RNA-binding proteins TDP-43 and FUS promote R-loop resolution and regulate transcription termination

TDP-43 and FUS are RNA-binding proteins involved in the regulation of diverse RNA-processing events and have been strongly implicated in neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). We have previously demonstrated the role of symmetrical dimethylation (me2s) of a conserved arginine residue (R1810 in human POLR2A) in the C-terminal domain (CTD) of RNA polymerase II (RNAPII), which facilitates the recruitment of the Tudor domain-containing protein SMN to resolve R-loops at transcriptional termination sites. Here, we demonstrate that TDP-43 and FUS contribute to transcription termination through the R1810me2s-SMN pathway. Our data show that TDP-43-and to a lesser extent, FUS-are recruited to chromatin via this pathway, and that disruption of their recruitment leads to defective RNAPII termination. This impairment results in the accumulation of R-loops and elevated DNA damage to gene terminators. Using transcriptome-wide analyses, we further show that TDP-43 RNA-binding sites are highly correlated with regions of R-loop formation. Importantly, we find that the RNA-binding activity of TDP-43 is essential for its role in resolving R-loops and promoting efficient transcription termination. These findings establish a mechanistic link between TDP-43/FUS, R-loop resolution, and transcription termination, providing new insights into how their dysfunction may drive genome instability and contribute to the pathogenesis of ALS and FTD.