Membrane dynamics in mammalian early embryonic development

Membrane dynamics in mammalian early embryonic development

clarification of function of microautophagy in signalling pathways and nutrient uptake

Sep 19, 2012

Under the leadership of Associate Professor You WADA at the Institute of Scientific and Industrial Research, Osaka University, Professor Akihiro HARADA at the Graduate School of Medicine, Osaka University, Assistant Professor Nobuyuki KAWAMURA and Professor Wada Ge-hong at the Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts, and Assistant Professor Shunsuke TAKASUGA and Professor Takehiko SASAKI at the Graduate School of Medicine, Akita University, a group of researchers have clarified that a unique membrane dynamic called microautophagy occurrs in murine early embryonic development and that this microautophagy requires the function of rab7 protein. In a mouse embryo without a function of rab7 protein, the formation of the embryo did not proceed normally, in fact, embryonic morphogenesis stopped 6 days after fertilization.

This research has clarified that the embryo used microautophagy and proceeded in a process of multiplication and differentiation in a coordinated way while uptaking nutrients. Their research provides a new viewpoint on the mother-child interrelationship in mammals in which fertilization and morphogenesis occurr inside the mother's body.

This research achievement was obtained by Grant-in-Aid for Scientific Research on Innovative Areas sponsored by MEXT, Cell Community (leader: FUJIMORI Toshihiko , Professor, National Institute for Basic Biology and other funds.
Abstract

"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."


To learn more about this research, please read the full research report entitled " Delivery of endosomes to lysosomes via microautophagy in the visceral endoderm of mouse embryos " on this page at the Nature Communications website.

Related link

Technical Glossary