Research article

An exo-cell assay for examining real-time γ-secretase activity and inhibition

Christopher C Shelton^1,3 , Yuan Tian^1,4 , Mark G Frattini² and Yue-Ming Li^1,3

¹  Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA

²  Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA

³  Department of Pharmacology, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10021, USA

⁴  Department of Physiology, Biophysics and Systems Biology, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10021, USA

author email corresponding author email

Molecular Neurodegeneration 2009, 4:22doi:10.1186/1750-1326-4-22

Published:	2 June 2009

Abstract

γ-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 γ-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 γ-secretase activity in any cellular system without limitation. Using a highly active, recombinant substrate this assay can quickly and easily ascertain the status of γ-secretase activity in cell systems and patient samples. We have applied this method to determine the activity of γ-secretase in primary cell samples where transfection and/or membrane isolation are not viable options. Importantly, it allows for the detection of real time γ-secretase activity after inhibitor or drug treatment. The application of this assay to determine the role of γ-secretase in physiological and pathological conditions will greatly facilitate our characterization of this complex protease and help in the development and evaluation of γ-secretase-targeted therapies in Alzheimer's disease or a variety of neoplasms.