Nance-Horan Syndrome-like 1 interacts with endophilin A2 and Ena/VASP proteins to promote fast endophilin-mediated endocytosis

Endocytosis, crucial for various physiological processes, facilitates receptor and extracellular material uptake. Fast endophilin-mediated endocytosis (FEME), driven by endophilin A2 (EndoA2), enables clathrin-independent, ligand-induced receptor uptake at the leading-edge of cells. Whilst F-actin polymerisation is essential for FEME, how actin dynamics are regulated to mediate FEME is unknown. NHSL1, a Nance-Horan Syndrome protein family member, localises to leading-edges of cells, where it regulates migration, and to vesicular puncta, where its function is undetermined. Here, we show that NHSL1 and its uncharacterised family member NHSL2 co-localise and engage in direct, multivalent interactions with EndoA2. NHSL1 also binds Ena/VASP proteins, a family of actin elongators. NHSL1 promotes FEME and its interactions with EndoA2 and Ena/VASP proteins are required for this function. NHSL1 does not control dynamin recruitment but enhances actin polymerisation at FEME sites. Thus, it may cooperate with EndoA2 and Ena/VASP proteins to control membrane invagination and actin polymerisation, thereby mediating FEME.