Ontogeny of the germline in non rodent mammals

点击翻译按钮获取中文摘要

A better knowledge of how the precursors of the gametes (the cells that make egg and sperm) develop in mammals has important implications for our understanding of animal development, with important applications in biotechnology, assisted reproduction and regenerative medicine.This project will investigate the developmental program of the precursors of the gametes, the primordial germ cells (PGCs), in mammals. Knowledge of mammalian PGCs originates primarily from studies in mice, but very little is known about this process in other mammals. In mice PGCs are set aside very early in development in response to inducing signals from the extraembryonic ectoderm (ExE), a derivative of the trophectoderm. However, the mouse embryo is anatomically different to most other mammals at this stage of development. The mouse embryo (epiblast) undergoes cavitation forming an egg cylinder containing the ExE. In other mammals the ExE does not exist, and the epiblast forms a flat disc of cells. This raises the question of how and when the PGCs originate in humans and other non-rodents mammals lacking the structures (the ExE) known to play a critical role in PGC induction in rodents. We hypothesize that the differences in embryo development underlie differences in the mechanisms of PGC specification in mammals. We will test this hypothesis by investigating PGC development in pig embryos, as they share similar anatomical and developmental features to early human embryos, which are not available for research. Discoveries made in this species can therefore be translated to humans.The aim of this project is to establish the genetic and epigenetic mechanisms of pig PGC development in vivo, followed by functional experiments with cultured isolated epiblasts to identify key master regulators of germ cell development. This knowledge will then be exploited to study human PGC development from human embryonic stem cells (hESC). These investigations will also allow us to determine the relationship between pluripotency and PGC development, which will underpin the development of new culture conditions for the establishment of pluripotent embryonic germ cells. The objectives of the project are: 1- To establish the gene expression profile and epigenetic reprogramming of early pig PGCs. These experiments will define the genetic and epigenetic signature of these cells and will inform on strategies for functional evaluation of PGC determinants. 2- To identify key master regulators that promote PGC differentiation from pig epiblasts and from hESC and pEpiSC/piPSC. These studies will establish the functional role of PGC-master genes during pig (in vivo and in vitro) and human (in vitro) embryonic development, and inform on new strategies for the differentiation of PGC precursors from pluripotent cells. 3- To develop culture conditions for the establishment of pig embryonic germ (EG) cells, the in vitro pluripotent derivatives of PGCs. These experiments will use the knowledge gained from previous objectives to establish pluripotent and germline competent pig EG cells. Insights into primordial germ cell formation will contribute to the development of methods for deriving new sources of pluripotent cells and for improving protocols of differentiation of gamete precursors and somatic cells in the laboratory. An important application of these technologies is in regenerative medicine and assisted reproduction. In addition, new sources of pluripotent cells in domestic animals are of great importance for increasing the efficiency of transgenesis. This project addresses questions of strategic relevance to the BBSRC, such as lifelong health and well-being. We anticipate that the outcomes of the current project will contribute to the academic and clinical advance in the areas of regenerative medicine and global food security.