Patterning of the Embryonic Germ Layers

University Of Texas, M.D. Anderson Cancer Center, Houston TX

Investigators

Abstract

A fundamental problem in developmental biology concerns the mechanism by which the maternal program regulates early embryogenesis. Recent studies have demonstrated that several maternal factors such as Tcf-3, VegT, and Xenopus nuclear factor 7 (xnf7), a gene that we are studying, play important roles in the specification, patterning, and differentiation of the embryonic germ layers. The effect of these maternal factors is evident at the late blastula-early gastrula stage by the region specific activation of zygotic gene expression such that the embryo is divided into a variety of subdomains. The most dorsal region forms the Spemann organizer which expresses a large variety of transcription and secreted factors. These are expressed in overlapping domains that divide the organizer into the head and trunk organizer regions. In addition specific groups of genes are expressed in the ventral region. One of the key problems is to understand the mechanism by which the maternal genetic program regulates the pattern of expression of both the organizer and ventral specific genes. Based on our recent data from this laboratory we hypothesize that xnf7 is one of several important maternal factors responsible for the global patterning of the embryo into dorsal/ventral domains and for patterning of the organizer in the dorsal most aspect. Our goal during this next grant period is to further define the precise mechanisms and molecular pathway through which xnf7 functions and to use xnf7 as a tool to gain insights into the general mechanisms of embryonic patterning and the specifics of how the organizer forms and is patterned. This will be accomplished by identifying potential xnf7 target genes; identifying nuclear partners of xnf7; and determining the role of xnf7 in patterning endoderm and ectoderm.