Genetic analysis and regulation of amyloids flux in the Drosophila heart

描述(申请人提供)：几种人类疾病与突变、错误折叠和易于聚集的淀粉样蛋白的表达有关。这些淀粉样蛋白的沉积、增殖或多聚体导致了几种神经疾病的发生，包括阿尔茨海默氏症和亨廷顿病。人类心脏中淀粉样蛋白的积累会导致心肌病。尽管有几种蛋白质被证明与心脏淀粉样变性有关，但导致这种疾病的确切机制尚不清楚。最近的证据表明，亨廷顿病和阿尔茨海默病患者心血管事件的发生率更高，但对这些疾病如何导致心力衰竭知之甚少。由于许多蛋白质依赖于细胞折叠环境，我们假设心脏中引起HD或AD的淀粉样蛋白的表达将由于氧化应激或整体错误折叠而破坏蛋白质折叠质量控制的整体平衡，导致组织功能丧失。为了验证我们的假设，我们将使用遗传易驯化的模式生物黑腹果蝇，并在探索和抑制心脏淀粉样变性方面采用综合方法。我们建议建立第一个果蝇模型来研究与阿尔茨海默病和亨廷顿病引起的淀粉样蛋白积聚相关的心脏缺陷。利用UAS-Gal4表达系统，我们将在果蝇心脏中表达UAS-聚谷氨酰胺(针对亨廷顿氏症)和UAS-A242肽(针对阿尔茨海默氏症)。我们将在生理和细胞生物学水平上检查由此产生的心脏缺陷。此外，我们将探索淀粉样蛋白在心肌中的表达如何影响自噬和其他应激标志物的表达。然后，我们计划使用遗传和药理学方法来抑制心脏淀粉样变性。基因抑制淀粉样蛋白诱导的心肌病将试图通过过量表达伴侣蛋白来减少整体蛋白的展开或通过超氧化物歧化酶来改善氧化应激。我们还将探索诸如伴侣诱导剂或抗氧化剂等药物对改善与淀粉样蛋白积聚相关的心脏缺陷的作用。我们提出的研究有机体--果蝇，具有对人类基因组高度保守的基因和许多操纵其基因表达的技术，将是探索阿尔茨海默氏症和亨廷顿病患者心力衰竭机制的极好模型，并可能被证明对开发人类疾病的治疗方法有用。最终，一旦建立了这个模型，就可以用来探索心脏淀粉样变性的发生和抑制与其他淀粉样前体蛋白的联系。因此，这一建议具有广泛的应用前景，适用于心脏病、阿尔茨海默氏症和亨廷顿病。这三种疾病都是毁灭性的，这项研究的结果可能为它们的起源提供重要线索。 公共卫生相关性：阿尔茨海默病和亨廷顿病都是心力衰竭的主要风险因素；拟议的研究首次使用模式生物果蝇黑素记录仪来探索淀粉样蛋白在这两种主要神经退行性疾病中引起的心功能障碍。我们将使用转基因和药理学方法来抑制诱导的心脏淀粉样变性。这项研究对于理解两种主要神经疾病的心力衰竭机制至关重要，一旦建立起这个果蝇模型，就可以用来探索与其他淀粉样前体蛋白相关的淀粉样蛋白诱导的心力衰竭。

DESCRIPTION (provided by applicant): Several human diseases are associated with the expression of mutated, misfolded and aggregation- prone amyloid proteins. Deposition of these amyloids, their proliferation or multimerization leads to the genesis of several neuropathies, including Alzheimer's and Huntington's diseases. Accumulation of amyloids in the human heart leads to cardiomyopathy. Despite several proteins being shown to be associated with cardiac amyloidosis, the precise mechanism that leads to the disease is poorly known. Recent evidence indicates that patients with Huntington's and Alzheimer's diseases demonstrate a greater occurrence of cardiovascular events but very little is known as to how these diseases lead to cardiac failure. Since many proteins are dependent on the cellular folding environment, we hypothesize that expression of HD- or AD-causing amyloids in the heart will disrupt the overall balance of protein folding quality control due to oxidative stress or global misfolding, resulting in loss of tissue function. To test our hypothesis, we will use the genetically tractable model organism Drosophila melanogaster and employ an integrative approach in exploration and suppression of cardiac amyloidosis. We propose to develop the first Drosophila model to investigate the cardiac defects associated with the accumulation of Alzheimer's and Huntington's disease-causing amyloid. Using the UAS-Gal4 expression system, we will express UAS-polyglutamine (for Huntington's) and UAS-A242 peptides (for Alzheimer's) in the Drosophila heart. We will examine the resulting cardiac defects at the physiological and cell biological levels. Furthermore, we will explore how expression of amyloid in the cardiac muscle afects expression of autophagy and other stress markers. We then plan to use genetic and pharmacological approaches to suppress cardiac amyloidosis. Genetic suppression of amyloids-induced cardiomyopathy will be attempted by over-expression of chaperones to reduce global protein unfolding or superoxide dismutase to ameliorate oxidative stress. We will also explore the effects of pharmacological agents such as chaperone inducers or antioxidants to ameliorate cardiac defects associated with amyloid accumulation. Our proposed study organism, Drosophila, with its high degree of gene conservation to the human genome and many techniques to manipulate its gene expression, will be an excellent model for exploring the mechanism of cardiac failure in Alzheimer's and Huntington's disease patients and may prove useful for developing therapies for human disease. Ultimately, once established, this model can be used for exploring genesis and suppression of cardiac amyloidosis linked with other amyloid precursor proteins. This proposal thus has broad applications and applies to cardiac, Alzheimer's and Huntington's diseases. All three diseases are devastating and the outcomes of this study may provide vital clues for their genesis. PUBLIC HEALTH RELEVANCE: Both Alzheimer's and Huntington's diseases are major risk factors for cardiac failure; the proposed study uses the model organism Drosophila melanogater for the first time to explore amyloid-induced cardiac dysfunction in these two major neurodegenerative diseases. We will use transgenic and pharmacological approaches for the suppression of the induced cardiac amyloidosis. This study is crucial for understanding the mechanism of cardiac failure in two major neuropathies and once established, this Drosophila model can be used to explore amyloid-induced cardiac failure associated with other amyloid precursor proteins.