A conformational change within the WAVE2 complex regulates its degradation following cellular activation

Abstract

WASp family Verprolin-homologous protein-2 (WAVE2), a member of the Wiskott-Aldrich syndrome protein (WASp) family of actin nucleation promoting factors, is a central regulator of actin cytoskeleton polymerization and dynamics. Multiple signaling pathways operate via WAVE2 to promote the actin-nucleating activity of the actin-related protein 2/3 (Arp2/3) complex. WAVE2 exists as a part of a pentameric protein complex known as the WAVE regulatory complex (WRC), which is unstable in the absence of its individual proteins. While the involvement of WAVE2 in actin polymerization has been well documented, its negative regulation mechanism is poorly characterized to date. Here, we demonstrate that WAVE2 undergoes ubiquitylation in a T-cell activation dependent manner, followed by proteasomal degradation. The WAVE2 ubiquitylation site was mapped to lysine 45, located at the N-terminus where WAVE2 binds to the WRC. Using Förster resonance energy transfer (FRET), we reveal that the autoinhibitory conformation of the WRC maintains the stability of WAVE2 in resting cells; the release of autoinhibition following T-cell activation facilitates the exposure of WAVE2 to ubiquitylation, leading to its degradation. The dynamic conformational structures of WAVE2 during cellular activation dictate its degradation.

Restrained activation of CYFIP2-containing WAVE complexes controls membrane protrusions and cell migration

“…When the assembly of these multiprotein complexes is blocked, assembly intermediates do not accumulate, because they are degraded by proteasomes. WAVE complexes are also degraded by proteasomes through direct ubiquitylation of WAVE2, after they have been conformationally activated [52]. WAVE stability is thus tightly controlled, probably as a way to maintain this powerful actin nucleator in check.…”

CB1-receptor-mediated inhibitory LTD triggers presynaptic remodeling via protein synthesis and ubiquitination

“…The WRC is intrinsically inactive at rest ( Derivery et al, 2009 ), but upon recruitment to the membrane by Rac1 the cytoplasmic side is opened for binding to Arp2/3 and actin ( Chen et al, 2010 ; Eden et al, 2002 ), leading to dissociation of WASF1. Although the exact mechanism of degradation has not been shown for Arp2/3 or WASF1/WAVE1, the non-neuronal, structurally homologous isoform WAVE2 was demonstrated to undergo activation-dependent dissociation from the WRC ubiquitination and proteasomal degradation ( Joseph et al, 2017 ). Therefore, Rac1 could be required for the degradation of WASF1/WAVE1, but its direct involvement in presynaptic degradation of Arp2/3 is not as clear.…”

The Impact of Bacteriophage on the Aging Brain and Inflammatory Response: Relevance to Parkinson’s Disease

“…Together they are indicative of glial activation, mobilization or senescence. In particular, WAVE2 is fundamental to cytoskeleton reorganization, actin polymerization regulation, tissue repair, immune response, embryonic development, migration and cell motility; it is particularly important in the formation of lamellipodia (Joseph et al, 2017;Oikawa et al, 2004).…”

“…Since actin is the main component of the cytoskeleton and the most abundant protein in the eukaryotic cell, its polymerization causes dystrophy in aged microglia (Cao, Yao & Zhang, 2015). The morphological changes in microglia that are associated with age may be due to WAVE2 deficits causing defective migration and lamellipodia formation (Lecours et al, 2018;Joseph et al, 2017).…”