Promyelocytic Leukemia Restricts Enterovirus 71 Replication by Inhibiting Autophagy

Area of Science:

• Virology
• Cell Biology
• Immunology

Background:

• Promyelocytic leukemia (PML) protein (TRIM19) organizes nuclear bodies and exhibits antiviral properties against various viruses.
• Enterovirus 71 (EV71) is a significant human pathogen responsible for Hand, foot, and mouth disease.

Purpose of the Study:

• To investigate the role of PML protein in cellular defense against EV71 infection.
• To elucidate the mechanisms by which PML influences EV71 replication and viral pathogenesis.

Main Methods:

• Utilized HeLa cells and short interfering RNAs (siRNAs) to manipulate PML expression levels.
• Assessed viral protein expression (VP1) and viral titers post-EV71 infection.
• Investigated the involvement of autophagy and proteasome pathways in PML-mediated antiviral activity.
• Identified the viral protease responsible for PML degradation.

Main Results:

• PML downregulation increased HeLa cell susceptibility to EV71 infection.
• Overexpression of PML isoforms (PMLIII, PMLIV) inhibited viral protein expression and reduced viral titers.
• PML deficiency led to increased viral protein VP1 expression and viral production.
• PML repressed EV71 replication partly by inhibiting autophagy; PML deficiency triggered autophagy.
• EV71 infection reduced PML levels via viral protease 3Cpro, independent of the proteasome pathway.

Conclusions:

• PML protein confers cellular antiviral protection against EV71 by inhibiting autophagy.
• Viral protease 3Cpro disrupts PML-mediated antiviral activity by degrading PML protein.
• Understanding the PML-EV71 interaction provides insights into viral pathogenesis and potential therapeutic targets.