1. Chemoproteomic profiling reveals that cathepsin D off-target activity drives ocular toxicity of β-secretase inhibitors.
- Author
-
Zuhl AM, Nolan CE, Brodney MA, Niessen S, Atchison K, Houle C, Karanian DA, Ambroise C, Brulet JW, Beck EM, Doran SD, O'Neill BT, Am Ende CW, Chang C, Geoghegan KF, West GM, Judkins JC, Hou X, Riddell DR, and Johnson DS
- Subjects
- Amyloid Precursor Protein Secretases metabolism, Animals, Cell Line, Enzyme Inhibitors chemistry, Enzyme Inhibitors pharmacology, Eye drug effects, Humans, Inhibitory Concentration 50, Mass Spectrometry, Mice, Knockout, Molecular Probes chemical synthesis, Molecular Probes chemistry, Peptides metabolism, Protein Binding, Rats, Wistar, Retinal Pigment Epithelium drug effects, Retinal Pigment Epithelium pathology, Staining and Labeling, Amyloid Precursor Protein Secretases antagonists & inhibitors, Cathepsin D metabolism, Enzyme Inhibitors toxicity, Eye pathology, Proteomics methods, Toxicity Tests
- Abstract
Inhibition of β-secretase BACE1 is considered one of the most promising approaches for treating Alzheimer's disease. Several structurally distinct BACE1 inhibitors have been withdrawn from development after inducing ocular toxicity in animal models, but the target mediating this toxicity has not been identified. Here we use a clickable photoaffinity probe to identify cathepsin D (CatD) as a principal off-target of BACE1 inhibitors in human cells. We find that several BACE1 inhibitors blocked CatD activity in cells with much greater potency than that displayed in cell-free assays with purified protein. Through a series of exploratory toxicology studies, we show that quantifying CatD target engagement in cells with the probe is predictive of ocular toxicity in vivo. Taken together, our findings designate off-target inhibition of CatD as a principal driver of ocular toxicity for BACE1 inhibitors and more generally underscore the power of chemical proteomics for discerning mechanisms of drug action.
- Published
- 2016
- Full Text
- View/download PDF