Lahav Galit, Rosenfeld Nitzan, Sigal Alex, Geva-Zatorsky Naama, Levine Arnold J, Elowitz Michael B, Alon Uri
Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
Nat Genet. 2004 Feb;36(2):147-50. doi: 10.1038/ng1293. Epub 2004 Jan 18.
The tumor suppressor p53, one of the most intensely investigated proteins, is usually studied by experiments that are averaged over cell populations, potentially masking the dynamic behavior in individual cells. We present a system for following, in individual living cells, the dynamics of p53 and its negative regulator Mdm2 (refs. 1,4-7): this system uses functional p53-CFP and Mdm2-YFP fusion proteins and time-lapse fluorescence microscopy. We found that p53 was expressed in a series of discrete pulses after DNA damage. Genetically identical cells had different numbers of pulses: zero, one, two or more. The mean height and duration of each pulse were fixed and did not depend on the amount of DNA damage. The mean number of pulses, however, increased with DNA damage. This approach can be used to study other signaling systems and suggests that the p53-Mdm2 feedback loop generates a 'digital' clock that releases well-timed quanta of p53 until damage is repaired or the cell dies.
肿瘤抑制蛋白p53是研究最为深入的蛋白质之一，通常通过对细胞群体进行平均的实验来研究，这可能会掩盖单个细胞中的动态行为。我们展示了一个用于在单个活细胞中追踪p53及其负调节因子Mdm2动态的系统（参考文献1、4 - 7）：该系统使用功能性的p53 - CFP和Mdm2 - YFP融合蛋白以及延时荧光显微镜。我们发现，DNA损伤后p53以一系列离散脉冲的形式表达。基因相同的细胞具有不同数量的脉冲：零个、一个、两个或更多。每个脉冲的平均高度和持续时间是固定的，且不依赖于DNA损伤的量。然而，脉冲的平均数量随DNA损伤而增加。这种方法可用于研究其他信号系统，并表明p53 - Mdm2反馈回路产生一个“数字”时钟，该时钟会释放定时的p53量子，直到损伤修复或细胞死亡。
