Affinity purification mass-spectrometry of tau pT217 implicates the CTLH E3 ubiquitin ligase as an early interactor — The Association Specialists
  1. Schedule
  2. Data Blitz Presentations: Imaging Neurodegeneration
  3. Affinity purification mass-spectrometry of tau pT217 implicates the CTLH E3 ubiquitin ligase as an early interactor

Affinity purification mass-spectrometry of tau pT217 implicates the CTLH E3 ubiquitin ligase as an early interactor (22061)

Tomas Kavanagh 1 , Manon Thierry 2 3 , Kaleah Balcomb 1 , Jackeline Ponce 4 , Glenda Halliday 1 , Beatrix Ueberheide 4 , Thomas Wisniewski 2 3 5 6 , Eleanor Drummond 1
  1. Brain and Mind Centre, School of Medical Science, The University of Sydney, Sydney, NSW, Australia
  2. Center for Cognitive Neurology, Grossman School of Medicine, New York University, New York, NY, USA
  3. Department of Neurology, Grossman School of Medicine, New York University, New York, NY, USA
  4. Proteomics Laboratory, Division of Advanced Research Technologies and Department of Biochemistry and Molecular Pharmacology, Grossman School of Medicine, New York University, New York, NY, USA
  5. Department of Pathology, Grossman School of Medicine, New York University, New York, NY, USA
  6. Department of Psychiatry, Grossman School of Medicine, New York University, New York, NY, USA

Hyperphosphorylation of tau at threonine 217 (pT217) and threonine 231 (pT231) are proving to be excellent early biomarkers of Alzheimer’s disease. However, it is not known how dysregulation of phosphorylation at these residues alters the role of tau in disease. Here we performed affinity purification mass spectrometry of two tau phosphorylated residues (pT217 and pT231) to determine how specific phosphorylation of tau alters its interactome in Alzheimer’s disease post-mortem brain tissue (n=10). pT217 affinity purification mass spectrometry identified 23 interacting proteins (SAINT score > 0.65). pT217 enriched tau had a unique phosphorylation signature compared to PHF1 but shared significant overlap (Thierry et al., 2024, 15 interactors shared, Fisher’s exact p=2.3x10-14), suggesting pT217 tau was an earlier state of dysregulation but had similar interactomes. pT217 interacting proteins enriched for biological processes involved in protein catabolic process, most notably with the CTLH E3 ubiquitin ligase complex (5 interacting subunits: WDR26, ARMC8, GID8, RANBP9, MAEA). We validated the interaction between tau, p62 and the CTLH component WDR26 with co-immunoprecipitation (n=3 AD, n=3 CTRL, n=1 CBD, PiD and PSP) and immunofluorescent microscopy of fixed post-mortem brain tissue (n=3 AD, n=3 Control) in independent cohorts. These interactions were confirmed in both experiments and showed predominant interaction between tau and p62 and WDR26 in select types of tau aggregates. In conclusion, our results highlight the CTLH complex as an early interactor of tau in Alzheimer’s disease that future studies can explore and potentially exploit to create early interventions for disease processes.