Protein Acetylation and Selective Autophagy

描述(申请人提供)：致病蛋白的积累和聚集是几种神经退行性疾病的特征，如帕金森氏症、阿尔茨海默氏症和亨廷顿病。神经退行性疾病研究的主要目标之一是通过选择性地激活自噬等降解机制来改善这些积累的蛋白质的清除。目前调节自噬的方法导致自噬和其他细胞通路的全局和非特异性激活。以亨廷顿病为例，我们报道了通过对突变的HTT进行翻译后修饰，通过在赖氨酸残基444(K444)上进行乙酰化，可以实现选择性清除。K444的乙酰化增强促进了突变的Htt进入自噬小体，显著提高了突变蛋白通过大范围自噬清除的能力，并在体外和体内逆转了突变的Huntingtin的毒性效应。这些初步研究表明，乙酰化在控制突变的亨廷顿蛋白的调节清除中起着关键作用。在这里，我们建议研究这种乙酰化介导的突变型HTT清除的分子途径。在Aim1中，我们建议通过建立表达乙酰化抗性全长突变体HTT的敲打小鼠模型来验证突变体HTT在体内的作用，以进行生化、神经病理学和行为学研究。目的2将研究自噬机制与乙酰化突变体亨廷顿蛋白的相互作用。去往自噬小体的蛋白质的货物识别过程还不是很清楚。我们建议评估乙酰-HTT与自噬机制的相互作用，特别是涉及将蛋白质货物运送到自噬小体的蛋白质。在目标3中，我们将研究HDAC抑制剂在促进突变的Huntingtin清除方面的作用。使用细胞模型系统，我们将检查各种HDAC在清除乙酰化突变Htt方面的相对贡献。总之，这项拟议的研究将研究细胞如何调节突变的Htt水平，这是HD的关键风险因素。识别控制突变Htt水平的机制可以通过直接靶向突变Htt来导致新的治疗策略。了解突变体Htt识别和选择性自噬清除的分子机制可能有助于研究在各种神经退行性疾病中积累的其他致病蛋白。 与公共卫生相关：致病蛋白的积累和聚集是帕金森氏症、阿尔茨海默氏症和亨廷顿病等几种神经退行性疾病的特征。神经退行性疾病研究的主要目标之一是改善这些积累的蛋白质的清除。我们建议开发选择性激活细胞降解机制的策略，以提高对突变亨廷顿蛋白的清除，并为HD和相关的神经退行性疾病寻找新的治疗靶点。

DESCRIPTION (provided by applicant): Accumulation and aggregation of disease-causing proteins is a hallmark of several neurodegenerative disorders such as Parkinson's, Alzheimer's and Huntington's disease. One of the main goals of research in neurodegenerative disorders has been to improve clearance of these accumulated proteins by selectively activating degradation machinery such as autophagy. Current approaches to modulate autophagy result in global and non-specific activation of autophagic and other cellular pathways. Using an example of Huntington's disease, we reported that selective clearance can be achieved by posttranslational modification of the mutant htt by acetylation at lysine residue 444 (K444). Increased acetylation at K444 facilitates trafficking of mutant Htt into autophagosomes, significantly improves clearance of the mutant protein by macroautophagy and reverses the toxic effects of mutant huntingtin in vitro and in vivo. These preliminary studies suggest a critical role for acetylation in the control of regulated clearance of mutant huntingtin. Here we propose to examine the molecular pathways of such acetylation-mediated clearance of mutant htt. In Aim1 we propose to validate the role of mutant htt acetylation in vivo by generating a knockin mouse model expressing acetylation-resistant full-length mutant htt to perform biochemical, neuropathological and behavioral studies. Aim 2 will examine the interactions of autophagy machinery with acetylated mutant huntingtin. The cargo recognition process of proteins destined for the autophagosome is not well understood. We propose to assess interactions of acetyl-htt with the autophagy machinery, specifically the proteins involved in shuttling protein cargo to the autophagosome. In Aim 3 we will examine the role of HDAC inhibitors in promoting clearance of mutant huntingtin. Using cellular models systems, we will examine the relative contribution of various HDACs to clearance of acetylated mutant Htt. In summary, the proposed study will examine how cells regulate mutant Htt levels, a critical risk factor for HD. Identifying the mechanisms that control mutant Htt levels could lead to novel therapeutic strategies by directly targeting mutant Htt. Understanding the molecular mechanisms involved in the recognition and selective autophagic clearance of mutant Htt may facilitate studies of other disease-causing proteins that accumulate in various neurodegenerative disorders. PUBLIC HEALTH RELEVANCE: Accumulation and aggregation of disease-causing proteins is a hallmark of several neurodegenerative disorders such as Parkinson's, Alzheimer's and Huntington's disease. One of the main goals of research in neurodegenerative disorders has been to improve clearance of these accumulated proteins. We propose to develop strategies to selectively activate cellular degradation machinery to improve clearance of mutant huntingtin and identify novel therapeutic targets for the treatment of HD and related neurodegenerative disorders.