Department of Biochemistry, Faculty of Pharmaceutical Sciences, Doshisha Women's College, Kyotanabe, Kyoto, Japan.
Nat Commun. 2012;3:1071. doi: 10.1038/ncomms2069.
The differentiation and patterning of murine early embryos are sustained by the visceral endoderm, an epithelial layer of polarised cells that has critical roles in multiple signalling pathways and nutrient uptake. Both nutritional and signalling functions rely upon the endocytosis of various molecules from the cell surface via the endocytic pathway. However, endocytic membrane dynamics in this embryonic tissue remain poorly understood. Here we show that the functions of rab7, a small GTP-binding protein regulating the late endocytic pathway, are essential for embryonic patterning during gastrulation. The endosomes of visceral endoderm cells are delivered via a unique microautophagy-like process to the apical vacuole, a large compartment exhibiting lysosomal characteristics. Loss of rab7 function results in severe inhibition of this endocytic pathway. Our results indicate that the microautophagic process and flow of the endocytic membrane have essential roles in early embryonic development.
小鼠早期胚胎的分化和模式形成由内脏内胚层维持，这是一层极化细胞的上皮层，在多种信号通路和营养物质摄取中具有关键作用。营养和信号功能都依赖于通过内吞作用从细胞表面内化各种分子。然而，这种胚胎组织中的内吞膜动力学仍知之甚少。在这里，我们表明 rab7 的功能，一种调节晚期内吞作用的小 GTP 结合蛋白，对于原肠胚形成期间的胚胎模式形成至关重要。内脏内胚层细胞的内体通过独特的微自噬样过程递送到顶端液泡，顶端液泡是一个具有溶酶体特征的大隔室。rab7 功能的丧失导致这种内吞作用途径的严重抑制。我们的结果表明，微自噬过程和内吞膜的流动在早期胚胎发育中具有重要作用。
