Identifying Cardiomyopathy Genes in Mice and Drosophila

描述（由申请人提供）：钙调磷酸酶是一种钙活化蛋白磷酸酶，对于心脏肥厚表型的发展是必要和充分的。在哺乳动物中，钙调磷酸酶依赖的活化T细胞核因子（NFAT）转录因子的去磷酸化导致肥大基因的诱导。相比之下，果蝇不含钙调磷酸酶调节的NFAT亚型，这表明存在NFAT独立机制。事实上，另一种转录因子，肌细胞增强因子2 (MEF2)，也与钙调磷酸酶介导的心肌肥厚有关。在这个竞争性的更新中，我们建议在果蝇中进行缺陷和EMS突变筛选，以鉴定新的不依赖于nfat的钙调磷酸酶信号通路的增强和抑制基因。为了实现这一目标，我们将利用Sullivan、Rubin、Gajewski和Schulz已经从筛选中获得的信息，他们已经在组成型活性钙调磷酸酶（canact）致敏的果蝇筛选中发现了苍蝇基因组的大区域作为抑制和增强位点。因此，我们假设钙调磷酸酶介导的心肌肥厚可以通过nfat不依赖的途径发展，并且在果蝇中进行遗传筛选将确定诱导心肌肥厚的新分子机制。我们提出以下具体目标：目标一。鉴定果蝇钙调磷酸酶诱导的肥厚信号通路的新抑制基因。nfat独立的钙调磷酸酶信号基因将通过使用表达心脏特异性canact的致敏苍蝇对先前绘制的抑制基因位点进行缺陷筛选来鉴定。目标2。在果蝇中鉴定钙调磷酸酶诱导的肥厚信号的新增强基因。nfat独立的钙调磷酸酶信号基因将通过使用表达心脏特异性canact的致敏苍蝇对先前绘制的增强子位点进行缺陷筛选来鉴定。目标3。在果蝇中鉴定EMS诱变诱导钙调磷酸酶诱导的肥厚信号的新基因修饰因子。EMS化学诱变筛选在表达actin- canact的致敏果蝇中诱导整个果蝇基因组突变。我们预计，拟议的研究将确定导致心脏肥厚的新基因和途径，并将更好地定义钙调磷酸酶在肥厚过程中的作用。此外，所提出的研究将为治疗人类心脏肥厚和心力衰竭提供新的靶点。

DESCRIPTION (provided by applicant): Calcineurin is a calcium-activated protein phosphatase that is both necessary and sufficient for the development of a cardiac hypertrophic phenotype. In mammals, calcineurin-dependent dephosphorylation of nuclear factor of activated T cells (NFAT) transcription factors lead to the induction of hypertrophic genes. In contrast, Drosophila do not contain calcineurin-regulated isoforms of NFAT suggesting the idea that NFAT-independent mechanisms exist. Indeed, another transcription factor, myocyte enhancer factor 2 (MEF2), has also been implicated in calcineurin-mediated cardiac hypertrophy. In this competing renewal we propose to carry out a deficiency and EMS mutagenesis screen in Drosophila to identify novel NFAT-independent enhancer and suppressor genes of the calcineurin signaling pathway. To accomplish this goal we will use information already available from screens performed by Sullivan and Rubin and Gajewski and Schulz who have identified large regions of fly genome that act as suppressor and enhancer loci in a Drosophila screen sensitized by constitutive active calcineurin (CanAAct). Accordingly, we hypothesize that calcineurin-mediated cardiac hypertrophy can develop through an NFAT-independent pathway, and that a genetic screen in the fly will identify new molecular mechanisms that induce cardiac hypertrophy. We propose the following specific aims: Aim 1. Identify novel Suppressor genes of Calcineurin-induced hypertrophic signaling in Drosophila. NFAT-independent calcineurin signaling genes will be identified by a deficiency screen of previously mapped suppressor loci using a sensitized fly expressing cardiac-specific CanAAct. Aim 2. Identify novel Enhancer genes of Calcineurin-induced hypertrophic signaling in Drosophila. NFAT-independent calcineurin signaling genes will be identified with by a deficiency screen of previously mapped enhancer loci using a sensitized fly expressing cardiac-specific CanAAct. Aim 3. Identify novel genetic modifiers of Calcineurin-induced hypertrophic signaling induced by EMS mutagenesis in Drosophila. EMS chemical mutagenesis screen to induce mutations across the entire Drosophila genome in a sensitized fly expressing actin- CanAAct. We anticipate that the proposed investigation will identify novel genes and pathways that lead to cardiac hypertrophy and will better define the role of calcineurin in the hypertrophic process. Furthermore, the proposed studies will lead to new targets to treat cardiac hypertrophy and heart failure in humans. PUBLIC HEALTH RELEVANCE: The proposed experiments will expand our knowledge of the molecular mechanisms of cardiac hypertrophy, which we believe will lead to new targets for the identification and treatment of patients with heart failure. Calcineurin is a nodal signaling pathway for cardiac hypertrophy. Simpler model systems, such as Drosophila, provide the unique ability to perform genetic screens to identify genetic modifiers of the Calcineurin pathway that otherwise would be very difficult to do in mammalian systems.