Mechanisms of PhIP-induced dopaminergic neurotoxicity

多巴胺(DA)能神经变性是帕金森病(PD)的一个病理标志，它会产生 主要的马达特征。文献中的主要差距仍然是关于饮食暴露是否以及如何普遍存在 在发病机制中起作用。这项提议旨在通过高度机械化的研究来解决这些差距 被称为杂环芳胺(HAAs)的饮食毒物的神经毒性。在第一个周期中 R01ES025750，我们取得了重大进展，表明HAAs在脑内产生选择性DA能神经毒性。 细胞、线虫和啮齿动物模型系统。我们还鉴定了HAA诱导的氧化损伤，蛋白质 聚集、自噬破坏和DNA加合物形成是关键的生化和分子结果 这对警局来说至关重要。在这个数据集中，我们取得了最重要的机械性进展， 为以行动机制为重点的更新做好准备。首先，神经黑色素(NM)对HAA至关重要 细胞内蓄积和神经毒性。这一发现指向了选择性，因为NM是在 人的儿茶酚胺能神经元，以及在NM细胞和动物模型中翻译的关键需求 HAAS的研究(NM在大多数PD模型中缺乏)。其次，HAAS又一次选择性地以线粒体为目标 指出了可能的选择性，因为DAR能神经元对线粒体毒性特别敏感。基座 在这些数据和文献的基础上，我们将检验以下机制假说：HAA诱导的DAERIC 神经毒性是通过NM和线粒体功能障碍之间的生化相互作用而介导的 会产生一连串的神经毒性。我们将通过三个目标来检验这一假设。在目标1中，我们将确定是否 NM形成大鼠表现出HAA诱导的DA能神经毒性增强。在新奇的形成NM的大鼠中，我们将 评估HAA蓄积、HAA脑代谢和神经毒性以确定帕金森病的相关性。在目标2中，我们 将确定介导HAA诱导的神经毒性的线粒体靶点。我们将会发现 HAAs的线粒体DNA加合物通过量化HAAs形成的加合物介导神经毒性 线粒体DNA与基因组DNA。此外，我们将确定HAA生物激活途径，从而导致 线粒体和基因组DNA加合物的形成。最后，我们将确定特定的线粒体基因和 DNA损伤引起的蛋白质损伤。在目标3中，我们将演示NM之间的联系， 线粒体功能障碍和蛋白质聚集。使用无细胞、细胞和动物模型系统，我们将 确定NM对HAA介导的线粒体功能、自噬(尤其是 有丝分裂)，以及利用生化和组织学的PD相关蛋白聚集的繁殖 技巧。总之，阐明了NM、有丝分裂/自噬和蛋白质聚集之间的相互作用 对HAA至关重要的神经毒性作用机制有望极大地促进对HAA- 诱导的神经毒性，更广泛地说，环境诱导的多巴胺能神经毒性。这些研究是 有望极大地促进对帕金森病病因的理解。

Dopamine (DA)-ergic neurodegeneration is a pathological hallmark of Parkinson’s disease (PD) that produces the cardinal motor features. Major gaps in the literature remain on if and how common dietary exposures may contribute to pathogenesis. This proposal aims to address these gaps through highly mechanistic studies of neurotoxicity from dietary toxicants known as heterocyclic aromatic amines (HAAs). In the first cycle of R01ES025750, we made major advances demonstrating that HAAs produce selective DAergic neurotoxicity in cellular, nematode, and rodent model systems. We also identified HAA-induced oxidative damage, protein aggregation, autophagy disruption, and DNA adduct formation as key biochemical and molecular outcomes that are of critical importance to PD. Within this dataset, we have made overarching mechanistic advances that set the stage for a mechanism-of-action-focused renewal. First, neuromelanin (NM) is critical to HAA intracellular accumulation and neurotoxicity. This finding points to selectivity because NM is formed in catecholaminergic neurons in humans, and a critical translational need for NM cell and animal models in the study of HAAs (NM is lacking in most PD models). Second, HAAs selectively target mitochondria, again pointing to possible selectivity because DAergic neurons are especially sensitive to mitochondrial toxicity. Based on these data and the literature, we will test the following mechanistic hypothesis: HAA-induced DAergic neurotoxicity is mediated through biochemical interactions between NM and mitochondrial dysfunction that produce a neurotoxic cascade. We will test this hypothesis through three aims. In Aim 1, we will determine if NM-forming rats exhibit heightened HAA-induced DAergic neurotoxicity. In novel, NM-forming rats, we will assess HAA accumulation, HAA brain metabolism, and neurotoxicity to establish PD relevance. In Aim 2, we will identify mitochondrial targets that mediate HAA-induced neurotoxicity. We will discover the role of mitochondrial DNA adducts of HAAs in mediating neurotoxicity by quantifying adducts formed in mitochondrial versus genomic DNA. Further, we will identify HAA bioactivation pathways that lead to mitochondrial and genomic DNA adduct formation. Finally, we will identify specific mitochondrial gene and protein impairments resulting from DNA damage. In Aim 3, we will demonstrate connections between NM, mitochondrial dysfunction, and protein aggregation. Using cell-free, cellular and animal model systems, we will determine the effects of NM on HAA-mediated perturbations of mitochondrial function, autophagy (especially mitophagy), and the propagation of PD-relevant protein aggregation using biochemical and histological techniques. Overall, elucidation of interactions between NM, mitophagy/autophagy, and protein aggregation as critical to HAA neurotoxic mechanism of action is expected to significantly advance understanding of HAA- induced neurotoxicity and, more broadly, environmentally induced DAergic neurotoxicity. These studies are expected to significantly advance understanding of PD etiopathogenesis.