Regulation of autophagy in dopaminergic cell death

描述（由申请人提供）：多巴胺能（DA）神经元对氧化损伤敏感，并在年龄相关性神经退行性疾病中退化。在神经元中发现了一种以显著的自噬空泡（AVs）为特征的受调控的细胞死亡形态。自噬通常是一个高度调节的过程，隔离细胞质组分用于溶酶体降解。然而，失调或过度的自噬可能对细胞有害，产生一种可被概念化为"自噬应激"的状况。“虽然在帕金森病及其体外和体内模型的退化DA神经元中观察到AV，但自噬在DA神经元损伤中的作用仍有待阐明。我们的研究表明，氧化性神经毒素引起DA神经元线粒体自噬增加。此外，这种损伤诱导的自噬的调节不同于营养剥夺系统。该提案调查的假设，即：自噬有助于损伤的DA神经元的轴突回缩和细胞死亡，活性氧和MARK信号调节损伤诱导的自噬。我们将使用复合物I抑制剂MPP+来产生靶向损伤，并使用氧化还原循环6-羟基多巴胺来模拟全身氧化应激，比较急性和慢性治疗。分子，生物化学，活细胞成像和转基因方法的组合将应用于DA细胞系，原代中脑培养物和小鼠，以确定自噬在DA神经突起收缩和细胞死亡中的作用，并研究MAPK和氧化磷脂信号参与其调节。这些研究的完成将产生重要的见解机制，自噬反应调节DA神经突变性和细胞死亡在氧化性神经元损伤。相关性：线粒体损伤和自噬应激是帕金森/路易体病的突出特征。与生理条件相反，在存在失调的病理力的情况下诱导自噬可能促进细胞死亡。更好地理解自噬应激的机制将有助于未来的研究工作集中在恢复系统的平衡上。因此，研究氧化损伤神经元中自噬反应的作用和调节可能会促进适用于年龄相关神经退行性疾病和其他涉及氧化应激的脑部疾病的新疗法的开发。

DESCRIPTION (provided by applicant): Dopaminergic (DA) neurons are sensitive to oxidative insults and degenerate in age-related neurodegenerative diseases. A morphologic form of regulated cell death characterized by prominent autophagic vacuoles (AVs) has been identified in neurons. Autophagy is normally a highly regulated process sequestering cytoplasmic components for lysosomal degradation. However, dysregulated or excessive autophagy can be harmful to cells, producing a condition that can be conceptualized as "autophagic stress." Although AVs are observed in degenerating DA neurons in Parkinson disease and its in vitro and in vivo models, the role of autophagy in DA neuronal injury remains to be elucidated. Our studies indicate that oxidative neurotoxins elicit increased mitochondrial autophagy in DA neurons. Moreover, the regulation of this injury-induced autophagy is different from that of nutrient-deprivation systems. This proposal investigates the hypotheses that: autophagy contributes to neurite retraction and cell death in injured DA neurons, and that reactive oxygen species and MARK signals regulate injury-induced autophagy. We will use the complex I inhibitor MPP+ to produce mitochondria-targeted injury, and the redox cycling 6- hydroxydopamine to model generalized oxidative stress, comparing acute and chronic treatments. A combination of molecular, biochemical, live cell imaging and transgenic approaches will be applied to DA cell lines, primary midbrain cultures and mice to determine the role of autophagy in DA neurite retraction and cell death, and to study MAPK and oxidative phospholipid signals involved in its regulation. Completion of these studies will yield important insights into mechanisms by which autophagic responses regulate DA neurite degeneration and cell death during oxidative neuronal injuries. Relevance: Mitchondrial impairment and autophagic stress are prominent features of Parkinson/Lewy body disease. In contrast to physiologic conditions, inducing autophagy in the presence of dysregulating pathologic forces may promote cell death. A better understanding of mechanisms that contribute to autophagic stress will help focus future research efforts to restore balance to the system. Thus, studying the role and regulation of autophagic responses in oxidatively-injured neurons may enhance development of novel therapies applicable to age-related neurodegenerative diseases and other brain disorders involving oxidative stress.