Microglia Polarize in Response to Transactive Response DNA-binding Protein-43 (TDP-43) and Display Partial Recovery After Removal of the Stimulus
Date of Completion
Biochemistry and Molecular Biology
Dr. David Donley
The proper response to protein signals is necessary for a healthy central nervous system (CNS), and protein dysregulation is a feature of neurodegenerative diseases. Transactive response DNA-binding protein-43 (TDP-43) is an intranuclear protein, but mislocalization is associated with amyotrophic lateral sclerosis (ALS). TDP-43 is released into the extracellular space where it is sensed by microglia, the CNS-resident immune cells. Our data and the literature suggest that microglia respond to TDP-43 dysregulation by increasing CNS inflammation. The goal of this study was to determine the impact of TDP-43 on microglial function and the extent to which microglia recovery. To study the inflammatory response, microglia were stimulated with TDP-43 in a 2x2 factorial design with other inflammatory stimuli. Using iNOS and arginase colorimetric assays, we found that TDP-43 caused microglia to lose the ability to appropriately respond to inflammation. To study recovery, cultured microglia were stimulated with TDP-43 or a vehicle; then the media was changed to remove the stimuli and allow a recovery period. Markers of activation were measured using flow cytometry and metabolic assays. After recovery, microglia had a slight decrease in phagocytic capability as compared to TDP-43 stimulation without recovery. Microglia also demonstrated a metabolic shift toward glycolysis, consistent with a proinflammatory phenotype but returned to baseline levels of metabolic activity after recovery. These data demonstrate that dysregulated TDP-43 shifts the balance of signaling pathways toward an inflammatory phenotype, but microglia begin to recover after removal of the inflammatory stimuli.
Wilcox, Alicen, "Microglia Polarize in Response to Transactive Response DNA-binding Protein-43 (TDP-43) and Display Partial Recovery After Removal of the Stimulus" (2021). Honors Theses. 4.