EV miRs in cognitive function decline associated with early life metal exposure

项目概要/摘要 生命早期接触超级基金金属毒物，如铅 (Pb)、砷 (As)、镉 (Cd) 和 锰 (Mn) 与衰老过程中认知功能较差有关，并且被怀疑 有助于神经退行性疾病的发展，例如阿尔茨海默病。然而， 这些关联背后的生物学机制仍然知之甚少。哺乳动物细胞，包括 神经元和神经干细胞，分泌到细胞外环境中的各种微小的膜封装 囊泡。这些细胞外囊泡 (EV) 含有功能性信号分子，可以被 受体细胞介导细胞间通讯。其中一组信号分子是 microRNA，通过降解靶 mRNA 和/或作为基因表达的主调谐器 禁止消息的翻译。由于 EV 被脂质双层膜包裹，分子 例如封闭在囊泡中的 microRNA 受到保护，免受核酸酶介导的降解，因此 因此非常稳定。因此，可以轻松检测和定量生物体液中的 EV microRNA 例如血浆/血清，已被用作多种人类疾病的新型生物标志物。虽然 一些有限的研究探索了 EV microRNA 在神经细胞中的作用，但没有研究检验过 EV microRNA 在金属等环境暴露情况下对认知功能的作用 有毒物质。我们假设生命早期接触的金属会改变大脑中的 EV microRNA，并且这些 EV microRNA 的变化影响神经元和神经干细胞的功能以加速认知 老化。我们提出了三个相互关联的具体目标来检验这一假设。目标 1 将确定 暴露于单个金属（Pb、As、Mn 和 Cd）以及“现实世界”金属的影响 混合物（在圣路易斯谷超级基金现场采集的修复前和修复后水样） 开发人类胎儿大脑类器官。目标 2 将确定生命早期暴露于个人的影响 金属（Pb 和 As）以及 EV miR 上的现实世界金属混合物以及认知功能 老鼠在以后的生活中。目标 3 将确定选定的 EV microRNA 在调节功能中的功能作用 小鼠大脑类器官和认知功能的研究。我们高度多学科的研究整合了小鼠 模型、人类流行病学和功能细胞研究旨在建立 EV microRNA，不仅作为 与金属暴露相关的认知功能的新型生物标志物，同时也作为金属暴露的机制基础 诱发神经毒性和认知障碍。该项目通过以下方式与 MEMCARE-SRC 链接 补充项目 1 中的人类研究，并寻求确定对健康影响的生物机制 超级基金地点的水污染。

PROJECT SUMMARY/ ABSTRACT Early-life exposure to Superfund metal toxicants such as lead (Pb), arsenic (As), cadmium (Cd) and Manganese (Mn) has been associated with worse cognitive function during aging and is suspected of contributing to the development of neurodegenerative diseases, such as Alzheimer’s disease. However, the biological mechanisms underlying the associations remain poorly understood. Mammalian cells, including neurons and neural stem cells, secrete into the extracellular milieu a variety of tiny membrane-encapsulated vesicles. These extracellular vesicles (EVs) contain functional signaling molecules that can be taken up by recipient cells to mediate intercellular communication. One such group of signaling molecules is microRNAs, which function as master tuners of gene expression by degrading target mRNA and/or inhibiting translation of the message. Since EVs are encapsulated by a lipid bilayer membrane, molecules such as microRNAs enclosed in the vesicles are protected from nuclease-mediated degradation and thus are thus very stable. As a result, EV microRNAs can be easily detected and quantitated in biological fluids such as plasma/serum and have been used as novel biomarkers for a variety of human diseases. Although some limited studies have explored the role of EV microRNAs in neural cells, no studies have examined the role of EV microRNAs on cognitive function in the context of environmental exposures such as metal toxicants. We hypothesize that metal exposures in early life alter EV microRNAs in the brain and that these changes in EV microRNAs affect the function of neurons and neural stem cells to accelerate cognitive aging. We propose three interconnected Specific Aims to test this hypothesis. Aim 1 will determine the effects of exposures to individual metal exposures (Pb, As, Mn, and Cd) as well as “real-world” metal mixtures (pre- and post-remediation water samples collected at the San Luis Valley Superfund site) on developing human fetal brain organoids. Aim 2 will determine the effects of early-life exposure to individual metals (Pb and As) as well as to the real-world metal mixtures on EV miRs and the cognitive function of mice later in life. Aim 3 will determine the functional role of selected EV microRNAs in modulating functions of brain organoids and cognitive function in mice. Our highly multidisciplinary study integrating mouse models, human epidemiology, and functional cellular studies seeks to establish EV microRNAs not only as novel biomarkers for metal exposure-related cognitive function, but also as a mechanistic basis for metal- induced neurotoxicity and cognitive impairment. This project links with the MEMCARE-SRC by complementing human studies in Project 1 and seeking to identify biologic mechanisms for health effects of water contamination at Superfund sites.