title: An exo-cell assay for examining real-time gamma-secretase activity and inhibition.
abstract: gamma-Secretase is an aspartyl protease that cleaves multiple substrates that are involved in broad biological processes ranging from stem cell development to neurodegeneration. The investigation of gamma-secretase has been limited by currently available assays that require genetic or biochemical manipulation in the form of substrate transfection or membrane preparation. Here we report an exo-cell assay that is capable of characterizing gamma-secretase activity in any cellular system without limitation. Using a highly active, recombinant substrate this assay can quickly and easily ascertain the status of gamma-secretase activity in cell systems and patient samples. We have applied this method to determine the activity of gamma-secretase in primary cell samples where transfection and/or membrane isolation are not viable options. Importantly, it allows for the detection of real time gamma-secretase activity after inhibitor or drug treatment. The application of this assay to determine the role of gamma-secretase in physiological and pathological conditions will greatly facilitate our characterization of this complex protease and help in the development and evaluation of gamma-secretase-targeted therapies in Alzheimer's disease or a variety of neoplasms.
authors.affiliation: Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA. liy2@mskcc.org.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Shelton
authors.forename: Yuan
authors.initials: Y
authors.lastname: Tian
authors.forename: Mark G
authors.initials: MG
authors.lastname: Frattini
authors.forename: Yue-Ming
authors.initials: YM
authors.lastname: Li