早老素通过下调CDK4使HEK293T细胞周期阻滞

早老素（progerin）的累积导致儿童早老症（Hutchinson Gilford progeria syndrome, HGPS）的发生，并与正常衰老相关。早老素能使细胞内稳态失衡但分子机制仍有待深入研究。本研究旨在探讨早老素导入人胚胎肾293T细胞（human embryo kidney 293T cell, HEK293T）后细胞增殖、周期变化的分子机制。形态学观察发现过表达早老素的HEK293T细胞密度下降，(57±2.47)%细胞核形态皱缩。细胞增殖和周期实验证明早老素使细胞增殖减慢，发生G1/S期阻滞，G1细胞从 (42.3±1.31)%升至(47.2±1.26)%，而S期细胞从 (43.1±1.36)%降至 (38.5±1.42)%。Western印迹结果显示早老素的高表达引起p21蛋白表达上调（103.2±1.49）%，CDK4下调（63±1.52）%，而p53、ATM、CyclinE1以及p16等蛋白质水平均不变；HEK293T细胞中早老素的过表达导致γ H2AX水平下调（53±1.36）%，H2O2处理后变化趋势不变。我们的研究结果提示，早老素通过上调p21和下调CDK4使细胞发生周期阻滞，不能增加HEK293T细胞的损伤及衰老。

Progerin Induces Cell Cycle Arrest by Targeting CDK4 in HEK293T

The accumulation of progerin is involved in Hutchinson Gilford progeria (HGPS), which is also associated with normal aging. Progerin can perturb cellular homeostasis, however, the detailed mechanisms remain unknown. In this study, we investigated whether progerin elicits changing of human embryonic kidney 293T cells (HEK293T) proliferation and cell cycle and the associated mechanisms. Morphological observation showed that lower cell density and nucleic shrinkage in HEK293T cells with progerin overexpression than that in the control group. Results of cell proliferation and cell cycle assays showed that progerin inhibited cellular proliferation and led to G1/S transition arrest. Cells of G1 phase increased from 42.3% to 47.2% and S phase cells decreased from 43.1% to 38.5%. Analysis of Western blot indicated that progerin increased p21 and decreased CDK4 expression in HEK293T cells, while the expression of p53, ATM, CyclinE1 and p16 at the protein level was not affected. Progerin reducedγ-H2AX expression in HEK293T cells, which was consistent with that in cells treated with H2O2. These data suggest that progerin can block cell cycle at G1/S transit by targeting CDK4 and p21 in HEK293T.