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

ABSTRACT: ?-Secretase is a multi-subunit enzyme whose aberrant activity is associated with Alzheimer's disease and cancer. While its structure is atomically resolved, ?-secretase localization in the membrane in situ relies mostly on biochemical data. Here, we combined fluorescent tagging of ?-secretase subunits with super-resolution microscopy in fibroblasts. Structured illumination microscopy revealed single ?-secretase complexes with a monodisperse distribution and in a 1:1 stoichiometry of PSEN1 and nicastrin subunits. In living cells, sptPALM revealed PSEN1/?-secretase mainly with directed motility and frequenting 'hotspots' or high track-density areas that are sensitive to ?-secretase inhibitors. We visualized ?-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/?-secretase transiently visits ADAM10 hotspots. Our results highlight the power of super-resolution microscopy for the study of ?-secretase distribution and dynamics in the membrane.

SUBMITTER: Escamilla-Ayala AA 

PROVIDER: S-EPMC7340497 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature