我们获得了一个V12斑马鱼突变体，其突变基因编码蛋白VCLa 与人Vincilin蛋白质具有高同源性。 Vinculin 在细胞与细胞以及细胞与细胞外基质链接中起重要作用。斑马鱼V12突变体心脏显示心房和心室均有扩张，心外膜细胞层增厚和瓣膜扩张，与人心肌扩张病表型类似。此外，心外细胞层YAP蛋白质显著上调，提示Hippo或者相关信号转导通路介导了VCLa的功能。 本申请计划研究：1) VCLa 如何在心脏形态建成中的功能是什么？ 2)VCLa下游信号通路如何调节心脏形态建成？ 3）VCLa 旁同源基因（paralog）VCL是否也参与心脏发育，它是否与VCLa存在冗余功能？ 4）人Vinculin基因是否可以挽救V12突变体表型？ 我们认为这些研究将有助于深入了解心脏发育形态建成的细胞生物学机制，同时也可能把V12突变体建立为人心肌扩张病的一个重要模型。

In recent years, zebrafish (Danio rerio) has been shown to be a very useful model system to study heart development. Analysis of zebrafish mutants have shed new light to fundamental processes of heart development. Some results of the studies also have strong implications to human heart development and related diseases. We have used Tol2 transposon-mediated gene trap approach to identify critical genes involved in embryonic patterning and organ morphogenesis. In this ongoing screen, we obtained an EGFP insertion mutant V12, which encodes a predicted polypeptide with high homology to human vinculin. The homozygotes of V12 show multiple cardiac defects and die at larva stage. Vinculin is an important cytoskeleton protein for cell-cell and cell-matrix adhesions. V12 mutant fish shows marked heart morphology changes, including expanded atrium and ventricle, thickened epicardium and enlarged valves. These phenotypes share similarity to dilated cardiomyopathy (DCM). In V12 mutants, early cardiac maker cmlc2 and nkx2.5 is not affected but the looping of heart tube is changed at 77 hpf, suggesting VCLa gene is not involved in cardiac progenitor specification, but in heart morphogenesis and maintenance. Furthermore, the epicardium cells of the mutant change from squamous epithelial cells to cuboidal shape cells and the endocardium cells has impaired attachement to muscle fibers.Our recent result indicate YAP expression is strongly upregulated in epicardium layers， suggesting Hippo or related pathways may mediate VCLa functions during heart development.Taken together, our current results strongly suggest that VCLa plays essential roles in zebrafish heart development and homeostasis and the mutant fish may serve as a good model to study the mechanisms of human DCM. We believe we are in a unique position using this EGFP trapped mutant to address the following questions: 1) What functions does VCLa exert in cellular changes during heartmorphogenesis? 2) How signaling pathways downstream of VCLa regulate heart morphogenesis? 3) Are null mutants of the VCLa paralog VCL also involved in heart development? Are there any biochemical redundancy between VCLa and VCL? 4) Whether human Vinculin gene can rescue VCLa mutant phenotypes? We expect our results will extend understanding of cellular mechanisms of zebrafish heart morphogenesis and will help establish the V12 mutant as a useful model to study DCM in human.