USP20 Promotes Cellular Antiviral Responses via Deconjugating K48-Linked Ubiquitination of MITA

Area of Science:

• Immunology
• Molecular Biology
• Virology

Background:

• Mediator of IRF3 activation (MITA), also known as STING, is a critical sensor for cyclic dinucleotides and cytoplasmic DNA-triggered innate immune signaling.
• The activity of MITA is tightly regulated by ubiquitination and deubiquitination processes.

Purpose of the Study:

• To investigate the role of USP20 in the regulation of MITA stability and function during innate immune responses.
• To elucidate the mechanism by which USP20 influences cellular antiviral activity, particularly against HSV-1.

Main Methods:

• Interaction studies to determine USP20's association with MITA.
• Analysis of ubiquitination status of MITA in the presence or absence of USP20.
• Assessment of MITA stability, IRF3 and IκBα phosphorylation, and cytokine induction in USP20-deficient cells and mice.
• Viral infection models (HSV-1) and cytoplasmic DNA challenge assays.

Main Results:

• USP20 interacts with MITA and removes K48-linked ubiquitin chains, thereby stabilizing MITA.
• Deletion of USP20 leads to accelerated degradation of MITA, impaired IRF3 and IκBα phosphorylation, and reduced induction of type I IFNs and proinflammatory cytokines.
• Usp20-deficient mice exhibit increased susceptibility to HSV-1 infection, aggravated viral replication, and diminished cytokine production.

Conclusions:

• USP20 plays a critical role in maintaining MITA stability through deubiquitination.
• USP20 is essential for promoting robust innate antiviral signaling and cellular defense against HSV-1.
• Targeting USP20 could be a potential strategy for enhancing antiviral immunity.