L-proline-mediated neural differentiation of mouse embryonic stem cells

Abstract

Early mammalian embryogenesis involves complex cellular and molecular mechanisms to guide cell fate. The embryo itself is a complex system, whose molecular circuitry tightly controls the emergent properties of that system, including cell differentiation, proliferation, morphology, migration and communication. These molecular circuits include those responsible for the control of gene and protein expression, as well as cell signalling and metabolism. Due in part to the complexity of this circuitry, and the relative inaccessibility of the mammalian embryo, in vitro models have proved a facile and informative approach to understanding the molecular mechanisms of development. Here we use cultured mouse embryonic stem cells (mESCs) as a tool to study the molecular mechanisms underlying embryonic nervous system development. We show for the first time that the conditionally essential amino acid L-proline can act like a growth factor to drive pluripotent mESCs to mature neural cell fates via pluripotent early primitive ectoderm-like (EPL) cells, the multipotent germ layer, definitive ectoderm, and the founder cells of the nervous system, neurectoderm. The data presented in this thesis provides evidence that induction of neurectoderm can occur via an instructive mechanism of differentiation rather than by a simple default mechanism. It is anticipated that our L-proline-based protocol will be used to gain a more comprehensive understanding of the molecular mechanisms that underlie differentiation towards the neural lineage, and the role that L-proline plays during early embryonic nervous system development.