Progressive Supranuclear Palsy PERK haplotype B selectively translates DLX1 promoting tau toxicity

The unfolded protein response 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. However, a careful examination employing puromycin-based proteomics revealed that a subset of mRNA translation events were permissible under PERK-B, but not 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 in human PSP brain tissue. 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 human brain, revealing new insights into PSP pathogenesis and potential therapeutic targets.