The mitophagy receptor NIX induces vIRF-1 oligomerization and interaction with GABARAPL1 for the promotion of HHV-8 reactivation-induced mitophagy

• Published in: PLoS pathogens 2023-07, Vol.19 (7), p.e1011548-e1011548
• Main Authors: Vo, Mai Tram, Choi, Chang-Yong, Choi, Young Bong
• Format: Article
• Language: English
• Subjects: Adaptor Proteins, Signal Transducing - genetics; Adaptor Proteins, Signal Transducing - metabolism; Antibodies; Apoptosis; Autophagy; Autophagy (Cytology); Biology and Life Sciences; Cell death; Cell receptors; Cytoplasm; Development and progression; Genetic aspects; Herpes; Herpes viruses; Herpesvirus 8, Human - physiology; Herpesvirus diseases; Human herpesvirus 8; Humans; Immune response; Infections; Innate immunity; Interferon regulatory factor; Interferon regulatory factor 1; Interferon Regulatory Factors - metabolism; Kaposi's sarcoma; Localization; Membrane Proteins - metabolism; Microtubule-Associated Proteins - metabolism; Mitochondria; Mitophagy; Mitophagy - physiology; Molecular modelling; Oligomerization; Physiological aspects; Protein-protein interactions; Proteins; Receptors; Replication; Research and Analysis Methods; Sarcoma; Transcription factors; Viral Proteins - genetics; Viral Proteins - metabolism; Virus research; Viruses
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1011548

Recently, viruses have been shown to regulate selective autophagy for productive infections. For instance, human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV), activates selective autophagy of mitochondria, termed mitophagy, thereby inhibiting antiviral innate immune responses during lytic infection in host cells. We previously demonstrated that HHV-8 viral interferon regulatory factor 1 (vIRF-1) plays a crucial role in lytic replication-activated mitophagy by interacting with cellular mitophagic proteins, including NIX and TUFM. However, the precise molecular mechanisms by which these interactions lead to mitophagy activation remain to be determined. Here, we show that vIRF-1 binds directly to mammalian autophagy-related gene 8 (ATG8) proteins, preferentially GABARAPL1 in infected cells, in an LC3-interacting region (LIR)-independent manner. Accordingly, we identified key residues in vIRF-1 and GABARAPL1 required for mutual interaction and demonstrated that the interaction is essential for mitophagy activation and HHV-8 productive replication. Interestingly, the mitophagy receptor NIX promotes vIRF-1-GABARAPL1 interaction, and NIX/vIRF-1-induced mitophagy is significantly inhibited in GABARAPL1-deficient cells. Moreover, a vIRF-1 variant defective in GABARAPL1 binding substantially loses the ability to induce vIRF-1/NIX-induced mitophagy. These results suggest that NIX supports vIRF-1 activity as a mitophagy mediator. In addition, we found that NIX promotes vIRF-1 aggregation and stabilizes aggregated vIRF-1. Together, these findings indicate that vIRF-1 plays a role as a viral mitophagy mediator that can be activated by a cellular mitophagy receptor.