α-Synuclein plasma membrane localization correlates with cellular phosphatidylinositol polyphosphate levels

We show that phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate, two highly acidic components of inner plasma membrane leaflets, mediate PM localization of endogenous pools of αSyn in A2780, HeLa, SK-MEL-2, and differentiated and undifferentiated neuronal SH-SY5Y cells

Reeba Susan Jacob; Cédric Eichmann; Alessandro Dema; Davide Mercadante; Philipp Selenko

2021

Scholarcy highlights

  • Aggregates of human a-synuclein constitute the main components of Lewy body inclusions in Parkinson’s disease and other synucleinopathies1. aSyn is expressed throughout the brain and abundantly found in presynaptic terminals of dopaminergic neurons, where it is involved in synaptic vesicle clustering and trafficking
  • plasma membrane localization of endogenous aSyn To determine the intracellular localization of aSyn, we selected a panel of human cell lines that expressed low but detectable amounts of the endogenous protein
  • Our results establish that clusters of endogenous aSyn are found at the plasma membrane of human A2780, HeLa, SH-SY5Y and SK-MEL-2 cells, where their native abundance correlates with PIP2 levels
  • We show that targeted overexpression of the PIP2-generating kinase PIPKIγ increases endogenous aSyn at the PM, whereas the PIP2-specific phosphatase INPP5E reduces the amount of PM aSyn
  • We further demonstrate that PIP3-dependent histamine and insulin signaling redistributes aSyn to the PM, which collectively suggests that changes in PM PIP2 and PIP3 levels affect intracellular aSyn localization in a dynamic and reversible manner
  • We cannot rule out that additional secondary protein-protein interactions contribute to PM targeting, we demonstrate that aSyn directly interacts with reconstituted PIP2 vesicles in vitro
  • Negative-Stain Electron Microscopy nuclear magnetic resonance samples of aSyn at 30- and 680-fold molar excess of PIP2 and PC-PIP2 lipids were diluted to a protein concentration of ~10 μM in NMR buffer

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