One of the important events that underlies the development of the vertebrate embryo is the segmentation of the paraxial mesodermal, into repeating, metameric structures called somites. Somites have been shown to be critical structures in the subsequent development of segmented tissues such as the vertebrae and associated muscle, as well as tissue elements in the central and peripheral nervous system. Previous studies have shown that somites arise from precursor structures, called somitomeres, which form within the paraxial mesoderm of early embryos. However, the mechanisms that cause the paraxial mesoderm to segment remain poorly understood. The goal of the proposed studies is to determine the mechanisms underlying the segmentation of the paraxial mesoderm, using Xenopus embryos as a model system. In preliminary studies, we have identified a number of genes that are expressed in a segmental pattern within the presomitic mesoderm, thus corresponding to its subdivision into somitomeres. These genes encode components of the Notch signaling pathway or novel proteins belonging to the family of basic helix-loop-helix transcription factors. The proposed studies will identify the function of these genes during segmentation, and how these genes interact to generate a segmental pattern. The results of the proposed studies are likely to contribute to a better understanding of how segmentation in the vertebrate embryo is mediated at a genetic level, leading to insights into the genetic diseases that result in segmentation defects in human development.
| Kim, S H; Jen, W C; De Robertis, E M et al. (2000) The protocadherin PAPC establishes segmental boundaries during somitogenesis in xenopus embryos. Curr Biol 10:821-30 |
