Nature: 細胞競爭的觀察及其所起作用

細胞競爭是一個動態平衡機制，最先在果蠅中被觀察到，在這個過程中，能夠存活、但並不是最佳的細胞被從後生動物的組織中清除掉。它的生物功能尚不清楚，但現在Miguel Torres及其同事首次演示了哺乳動物組織中正在發生的這一現象，並且提出了它有可能發揮的一個功能。作者採用一種活體遺傳方法在小鼠外胚層（含有生成整個胚胎的多能幹細胞的胚胎組織）中生成了Myc蛋白的「馬賽克」表達。他們發現，細胞競爭受到相鄰細胞間在Myc劑量上天然出現的一個不平衡的促進，同時他們也演示了通過凋亡來清除Myc水平相對較低的細胞。這些發現說明細胞競爭在外胚層幹細胞池的優化中扮演一個角色。本期封面所示為對細胞競爭水平（從左向右）正在加劇的胚胎中的細胞類群的變化所做的螢光檢測。（生物谷 Bioon.com）

生物谷推薦的英文摘要

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.