p21(WAF1/CIP1) inhibits cell cycle progression but not G2/M-phase transition following methylmercury exposure.
p21(WAF1/CIP1) inhibits cell cycle progression but not G2/M-phase transition following methylmercury exposure.
复制标题
p21(WAF1/CIP1) 会抑制细胞周期进程，但不会抑制甲基汞暴露后的 G2/M 相转变。
DOI：
10.1006/taap.2001.9267
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
Faustman,ElaineM
中科院分区：
文献类型：
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作者：
Mendoza,MaAileenC;Ponce,RafaelA;Ou,YingC;Faustman,ElaineM
甲基汞 (MeHg) 是一种环境中普遍存在的有机金属，对发育中的中枢神经系统 (CNS) 特别有毒。产前甲基汞暴露与大脑尺寸和重量的减小以及神经元数量的减少有关，而这又与细胞增殖受损有关。我们评估了 p21（一种参与 G1 和 G2 期检查点控制的细胞周期蛋白）在 MeHg 诱导的细胞周期抑制中的作用。在妊娠第 14 天分离出不同 p21 基因型（野生型、杂合型和无效型）的原代小鼠胚胎成纤维细胞 (MEF)，并在第 4-6 代时用 0、2、4 或 6 μM MeHg 或 50 nM 秋水仙碱处理 24 小时。使用 DAPI 通过基于 DNA 含量的流式细胞术分析连续毒物处理后细胞周期分布的变化。无论 p21 基因型如何，2 和 4 μM MeHg (p ≤ 0.05) 下 MeHg 都会诱导 G2/M 细胞比例增加。随后使用 BrdU-Hoechst 流式细胞术分析评估甲基汞对细胞周期进展的影响。连续暴露于甲基汞 24 和 48 小时后，所有 p21 基因型均观察到细胞周期进展受到抑制。与野生型 (+/-) 和杂合 (+/-) 细胞相比，p21 无效 (−/−) 细胞达到第二轮 G1 的比例更高 (p ≤ 0.05)。这些数据支持之前的观察结果，即甲基汞通过延迟 G2/M 转变抑制细胞周期进程。虽然 MeHg 诱导的 G2/M 积累与 p21 状态无关，但与 p21(+/-) 或 p21(+/-) 细胞相比，更大比例的 p21(−/−) 细胞能够在 MeHg 存在下完成一轮细胞分裂。这些数据表明，在接触甲基汞后，p21 在延缓细胞周期进程中发挥作用，但没有抑制有丝分裂。
Methylmercury (MeHg) is an environmentally prevalent organometal that is particularly toxic to the developing central nervous system (CNS). Prenatal MeHg exposure is associated with reduced brain size and weight and a reduced number of neurons, which have been associated with impaired cell proliferation. We evaluate the role of p21, a cell cycle protein involved in the G1- and G2-phase checkpoint control, in the cell cycle inhibition induced by MeHg. Primary mouse embryonic fibroblasts (MEFs) of different p21 genotypes (wild-type, heterozygous, and null) were isolated at day 14 of gestation and treated at passages 4–6 with either 0, 2, 4, or 6 μM MeHg or 50 nM colchicine for 24 h. Changes in cell cycle distribution after continuous toxicant treatment were analyzed by DNA content-based flow cytometry using DAPI. MeHg induced an increase in the proportion of cells in G2/M at 2 and 4 μM MeHg (p ≤ 0.05) irrespective of p21 genotype. Effects of MeHg on cell cycle progression were subsequently evaluated using BrdU–Hoechst flow cytometric analysis. Inhibition of cell cycle progression was observed in all p21 genotypes after continuous exposure to MeHg for 24 and 48 h. p21 null (−/−) cells reached the second-round G1at a higher fraction compared to the wild type (+/+) and heterozygous (+/−) cells (p ≤ 0.05). These data support previous observations that MeHg inhibits cell cycle progression through delayed G2/M transition. Whereas the G2/M accumulation induced by MeHg was independent of p21 status, a greater proportion of p21(−/−) cells were able to complete one round of cell division in the presence of MeHg compared to p21(+/−) or p21(+/+) cells. These data suggest a role for p21 in retarding cell cycle progression, but not mitotic inhibition, following exposure to MeHg.