The effect of pH alterations on TDP-43 in a cellular model of amyotrophic lateral sclerosis

Abstract

Amyotrophic Lateral Sclerosis (ALS) is the most common neurodegenerative disease affecting motor neurons. The pathophysiology of ALS is not well understood but TDP-43 proteinopathy (aggregation and mislocalization) is one of the major phenomena described. Several factors can influence TDP-43 behavior such as mild pH alterations that can induce conformational changes in recombinant TDP-43, increasing its propensity to aggregate. However to our knowledge, no studies have been conducted yet in a cellular setting, in the context of ALS. We therefore tested the effect of cellular pH alterations on the localization and aggregation of TDP-43. HEK293T cells overexpressing wildtype TDP-43 were incubated for 1h with solutions of different pH (6.4, 7.2, and 8). Incubation of cells for 1h in solutions of pH 6.4 and 8 led to an increase in TDP-43-positive puncta, an effect that was lost after 2h of incubation. This was accompanied by the mislocalization of TDP-43 from the nucleus to the cytoplasm. Our resulats suggest that small alterations in cellular pH affect TDP-43 and increase its mislocalization into cytoplasmic TDP-43-positive puncta, which might suggest a role of TDP-43 in the response of cells to pH alterations.