Progressive Supranuclear Palsy PERK Haplotype B Selectively Translates DLX1 Promoting Tau Toxicity.

The unfolded protein response (UPR) sensor PERK exists in haplotypes A and B. PERK-B confers increased risk for tauopathies like progressive supranuclear palsy (PSP), but the mechanisms distinguishing its function from PERK-A and contributing to its association with tauopathy remain unknown. Here, we developed a controlled cellular model for a pair-wise comparison of the two PERK haplotypes, finding their UPR functions nearly indistinguishable. Puromycin-based proteomics highlighted a subset of mRNA translation events that was permissible under the PERK-B-dependent, but not the PERK-A-dependent, UPR. One of the targets that escaped PERK-B suppression was the transcription factor DLX1, which is genetically linked to PSP risk. We found that DLX1 solubility shifted to a detergent-insoluble fraction in the human brain tissue from male and female PSP donors. Furthermore, silencing the fly homolog of DLX1 was sufficient to decrease tau-induced toxicity in vivo. Our results detail the haplotype-specific PERK-B/DLX-1 pathway as a novel driver of tau pathology in cells, flies, and likely the human brain, revealing new insights into PSP pathogenesis and potential therapeutic targets.