Check out this article titled "LC3B is lipidated to large lipid droplets during prolonged starvation for noncanonical autophagy" by Mohyeddine Omrane and al. which explores how lipid droplets (LDs) interact with autophagosomes under starvation conditions.
This study highlights the crucial role of organelles in cellular processes, underscoring their importance in research and their potential implications for understanding and treating various diseases.
LC3B Lipidation on Large Lipid Droplets: During extended periods of starvation, LC3B, a protein associated with autophagy, is lipidated onto large lipid droplets.
Role of ATG3: The enzyme ATG3 binds to lipid droplets independently and facilitates the lipidation of LC3B.
Proximity to Autophagosome-like Membranes: These LC3B-lipidated lipid droplets are found near autophagosome-like membranes.
Noncanonical Autophagic Degradation: Prolonged starvation triggers a unique autophagic degradation process on lipid droplets, distinct from traditional macrolipophagy.
Lipid droplets (LDs) are essential cellular structures that store lipids, which can be mobilized during times of nutrient scarcity through autophagic and lysosomal pathways. However, the interaction between LDs and autophagosomes has remained somewhat elusive. This study uncovers that the E2 autophagic enzyme, ATG3, localizes to the surface of ultra-large LDs in differentiated murine 3T3-L1 adipocytes or Huh7 human liver cells during prolonged starvation. ATG3 then lipidates microtubule-associated protein 1 light-chain 3B (LC3B) to these LDs.
In vitro experiments demonstrated that ATG3 could independently bind to purified and artificial LDs to mediate this lipidation reaction. Observations showed that LC3B-lipidated LDs were consistently near collections of LC3B-membranes and lacked Plin1, a protein typically associated with LDs. This phenomenon is distinct from macrolipophagy but requires autophagy, as it disappears following ATG5 or Beclin1 knockout.
The data suggest that extended starvation triggers a noncanonical autophagy mechanism, akin to LC3B-associated phagocytosis, where the surface of large LDs serves as an LC3B lipidation platform for autophagic processes.
