Novel pathways modulating Raf-mediated cardiac hypertrophy

描述（由申请人提供）：心脏肥大和进展为明显心力衰竭与显著的发病率和死亡率相关。哺乳动物心血管疾病模型对研究心脏生理学和信号通路非常有帮助，然而，这些模型不容易接受大的遗传筛选。因此，开发了使用果蝇作为模型来鉴定引起或改变心肌病的新基因的策略，以规避与心血管疾病的哺乳动物模型相关的一些复杂性。 表皮生长因子受体（epidermal growth factor receptor，EGFR）是维持果蝇发育后正常心脏功能所必需的.此外，EGFR的激活和随后向小GT3、Ras和激酶Raf和MEK 1的信号导致果蝇和哺乳动物的心脏肥大。通过激酶Hippo的信号传导改变了共转录激活因子Yorkie的活性，也产生了类似于果蝇中EGFR/Ras/Raf通路的心脏肥大。长期目标是利用果蝇遗传学作为发现平台，了解调节心脏肥大和扩张型心肌病发展和进展的分子信号，并将发现转化为人类。本申请的总体目标是检查Raf-MEK 1通路和心脏肥大中约克犬的激活。核心假设是Raf-MEK 1和Hippo-YAP 1通路之间的串扰驱动心肌细胞决定肥大或增生。 将检查以下特定目的以检验中心假设：（1）确定Raf-MEK 1介导的心脏肥大是否通过调节果蝇中的Hippo-yorkie途径发生，并鉴定在yorkie下游起作用的信号传导途径; (2)鉴定哺乳动物YAP 1中驱动心肌细胞肥大或增殖的特定模块结构域;和（3）确定雅普-1的减少是否改变TAC诱导的压力超负荷后RafL 613 V/+敲入小鼠或野生型小鼠中心脏肥大或心力衰竭的严重程度。该提案在利用果蝇快速鉴定两种进化上保守的信号通路中的新分子并将这些发现转化为哺乳动物方面具有创新性。该提案预计将确定以前未知的修改Raf-dependent心脏肥大的成分，并导致更好地了解驱动人类病理性肥大的途径。

DESCRIPTION (provided by applicant): Cardiac hypertrophy and progression to overt heart failure is associated with significant morbidity and mortality. Mammalian models of cardiovascular disease are tremendously helpful to study cardiac physiology and signaling pathways, however; these models are not readily amenable to large genetic screens. Therefore, strategies using Drosophila as model to identify new genes that cause or modify cardiomyopathies were developed to circumvent some of the complexities associated with mammalian models of cardiovascular disease. The epidermal growth factor receptor (EGFR) is necessary to maintain normal post- developmental cardiac function in adult Drosophila. Moreover, the activation of EGFR and subsequent signals to the small GTPase, Ras, and the kinases, Raf and MEK1, cause cardiac hypertrophy in flies and mammals. Signaling through the kinase, Hippo, alters the activity of the co-transcriptional activator, yorkie, and also produces cardiac hypertrophy similar to the EGFR/Ras/Raf pathway in flies. The long-term goal is understand the molecular signals that modulate the development and progression of cardiac hypertrophy and dilated cardiomyopathy using Drosophila genetics as a discovery platform and translate the findings to humans. The overall objective for this application is to examine the Raf-MEK1 pathway and the activation of yorkie in cardiac hypertrophy. The central hypothesis is that crosstalk between the Raf-MEK1 and Hippo-YAP1 pathways drives cardiomyocyte decisions towards hypertrophy or hyperplasia. The following Specific Aims will be examined to test the central hypothesis: (1) Determine whether Raf-MEK1-mediated cardiac hypertrophy occurs via regulation of the Hippo- yorkie pathway in flies and identify signaling pathways that function downstream of yorkie.; (2) Identify the specific modular domains in mammalian YAP1 that drive cardiomyocyte hypertrophy or proliferation; and (3) Determine whether a reduction in YAP-1 modifies the severity of cardiac hypertrophy or heart failure in RafL613V/+ knock-in mice or wild-type mice after TAC-induced pressure overload. This proposal is innovative in its use of Drosophila to rapidly identify novel molecules in two evolutionarily conserved signaling pathways and translate these findings to mammals. The proposal is expected to identify previously unknown components that modify Raf-dependent cardiac hypertrophy and lead to better understanding of pathways that drive pathologic hypertrophy in humans.