Identifying Cardiomyopathy Genes in Mice and Drosophila

描述（由申请人提供）：遗传学方法，优选在模型系统中，既允许准确测量心脏功能，又允许有效的遗传筛选，对于在鉴定心力衰竭的遗传基础方面取得实质性进展是必要的。在建议中，我们将测试的假设，强大的诱变剂，N-乙基-N-亚硝基脲（ENU），在小鼠中的诱变，和基因缺失的果蝇筛选，将导致发现新的致病和疾病修饰基因的人类心力衰竭。为了验证这些假设，我们在8周龄和16周龄的成年小鼠中使用非侵入性超声心动图进行了隐性突变筛查，以筛查心脏功能异常，并已经确定了1号染色体上映射到心肌病表型的遗传区域。为了补充小鼠研究，我们建议使用果蝇来鉴定新的心肌病基因。果蝇遗传学提供了超过19，000个分子定义的P-元件插入整个果蝇基因组，促进高密度基因组覆盖的产生。我们已经开发出一种创新的方法，在成年清醒的果蝇表型心脏功能，并确定了一个P-元件突变的短原肠胚（sog）基因，导致扩张型心肌病。基于我们的初步研究结果，我们提出，小鼠和果蝇遗传学可以确定新的基因和机制，是负责人类扩张型心肌病。因此，我们提出了以下具体目标：目标1：确定新的基因引起心肌病使用ENU表型驱动的隐性筛选成年小鼠。我们建议对心脏功能异常的ENU家族中位于1号染色体上的致病基因进行定位。目标二：研究dpp/BMP信号通路突变导致成年果蝇扩张型心肌病的生化和遗传机制。基因互补实验将在果蝇中进行，以证明sog缺乏导致心肌病。目标3：为了测试在小鼠中BMP途径的拮抗作用降低是否会在压力超负荷条件下导致心肌病表型。TAG实验将在内源性哺乳动物BMP拮抗剂弦蛋白和头蛋白缺陷的敲除小鼠中进行。目的4：通过在果蝇中进行全基因组缺失突变体筛选来鉴定引起心肌病的新基因。将使用光学相干断层扫描，随后对致病基因进行精细定位，对Exelixis收集的PiggyBac衍生缺失突变体杂合果蝇进行心肌病筛查。因此，这四个综合目标将利用小鼠和果蝇遗传学的力量来识别和评估新的候选基因在心肌病中的作用。

DESCRIPTION (provided by applicant): Genetic approaches, preferentially in model systems that both allow accurate measurement of heart function as well as efficient genetic screening, are necessary for substantial progress in identifying the genetic basis of heart failure. In proposal, we will test the hypothesis that the powerful mutagen, N-ethyl-N- nitrosourea (ENU), mutagenesis in mice, and gene-deletion screens in Drosophila, will lead to the discovery of novel disease-causing and disease-modifying genes for human heart failure. In order to test these hypotheses, we have performed a recessive mutagenesis screen in adult mice at 8 and 16 weeks of age using non-invasive echocardiography to screen for abnormalities in cardiac function and have already identified a heritable region on chromosome 1 that maps to a cardiomyopathic phenotype. To complement the mouse studies we propose to use the fly to identify novel cardiomyopathic genes. Drosophila genetics provides more than 19,000 molecularly-defined P-elements inserted throughout the Drosophila genome that facilitate the generation of high-density genomic coverage. We have developed an innovative approach to phenotype cardiac function in adult awake Drosophila and have identified a P-element mutation in the short gastrulation (sog) gene that results in dilated cardiomyopathy. Based on our preliminary findings, we propose that mouse and Drosophila genetics can identify novel genes and mechanisms that are responsible for human dilated cardiomyopathies. Accordingly, we propose the following specific aims: Aim 1: To identify novel genes causing cardiomyopathy using an ENU phenotype-driven recessive screen in adult mice. We propose to map the disease causing gene located on chromosome 1 in the ENU family with abnormal cardiac function. Aim 2: To investigate the biochemical and genetic mechanisms through which mutations in the dpp/BMP signaling pathway lead to dilated cardiomyopathy in adult Drosophila. Genetic complementation experiments will be performed in Drosophila to prove that sog deficiency causes cardiomyopathy. Aim 3: To test whether decreased antagonism of the BMP pathway in mice, will result in a cardiomyopathic phenotype under conditions of pressure overload. TAG experiments will be performed in knock out mice deficient in the endogenous mammalian BMP antagonists chordin and noggin. Aim 4: To identify novel genes causing cardiomyopathy by performing a genome-wide screen of deletion mutants in Drosophila. Flies heterozygous for PiggyBac derived deletion mutants from the Exelixis collection will be screened for cardiomyopathy using optical coherence tomography followed by fine mapping of the disease-causing gene(s). Thus, these four integrated aims will harness the power of mouse and Drosophila genetics to identify and evaluate novel candidate genes for their role in cardiomyopathy.