The autophagy elongation complex (ATG5-12/16L1) positively regulates HCV replication and is required for wild-type...

Area of Science:

• Virology
• Cell Biology
• Autophagy Research

Background:

• Hepatitis C virus (HCV) infection triggers intracellular membrane rearrangements, forming a membranous web (MW) crucial for viral replication and assembly.
• The precise mechanisms and cellular components involved in HCV-induced MW formation, particularly the role of autophagy, remain incompletely understood.
• While autophagy machinery has been implicated, direct evidence linking specific autophagy proteins to the formation of double-membrane vesicles (DMVs) within the MW is lacking.

Purpose of the Study:

• To investigate the role of the autophagy elongation complex, specifically ATG5-12/16L1, in Hepatitis C virus (HCV) replication.
• To determine the involvement of the ATG5-12 conjugate and LC3 in the formation of the HCV-induced membranous web (MW).
• To elucidate the direct contribution of autophagy proteins to the characteristic structure of wild-type MWs.

Main Methods:

• Utilized a dominant-negative form of ATG12 and siRNA-mediated knockdown to inhibit the autophagy elongation complex.
• Assessed the impact of ATG5-12 inhibition on HCV replication efficiency.
• Purified HCV-induced membranous webs (MWs) and analyzed the co-localization of autophagy proteins (ATG5-12, ATG16L1, LC3) with HCV nonstructural proteins.

Main Results:

• The ATG5-12 conjugate, but not LC3-II formation, was found to be critical for efficient HCV replication.
• Purified HCV MWs contained ATG5-12 and ATG16L1, but LC3 was not recruited to the viral replication sites alongside the elongation complex.
• Inhibition of the autophagy elongation complex significantly impaired the formation of the wild-type MW phenotype, whereas LC3 inhibition had no such effect.

Conclusions:

• This study provides the first direct evidence implicating the autophagy elongation complex (ATG5-12/16L1) in the formation of Hepatitis C virus (HCV)-induced membranous webs (MWs).
• The ATG5-12 conjugate plays a crucial role in HCV replication and MW biogenesis, independent of LC3 recruitment.
• These findings highlight a specific function of autophagy machinery components in viral structural organization, distinct from canonical autophagic flux.