p38 MAPK activation as a therapeutic target for Friedreich ataxia

项目摘要/摘要 目前还没有批准的治疗常染色体隐性遗传性神经和心脏退行性疾病的方法 共济失调(FA)。FA是由编码蛋白质Frataxin的基因亚型突变引起的。Frataxin本地化 对线粒体基质和在铁-硫簇(ISCs)生物发生中的作用，这是重要的 线粒体内和线粒体外酶的修复组。我们发现p38的MAPK应激- FA细胞中的反应通路结构性过度激活，可能是持续的氧化应激和/或 正在进行的DNA损伤反应(DDR)。我们的工作假说是p38的慢性过度激活 调节ISC生物发生复合体中的关键蛋白的途径是适应不良反馈环的一部分 这进一步抑制了FA细胞中ISC的生物发生；因此，抑制p38途径或其激活， 抵消Frataxin功能降低的有害影响。我们的初步研究表明， 过氧化和端粒损伤在FA发病机制中的作用，两者都激活了p38，并且两者都是 ISC缺陷的后果。我们假设FA细胞中ISC的生物生成将增加，并且FA- 相关缺陷通过(I)抑制p38和/或将p38连接到ISC生物发生的MK2；或(Ii)a 通过减少氧化应激(特别是脂质过氧化)或通过 DDR降低(尤其是继发于临界端粒缩短)。以基因为补充 方法，我们将测试已知的针对这些途径的化合物，使我们能够阐明其作用 在FA发病机制中的这些途径，同时推进我们的总体目标，识别和 为潜在的临床开发优先考虑化合物。我们的具体目标是：目标1.利用成纤维细胞 探讨p38-MAPK通路、氧化应激和DNA相互作用的模型 FA发病机制中的损害，并检测相关药物和药物靶点以求改善 与FA相关的缺陷。我们将检验我们的假设，即p38通路的结构性过度激活 FA细胞代表着一个不适应的反馈循环，抑制这一途径可以抵消有害的 Frataxin功能降低的影响，从而改善FA相关的缺陷。使用以下组合 通过遗传学和小分子方法，我们将测试抗氧化剂、抗DDR药物和p38/MK2的效果 抑制p38的激活、ISC的生物发生和FA相关的缺陷。目标2和3。要使用FA IPSC- 衍生的心肌细胞和感觉神经元(目标2)和FA斑马鱼(目标3)，以测试我们的 在体外和体内影响细胞类型的假设。使用遗传和小分子的组合 方法，我们将测试抗氧化剂、抗DDR药物和p38/MK2抑制对p38激活的影响。 ISC生物发生，以及在这些模型中验证的FA相关缺陷。我们预计会产生重大的积极影响： 我们的初步研究已经将这些途径与FA病理生理学联系起来，并针对这些化合物 已经开发出了治疗其他疾病的途径，在某些情况下，已经在进行临床试验。

PROJECT SUMMARY/ABSTRACT There are no approved therapies for the autosomal-recessive neuro- and cardio-degenerative disorder Friedreich ataxia (FA). FA is caused by hypomorphic mutations in the gene encoding the protein frataxin. Frataxin localizes to the mitochondrial matrix and functions in the biogenesis of iron-sulfur-clusters (ISCs), which are important prosthetic groups for both intra- and extra-mitochondrial enzymes. We found that the p38 MAP kinase stress- response pathway is constitutively hyperactivated in FA cells, likely as a result of ongoing oxidative stress and/or an ongoing DNA damage response (DDR). Our working hypothesis is that chronic hyperactivation of the p38 pathway, which modulates a key protein in the ISC biogenesis complex, is part of a maladaptive feedback loop that further suppresses ISC biogenesis in FA cells; hence, inhibition of the p38 pathway, or of its activation, counteracts the deleterious effects of decreased frataxin function. Our preliminary studies have implicated lipid peroxidation and telomere damage in FA pathogenesis, both of which activate p38, and both of which are consequences of ISC deficiency. We hypothesize that ISC biogenesis in FA cells will be increased, and FA- associated defects ameliorated, by (i) inhibition of p38 and/or MK2, which links p38 to ISC biogenesis; or (ii) a reduction in p38 activation, either through a decrease in oxidative stress (particularly lipid peroxidation) or a decrease in the DDR (particularly secondary to critical telomere shortening). Complemented by genetic approaches, we will test compounds that are known to target these pathways, allowing us to elucidate the roles of these pathways in FA pathogenesis while simultaneously advancing our overall goal of identifying and prioritizing compounds for potential clinical development. Our Specific Aims are: Aim 1. To use fibroblast models to interrogate the interrelated roles of the p38-MAPK pathway, oxidative stress, and DNA damage in the pathogenesis of FA, and to test relevant drugs and drug targets for amelioration of FA-associated defects. We will test our hypothesis that constitutive hyperactivation of the p38 pathway in FA cells represents a maladaptive feedback loop, and that inhibiting this pathway counteracts the deleterious effects of decreased frataxin function, thereby ameliorating FA-associated defects. Using a combination of genetic and small-molecule approaches, we will test the effects of antioxidants, anti-DDR agents, and p38/MK2 inhibition on p38 activation, ISC biogenesis, and FA-associated defects. Aims 2 and 3. To use FA iPSC- derived cardiomyocytes and sensory neurons (Aim 2), and FA zebrafish (Aim 3), to test our hypotheses in affected cell types in vitro and in vivo. Using a combination of genetic and small-molecule approaches, we will test the effects of antioxidants, anti-DDR agents, and p38/MK2 inhibition on p38 activation, ISC biogenesis, and FA-associated defects validated in these models. We anticipate a significant positive impact: our preliminary studies already link these pathways to FA pathophysiology, and compounds targeting these pathways have been developed and, in some cases, are already in clinical trials for other disorders.