Department of Endocrinology, Key Laboratory of Endocrinology Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China. Email:
Chin Med J (Engl). 2013 Nov;126(21):4048-53.
Suppressor of cytokine signaling (SOCS) proteins are inhibitors of cytokine signaling pathway involved in negative feedback loops. Although SOCS1 is an important intracellular suppressor of apoptosis in a variety of cell types, its role in cytokine-induced pancreatic β-cell apoptosis remains unclear. The present study investigated potential effects of SOCS1 on the cytokine-induced pancreatic β-cell apoptosis.
After successfully transfected with SOCS1/pEGFP-C1 or pEGFP-C1 plasmids to overexpress SOCS1, RINm5F (rat insulinoma cell line) cells were exposed to cytokines, interferon (IFN)-γ alone, IFN-γ+interleukin (IL)-1β, IFN-β+IL-1β+tumor necrosis factor (TNF)-α respectively. Pancreatic β-cell apoptosis was assessed by using MTT, FACS, and caspase-3 activity assays. Protein phosphorylation of Janus kinase 2 (JAK2) and signal transducers and activators of transcription 1 (STAT1) were verified by Western blotting and mRNA expression of inducible nitric oxide synthase (iNOS), NF-κB and Fas were analyzed by RT-PCR.
Overexpression of SOCS1 in RINm5F cells was shown to attenuate IFN-γ alone, IFN-γ+IL-1β and IFN-γ+TNF-α+IL-1β mediated apoptosis. Phosphorylation of JAK2 and STAT1 significantly decreased in RINm5F cells which overexpressed SOCS1 protein. Overexpression of SOCS1 significantly suppressed cytokine-induced iNOS mRNA levels.
Overexpression of SOCS1 protects pancreatic islets from cytokine-induced cell apoptosis via the JAK2/STAT1 pathway.
细胞因子信号转导抑制蛋白（SOCS）是细胞因子信号通路的负反馈调节因子。虽然 SOCS1 是多种细胞类型中细胞凋亡的重要细胞内抑制剂，但它在细胞因子诱导的胰岛β细胞凋亡中的作用尚不清楚。本研究旨在探讨 SOCS1 对细胞因子诱导的胰岛β细胞凋亡的潜在影响。
成功转染 SOCS1/pEGFP-C1 或 pEGFP-C1 质粒以过表达 SOCS1 后，用干扰素（IFN）-γ、IFN-γ+白细胞介素（IL）-1β、IFN-β+IL-1β+肿瘤坏死因子（TNF）-α分别处理 RINm5F（大鼠胰岛素瘤细胞系）细胞。采用 MTT、FACS 和 caspase-3 活性测定法评估胰岛β细胞凋亡情况。通过 Western blot 验证 JAK2 和信号转导子和转录激活子 1（STAT1）的蛋白磷酸化，通过 RT-PCR 分析诱导型一氧化氮合酶（iNOS）、NF-κB 和 Fas 的 mRNA 表达。
在 RINm5F 细胞中过表达 SOCS1 可减轻 IFN-γ 单独、IFN-γ+IL-1β 和 IFN-γ+TNF-α+IL-1β 介导的细胞凋亡。SOCS1 蛋白过表达的 RINm5F 细胞中 JAK2 和 STAT1 的磷酸化明显降低。SOCS1 过表达显著抑制细胞因子诱导的 iNOS mRNA 水平。
SOCS1 的过表达通过 JAK2/STAT1 途径保护胰岛免受细胞因子诱导的细胞凋亡。
