Development of MESH1 inhibitors to treat ferroptosis-associated neurodegeneration

所有生物都会遇到各种各样的代谢和环境应激，并发展出各种促进生存的应激反应机制。在细菌中，主要的应激反应机制是由警报酮(p)ppGpp积累引发的“严格反应”。它协调广泛的转录变化来促进应激生存。后生动物基因组编码细菌SpoT - mesh1的同源物，该同源物可以在体外水解ppGpp，并在功能上补充大肠杆菌中的SpoT。然而，在后生动物中既没有发现(p)ppGpp合成酶的同源物，也没有发现(p)ppGpp本身，这使MESH1在哺乳动物细胞中的功能和相关底物变得神秘。最近，我们的研究发现MESH1是第一个对铁下垂至关重要的细胞质NADPH磷酸酶。铁下垂是一种新认识的细胞死亡形式，其特征是铁依赖性和脂质过氧化。铁下垂诱导MESH1有助于NADPH和GSH的消耗。因此，遗传去除MESH1可以有效地保护细胞免于铁下垂。由于铁下垂参与神经退行性疾病，如阿尔茨海默病和阿尔茨海默病相关痴呆（AD/ADRD）的神经元细胞死亡，我们假设小分子MESH1抑制剂抑制铁下垂可能保护AD/ADRD中的神经元免于铁下垂。为了验证我们的假设，我们组建了一个具有互补专业知识的综合科学团队，并提出以下两个具体目标：首先，我们将开发和优化从前两种经过验证的hit化合物衍生的小分子MESH1抑制剂。接下来，我们将确定MESH1抑制剂在培养细胞和AD/ADRD器官型脑切片培养模型中阻断铁下垂的活性和特异性。总的来说，该提案的成功实施将确定mes1和铁下垂的新型化学抑制剂，以改善年龄相关性AD/ADRD患者的治疗结果。

All living organisms encounter a wide variety of metabolic and environmental stress and have developed various stress-response mechanisms that promote survival. In bacteria, the main stress-response mechanism is the “stringent response” which is triggered by the accumulation of the alarmone (p)ppGpp. It orchestrates extensive transcriptional changes to promote stress survival. Metazoan genomes encode a homolog of bacterial SpoT—MESH1—that can hydrolyze ppGpp in vitro and functionally complements SpoT in E. coli. However, neither a homolog of the (p)ppGpp synthetase nor (p)ppGpp itself has been found in metazoans, mystifying the function and relevant substrate(s) of MESH1 in mammalian cells. Recently, our research has revealed that MESH1 is the first cytosolic NADPH phosphatase that is essential for ferroptosis. Ferroptosis is a newly- recognized form of cell death which is characterized by iron dependency and lipid peroxidation. The induction of MESH1 under ferroptosis contributes to NADPH and GSH depletion. Therefore, genetic removal of MESH1 robustly protects cells from ferroptosis. As ferroptosis is involved in neuronal cell death in neurodegenerative diseases, such as Alzheimer's Disease and Alzheimer's Disease Related Dementias (AD/ADRD), we hypothesize that inhibition of ferroptosis by small molecule MESH1 inhibitors may protect neurons from ferroptosis in AD/ADRD. To test our hypothesis, we assemble an integrative scientific team with complementary expertise and propose the following two specific aims: First, we will develop and optimize small molecule MESH1 inhibitors derived from the top two validated hit compounds. Next, we will determine the activity and specificity of MESH1 inhibitors to block ferroptosis in cultured cells and in organotypic brain slice culture models of AD/ADRD. Collectively, the successful execution of the proposal will identify novel chemical inhibitors of MESH1 and ferroptosis to improve treatment outcomes for patients with age-related AD/ADRD.