The Arp2/3 activator WASH regulates α5β1-integrin-mediated invasive migration

Abstract

SummaryThe actin cytoskeleton provides scaffolding and physical force to effect fundamental processes such as motility, cytokinesis and vesicle trafficking. The Arp2/3 complex nucleates actin structures and contributes to endocytic vesicle invagination and trafficking away from the plasma membrane. Internalisation and directed recycling of integrins are major driving forces for invasive cell motility and potentially for cancer metastasis. Here, we describe a direct requirement for WASH and Arp2/3-mediated actin polymerisation on the endosomal membrane system for a5b1 integrin recycling. WASH regulates the trafficking of endosomal a5b1 integrin to the plasma membrane and is fundamental for integrin-driven cell morphology changes and integrin-mediated cancer cell invasion. Thus, we implicate WASH and Arp2/3-driven actin nucleation in receptor recycling leading to invasive motility.

WASH drives early recycling from macropinosomes and phagosomes to maintain surface phagocytic receptors

“…7E). Integrins are also internalized by macropinocytosis in mammalian cells (53) and α5β1 integrins have been reported to be recycled from mammalian endosomes by WASH (28,29). We therefore asked whether WASH was also important to recycle integrins from macropinosomes.…”

“…and β2-adrenoreceptor as well as in targeting the epidermal growth factor receptor (EGFR) to the lysosome (23,25,28,29,31). The WASH complex also directly interacts with the retromer sorting complex and is thus required for the specific retrieval of retromer cargos from several endocytic compartments (23,32).…”

“…However, the mechanisms underpinning protein sorting before degradation are poorly understood. WASH has been shown to drive the recycling of several plasma membrane proteins from sorting endosomes back to the cell surface (28,29,45). We therefore asked whether the early phase of WASH and retromer activity provides a way to recover plasma membrane components from nascent macropinosomes before degradation.…”

“…In particular, significant progress has been made in defining the role of actin in the segregation and extraction of specific proteins (22). Many studies describe a role for the WASH (WASP and SCAR homolog) complex in driving endosomal actin polymerization (23)(24)(25)(26)(27)(28)(29)(30). WASH has been implicated in the endosome-to-surface trafficking of a number of cargos, including the transferrin receptor (TfnR), α5β1 integrins,…”

Cellular functions of WASP family proteins at a glance

“…WASH localizes to endosomes (Derivery et al, 2009;Gomez and Billadeau, 2009;Harbour et al, 2012;Jia et al, 2012;Monfregola et al, 2010;Monteiro et al, 2013;Ryder et al, 2013), and WASHgenerated F-actin not only regulates the architecture of the endolysosomal system, but also spares specific cargo from lysosomal degradation or missorting (Bartuzi et al, 2016;Derivery et al, 2009Derivery et al, , 2012Duleh and Welch, 2010;Gomez and Billadeau, 2009;Gomez et al, 2012;Monteiro et al, 2013;Zech et al, 2011). WASH is recruited to retromer-positive endosomal subdomains via the interaction of the extended C-terminal tail of FAM21 with the retromer subunit VPS35 (Harbour et al, 2012;Jia et al, 2012).…”