ORP-Mediated ER Contact with Endocytic Sites Facilitates Actin Polymerization

Publication date: Available online 22 November 2017
Source:Developmental Cell
Author(s): Javier Encinar del Dedo, Fatima-Zahra Idrissi, Isabel María Fernandez-Golbano, Patricia Garcia, Elena Rebollo, Marek K. Krzyzanowski, Helga Grötsch, Maria Isabel Geli
Oxysterol binding protein-related proteins (ORPs) are conserved lipid binding polypeptides, enriched at ER contacts sites. ORPs promote non-vesicular lipid transport and work as lipid sensors in the context of many cellular tasks, but the determinants of their distinct localization and function are not understood. Here, we demonstrate that the yeast endocytic invaginations associate with the ER and that this association specifically requires the ORPs Osh2 and Osh3, which bridge the endocytic myosin-I Myo5 to the ER integral-membrane VAMP-associated protein (VAP) Scs2. Disruption of the ER contact with endocytic sites using ORP, VAP, myosin-I, or reticulon mutants delays and weakens actin polymerization and interferes with vesicle scission. Finally, we provide evidence suggesting that ORP-dependent sterol transfer facilitates actin polymerization at endocytic sites.

Graphical abstract

Teaser

Clathrin-mediated endocytosis from the plasma membrane is thought to mostly rely on the assembly of a coat built from cytosolic proteins. In contrast, Encinar et al. demonstrate that the ER contacts endocytic sites and plays a role in facilitating membrane invagination for endocytosis.


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