Mencherini F, Khochbin S, Chabanas A, Lawrence J J
INSERM Unité 309, Département de Biologie Moléculaire et Structurale, Centre d'Etudes Nucléaires de Grenoble.
Cytometry. 1992;13(5):518-24. doi: 10.1002/cyto.990130511.
Cell cycle modifications are among the early events which take place during the induced differentiation of murine erythroleukemia (MEL) cells; a transient accumulation of the cells in the G1 phase of the cell cycle, followed by a re-entry of the cells into a proliferation state, has been described. In order to characterize a putative role of serum in such variations, we have studied the modifications of the cell cycle parameters when cells were induced to differentiate in the presence or in the absence of seric factors. We show that, in the absence of exogenous factors brought by serum, the G1 accumulation was enhanced both in amplitude and in duration, but cells were still able to bypass the G1 block and re-enter into the S phase. These results indicate that the resumption of cell proliferation after the transient block is under synergistic control of seric and endogenous factors, but these later are sufficient to overcome the block. However, MEL cells were unable to differentiate in the absence of seric factors, as measured by the number of benzidine-positive cells during induction with hexamethylene-bisacetamide (HMBA) or butyric acid. This capacity to differentiate was recovered when serum was added back to the culture medium, and the efficiency of recovery was maximal when cells underwent a full round of DNA replication in the presence of serum after the G1 block. The analysis of two molecular markers of cell differentiation confirmed these results.
细胞周期修饰是小鼠红白血病（MEL）细胞诱导分化过程中发生的早期事件之一；已有描述称，细胞在细胞周期的G1期短暂积累，随后重新进入增殖状态。为了描述血清在这种变化中的假定作用，我们研究了在有或无血清因子存在的情况下诱导细胞分化时细胞周期参数的修饰。我们发现，在没有血清带来的外源性因子的情况下，G1期积累在幅度和持续时间上均增强，但细胞仍能够绕过G1期阻滞并重新进入S期。这些结果表明，短暂阻滞之后细胞增殖的恢复受血清和内源性因子的协同控制，但后者足以克服阻滞。然而，通过在用六亚甲基双乙酰胺（HMBA）或丁酸诱导期间联苯胺阳性细胞的数量来衡量，MEL细胞在没有血清因子的情况下无法分化。当将血清重新添加到培养基中时，这种分化能力得以恢复，并且当细胞在G1期阻滞之后在有血清的情况下经历一整轮DNA复制时，恢复效率最高。对细胞分化的两个分子标记的分析证实了这些结果。
