TDP-43 overexpression affects global brain global translation

ALEJANDRO COLMAN-LERNER; SANTIAGO CHARIF; MATÍAS BLAUSTEIN; ANTONELLA VILA; LIONEL MULLER IGAZ

Congreso; Reunión Anual de la Sociedad Argentina de Investigación en Neurociencias; 2019

TDP-43 is an RNA-binding protein that, amongst other functions, participates in mRNA metabolism, and it is a major component of inclusions observed in neurodegenerative diseases like frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Previous results from our lab showed a decrease in global mRNA translation as compared to wild-type animals, revealed by polysome profiling of brain cortex from hTDP-43 expressing mice. To further understand the role of TDP-43 in mRNA and protein metabolism, we used a combined approach with animal and cellular models. Application of SUNSET method (which assesses ongoing translation) in brain slices from control and hTDP-43-ΔNLS expressing mice revealed a decrease in puromycin incorporation in brain cortex cells of ΔNLS mice when compared to control animals. Complementary immunoblot analysis corroborates that puromycin is actively incorporated during translation of new proteins. The Unfolded Protein Response (UPR) is a major cellular process that also regulates translation. To assess in vitro how TDP-43 modulates the UPR, HEK293 cells were transfected with TDP-43 variants and treated with vehicle or ER stress inducers. We are currently analyzing ATF4 and ATF6 pathways; preliminary data corroborate that MG132 induces ATF6 cleavage and ATF4 protein levels. These results suggest that dysregulation of TDP-43 might alter global translation and that cytotoxic effects in FTD/ALS might be due to alterations in proteostasis by TDP-43.