Harnessing the Noncanonical Keap1-Nrf2 Pathway for Human Cytomegalovirus Control

Area of Science:

• Virology and Molecular Biology
• Cellular Signaling Pathways
• Drug Discovery

Background:

• Host cellular pathways can impede virus replication, presenting therapeutic targets for herpesviruses like human cytomegalovirus (HCMV).
• Existing antiviral treatments for HCMV are limited and prone to resistance development.
• The autophagy receptor sequestosome 1 (SQSTM1)/p62 is known to interact with HCMV proteins, suggesting a role in viral replication.

Purpose of the Study:

• To investigate the role of the sequestosome 1 (SQSTM1)/p62 pathway in human cytomegalovirus (HCMV) suppression.
• To elucidate the mechanism by which the compound ARP101 inhibits HCMV replication.
• To explore the potential of the Keap1-Nrf2 axis as a novel antiviral strategy.

Main Methods:

• Treatment of HCMV-infected cells with the small-molecule probe ARP101.
• Analysis of protein levels (LC3 II, SQSTM1/p62) and phosphorylation.
• Assessment of Nrf2 stabilization, nuclear translocation, and binding to antioxidant response elements (ARE).
• HCMV replication assays and Nrf2 knockdown experiments.

Main Results:

• ARP101 treatment increased LC3 II and SQSTM1/p62 levels and induced SQSTM1/p62 phosphorylation, enhancing its affinity for Keap1.
• ARP101 treatment led to Nrf2 stabilization, nuclear translocation, and subsequent transcription of antioxidant enzymes, resulting in HCMV suppression.
• Nrf2 knockdown restored HCMV replication, confirming the Keap1-Nrf2 axis's role in ARP101-mediated HCMV inhibition.

Conclusions:

• ARP101 activates a noncanonical Keap1-Nrf2 pathway via SQSTM1/p62 phosphorylation, leading to HCMV inhibition.
• This study uncovers a novel role for SQSTM1/p62 in HCMV suppression and identifies the Keap1-Nrf2 axis as a potential antiviral target.
• Further research into the kinases involved and the biological events of this pathway could lead to new antiviral interventions for HCMV.