Epsin deficiency impairs endocytosis by stalling the actin-dependent invagination of endocytic clathrin-coated pits

Abstract

Epsin is an evolutionarily conserved endocytic clathrin adaptor whose most critical function(s) in clathrin coat dynamics remain(s) elusive. To elucidate such function(s), we generated embryonic fibroblasts from conditional epsin triple KO mice. Triple KO cells displayed a dramatic cell division defect. Additionally, a robust impairment in clathrin-mediated endocytosis was observed, with an accumulation of early and U-shaped pits. This defect correlated with a perturbation of the coupling between the clathrin coat and the actin cytoskeleton, which we confirmed in a cell-free assay of endocytosis. Our results indicate that a key evolutionary conserved function of epsin, in addition to other roles that include, as we show here, a low affinity interaction with SNAREs, is to help generate the force that leads to invagination and then fission of clathrin-coated pits.DOI: http://dx.doi.org/10.7554/eLife.03311.001

Zero Tolerance: Amphipathic Helices in Endocytosis

“…Both the lipid-induced co-assembly of Ent1-Sla2 and the coupling to the actin cytoskeleton are consistent with recent work on epsin and HIP1R in mouse (Messa et al, 2014) indicating that these observations in yeast are likely conserved in higher organisms.…”

Helping Hands for Budding Prospects: ENTH/ANTH/VHS Accessory Proteins in Endocytosis, Vacuolar Transport, and Secretion

“…Recent reports suggest that Epsins link vesicle budding sites with the cytoskeleton. The yeast epsin Ent1 directly interacts with actin via a phospho-regulated binding domain (Skruzny et al, 2012), and a similar acting binding activity has been found in mammalian Epsin1 (Messa et al, 2014). Thus, the membrane destabilizing properties of the ENTH domain, combined with mechanical force introduced by the actin cytoskeleton might lead to membrane bulging and, eventually, vesicle fission.…”

“…A role in scission of the budding CCV is also supported by the finding that Epsin seems to concentrate toward the neck of a forming vesicle, whereas AP-2 is found in the opposite, oldest part (Saffarian et al, 2009). Finally, mouse cells with near complete loss of all Epsin activity exhibit failure in CCV scission at the PM (Messa et al, 2014).…”

“…Thus, the membrane destabilizing properties of the ENTH domain, combined with mechanical force introduced by the actin cytoskeleton might lead to membrane bulging and, eventually, vesicle fission. Apart from their function in vesicle assembly, Epsins and other ENTH proteins may have additional roles in recruiting cargo: Several lines of evidence, including identification of the actual interaction surface, demonstrate that Epsin can interact with soluble N-ethylmaleimidesensitive fusion protein-attachment protein receptors (SNAREs) that are important for fusion of the vesicle with its target membrane (Chidambaram et al, 2004;Miller et al, 2007;Messa et al, 2014).…”

Selective Targeting of a Novel Epsin–VEGFR2 Interaction Promotes VEGF-Mediated Angiogenesis

“…In further support, our recent study showed that genetic reduction of VEGFR2 in endothelial cells decreases elevated VEGF signaling and rescues aberrant angiogenesis caused by epsins 1 and 2 deficiencies 10 . Intriguingly, epsins 1, 2 and 3 have been implicated in the generation of membrane curvature that is critical for clathrin-mediated endocytosis 31 . Deficiency of all three epsins impairs endocytosis in general by stalling the actin-dependent invagination of endocytic clathrin-coated pits 31 .…”