A cell-permeable tool for analysing APP intracellular domain function and manipulation of PIKfyve activity

Benjamin Guscott, Zita Balklava, Stephen T. Safrany, Thomas Wassmer*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The mechanisms for regulating PIKfyve complex activity are currently emerging. The PIKfyve complex, consisting of the phosphoinositide kinase PIKfyve (also known as FAB1), VAC14 and FIG4, is required for the production of phosphatidylinositol-3,5-bisphosphate (PI(3,5)P2). PIKfyve function is required for homeostasis of the endo/lysosomal system and is crucially implicated in neuronal function and integrity, as loss of function mutations in the PIKfyve complex lead to neurodegeneration in mouse models and human patients. Our recent work has shown that the intracellular domain of the Amyloid Precursor Protein (APP), a molecule central to the aetiology of Alzheimer's disease binds to VAC14 and enhances PIKfyve function. Here we utilise this recent advance to create an easy-to-use tool for increasing PIKfyve activity in cells. We fused APP's intracellular domain (AICD) to the HIV TAT domain, a cell permeable peptide allowing proteins to penetrate cells. The resultant TAT-AICD fusion protein is cell permeable and triggers an increase of PI(3,5)P2. Using the PI(3,5)P2 specific GFP-ML1Nx2 probe we show that cell-permeable AICD alters PI(3,5)P2 dynamics. TAT-AICD also provides partial protection from pharmacological inhibition of PIKfyve. All three lines of evidence show that the APP intracellular domain activates the PIKfyve complex in cells, a finding that is important for our understanding of the mechanism of neurodegeneration in Alzheimer's disease.
Original languageEnglish
Article numbere00319
JournalBioscience Reports
Issue number2
Early online date2 Mar 2016
Publication statusPublished - 15 Apr 2016

Bibliographical note

-© 2016 The Author(s). This is an open access article published by Portland Press Limited on behalf of the Biochemical Society and distributed under the Creative Commons Attribution Licence 4.0 (CC BY).

Funding: Alzheimer’s Research UK (ARUK-PhD-2012/13); and BBSRC (BBK014862/1).


  • Alzheimer's disease
  • FAB1
  • FIG4
  • Neurodegeneration
  • Phosphoinositide
  • VAC14
  • Vacuolar H-ATPase (V-ATPase)


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