Department of Medicine and Therapeutics, The Chinese University of Hong Kong, The Prince of Wales Hospital, Shatin, Hong Kong SAR, China.
Diabetes Obes Metab. 2010 Sep;12(9):815-24. doi: 10.1111/j.1463-1326.2010.01238.x.
Glucagon-like peptide-1 (GLP-1) stimulates beta-cell proliferation and enhances beta-cell survival, whereas oligomerization of human islet amyloid polypeptide (hIAPP) may induce beta-cell apoptosis and reduce beta-cell mass. Type 2 diabetes is associated with increased expression of IAPP. As GLP-1-based therapy is currently developed as a novel antidiabetic therapy, we examined the potential protective action of the GLP-1 receptor agonist exendin-4 on hIAPP-induced beta-cell apoptosis.
The study was performed in clonal insulinoma (INS-1E) cells. Both method of transcriptional and translational and sulphorhodamine B (SRB) assays were used to evaluate cell viability and cell mass. Western blot analysis was applied to detect protein expression. Transfection of constitutively active protein kinase B (PKB/AKT) was performed to examine the role of AKT. Mitochondrial biogenesis was quantified by mitogreen staining and RT-PCR.
First, we confirmed that hIAPP induced cell apoptosis and growth inhibition in INS-1E cells. These effects were partially protected by exendin-4 in association with partial recovery of the hIAPP-mediated AKT inhibition. Furthermore, AKT constitutive activation attenuated hIAPP-induced apoptosis, whereas PI3K/AKT inhibition abrogated exendin-4-mediated effects. These findings suggest that the antiapoptotic and proliferative effects of exendin-4 in hIAPP-treated INS-1E cells were partially mediated through AKT pathway. Moreover, hIAPP induced FOXO1 but inhibited pdx-1 nucleus translocation. These effects were restored by exendin-4. Finally, mitogreen staining and RT-PCR revealed enhanced mitochondrial biogenesis by exendin-4 treatment.
Collectively, these results suggest that GLP-1 receptor agonist protects beta cells from hIAPP-induced cell death partially through the activation of AKT pathway and improved mitochondrial function.
胰高血糖素样肽-1（GLP-1）可刺激β细胞增殖并增强β细胞存活，而人胰岛淀粉样多肽（hIAPP）的寡聚化可能诱导β细胞凋亡并减少β细胞数量。2 型糖尿病与 IAPP 的表达增加有关。由于基于 GLP-1 的治疗目前被开发为新型抗糖尿病疗法，我们研究了 GLP-1 受体激动剂 exendin-4 对 hIAPP 诱导的β细胞凋亡的潜在保护作用。
该研究在克隆胰岛素瘤（INS-1E）细胞中进行。采用转录和翻译法以及磺酰罗丹明 B（SRB）测定法来评估细胞活力和细胞数量。采用 Western blot 分析检测蛋白表达。进行组成型激活蛋白激酶 B（PKB/AKT）转染以研究 AKT 的作用。通过 mitogreen 染色和 RT-PCR 定量检测线粒体生物发生。
首先，我们证实 hIAPP 可诱导 INS-1E 细胞发生细胞凋亡和生长抑制。这些作用可通过 exendin-4 部分保护，同时部分恢复 hIAPP 介导的 AKT 抑制。此外，AKT 组成型激活减弱了 hIAPP 诱导的凋亡，而 PI3K/AKT 抑制则消除了 exendin-4 介导的作用。这些发现表明，exendin-4 在 hIAPP 处理的 INS-1E 细胞中的抗凋亡和增殖作用部分通过 AKT 途径介导。此外，hIAPP 诱导 FOXO1 但抑制 pdx-1 核易位。这些作用可通过 exendin-4 恢复。最后，mitogreen 染色和 RT-PCR 显示 exendin-4 处理可增强线粒体生物发生。
总之，这些结果表明 GLP-1 受体激动剂通过激活 AKT 途径和改善线粒体功能，部分保护β细胞免受 hIAPP 诱导的细胞死亡。
Zotero 插件