Tsuda H, Neckers L M, Pluznik D H
Proc Natl Acad Sci U S A. 1986 Jun;83(12):4317-21. doi: 10.1073/pnas.83.12.4317.
Granulocyte-colony stimulating factor (G-CSF) induces differentiation of M1 murine myeloid leukemia cells into mature granulocytes/macrophages and also causes accumulation of the cells in the G1 phase of the cell cycle. We examined, therefore, whether synchronization of M1 cells in the G1 phase could affect G-CSF-induced differentiation as quantitated by expression of Fc fragment receptors (FcR) and lysozyme activity. Cells were arrested in early G1 by density inhibition in the absence of serum and in late G1 by addition of aphidicolin. Cells synchronized in early G1, when stimulated with G-CSF, showed enhanced expression of FcR and lysozyme activity. Eighty percent of the cells expressed FcR 18 hr after addition of G-CSF while, in exponentially growing cells, this percentage was reached 72 hr after addition of G-CSF. Cells synchronized in late G1 did not show enhanced expression of differentiation markers. These results imply that with respect to G-CSF-induced differentiation, the G1 phase can be separated into an early permissive and a later nonpermissive stage.
粒细胞集落刺激因子（G-CSF）可诱导M1小鼠髓系白血病细胞分化为成熟的粒细胞/巨噬细胞，还会使细胞在细胞周期的G1期积累。因此，我们研究了将M1细胞同步于G1期是否会影响G-CSF诱导的分化，分化程度通过Fc片段受体（FcR）的表达和溶菌酶活性来定量。细胞在无血清条件下通过密度抑制被阻滞在G1早期，通过添加阿非迪霉素被阻滞在G1晚期。在早期G1期同步化的细胞，在用G-CSF刺激时，显示出FcR表达增强和溶菌酶活性增强。添加G-CSF后18小时，80%的细胞表达FcR，而在指数生长的细胞中，添加G-CSF后72小时才达到这个百分比。在晚期G1期同步化的细胞未显示分化标志物表达增强。这些结果表明，就G-CSF诱导的分化而言，G1期可分为早期允许阶段和晚期非允许阶段。
