细胞竞争是一个动态平衡机制，最先在果蝇中被观察到，在这个过程中，能够存活、但并不是最佳的细胞被从后生动物的组织中清除掉。它的生物功能尚不清楚，但现在Miguel Torres及其同事首次演示了哺乳动物组织中正在发生的这一现象，并且提出了它有可能发挥的一个功能。作者采用一种活体遗传方法在小鼠外胚层（含有生成整个胚胎的多能干细胞的胚胎组织）中生成了Myc蛋白的“马赛克”表达。他们发现，细胞竞争受到相邻细胞间在Myc剂量上天然出现的一个不平衡的促进，同时他们也演示了通过凋亡来清除Myc水平相对较低的细胞。这些发现说明细胞竞争在外胚层干细胞池的优化中扮演一个角色。本期封面所示为对细胞竞争水平（从左向右）正在加剧的胚胎中的细胞类群的变化所做的荧光检测。（生物谷 Bioon.com）
生物谷推荐的英文摘要
Nature doi:10.1038/nature12389
Myc-driven endogenous cell competition in the early mammalian embryo
Cristina Clavería Giovanna Giovinazzo Rocío Sierra Miguel Torres
The epiblast is the mammalian embryonic tissue that contains the pluripotent stem cells that generate the whole embryo. We have established a method for inducing functional genetic mosaics in the mouse. Using this system, here we show that induction of a mosaic imbalance of Myc expression in the epiblast provokes the expansion of cells with higher Myc levels through the apoptotic elimination of cells with lower levels, without disrupting development. In contrast, homogeneous shifts in Myc levels did not affect epiblast cell viability, indicating that the observed competition results from comparison of relative Myc levels between epiblast cells. During normal development we found that Myc levels are intrinsically heterogeneous among epiblast cells, and that endogenous cell competition refines the epiblast cell population through the elimination of cells with low relative Myc levels. These results show that natural cell competition in the early mammalian embryo contributes to the selection of the epiblast cell pool.
