Displacement of p130Cas from focal adhesions links actomyosin contraction to cell migration

Abstract

BSTRACTCell adhesion complexes provide platforms where cell-generated forces are transmitted to the extracellular matrix (ECM). Tyrosine phosphorylation of focal adhesion proteins is crucial for cells to communicate with the extracellular environment. However, the mechanisms that transmit actin cytoskeletal motion to the extracellular environment to drive cell migration are poorly understood. We find that the movement of p130Cas (Cas, also known as BCAR1), a mechanosensor at focal adhesions, correlates with actin retrograde flow and depends upon actomyosin contraction and phosphorylation of the Cas substrate domain (CasSD). This indicates that CasSD phosphorylation underpins the physical link between Cas and the actin cytoskeleton. Fluorescence recovery after photobleaching (FRAP) experiments reveal that CasSD phosphorylation, as opposed to the association of Cas with Src, facilitates Cas displacement from adhesion complexes in migrating cells. Furthermore, the stabilization of Src-Cas binding and inhibition of myosin II, both of which sustain CasSD phosphorylation but mitigate Cas displacement from adhesion sites, retard cell migration. These results indicate that Cas promotes cell migration by linking actomyosin contractions to the adhesion complexes through a dynamic interaction with Src as well as through the phosphorylation-dependent association with the actin cytoskeleton.

The ubiquitin-proteasome system regulates focal adhesions at the leading edge of migrating cells

“…Accordingly, phosphorylated Cas levels in FAs increased approximately 3-fold when Cul5 expression was inhibited, especially in FAs in the front 6 µm of the cell (Figure 5—figure supplement 3). Since Cas exchanges rapidly between the cytosol and FAs (Janostiak et al, 2011; Machiyama et al, 2014), the increase in pYCas in FAs could be secondary to the increased Cas in the cytosol. Moreover, the chronic increase in pYCas in adhesions could accelerate adhesion turnover regardless of whether SOCS6 targets Cas in the cytosol or in FAs.…”

“…Removal of Cas by this mechanism would be expected to open up sites in the FA where other Cas molecules could bind. It is known that most of the Cas in a FA exchanges with Cas from the cytosol with a very rapid (~20 s) rate constant (Janostiak et al, 2011; Machiyama et al, 2014). It seems remarkable that ubiquitination and degradation of pYCas would affect the kinetics of FA disassembly if new Cas molecules could replace degraded molecules with such speed.…”

A truncated phosphorylated p130Cas substrate domain is sufficient to drive breast cancer growth and metastasis formation in vivo

“…This region contains the tyrosine motifs 6-10 of the human SD (Y236, Y249, Y267, Y287, and Y306). Phosphorylation of the SD is essential for the dynamic assembly and disassembly of focal adhesions [19]. Each of these motifs was found to be phosphorylated in more than 190 proteomic studies as curated at PhosphoSitePlus [18], whereas most of the other SD motifs were significantly less often phosphorylated.…”

“…The importance of these results is further indicated because p130Cas SD phosphorylation is a central step in the regulation of cell adhesion, migration, and invasion as well as proliferation and survival [6,[19][20][21]. In the past few years, p130Cas was also identified as a mechanosensor in response to extracellular matrix-integrin engagement [22,23].…”

Altered protein expression profile associated with phenotypic changes in lung fibroblasts co-cultured with gold nanoparticle-treated small airway epithelial cells

“…PXN is a focal adhesion (FA) associated adapter protein which regulates cell spreading and motility [31]. While PXN is believed to play a role in targeting vinculin to FAs, BCAR1 (also known as p130Cas), has been reported to be important in controlling spreading and motility of cancer cells through regulating FA [32,33]. Cav-1 is known to mediate cancer metastasis and reports have suggested that upregulation of Cav-1 induced cell attachment [34e36].…”