Sage J, Mulligan G J, Attardi L D, Miller A, Chen S, Williams B, Theodorou E, Jacks T
Department of Biology and Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Genes Dev. 2000 Dec 1;14(23):3037-50. doi: 10.1101/gad.843200.
The retinoblastoma protein, pRB, and the closely related proteins p107 and p130 are important regulators of the mammalian cell cycle. Biochemical and genetic studies have demonstrated overlapping as well as distinct functions for the three proteins in cell cycle control and mouse development. However, the role of the pRB family as a whole in the regulation of cell proliferation, cell death, or cell differentiation is not known. We generated embryonic stem (ES) cells and other cell types mutant for all three genes. Triple knock-out mouse embryonic fibroblasts (TKO MEFs) had a shorter cell cycle than wild-type, single, or double knock-out control cells. TKO cells were resistant to G(1) arrest following DNA damage, despite retaining functional p53 activity. They were also insensitive to G(1) arrest signals following contact inhibition or serum starvation. Finally, TKO MEFs did not undergo senescence in culture and do possess some characteristics of transformed cells. Our results confirm the essential role of the Rb family in the control of the G(1)/S transition, place the three Rb family members downstream of multiple cell cycle control pathways, and further the link between loss of cell cycle control and tumorigenesis.
视网膜母细胞瘤蛋白pRB以及与之密切相关的蛋白p107和p130是哺乳动物细胞周期的重要调节因子。生化和遗传学研究表明，这三种蛋白在细胞周期调控和小鼠发育过程中具有重叠以及不同的功能。然而，pRB家族作为一个整体在细胞增殖、细胞死亡或细胞分化调控中的作用尚不清楚。我们构建了所有这三个基因均突变的胚胎干细胞（ES细胞）和其他细胞类型。三重敲除小鼠胚胎成纤维细胞（TKO MEF）的细胞周期比野生型、单基因敲除或双基因敲除的对照细胞短。尽管保留了功能性p53活性，但TKO细胞在DNA损伤后对G1期阻滞具有抗性。它们对接触抑制或血清饥饿后的G1期阻滞信号也不敏感。最后，TKO MEF在培养中不会衰老，并且确实具有一些转化细胞的特征。我们的结果证实了Rb家族在控制G1/S转换中的重要作用，将三个Rb家族成员置于多个细胞周期控制途径的下游，并进一步揭示了细胞周期控制丧失与肿瘤发生之间的联系。
