Chemical biology on PINs and NeeDLes

TOXI 141

Stephen W. Michnick, stephen.michnick@umontreal.ca, biochimie, Université de Montréal, CP 6128, Succ. Centre-ville, Montréal, QC H3C 3J7, Canada
The organization of the biochemical networks of living cell can be defined by studying the dynamics of protein-protein interaction. Here we describe recent conceptual and experimental advances that can achieve this aim. We show how chemical perturbations of interactions can be used to identify off-target effects and hidden phenotypes of drugs by directly probing biochemical pathways that underlie therapeutic or toxic mechanisms in intact, living cells. We use protein-fragment complementation assays (PCAs) to measure spatial and temporal changes in protein complexes in response to drugs that activate or inhibit particular pathways. This strategy reproduced known structure-function relationships, and also predicted ‘hidden', potent antiproliferative activities for four drugs with novel mechanisms of action, including disruption of mitochondrial membrane potential. A simple algorithm identifies highly predictive assay panels and suggests a strategy for therapeutic discovery that identifies novel, unpredicted mechanisms of drug action and potential toxicity.