Investigation of Neuronal Manganese Regulation in Physiology and Disease Using High Throughput Screening, Induced Pluripotent Stem Cells, and Chemical Biology Approaches.

Abstract

Manganese (Mn) is both an essential biological cofactor and neurotoxicant. Disruption of Mn biology in the basal ganglia has been implicated in the pathogenesis of neurodegenerative disorders, such as parkinsonism and Huntington’s disease (HD). However, beyond several non-selective transporters, little is known about the intracellular processes regulating neuronal Mn homeostasis. We hypothesized that small molecules that modulate intracellular Mn could provide insight into cell-level Mn regulatory mechanisms. We performed a high throughput screen of 40,167 small molecules for modifiers of cellular Mn content. Utilizing the identified small molecules, we tested for differential regulation of Mn handling in human floor-plate lineage dopaminergic neurons, a lineage especially vulnerable to environmental Mn exposure. We report differential Mn accumulation between developmental stages and stage-specific differences in the Mn-altering activity of individual small molecules, demonstrating cell-level regulation of Mn content across neuronal differentiation. In a parallel study, we sought to reveal any cellular metabolic phenotypes influenced by Mn exposure and/or the mutant HD genotype using an unbiased metabolomics approach. Our analysis revealed metabolic evidence of an interaction between the HD genotype and environmentally relevant Mn exposures in a striatal neural lineage. The metabolic phenotypes detected support existing hypotheses that changes in energetic processes underlie the pathogenesis of both HD and Mn neurotoxicity.