Role of DNA damage response in Mn-induced neurotoxicity in C. elegans

锰（Mn）是人体必需的微量元素，对人体健康具有重要的生理功能。然而，环境或职业过度暴露可能导致一种被称为锰中毒的不可逆状况，其与帕金森病（PD）具有相似的神经病理学，明显的多巴胺能（DAergic）细胞损失与运动和认知缺陷的表现相关。尽管潜在的机制尚不清楚，但最近我们发现DNA损伤相关的信号反应聚（adp -核糖基）化对体外Mn暴露高度敏感。对DNA损伤的缺陷反应已被证明在包括帕金森病在内的许多神经系统疾病的病因学中发挥作用，强调了DNA修复在神经稳态中的重要性。因此，本研究旨在评估DNA损伤反应在Mn诱导的神经毒性中的作用，特别关注DNA反应基因与Mn的相互作用，使用体内模型生物秀丽隐杆线虫（C. elegans）。项目研究的第一部分将确定mn诱导的毒性是否会加剧DNA损伤反应（pme-1, pme-2, pme-3, pme-4（人类PARPs的秀丽隐杆线虫同源物））缺失突变体。毒性终点将包括致死性、细胞应激和DNA损伤，同时将评估锰含量和对其他金属稳态（如铁、铜、锌和钙）的影响，以将观察到的影响与生理相关浓度联系起来。将多巴胺能（DAergic）神经变性、DAergic信号和功能与锰暴露后DNA损伤反应相关信号联系起来，将为理解锰诱导的神经毒性提供新的见解。此外，DNA损伤反应基因pme-1与各种修复途径基因的相互作用尚不清楚。对选定的DNA修复基因的研究将在pme-1功能丧失和Mn存在的背景下进行，以指导未来对Mn诱导的神经毒性中涉及的最相关途径的研究。此外，还将研究Mn暴露是否会抑制野生型蠕虫以及pme-1相关基因（如sirtuins、pink1、α -synuclein）的转基因突变体的DNA损伤反应。为了进一步确定mn诱导毒性gaba能性神经变性的新靶点，我们将研究其对pme-1缺失突变体中MAPK信号的影响。确定锰致神经毒性的新机制将为治疗策略提供新的靶点，并可能为确定包括食物成分对锰致神经毒性的神经保护特性在内的神经保护策略奠定基础。

Manganese (Mn) is an essential trace element occupying important physiological functions for human health. However, environmental or occupational overexposure may result in an irreversible condition known as manganism that shares similar neuropathology with Parkinson disease (PD), with overt dopaminergic (DAergic) cell loss associated with the presentation of motor and cognitive deficits. Although the underlying mechanism remains unclear, recently we identified the DNA damage related signaling reaction poly(ADP-ribosyl)ation to be highly sensitive to in vitro Mn exposure. A defective response to DNA damage has been shown to play a role in the etiology of a host of neurological disorders, including Parkinson disease, emphasizing the importance of DNA repair in neural homeostasis. Accordingly, this study is designed to assess the role of the DNA damage response in Mn-induced neurotoxicity with a special focus on interactions of DNA response genes and Mn using the in vivo model organism Caenorhabditis elegans (C. elegans). The first part of the project studies will determine if Mn-induced toxicity is exacerbated in DNA damage response (pme-1, pme-2, pme-3, pme-4 (C. elegans orthologs of human PARPs)) deletion mutants. Toxicity endpoints will include lethality, cellular stress and DNA damage, while in parallel the Mn content and the impact on other metal homeostasis e.g. Fe, Cu, Zn and Ca will be assessed to link the observed effects with physiologically relevant concentrations. Correlating dopaminergic (DAergic) neurodegeneration, DAergic signaling and function with DNA damage response related signaling following Mn exposure will provide novel insights in understanding Mn-induced neurotoxicity. Additionally, the interaction of the DNA damage response gene pme-1 with genes of various repair pathways is poorly understood. Studies on selected DNA repair genes will be carried out in the background of a loss-of-function pme-1 and in the presence of Mn to guide future studies on the most relevant pathways that are involved in Mn-induced neurotoxicity. Moreover, it will be investigated whether Mn exposure is inhibiting DNA damage response in wildtype worms as well as transgenic mutants of genes related to pme-1 (e.g. sirtuins, pink1, alpha-synuclein). To further identify novel targets of Mn-induced toxicity GABAergic neurodegeneration and the effect on MAPK signaling in the pme-1 deletion mutants will be studied. Identifying novel underlying mechanisms of Mn-induced neurotoxicity will provide novel targets for therapy strategies and may lay the foundation to identify neuroprotective strategies including neuroprotective properties of food constituents against Mn-induced neurotoxicity.