Department of Clinical Nutrition, The Second Affiliated Hospital of Zhejiang University, Hangzhou, Zhejiang 310009, P.R. China.
Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University, Hangzhou, Zhejiang 310009, P.R. China.
Mol Med Rep. 2019 Nov;20(5):4277-4284. doi: 10.3892/mmr.2019.10653. Epub 2019 Sep 9.
The objective of the present study was to investigate the effects of polo‑like kinase 1 (PLK1) and the phosphorylation of human cell division cycle protein 14A (Cdc14A) by PLK1 on β‑cell function and cell cycle regulation. Mouse β‑TC3 cells were incubated with small interfering RNA (siRNA) to knock down the expression of PLK1. Cell cycle analysis was performed using flow cytometry, and cell proliferation and apoptosis was determined. Insulin secretion was evaluated by a radioimmunoassay under both low and high glucose conditions. Mouse β‑TC3 cells were transfected with a wild type or a non‑phosphorylatable Cdc14A mutant (Cdc14AS351A/363A; Cdc14AAA) to investigate whether the phosphorylation of Cdc14A is involved in cellular regulation of PLK1 under high glucose conditions. It was found that PLK1 siRNA significantly promoted cellular apoptosis, inhibited cell proliferation, decreased insulin secretion and reduced Cdc14A expression under both low and high glucose conditions. Cdc14A overexpression promoted β‑TC3 cell proliferation and insulin secretion, while Cdc14AAA overexpression inhibited cell proliferation and insulin secretion under high glucose conditions. PLK1 siRNA partially reversed the proliferation‑promoting effects of Cdc14A and further intensified the inhibition of proliferation by Cdc14AAA under high glucose conditions. Similarly, Cdc14A overexpression partially reversed the insulin‑inhibiting effects of PLK1 siRNA, while Cdc14AAA overexpression showed a synergistic inhibitory effect on insulin secretion with PLK1 siRNA under high glucose conditions. In conclusion, PLK1 promoted cell proliferation and insulin secretion while inhibiting cellular apoptosis in β‑TC3 cell lines under both low and high glucose conditions. In addition, the phospho‑regulation of Cdc14A by PLK1 may be involved in β‑TC3 cell cycle regulation and insulin secretion under high glucose conditions.
本研究旨在探讨 Polo 样激酶 1 (PLK1) 和 PLK1 对人细胞分裂周期蛋白 14A (Cdc14A) 的磷酸化对β细胞功能和细胞周期调控的影响。使用小干扰 RNA (siRNA) 孵育小鼠β-TC3 细胞以敲低 PLK1 的表达。通过流式细胞术进行细胞周期分析，并测定细胞增殖和凋亡。在低糖和高糖条件下通过放射免疫测定法评估胰岛素分泌。将野生型或非磷酸化 Cdc14A 突变体 (Cdc14AS351A/363A; Cdc14AAA) 转染至小鼠β-TC3 细胞，以研究在高糖条件下 Cdc14A 的磷酸化是否参与 PLK1 的细胞调控。结果发现，PLK1 siRNA 显著促进细胞凋亡，抑制细胞增殖，减少胰岛素分泌，并降低低糖和高糖条件下的 Cdc14A 表达。Cdc14A 过表达促进β-TC3 细胞增殖和胰岛素分泌，而 Cdc14AAA 过表达抑制高糖条件下的细胞增殖和胰岛素分泌。PLK1 siRNA 部分逆转了 Cdc14A 的促增殖作用，并在高糖条件下进一步增强了 Cdc14AAA 的抑制增殖作用。同样，Cdc14A 过表达部分逆转了 PLK1 siRNA 的胰岛素抑制作用，而 Cdc14AAA 过表达在高糖条件下与 PLK1 siRNA 表现出协同抑制胰岛素分泌的作用。综上所述，PLK1 在低糖和高糖条件下促进β-TC3 细胞系的细胞增殖和胰岛素分泌，同时抑制细胞凋亡。此外，PLK1 对 Cdc14A 的磷酸化调节可能参与β-TC3 细胞周期调控和高糖条件下的胰岛素分泌。
