1. Academic Validation
  2. Bif-1 regulates Atg9 trafficking by mediating the fission of Golgi membranes during autophagy

Bif-1 regulates Atg9 trafficking by mediating the fission of Golgi membranes during autophagy

  • Autophagy. 2011 Jan;7(1):61-73. doi: 10.4161/auto.7.1.14015.
Yoshinori Takahashi 1 Cheryl L Meyerkord Tsukasa Hori Kristin Runkle Todd E Fox Mark Kester Thomas P Loughran Hong-Gang Wang
Affiliations

Affiliation

  • 1 Department of Pharmacology, The Pennsylvania State University College of Medicine, Hershey, PA, USA. yut4@psu.edu
Abstract

Atg9 is a transmembrane protein essential for Autophagy which cycles between the Golgi network, late endosomes and LC3-positive autophagosomes in mammalian cells during starvation through a mechanism that is dependent on ULK1 and requires the activity of the class III phosphatidylinositol-3-kinase (PI3KC3). In this study, we demonstrate that the N-BAR-containing protein, Bif-1, is required for Atg9 trafficking and the fission of Golgi membranes during the induction of Autophagy. Upon starvation, Atg9-positive membranes undergo continuous tubulation and fragmentation to produce cytoplasmic punctate structures that are positive for Rab5, Atg16L and LC3. Loss of Bif-1 or inhibition of the PI3KC3 complex II suppresses starvation-induced fission of Golgi membranes and peripheral cytoplasmic redistribution of Atg9. Moreover, Bif-1 mutants, which lack the functional regions of the N-BAR domain that are responsible for membrane binding and/or bending activity, fail to restore the fission of Golgi membranes as well as the formation of Atg9 foci and autophagosomes in Bif-1-deficient cells starved of nutrients. Taken together, these findings suggest that Bif-1 acts as a critical regulator of Atg9 puncta formation presumably by mediating Golgi fission for autophagosome biogenesis during starvation.

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