Vinculin controls focal adhesion formation by direct interactions with talin and actin

TLDR

Focal adhesions coordinate cell migration, and vinculin, a key FA component, can link signaling pathways, yet its precise molecular mechanisms remain poorly understood. The study aims to delineate distinct functional roles of vinculin’s head and tail domains and to propose a comprehensive model of vinculin-mediated FA regulation. Using targeted vinculin mutants, the authors dissected head and tail regions to assign specific functions to each domain. They found that the head domain controls integrin dynamics and clustering, the tail domain connects FAs to the actin cytoskeleton and mechanotransduction forces, and that exposing binding sites in either domain promotes FA growth through direct talin interaction, increases integrin residency, and recruits paxillin independently of the tail’s binding site.

Abstract

Focal adhesions (FAs) regulate cell migration. Vinculin, with its many potential binding partners, can interconnect signals in FAs. Despite the well-characterized structure of vinculin, the molecular mechanisms underlying its action have remained unclear. Here, using vinculin mutants, we separate the vinculin head and tail regions into distinct functional domains. We show that the vinculin head regulates integrin dynamics and clustering and the tail regulates the link to the mechanotransduction force machinery. The expression of vinculin constructs with unmasked binding sites in the head and tail regions induces dramatic FA growth, which is mediated by their direct interaction with talin. This interaction leads to clustering of activated integrin and an increase in integrin residency time in FAs. Surprisingly, paxillin recruitment, induced by active vinculin constructs, occurs independently of its potential binding site in the vinculin tail. The vinculin tail, however, is responsible for the functional link of FAs to the actin cytoskeleton. We propose a new model that explains how vinculin orchestrates FAs.