Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, 221002, Jiangsu, China.
Acta Diabetol. 2024 Apr;61(4):485-494. doi: 10.1007/s00592-023-02221-w. Epub 2023 Dec 27.
FoxO1 is an important factor in the β-cell differentiation in type 2 diabetes mellitus (T2DM). Sirt3 is found to be involved in FoxO1 function. This study investigated the role of Sirt3 in the β-cell dedifferentiation and its mechanism.
Twelve-week-old db/db mice and INS1 cells transfected with Sirt3-specific short hairpin RNA (shSirt3) were used to evaluate the dedifferentiation of β-cell. Insulin levels were measured by enzyme linked immunosorbent assay. The proteins of Sirt3, T-FoxO1, Ac-FoxO1 and differentiation indexes such as NGN3, OCT4, MAFA were determined by western blot or immunofluorescence staining. The combination of Sirt3 and FoxO1 was determined by the co-immunoprecipitation assay. The transcriptional activity of FoxO1 was detected by dual luciferase reporter assay.
Both the in vivo and in vitro results showed that Sirt3 was decreased along with β-cell dedifferentiation and decreased function of insulin secretion under high glucose conditions. When Sirt3 was knocked down in INS1 cells, increased β-cell dedifferentiation and lowered insulin secretion were observed. This effect was closely related to the amount loss and the decreased deacetylation of FoxO1, which resulted in a reduction in transcriptional activity.
Downregulation of Sirt3 contributes to β-cell dedifferentiation in high glucose via FoxO1. Intervention of Sirt3 may be an effective approach to prevent β-cell failure in T2DM.
FoxO1 是 2 型糖尿病（T2DM）β 细胞分化的重要因素。Sirt3 被发现参与 FoxO1 功能。本研究探讨了 Sirt3 在β 细胞去分化中的作用及其机制。
使用 12 周龄 db/db 小鼠和转染 Sirt3 特异性短发夹 RNA（shSirt3）的 INS1 细胞来评估β细胞的去分化。通过酶联免疫吸附测定法测量胰岛素水平。通过 Western blot 或免疫荧光染色测定 Sirt3、T-FoxO1、Ac-FoxO1 和分化指标（如 NGN3、OCT4、MAFA）的蛋白水平。通过共免疫沉淀测定 Sirt3 和 FoxO1 的结合。通过双荧光素酶报告基因检测法检测 FoxO1 的转录活性。
体内和体外结果均表明，随着β细胞去分化和高糖条件下胰岛素分泌功能下降，Sirt3 减少。当 INS1 细胞中的 Sirt3 被敲低时，观察到β细胞去分化增加和胰岛素分泌降低。这种作用与 FoxO1 的量减少和去乙酰化减少密切相关，导致转录活性降低。
高糖环境下 Sirt3 的下调通过 FoxO1 导致β 细胞去分化。Sirt3 的干预可能是预防 T2DM 中β 细胞衰竭的有效方法。
