Benchmarking a highly selective USP30 inhibitor for enhancement of mitophagy and pexophagy.

Abstract

The deubiquitylase USP30 is an actionable target considered for treatment of conditions associated with defects in the PINK1/Parkin pathway leading to mitophagy. These include Parkinsons disease and pulmonary fibrosis. We provide a detailed cell biological characterisation of a benzenesulphonamide molecule, compound 39, that has previously been reported to inhibit USP30 in an in vitro enzymatic assay. The current compound offers increased selectivity over previously described inhibitors. It enhances mitophagy and generates a signature response for USP30 inhibition following mitochondrial depolarisation. This includes enhancement of TOM20 and SYNJ2BP ubiquitylation and phosphoubiquitin accumulation, alongside increased mitophagy. In dopaminergic neurons, generated from Parkinsons disease patients carrying loss of function Parkin mutations, compound 39 could significantly restore mitophagy to a level approaching control values. USP30 is located on both mitochondria and peroxisomes and has also been linked to the PINK1 independent pexophagy pathway. Using a fluorescence reporter of pexophagy expressed in U20S cells, we observe increased pexophagy upon application of compound 39 that recapitulates the previously described effect for USP30 depletion. This provides the first pharmacological intervention with a synthetic molecule to enhance peroxisome turnover.