Drosophila vinculin is more harmful when hyperactive than absent, and can circumvent integrin to form adhesion complexes

Abstract

Vinculin is a highly conserved protein involved in cell adhesion and mechanotransduction, and both gain and loss of its activity causes defective cell behaviour. Here, we examine how altering vinculin activity perturbs integrin function within the context of Drosophila development. Whereas loss of vinculin produced relatively minor phenotypes, gain of vinculin activity, through a loss of head–tail autoinhibition, caused lethality. The minimal domain capable of inducing lethality is the talin-binding D1 domain, and this appears to require talin-binding activity, as lethality was suppressed by competition with single vinculin-binding sites from talin. Activated Drosophila vinculin triggered the formation of cytoplasmic adhesion complexes through the rod of talin, but independently of integrin. These complexes contain a subset of adhesion proteins but no longer link the membrane to actin. The negative effects of hyperactive vinculin were segregated into morphogenetic defects caused by its whole head domain and lethality caused by its D1 domain. These findings demonstrate the crucial importance of the tight control of the activity of vinculin.

Chlamydial virulence factor TarP mimics talin to disrupt the talin‐vinculin complex

“…Since TarP VBS1 binds to the same site on vinculin as the talin VBS, this raises the possibility that TarP binding might compete with talin for vinculin binding. A similar phenomenon was seen in Drosophila recently, where expression of a GFP-VBS construct was found to disrupt talin:vinculin interactions in vivo [34]. Using analytical gel filtration, we measured the interaction between Vd1 and a VBS-containing talin helical bundle.…”

Force-independent interactions of talin and vinculin govern integrin-mediated mechanotransduction

“…Indeed, none of the above interactions were affected by blebbistatin, Y-27632 or cytochalasin D demonstrating that force exerted by actomyosin contraction is not essential for activated vinculin to bind talinFL or vice versa. Similar stable interactions between activated vinculin constructs and full-length talin have been observed in the cytoplasm of Drosophila embryos, (Maartens et al, 2016), a site where forces would not be expected to contribute to complex assembly.…”

Analysis of a vinculin homolog in a sponge (phylum Porifera) reveals that vertebrate-like cell adhesions emerged early in animal evolution

“…Disruption of DEB-1 function leads to disorganized muscles and paralyzed embryos and is lethal (93)(94)(95)(96). In contrast, D. melanogaster vinculin is nonessential (97), but constitutive activation caused the formation of abundant cytoplasmic adhesion complexes with talin, producing morphological defects and death (97,98). Biochemical differences between vertebrate and invertebrate ␣-catenin have been detailed elsewhere (40,99), but all ␣-catenins characterized to date bind ␤-catenin and F-actin at the AJ and developmental disruption of ␣-catenin leads to morphological abnormalities and death (80, 100 -102).…”