N-WASP deficiency impairs EGF internalization and actin assembly at clathrin-coated pits

Citations Over TimeTop 10% of 2005 papers

Abstract

WASP and WAVE family proteins promote actin polymerization by stimulating Arp2/3-complex-dependent filament nucleation. Unlike WAVE proteins, which are known to drive the formation of protrusions such as lamellipodia and membrane ruffles, vertebrate cell functions of WASP or N-WASP are less well established. Recent work demonstrated that clathrin-coated pit invagination can coincide with assembly of actin filaments and with accumulation of N-WASP and Arp2/3 complex, but the relevance of their recruitment has remained poorly defined. We employed two-colour total internal reflection microscopy to study the recruitment and dynamics of various components of the actin polymerization machinery and the epidermal growth factor receptor signalling machinery during clathrin-coated pit internalization in control cells and cells genetically deficient for functional N-WASP. We found that clathrin-coated pit endocytosis coincides with the recruitment of N-WASP, Arp2/3 complex and associated proteins, but not of WAVE family members. Actin accumulation at clathrin-coated pits requires the Arp2/3 complex, since Arp2/3 complex sequestration in the cytosol abolished any detectable actin assembly. The absence of N-WASP caused a significant reduction in the frequencies of actin and Arp2/3 complex accumulations at sites of clathrin-coated pit invagination and vesicle departure. Although N-WASP was not essential for Arp2/3-complex-mediated actin assembly at these sites or for EGF receptor-mediated endocytosis, N-WASP deficiency caused a marked reduction of EGF internalization. We conclude that the assembly of WASP subfamily proteins and associated factors at sites of clathrin-coated pit invagination amplifies actin accumulations at these sites promoting efficient internalization of ligands via clathrin-mediated endocytosis.

Related Papers

• → Scar1 and the related Wiskott–Aldrich syndrome protein, WASP, regulate the actin cytoskeleton through the Arp2/3 complex(1998)929 cited
• → Actin-filament cross-linking protein T-plastin increases Arp2/3-mediated actin-based movement(2005)79 cited
• → Swiprosin-1 modulates actin dynamics by regulating the F-actin accessibility to cofilin(2013)41 cited
• → CRMP-1 enhances EVL-mediated actin elongation to build lamellipodia and the actin cortex(2017)26 cited
• → Dynamin2 Organizes Lamellipodial Actin Networks to Orchestrate Lamellar Actomyosin(2014)13 cited