SARS-CoV-2 and oncolytic EV-D68-encoded proteases differentially regulate pyroptosis

Area of Science:

• Molecular Biology
• Virology
• Immunology

Background:

• Pyroptosis, a pro-inflammatory programmed cell death, is implicated in viral pathogenesis, including coronavirus disease 2019 (COVID-19).
• Gasdermin family proteins (GSDMs), specifically GSDMD and GSDME, are critical effectors of pyroptosis.
• Mechanisms by which viruses modulate pyroptosis remain incompletely understood.

Purpose of the Study:

• To screen viral proteins for their ability to interfere with GSDMD localization and function.
• To elucidate how SARS-CoV-2 and EV-D68 proteases modulate GSDM-mediated pyroptosis.
• To investigate the potential oncolytic effects of EV-D68 infection.

Main Methods:

• Utilized a mCherry-GSDMD fluorescent reporter assay for high-throughput screening in living cells.
• Investigated the cleavage sites and functional consequences of SARS-CoV-2 proteases (NSP5, NSP3) on GSDMD and GSDME.
• Examined the effects of EV-D68 proteases (3C, 2A) on GSDMD and GSDME function and pyroptosis induction.

Main Results:

• SARS-CoV-2 main protease NSP5 inhibited GSDMD-mediated pyroptosis by cleaving GSDMD at Q29 and Q193.
• SARS-CoV-2 protease NSP3 activated GSDME-mediated pyroptosis by cleaving GSDME at G370.
• EV-D68 proteases 3C and 2A inactivated GSDMD while initiating GSDME-mediated pyroptosis, similar to SARS-CoV-2 proteases.
• EV-D68 infection induced pyroptotic cell death and exhibited oncolytic effects on human cancer cells.

Conclusions:

• Respiratory viruses, including SARS-CoV-2 and EV-D68, possess distinct proteases that differentially regulate host cell pyroptosis.
• Viral manipulation of GSDMD and GSDME pathways offers insights into viral pathogenesis and host immune responses.
• The findings suggest potential therapeutic targets for antiviral strategies and cancer treatment, particularly leveraging EV-D68's oncolytic properties.