This laboratory's research program is focused on the genetics and cell and molecular biology of cardiovascular development. An integration of whole animal imaging, microscopy, and genomic and proteomic approaches are being utilized to elucidate the cell signaling pathways that regulate cardiovascular development. One project entail studies aimed at understanding the role of two extracardiac cell populations, the cardiac neural crest and the proepicardially derived cells, in the modulation of cardiovascular development and function. These studies will help elucidate cellular and molecular mechanisms that regulate outflow tract morphogenesis and coronary artery development. An integration of cell biological and molecular approaches together with animal imaging studies with microCT scanning are being used for these studies. A related second area of research interest is the cell signaling function of connexin gap junction protein, and its role in modulating cardiovascular development through the regulation of proepicardial and neural crest cell migration. Present studies are focused on identifying protein-protein interactions essential in this novel connexin mediated cell signaling function. These studies entail the use of transgenic animal models and cultured cells together with proteomic methods, including mass spectrometry, to identify the interacting proteins. A third project involves the use of a discovery approach to identify novel genes essential for mammalian cardiovascular development. Noninvasive prenatal ultrasound imaging is being used to screen ENU mutagenized mice for congenital cardiovascular defects. Nearly 5,000 mouse fetuses have been ultrasound scanned thus far from over 200 ENU mutagenized families. More then 50 of these families were identified with congenital heart defects and together they show phenotypes that include all of the major congenital heart defects seen clinically. Heritability testing and genome scans with microsatellite DNA markers are under way to map the mutations and identify candidate genes. Such studies will help identify novel genes and reveal novel gene functions essential for cardiovascular development and function. A fourth project underway entails using a genotype based screen of EMS mutagenized embryonic stem cells to generate new mouse models harboring connexin gene mutations. At present over 10 connexin mutations have been identified, and two of these have been converted to mice for phenotypic analysis. Such studies should provide new insights into connexin function in cardiovascular development. A fifth project initiated this past year entails the development of episcopic fluorescence image capture (EFIC) for phenotyping mouse cardiovascular development using 3 dimensional (3D) histological reconstructions. EFIC is being combined with laser capture microscopy to retrieve RNA from tissue sections for gene expression profiling by gene chip microarray analysis. The expression profiles obtained are to be mapped back to the 3D volumes to generate 3D gene expression maps of the developing cardiovascular system. We plan to use this experimental approach to characterize the gene expresson profiles of abnormal development associated with mutant mouse models exhibiting congenital cardiovascular anomalies.
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