bims-nocaut Biomed News
on Non-canonical autophagy
Issue of 2023–08–20
two papers selected by
Quentin Frenger, University of Strasbourg
  1. Post-translational modifications of ATG8 proteins - an emerging mechanism of autophagy control.
  2. The autophagy machinery interacts with EBV capsids during viral envelope release.
  1. J Cell Sci. 2023 Aug 15. pii: jcs259725. [Epub ahead of print]136(16):
    Post-translational modifications of ATG8 proteins - an emerging mechanism of autophagy control.
    Jose L Nieto-Torres, Sviatlana Zaretski, Tianhui Liu, Peter D Adams, Malene Hansen.
      Autophagy is a recycling mechanism involved in cellular homeostasis with key implications for health and disease. The conjugation of the ATG8 family proteins, which includes LC3B (also known as MAP1LC3B), to autophagosome membranes, constitutes a hallmark of the canonical autophagy process. After ATG8 proteins are conjugated to the autophagosome membranes via lipidation, they orchestrate a plethora of protein-protein interactions that support key steps of the autophagy process. These include binding to cargo receptors to allow cargo recruitment, association with proteins implicated in autophagosome transport and autophagosome-lysosome fusion. How these diverse and critical protein-protein interactions are regulated is still not well understood. Recent reports have highlighted crucial roles for post-translational modifications of ATG8 proteins in the regulation of ATG8 functions and the autophagy process. This Review summarizes the main post-translational regulatory events discovered to date to influence the autophagy process, mostly described in mammalian cells, including ubiquitylation, acetylation, lipidation and phosphorylation, as well as their known contributions to the autophagy process, physiology and disease.
    Keywords:  ATG8; Autophagy; GABARAP; LC3; Phosphorylation; Post-translational modifications
    DOI:  https://doi.org/10.1242/jcs.259725
  2. Proc Natl Acad Sci U S A. 2023 Aug 22. 120(34): e2211281120
    The autophagy machinery interacts with EBV capsids during viral envelope release.
    Maria Pena-Francesch, Liliana Danusia Vanoaica, Gao-Feng Zhu, Michael Stumpe, Devanarayanan Siva Sankar, Heike Nowag, Alma Delia Valencia-Camargo, Wolfgang Hammerschmidt, Jörn Dengjel, Laure-Anne Ligeon, Christian Münz.
      Autophagy serves as a defense mechanism against intracellular pathogens, but several microorganisms exploit it for their own benefit. Accordingly, certain herpesviruses include autophagic membranes into their infectious virus particles. In this study, we analyzed the composition of purified virions of the Epstein-Barr virus (EBV), a common oncogenic γ-herpesvirus. In these, we found several components of the autophagy machinery, including membrane-associated LC3B-II, and numerous viral proteins, such as the capsid assembly proteins BVRF2 and BdRF1. Additionally, we showed that BVRF2 and BdRF1 interact with LC3B-II via their common protein domain. Using an EBV mutant, we identified BVRF2 as essential to assemble mature capsids and produce infectious EBV. However, BdRF1 was sufficient for the release of noninfectious viral envelopes as long as autophagy was not compromised. These data suggest that BVRF2 and BdRF1 are not only important for capsid assembly but together with the LC3B conjugation complex of ATG5-ATG12-ATG15L1 are also critical for EBV envelope release.
    Keywords:  EBV; autophagy; viral capsid assembly; viral envelope; xenophagy
    DOI:  https://doi.org/10.1073/pnas.2211281120
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