Small ubiquitin-like modifiers (SUMO) have been implicated in several neurodegenerative diseases. SUMO1 conjugation has been shown to promote aggregation and regulate phosphorylation of the tau protein linked to Alzheimer‘s disease and related tauopathies. The current study has demonstrated that SUMO1 colocalizes with intraneuronal tau inclusions in progressive supranuclear palsy (PSP). To examine the effects of SUMOylation on the tau based pathology of PSP, several tau-SUMO fusion proteins were prepared. As the results, truncated tau especially showed a higher propensity for tau oligomerization and accumulation on microtubules as compared to the full-length protein. In addition, tau-SUMO1 fusion protein
showed the greater effect than SUMO2 fusion protein. PSP may represent a detrimental event that promotes aggregation and impedes the ability of cells to remove the resulting protein deposits. This combination of tau truncation and SUMO1 modification may be a contributing factor in PSP pathogenesis.