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To study these problems, our laboratory uses many different cell biological, molecular biological, genomics-based, and embryological approaches. These include embryo micromanipulation, in vivo protein tagging, targeted protein mutagenesis, cell isolation and culture, perturbation of gene expression by injection of mRNAs and morpholino antisense oligoinucleotides, protein biochemistry, immunochemical methods, large-scale DNA sequencing, and microarray analysis. Modern, fluorescence-based light optical technologies are used to analyze cell behavior and molecular dynamics. Links: Pittsburgh Developmental Mechanisms Group (PDMG): http://www.andrew.cmu.edu/org/pdmg/ Selected Publications Ettensohn CA, Kitazawa C, Cheers MS, Leonard JD, Sharma, T (2007) Gene regulatory networks and developmental plasticity in the early sea urchin embryo: alternative deployment of the skeletogenic gene regulatory network. Development 134, 3077-3087. Sea Urchin Genome Sequencing Consortium (2006) The genome of the sea urchin Strongylocentrotus purpuratus. Science 341, 941-952. Ettensohn, CA (2006) The emergence of pattern in embryogenesis: Regulation of beta-catenin localization during early sea urchin development. STKE Perspective, Science Nov. 14, (361). Weitzel HE, Illies MR, Byrum CA, Xu R, Wikramanayake AH, Ettensohn CA. (2004) Differential stability of beta-catenin along the animal-vegetal axis of the sea urchin embryo mediated by dishevelled. Development 131, 2947-2956. Ettensohn CA, Illies MR, Oliveri P, De Jong, DL. (2003) Alx1, a member of the Cart1/Alx3/Alx4 subfamily of Paired-class homeodomain proteins, is an essential component of the gene network controlling skeletogenic fate specification in the sea urchin embryo. Development 130, 2917-2928. |
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We are interested in understanding how the genome encodes the program of development. During embryogenesis, linear (one-dimensional) information contained in the genomic DNA sequence is translated into multicellular (three-dimensional) form. We study this problem using the sea urchin embryo as an experimental model. The complete sequence of the sea urchin genome has been determined and powerful tools are available for manipulating and analyzing gene expression. The rapid, external development and optical transparency of this embryo make it ideally suited to studies of dynamic cell and molecular processes in vivo. The ability to raise large numbers of synchronously developing embryos facilitates molecular biological and biochemical approaches. Lastly, echinoderms are close relatives of vertebrates and many features of their early development are highly conserved. 
Our research focuses on three fundamental processes: 1) early patterning, 2) morphogenesis, and 3) the control of development by gene regulatory networks. With respect to the first, we are studying a highly conserved, ancient molecular pathway (the canonical Wnt/beta-catenin pathway) that operates during early development to polarize the embryo. With respect to the problem of morphogenesis, our research focuses on gastrulation and the assembly and patterning of the skeletal system. These processes involve several fundamental cell behaviors, including epithelial-mesenchymal transition, directional cell migration, cell-cell fusion, epithelial invagination, and epithelial cell rearrangement. Lastly, we study transcriptional gene regulatory networks (GRNs) that drive early development. GRNs can be thought of as complex, interconnected systems of interacting genes that influence each other's expression. We are interested in the architecture, developmental function, and evolution of GRNs.