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Evidence for ESCRT- and clathrin-dependent microautophagy

Masahide Oku1, Yuichiro Maeda1, Yoko Kagohashi1

  • 1Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan.

The Journal of Cell Biology
|August 26, 2017
PubMed

Insights

This study reveals the molecular mechanisms of microautophagy in yeast, showing the endosomal sorting complex required for transport (ESCRT) machinery is crucial. It highlights Vps27

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Autophagy Research

Background:

  • Microautophagy is a cellular process where the lysosomal/vacuolar membrane directly engulfs cellular components.
  • The precise molecular machinery governing microautophagy membrane dynamics remains largely unknown.
  • Autophagy, including microautophagy, plays critical roles in cellular homeostasis and stress response.

Purpose of the Study:

  • To elucidate the molecular machinery driving microautophagy in Saccharomyces cerevisiae.
  • To investigate the role of the endosomal sorting complex required for transport (ESCRT) machinery in microautophagy.
  • To understand the mechanism of cargo recognition and engulfment during microautophagy.

Main Methods:

  • Utilized immunochemical monitoring of fluorescently tagged yeast vacuolar transmembrane proteins (Vph1 and Pho8).
  • Observed changes in protein localization following a diauxic shift.
  • Investigated the requirement of ESCRT components, specifically Vps27 and its interaction with clathrin.

Main Results:

  • Demonstrated induction of microautophagy in yeast after a diauxic shift.
  • Identified the ESCRT machinery, including Vps27, as essential for this microautophagy process.
  • Showed Vps27 relocalizes to the vacuolar membrane and its interaction with clathrin is functionally important for lipid droplet uptake.

Conclusions:

  • The ESCRT machinery, particularly Vps27, plays a critical role in mediating microautophagy.
  • This pathway of microautophagy does not depend on the core Atg proteins typically associated with autophagy.
  • The findings provide new insights into the non-canonical mechanisms of autophagy and cellular cargo trafficking.

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