Metals and Metal Mixtures: Cognitive Aging, Remediation and Exposure Sources (MEMCARE)

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PROJECT DESCRIPTION: Increased global life expectancy has led to higher incidences of incurable neurodegenerative disorders. Although genetic predisposition and age are known risk factors for neurodegenerative disorders, it has become increasingly clear – via an unknown mechanism, exposure to lead (Pb) increases the risk of these cognitive disorders. Identifying the molecular mechanism by which early-life exposure to Pb results in neurodegeneration is essential for the development of therapies to prevent its onset. The progressive loss of structure and function in neurons which characterizes neurodegenerative disorders involves complex communication between neurons and microglia. Known for radically altering their morphology and function in response to their environmental, microglia respond to toxins, such as Pb, inducing stress and death in neighboring neurons. Using molecular and cell biology-based approaches, my current Superfund research at the MEMCARE-SRC characterizes how Pb exposure impacts signaling molecules generated by induced pluripotent stem cell (iPSC)-derived microglia. This work characterizes the extracellular signaling molecules released by microglia which potentiate neurotoxicity and may serve as biomarkers of cognitive disorders. Identifying the intracellular mechanism through which Pb alters these signaling molecules released by microglia would greatly benefit the goals of MEMCARE, which aims to evaluate how early-life exposure to metals contributes to cognitive decline. I propose to leverage a K.C. Donnelly Externship hosted in the lab of Dr. Chris Chang of the Toxic Substances in the Environment Superfund Research Program at University of California Berkeley to investigate how Pb exposure modifies microglia signaling molecules using a novel chemical-biology based approach. We hypothesize that Pb exposure increases cellular stress in iPSC-derived microglia culture. I will be trained to apply an activity-based sensing (ABS) and labeling assay to visualize and quantify two molecular markers of cellular stress in iPSC-derived microglia exposed to Pb. iPSCs will be differentiated into a stable microglia precursor in my home lab then shipped to Berkeley using an established protocol. Precursor microglia will be developed into fully matured microglia and subsequently exposed to Pb. ABS and labeling will fluorescently tag two markers of cellular stress, hydrogen peroxide and malondialdehyde, using probes developed by the Chang lab. Confocal microscopy and flow cytometry will detect and quantify these markers, respectively. Completion of this project will reveal if Pb induced cellular stress is the modifying mechanism of microglia signaling molecule release, narrowing down molecular targets for therapies aimed to prevent microglia-mediated neurotoxicity. Further, I will be trained in the use of ABS and will integrate this innovative chemical sensor with a powerful, relevant model of microglia cell function to the benefit of both Superfund centers.