Super-resolution microscopy reveals majorly mono- and dimeric presenilin1/γ-secretase at the cell surface

Elife. 2020 Jul 7;9:e56679. doi: 10.7554/eLife.56679.

Abstract

γ-Secretase is a multi-subunit enzyme whose aberrant activity is associated with Alzheimer's disease and cancer. While its structure is atomically resolved, γ-secretase localization in the membrane in situ relies mostly on biochemical data. Here, we combined fluorescent tagging of γ-secretase subunits with super-resolution microscopy in fibroblasts. Structured illumination microscopy revealed single γ-secretase complexes with a monodisperse distribution and in a 1:1 stoichiometry of PSEN1 and nicastrin subunits. In living cells, sptPALM revealed PSEN1/γ-secretase mainly with directed motility and frequenting 'hotspots' or high track-density areas that are sensitive to γ-secretase inhibitors. We visualized γ-secretase association with substrates like amyloid precursor protein and N-cadherin, but not with its sheddases ADAM10 or BACE1 at the cell surface, arguing against pre-formed megadalton complexes. Nonetheless, in living cells PSEN1/γ-secretase transiently visits ADAM10 hotspots. Our results highlight the power of super-resolution microscopy for the study of γ-secretase distribution and dynamics in the membrane.

Keywords: Alzheimer's disease; cell biology; gamma-secretase; human; mouse; presenilin1; single-particle tracking; super-resolution microscopy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyloid Precursor Protein Secretases / genetics*
  • Amyloid Precursor Protein Secretases / metabolism
  • Animals
  • Cell Line
  • Cell Membrane / metabolism
  • Fibroblasts
  • Humans
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Mice
  • Microscopy
  • Presenilin-1 / genetics*
  • Presenilin-1 / metabolism

Substances

  • Membrane Proteins
  • PSEN1 protein, human
  • PSENEN protein, human
  • Presenilin-1
  • presenilin 1, mouse
  • Amyloid Precursor Protein Secretases