Department of Endocrinology, Fujian Institute of Endocrinology, Union Hospital of Fujian Medical University, 29 Xinquan Road, Fuzhou, Fujian 350001, People's Republic of China.
J Endocrinol Invest. 2013 Nov;36(10):803-11. doi: 10.3275/8938. Epub 2013 Apr 18.
Glucagon-like peptide-1 (GLP-1) and its potent analog, exendin-4, are well known to inhibit β- cell apoptosis and promote β-cell proliferation. Meanwhile, cytokines, such as interleukin-1β (IL-1β), stimulate inducible nitric oxide synthase (iNOS) expression and nitric oxide overproduction leading to β-cell damage. However, the protective mechanisms of GLP-1 in β-cells exposed to cytokines have not been fully elucidated.
In this study, the protective effects of exendin-4 on IL-1β-induced apoptosis were investigated in murine MIN6 pancreatic β-cells. The role of nuclear factor-κB (NF-κB) signaling in this process was also explored.
The effects of exendin-4 pre-treatment on IL-1β-induced apoptosis were investigated by Hoechst/PI and Annexin V/PI staining. Levels of iNOS and NF-κB proteins were investigated by Western blotting and cytoplasmic nitrite levels were determined using Griess reagent.
IL-1β treatment (range, 5-40 ng/ml) for 24 h was positively correlated with nitrite production (R2=0.9668, p<0.01), a significant increase in the percentage of apoptotic cells (p<0.01) and a concomitant dose-dependent increase in cytoplasmic levels of iNOS and NF-κB p65 activation. N-acetyl- L-cysteine (NAC), NG-nitro-L-arginine methyl ester (L-NAME) and pyrrolidine dithiocarbamate (PDTC), partially rescued apoptotic β-cells, suggesting involvement of NF-κB-iNOS-nitrite in this process. Exendin-4 (100 nM) treatment significantly decreased IL-1β-induced apoptosis (p<0.01), downregulated NF-κB activation and subsequently decreased iNOS and nitrite levels in IL-1β-induced β-cells (p<0.001), in a similar manner to L-NAME, PDTC and NAC.
These results suggest that exendin-4 protects against IL-1β- induced apoptosis in β-cells via downregulation of the NF- κB-iNOS-nitrite pathway.
胰高血糖素样肽-1（GLP-1）及其有效类似物 Exendin-4 已被证实可抑制β细胞凋亡并促进β细胞增殖。同时，细胞因子如白细胞介素-1β（IL-1β）可刺激诱导型一氧化氮合酶（iNOS）表达和一氧化氮产生过多，导致β细胞损伤。然而，GLP-1 对暴露于细胞因子的β细胞的保护机制尚未完全阐明。
本研究旨在探讨 Exendin-4 对 IL-1β诱导的 MIN6 胰岛β细胞凋亡的保护作用，并探讨核因子-κB（NF-κB）信号通路在此过程中的作用。
通过 Hoechst/PI 和 Annexin V/PI 染色法研究 Exendin-4 预处理对 IL-1β诱导的凋亡的影响。采用 Western blot 法检测 iNOS 和 NF-κB 蛋白水平，用 Griess 试剂测定细胞质中亚硝酸盐水平。
24 h 内，IL-1β（5-40 ng/ml）处理与亚硝酸盐生成呈正相关（R2=0.9668，p<0.01），细胞凋亡百分率显著增加（p<0.01），细胞质中 iNOS 和 NF-κB p65 激活呈剂量依赖性增加。N-乙酰-L-半胱氨酸（NAC）、NG-硝基-L-精氨酸甲酯（L-NAME）和吡咯烷二硫代氨基甲酸盐（PDTC）部分挽救了凋亡的β细胞，提示 NF-κB-iNOS-亚硝酸盐在此过程中发挥作用。Exendin-4（100 nM）处理可显著降低 IL-1β诱导的细胞凋亡（p<0.01），下调 NF-κB 激活，进而降低 IL-1β诱导的β细胞中 iNOS 和亚硝酸盐水平（p<0.001），作用方式与 L-NAME、PDTC 和 NAC 相似。
这些结果表明，Exendin-4 通过下调 NF-κB-iNOS-亚硝酸盐通路来保护β细胞免受 IL-1β诱导的凋亡。
Zotero 插件