CONICET | Buscador de Institutos y Recursos Humanos

TDP-43 is a major component of cytoplasmic inclusions observed in neurodegenerative diseases like frontotemporal dementia (FTD)and amyotrophic lateral sclerosis (ALS). To further understand the role of TDP-43 in mRNA/protein metabolism and proteostasis,we used a combined approach with cellular and animal models overexpressing a cytoplasmic form of human TDP‐43 (TDP‐43‐ΔNLS),recapitulating ALS/FTD features. We applied in HEK293 cells a method for labeling de novo translation, surface sensing oftranslation (SUnSET), based on puromycin (PURO) incorporation. While control cells displayed robust puromycilation, TDP‐43‐NLStransfected cells exhibited reduced ongoing protein synthesis. Next, by using a transgenic mouse overexpressing cytoplasmicTDP‐43 in the forebrain (TDP‐43‐ΔNLS mice) we assessed whether cytoplasmic TDP‐43 regulates global translation in vivo. Polysomeprofiling of brain cortices from transgenic mice showed a shift towards non-polysomal fractions as compared to wild-typelittermates, indicating a decrease in global translation. Lastly, cellular level translational assessment by SUNSET was performed inTDP‐43‐ΔNLS mice brain slices. Control mice slices incubated with PURO exhibited robust cytoplasmic PURO signal in layer 5 neuronsfrom motor cortex, and normal nuclear TDP‐43 staining. Neurons in TDP‐43‐NLS mice slices incubated with PURO exhibited highcytoplasmic expression of TDP-43 and reduced puromycilation respect to control mice. These in vitro and in vivo results indicatethat cytoplasmic TDP-43 decreases global translation and potentially cause functional/cytotoxic effects as observed in ALS/FTD. Ourstudy provide in vivo evidence (by two independent and complementary methods) for a role of mislocalized TDP-43 in theregulation of global mRNA translation, with implications for TDP-43 proteinopathies.

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