Regulation of autophagy in dopaminergic cell death

描述(申请人提供)：多巴胺(DA)能神经元对氧化损伤敏感，在与年龄相关的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)为特征的调节性细胞死亡的形态。自噬通常是一个高度受调控的过程，隔离溶酶体降解的细胞质成分。然而，调节失调或过度的自噬可能对细胞有害，产生一种可以概念化的“自噬应激”。虽然在帕金森病及其体外和体内模型的退行性DA神经元中观察到了AVs，但自噬在DA神经元损伤中的作用仍不清楚。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的调节。这项建议调查的假设是：自噬有助于损伤的DA神经元的轴突回缩和细胞死亡，以及活性氧和Mark信号调节损伤诱导的自噬。我们将使用复合I抑制剂MPP+来产生线粒体靶向损伤，并使用氧化还原循环6-羟基多巴胺来模拟全身性氧化应激，比较急性和慢性治疗。本研究将结合分子生物学、生物化学、活细胞成像和转基因技术，应用于DA细胞系、原代培养的中脑和小鼠，以确定自噬在DA突起回缩和细胞死亡中的作用，并研究参与其调控的MAPK和氧化磷脂信号。这些研究的完成将对自噬反应在氧化性神经元损伤过程中调节DA轴突变性和细胞死亡的机制产生重要的见解。相关性：线粒体损害和自噬应激是帕金森/路易体病的显著特征。与生理条件相反，在失调的病理性力量存在的情况下诱导自噬可能会促进细胞死亡。更好地了解导致自噬应激的机制将有助于将未来的研究重点放在恢复该系统的平衡上。因此，研究自噬反应在氧化损伤神经元中的作用和调控可能会促进新疗法的发展，适用于年龄相关的神经退行性疾病和其他涉及氧化应激的大脑疾病。

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.