AMPK/SIRT1/PGC-1α, a critical pathway in dry AMD

摘要： ! 视网膜相关性黄斑变性（AMD）是55岁以上人群失明的主要原因， 美国和发达国家。AMD的两种形式之一是“干”形式，目前没有 有效的治疗。因此，存在开发用于治疗癌症的新疗法的未满足的医学需求。 AMD.包括AMD在内的许多视网膜疾病与线粒体功能障碍有关5。 功能障碍的线粒体诱导活性氧（ROS）水平升高，并导致代谢缺陷。 活动自噬丧失也导致线粒体功能障碍，并被认为增加了对 氧化应激和AMD。我们最近发现了功能失调的自噬，增加的ROS， 来自AMD供体眼睛的RPE中的线粒体功能障碍。然而，潜在的机制 导致AMD的这些缺陷性代谢稳态的诱导仍然未知。 过氧化物酶体增殖物激活受体-γ共激活因子（PGC-1α）在肿瘤的发生发展中起着重要的作用。 在线粒体生物合成和氧化代谢中起重要作用。它还调节自噬和线粒体自噬。 PGC-1α活性受两个主要因素刺激：AMP活化蛋白激酶（AMPK）和NAD+- 依赖性脱乙酰酶，SIRT 1。我们实验室的初步证据表明AMPK/SIRT- 1/PGC-1α在AMD RPE中下调。根据我们的初步数据，我们假设 RPE中抑制的AMPK/SIRT 1/PGC-1α通路诱导线粒体自噬功能障碍， ROS产生增加，导致代谢活动异常、脂质和糖原积累，以及 玻璃疣形成，导致AMD的病理生理学。为了验证我们的假设，我们开发了一个 通过从AMD供体的眼睛中分离天然RPE，随后通过在体外建立无穷尽的AMD疾病模型， iPSC的产生，以及随后分化为RPE（AMD RPE-iPSC-RPE）。我们还 从作为对照的年龄匹配的正常供体的RPE产生iPSC（正常RPE-iPSC-RPE）。我们 证实了AMD RPE-iPSC-RPE模拟其亲本供体的疾病表型，即主要的 AMD RPE，它验证了我们的模型。此外，我们还建立了一种动物模型来检测PGC-1α的作用 抑制RPE和视网膜健康，并观察RPE和感光细胞变性。我们提出了两 目的：本研究旨在利用我们建立的AMPK/SIRT-1/PGC-1α通路抑制模型，检测AMPK/SIRT-1/PGC-1α通路抑制在干性AMD中的作用。 来自AMD供体和AMD患者的体外模型。Aim 2将研究细胞和分子机制 PGC-1α在小鼠模型中对RPE和视网膜健康的作用。最终，这些研究将提供 研究干性AMD的分子机制，可能有助于开发新的治疗干预措施。

ABSTRACT: ! Age-related macular degeneration (AMD) is the major cause of blindness in people over age 55 in the U.S. and the developed world. One of the two forms of AMD is the “dry” form for which currently there are no effective treatments. Consequently, there is an unmet medical need for development of new therapies for AMD. A number of retinal diseases including AMD are associated with mitochondrial dysfunction5. Dysfunctional mitochondria induce increased levels of reactive oxygen species (ROS), and defective metabolic activity. Autophagy loss also results in mitochondrial dysfunction and is suggested to increase susceptibility to oxidative stress and AMD. We have recently shown dysfunctional autophagy, increased ROS, and dysfunctional mitochondria in RPE derived from AMD donor eyes. However, the underlying mechanisms inducing these defective metabolic homeostases leading to AMD remain unknown. The Peroxisome proliferator-activated receptor-gamma coactivator (PGC)-1alpha (PGC-1α) plays a major role in mitochondrial biogenesis and oxidative metabolism. It also regulates autophagy and mitophagy. PGC-1α activity is stimulated by two main factors: AMP-activated protein kinase (AMPK) and NAD+- dependent deacetylase, SIRT1. Preliminary evidence from our laboratory suggests that the AMPK/SIRT- 1/PGC-1α is down regulated in AMD RPE. Based on our preliminary data, we hypothesize that the repressed AMPK/SIRT1/PGC-1α pathway in RPE induces mitochondrial, autophagic dysfunction, and increased ROS production, which result in abnormal metabolic activity, lipid and glycogen accumulation, and drusen formation, leading to the AMD pathophysiology. To test our hypothesis, we have developed an inexhaustible AMD in vitro disease model by isolating native RPE from AMD donors' eyes followed by generation of iPSC, and their subsequent differentiation into RPE (AMD RPE-iPSC-RPE). We have also generated iPSC from RPE of age-matched normal donors (Normal RPE-iPSC-RPE) that serve as control. We confirmed that the AMD RPE-iPSC-RPE mimic the disease phenotypes of their parental donors, the primary AMD RPE, which validates our model. Additionally, we established an animal model to test the role of PGC-1α repression on RPE and retinal health and observed RPE and photoreceptor degeneration. We propose two aims: Aim1 will test the role of AMPK/SIRT-1/PGC-1α pathway inhibition in dry AMD using our established in vitro model from AMD donors and AMD patients. Aim2 will investigate the cellular and molecular mechanisms of PGC-1α actions on RPE and retinal health in a mouse model. Ultimately, these studies will provide insight into the molecular mechanisms of dry AMD and may facilitate development of new therapeutic interventions.