Alleviating Mitochondrial Dysfunction in PERK-deficient Neurodegenerative Disease

项目摘要 线粒体功能障碍和内质网（ER）应激是病理性衰老的标志， 与病因多样的神经退行性疾病的发病和发病机制密切相关，包括 阿尔茨海默病（AD）和相关痴呆（ADRD）。这引起了人们对理解的浓厚兴趣 细胞如何调节线粒体对内质网应激的反应。有趣的是，ER应激反应激酶PERK 定位于内质网-线粒体接触位点，在那里它作为未折叠蛋白质反应的效应物 (UPR)综合应激反应（ISR）。此外，PERK依赖性转录和翻译 信号转导几乎调节线粒体生物学的所有方面，包括线粒体嵴的重塑， 呼吸复合物以增强能量能力，调节线粒体蛋白质稳态（即，蛋白质输入， 分子伴侣活性和蛋白水解），以及重塑膜磷脂组成以诱导保护性 线粒体延长通过这些机制，PERK在ER应激期间保护线粒体;然而， 由严重或慢性ER应激诱导的持续PERK活化导致细胞凋亡。因此，PERK信令 都促进适应性线粒体重塑，并决定细胞命运，以响应不同水平的细胞凋亡。 应力PERK在调节适应和存活中的重要性得到了临床，遗传， 药理学证据表明，不平衡的PERK信号转导有助于发病机制， 病因多样的神经退行性疾病。编码PERK的基因中的亚型变体 （EIF 2AK 3）使个体易患tau蛋白病，如进行性核上性麻痹（PSP）和晚期tau蛋白病。 AD.此外，外源性PERK激活减轻了PSP中的tau病理，进一步表明保护性PERK激活可减轻PSP中的tau病理。 PERK信号传导在这种疾病的发病机制中是不足的。总的来说，这些观察结果表明， PERK作为线粒体适应细胞损伤的关键调节因子，并表明PERK的不平衡 信号传导导致涉及神经变性疾病发病机制的线粒体功能障碍。使用 细胞培养模型来源于患者表达一个亚型PERK变异，我将表明，不足之处， 在PERK信号传导中，线粒体受损并导致神经变性表型，如tau病理学 (Aim 1）。此外，我将证明，药物激活的ISR-一个应激反应程序， 由eIF 2 α激酶GCN 2、HRI、PKR和PERK组成，减轻线粒体功能障碍， PERK缺陷性神经变性的人神经元模型中的神经元存活（目的2）。这些努力 重要的是，它们将定义PERK在调节线粒体适应过程中的关键作用。 神经变性和建立药理学ISR激活作为一种潜在的治疗策略， 神经退行性疾病-目前还没有改善疾病的治疗方法。

PROJECT SUMMARY Mitochondrial dysfunction and endoplasmic reticulum (ER) stress are hallmarks of pathologic aging and are intricately linked in the onset and pathogenesis of etiologically-diverse neurodegenerative disorders including Alzheimer’s disease (AD) and related dementias (ADRDs). This has led to significant interest in understanding how cells regulate mitochondria in response to ER stress. Intriguingly, the ER stress-responsive kinase PERK is localized to ER-mitochondria contact sites where it acts as an effector of both the unfolded protein response (UPR) and the integrated stress response (ISR). Additionally, PERK-dependent transcriptional and translational signaling modulates nearly all aspects of mitochondrial biology including remodeling of mitochondrial cristae and respiratory complexes to enhance energy capacity, regulation of mitochondrial proteostasis (i.e., protein import, chaperone activity, and proteolysis), and remodeling of membrane phospholipid composition to induce protective mitochondrial elongation. Through these mechanisms PERK protects mitochondria during ER stress; however, persistent PERK activation induced by severe or chronic ER stress leads to apoptosis. Thus, PERK signaling both promotes adaptive mitochondrial remodeling and dictates cell fate in response to varying levels of cellular stress. The importance of PERK in regulating adaptation and survival is further supported by clinical, genetic, and pharmacologic evidence demonstrating that imbalanced PERK signaling contributes to the pathogenesis of etiologically-diverse neurodegenerative diseases. Hypomorphic variants in the gene that encodes PERK (EIF2AK3) predispose individuals to tauopathies such as progressive supranuclear palsy (PSP) and late-stage AD. In addition, exogenous PERK activation mitigates tau pathology in PSP, further indicating that protective PERK signaling is insufficient in the pathogenesis of this disease. Collectively, these observations establish PERK as a critical regulator of mitochondrial adaptation to cellular insult and suggest that imbalances in PERK signaling contribute to mitochondrial dysfunction implicated in neurodegenerative disease pathogenesis. Using cell culture models derived from patients expressing a hypomorphic PERK variant, I will show that deficiencies in PERK signaling impair mitochondria and contribute to neurodegenerative phenotypes such as tau pathology (Aim 1). Further, I will demonstrate that pharmacologic activation of the ISR—a stress-responsive program comprised of the eIF2α kinases GCN2, HRI, PKR, and PERK—mitigates mitochondrial dysfunction and improves neuronal survival in a human neuronal model of PERK-deficient neurodegeneration (Aim 2). These efforts are significant as they will define a critical role for PERK in regulating mitochondrial adaptation during neurodegeneration and establish pharmacologic ISR activation as a potential therapeutic strategy against neurodegenerative disease—for which no disease-modifying treatments are currently available.