Regulation of germ layer formation by pluripotency factors during embryogenesis

Ying Cao

doi:10.1186/2045-3701-3-15

Abstract

The classical pluripotency factors Oct4, Klf4, Sox2, and Nanog are required for the maintenance of pluripotency and self-renewal of embryonic stem (ES) cells and can reprogram terminally differentiated cells into a pluripotent state. Alteration in the levels of these factors in ES cells will cause differentiation into different lineages, suggesting that they are critical determinants of cell fates. These factors show dynamic expression patterns during embryogenesis, in particular in the pluripotent or multipotent cells of an early stage embryo, implying that they are involved in the cell fate decision during early embryonic development. Functions and the underlying molecular mechanisms have been extensively studied for these factors in ES cells under cultured conditions. However, this does not mean that the results also hold true for intact embryos. In the review, I have summarized and discussed the findings on the functions and the underlying mechanisms of the classical pluripotency factors during early embryogenesis, in particular during germ layer formation.

Highlights

Pluripotency and self-renewal are two distinct features of mammalian embryonic stem (ES) cells
Based on Xenopus study, we propose a model for the germ layer formation (Figure 2)
Here I summarize the discovery of the functions of the 'classical' pluripotency factors during early embryonic development, especially germ layer formation

Summary

Introduction

Pluripotency and self-renewal are two distinct features of mammalian embryonic stem (ES) cells. Early embryonic cells lose the responsiveness to the activity of inducing signals such as Nodal/ Activin, and the genes involved in body axis patterning fail to express [68] It seems that Klf is a competence factor for germ layer differentiation and body axis patterning in Xenopus embryos. During Xenopus or zebrafish embryogenesis, Nr5a2 ( named Lrh, Ftz-f1) is not present in early cleavage and gastrula embryos [94,95] This expression pattern rules out the possibility of the involvement in the early events of embryonic development, for example, germ layer induction and pattern formation. The functions of most of these ‘nonclassical’ pluripotency factors during early embryogenesis remain to be elucidated

Conclusions and perspectives Here

74. Kiefer JC: Back to basics