Resveratrol-mediated autophagy requires WIPI-1-regulated LC3 lipidation in the absence of induced phagophore formationMauthe, M., Jacob, A., Freiberger, S., Hentschel, K., Stierhof, Y-D., Codogno, P. & Proikas-Cezanne, T., 7-Dec-2011, In : Autophagy. 7, 12, p. 1448-1461 14 p.
Research output: Contribution to journal › Article › Academic › peer-review
Canonical autophagy is positively regulated by the Beclin 1/phosphatidylinositol 3-kinase class III (PtdIns3KC3) complex that generates an essential phospholipid, phosphatidylinositol 3-phosphate (PtdIns(3)P), for the formation of autophagosomes. Previously, we identified the human WIPI protein family and found that WIPI-1 specifically binds PtdIns(3)P, accumulates at the phagophore and becomes a membrane protein of generated autophagosomes. Combining siRNA-mediated protein downregulation with automated high through-put analysis of PtdIns(3)P-dependent autophagosomal membrane localization of WIPI-1, we found that WIPI-1 functions upstream of both Atg7 and Atg5, and stimulates an increase of LC3-II upon nutrient starvation. Resveratrol-mediated autophagy was shown to enter autophagic degradation in a noncanonical manner, independent of Beclin 1 but dependent on Atg7 and Atg5. By using electron microscopy, LC3 lipidation and GFP-LC3 puncta-formation assays we confirmed these results and found that this effect is partially wortmannin-insensitive. In line with this, resveratrol did not promote phagophore localization of WIPI-1, WIPI-2 or the Atg16L complex above basal level. In fact, the presence of resveratrol in nutrient-free conditions inhibited phagophore localization of WIPI-1. Nevertheless, we found that resveratrol-mediated autophagy functionally depends on canonical-driven LC3-II production, as shown by siRNA-mediated downregulation of WIPI-1 or WIPI-2. From this it is tempting to speculate that resveratrol promotes noncanonical autophagic degradation downstream of the PtdIns(3)P-WIPI-Atg7-Atg5 pathway, by engaging a distinct subset of LC3-II that might be generated at membrane origins apart from canonical phagophore structures.
|Number of pages||14|
|Publication status||Published - 7-Dec-2011|
- Androstadienes/pharmacology, Animals, Autophagy/drug effects, Autophagy-Related Protein 12, Autophagy-Related Protein 5, Autophagy-Related Protein 7, Autophagy-Related Proteins, Carrier Proteins/drug effects, Cell Line, Green Fluorescent Proteins/metabolism, Humans, Lipids/chemistry, Membrane Proteins/metabolism, Mice, Microtubule-Associated Proteins/metabolism, Phagosomes/drug effects, Phosphatidylinositol Phosphates/metabolism, Protein Transport/drug effects, Recombinant Fusion Proteins/metabolism, Resveratrol, Small Ubiquitin-Related Modifier Proteins/metabolism, Stilbenes/pharmacology, Ubiquitin-Activating Enzymes/metabolism, Wortmannin