"Role of Pitx3 signaling cascades in the regulation of Xenopus eye, laterality, and somite development"

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Surprisingly, much of what we have learned about human eye development was first pioneered in studies and manipulations of amphibian embryos. The developmental, structural, and genetic similarities are striking: irrespective of whether you study human, mouse, fish or frog, the same genes interact to produce similar structures. For example, mutation of the human PITX3 homeobox gene results in a failure of lenses to form or in congenital cataracts. The same issues can be re-capitulated in developing mouse, frog, and even fish embryos, where the genes and processes that are involved can be studied and manipulated. The benefit of studying the genes in frog is that the embryos are comparatively large, they develop externally (where you can see them), and they can be cheaply manipulated. The genome is nearly sequenced for the frog Xenopus, and there are many useful probes and techniques for studying eye development in this species, so the organism is useful for testing our theories regarding human eye development and disease. During our recent studies of the role of Pitx3 in frog, we discovered that the gene plays a role not only in eye development, but also in organ asymmetry (heart, gall bladder, gut), and vertebrae. We have identified some of the genes that Pitx3 controls, and these genes play a role in establishing the embryonic body plan, as well as regulating some of the processes important to cell shape, structure, and activity. We have developed strategies to assess how the Pitx3 signaling cascade unfolds to control development and health of the eye, as well as the agenda for development of visceral organs and spine. We are requesting funds to continue this work and to study how Pitx3 turns on some downstream target genes, while turning off others. We hope to reach a better understanding of how the activity of one gene installs an agenda for development. Preliminary work using our newly developed protocol using a flow cytometry based approach to asses Pitx3 effects upon individual cells and genes has produced a number of downstream signaling cascades that we need to test and manipulate in order to refine our understanding of how early events are regulated in vertebrate embryos.