Altered brain global translation in TDP-43 transgenic mice: evidence from polysome profiling and SUNSET method

SANTIAGO CHARIF; MARÍA COTARELO; LUCIANA LUCHELLI; ALEJANDRO COLMAN-LERNER; MATÍAS BLAUSTEIN; LIONEL MULLER IGAZ

Córdoba

Congreso; XXXIII Reunión Anual de la Sociedad Argentina de Investigación en Neurociencias; 2018

SAN

TDP-43 is a RNA-binding protein that participates in a plethora of functions, including mRNA metabolism, and it is a major component of inclusions observed in neurodegenerative diseases like frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). We aimed to deepen our understanding about the role of TDP-43 in the regulation of mRNA translation and protein metabolism, using two complementary approaches. To assess if TDP-43 regulates active translation we performed subcellular fractionation of brain cortex by sucrose gradient centrifugation. The polysome profile of hTDP-43-expressing brains was significantly altered by a shift towards light fractions as compared to wild-type littermates, indicated a decrease in global mRNA translation. In brain slices, application of SUNSET method (which assesses ongoing translation by antibody detection of incorporated puromycin into newly synthetized proteins) indicating that hTDP-43 overexpression leads to decreased puromycin labeling. No puromycin-positive cells were observed in vehicle-incubated slices. Together, these results suggest that manipulating TDP-43 levels lead to changes in global translation and that the cytotoxic effects observed in FTD/ ALS might be related to alterations in proteostasis by TDP-43. We are currently evaluating if TDP-43 regulates the unfolded protein response, a process that modifies global protein synthesis. These findings will contribute to understand the etiology of TDP-43 proteinopathies.