Endogenous TDP-43 prevents retrotransposons activation through Dicer-2 activity and the RNA silencing machinery in Drosophila

The aberrant expression of retrotransposable elements (RTEs) was observed in different neurodegenerative diseases including amyotrophic lateral sclerosis (ALS), a terminal disorder characterized by functional alterations in the small RNA-binding protein TDP-43, suggesting that these events might be connected. Using genome wide gene expression profiles, we detected RTEs highly upregulated in TDP-43-null Drosophila heads while, the genetic rescue of TDP-43 function reverted these modifications. Furthermore, we found that TDP-43 modulates the small interfering RNA (siRNA) silencing machinery responsible for RTEs repression. Molecularly, we observed that TDP-43 regulates the expression levels of Dicer-2 by direct protein-mRNA interactions in vivo. Accordingly, the genetic or pharmacological recovery of Dicer-2 activity was sufficient to repress retrotransposons activation and revert the neurodegeneration in TDP-43-null Drosophila motoneurons. Our results, describe a novel physiological role of endogenous TDP-43 in the prevention of RTEs-induced neurodegeneration through the modulation of Dicer-2 activity and the siRNA pathway.