The deubiquitinase OTULIN regulates tau expression in neurons

Degradation of aggregation-prone tau is regulated by the ubiquitin-proteasome system (UPS) and autophagy, which are impaired in Alzheimer’s disease (AD) and related tauopathies causing tau aggregation. Protein ubiquitination with linkage specificity determines the fate of proteins that can be either degradative or stabilization signals. While the linear M1-linked ubiquitination on protein aggregates is a signaling hub that recruits various ubiquitin-binding proteins for coordinated actions of protein aggregates turnover and inflammatory NF-kB activation, the deubiquitinase OTULIN counteracts with the M1-linked ubiquitin signaling. However, the exact role of OTULIN on tau aggregate clearance in AD is unknown. We did bulk RNA sequencing in wild-type and OTULIN knockout (by CRISPR-Cas9) SH-SY5Y human neuroblastoma cells. Our results showed a 14.39-fold down-regulation of tau mRNA levels and differential expression of many other genes associated with autophagy, the ubiquitin-proteasome system (UPS), NF-kB pathway, and RNA metabolism. Together, our results suggest for the first time a non-canonical function for OTULIN in regulating gene expression and RNA metabolism, which may have a significant pathogenic role in AD and related tauopathies.