-1, a potential therapeutic agent in the treatment of diabetes, activates phosphatidylinositol-3 kinase/protein kinase B signalling in the pancreatic beta cell. Since this pathway promotes cell survival in a variety of systems, we tested whether glucagon-like peptide-1 protects beta cells against cell death induced by elevated glucose and/or non-esterified fatty acids.
Human islets and INS832/13 cells were cultured at glucose concentrations of 5 or 25 mmol/l in the presence or absence of palmitate. Apoptosis was evaluated by monitoring DNA fragmentation and chromatin condensation. Wild-type and protein kinase B mutants were overexpressed in INS832/13 cells using adenoviruses. Nuclear factor-kappa B DNA binding was assayed by electrophoretic mobility shift assay.
In human pancreatic beta cells and INS832/13 cells, glucagon-like peptide-1 prevented beta cell apoptosis induced by elevated concentrations of (i) glucose (glucotoxicity), (ii) palmitate (lipotoxicity) and (iii) both glucose and palmitate (glucolipotoxicity). Overexpression of a dominant-negative protein kinase B suppressed the anti-apoptotic action of glucagon-like peptide-1 in INS832/13 cells, whereas a constitutively active protein kinase B prevented beta cell apoptosis induced by elevated glucose and palmitate. Glucagon-like peptide-1 enhanced nuclear factor-kappa B DNA binding activity and stimulated the expression of inhibitor of apoptosis protein-2 and Bcl-2, two anti-apoptotic genes under the control of nuclear factor-kappa B. Inhibition of nuclear factor-kappa B by BAY 11-7082 abolished the prevention of glucolipotoxicity by glucagon-like peptide-1.
CONCLUSIONS/INTERPRETATION: The results demonstrate a potent protective effect of glucagon-like peptide-1 on beta cell gluco-, lipo- and glucolipotoxicity. This effect is mediated via protein kinase B activation and possibly its downstream target nuclear factor-kappa B.
目的/假设：我们已提供证据表明，胰高血糖素样肽-1作为治疗糖尿病的一种潜在治疗药物，可激活胰腺β细胞中的磷脂酰肌醇-3激酶/蛋白激酶B信号通路。由于该通路在多种系统中促进细胞存活，我们测试了胰高血糖素样肽-1是否能保护β细胞免受高糖和/或非酯化脂肪酸诱导的细胞死亡。
人胰岛和INS832/13细胞在5或25 mmol/l葡萄糖浓度下培养，同时存在或不存在棕榈酸。通过监测DNA片段化和染色质浓缩来评估细胞凋亡。使用腺病毒在INS832/13细胞中过表达野生型和蛋白激酶B突变体。通过电泳迁移率变动分析测定核因子-κB DNA结合情况。
在人胰腺β细胞和INS832/13细胞中，胰高血糖素样肽-1可预防由以下因素诱导的β细胞凋亡：（i）高浓度葡萄糖（糖毒性），（ii）棕榈酸（脂毒性），以及（iii）葡萄糖和棕榈酸共同作用（糖脂毒性）。显性负性蛋白激酶B的过表达抑制了胰高血糖素样肽-1在INS832/13细胞中的抗凋亡作用，而组成型活性蛋白激酶B则可预防高糖和棕榈酸诱导的β细胞凋亡。胰高血糖素样肽-1增强了核因子-κB DNA结合活性，并刺激了凋亡抑制蛋白-2和Bcl-2的表达，这两个抗凋亡基因受核因子-κB调控。BAY 11-7082对核因子-κB的抑制作用消除了胰高血糖素样肽-1对糖脂毒性的预防作用。
结论/解读：结果表明胰高血糖素样肽-1对β细胞的糖毒性、脂毒性和糖脂毒性具有强大的保护作用。这种作用是通过蛋白激酶B激活及其下游靶点核因子-κB介导的。
