An Enzymatic TMPRSS2 Assay for Assessment of Clinical Candidates and Discovery of Inhibitors as Potential Treatment of COVID-19.

ABSTRACT: SARS-CoV-2 is the viral pathogen causing the COVID19 global pandemic. Consequently, much research has gone into the development of pre-clinical assays for the discovery of new or repurposing of FDA-approved therapies. Preventing viral entry into a host cell would be an effective antiviral strategy. One mechanism for SARS-CoV-2 entry occurs when the spike protein on the surface of SARS-CoV-2 binds to an ACE2 receptor followed by cleavage at two cut sites ('priming') that causes a conformational change allowing for viral and host membrane fusion. This fusion event is proceeded by release of viral RNA within the host cell. TMPRSS2 has an extracellular protease domain capable of cleaving the spike protein to initiate membrane fusion. Additionally, knock-out studies in mice have demonstrated reduced infection in the absence of TMPRSS2 with no detectable physiological impact; thus, TMPRSS2 is an attractive target for therapeutic development. A validated inhibitor of TMPRSS2 protease activity would be a valuable tool for studying the impact TMPRSS2 has in viral entry and potentially be an effective antiviral therapeutic. To enable inhibitor discovery and profiling of FDA-approved therapeutics, we describe an assay for the biochemical screening of recombinant TMPRSS2 suitable for high throughput application. We demonstrate effectiveness to quantify inhibition down to subnanomolar concentrations by assessing the inhibition of camostat, nafamostat and gabexate, clinically approved agents in Japan for pancreatitis due to their inhibition of trypsin-like proteases. Nafamostat and camostat are currently in clinical trials against COVID19. The rank order potency for the three inhibitors is: nafamostat (IC50 = 0.27 nM), camostat (IC50 = 6.2 nM) and gabexate (IC50 = 130 nM). Further profiling of these three inhibitors against a panel of proteases provides insight into selectivity and potency.

SUBMITTER: Shrimp JH 

PROVIDER: S-EPMC7315994 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature