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ARHGAP4-SEPT2-SEPT9 complex enables both up- and down-modulation of integrin-mediated focal adhesions, cell migration, and invasion.

ABSTRACT: The Rho family of GTPases are inactivated in a cell context-dependent manner by Rho-GTPase-activating proteins (Rho-GAPs), but their signaling mechanisms are poorly understood. Here we demonstrate that ARHGAP4, one of the Rho-GAPs, forms a complex with SEPT2 and SEPT9 via its Rho-GAP domain and SH3 domain to enable both up- and down-modulation of integrin-mediated focal adhesions (FAs). We show that silencing ARHGAP4 and overexpressing its two mutually independent upstream regulators, SEPT2 and SEPT9, all induce reorganization of FAs to newly express Integrin Beta 1 and also enhance both cell migration and invasion. Interestingly, even if these cell migration/invasion-associated phenotypic changes are induced upon perturbations to the complex, it does not necessarily cause enhanced clustering of FAs. Instead, its extent depends on whether the microenvironment contains ligands suitable for the up-regulated Integrin Beta 1. These results provide novel insights into cell migration, invasion, and microenvironment-dependent phenotypic changes regulated by the newly identified complex.

SUBMITTER: Kang N

PROVIDER: S-EPMC8693978 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Both SEPT2 and MLL are down-regulated in MLL-SEPT2 therapy-related myeloid neoplasia.

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Titin-Based Nanoparticle Tension Sensors Map High-Magnitude Integrin Forces within Focal Adhesions.

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Project description:BACKGROUND:The spatiotemporal regulation of adhesion to the extracellular matrix is important in metazoan cell migration and mechanosensation. Although adhesion assembly depends on intracellular and extracellular tension, the biophysical regulation of force transmission between the actin cytoskeleton and extracellular matrix during this process remains largely unknown. RESULTS:To elucidate the nature of force transmission as myosin II tension is applied to focal adhesions, we correlated the dynamics of focal adhesion proteins and the actin cytoskeleton to local traction stresses. Under low extracellular tension, newly formed adhesions near the cell periphery underwent a transient retrograde displacement preceding elongation. We found that myosin II-generated tension drives this mobility, and we determine the interface of differential motion, or "slip," to be between integrin and the ECM. The magnitude and duration of both adhesion slip and associated F-actin dynamics is strongly modulated by ECM compliance. Traction forces are generated throughout the slip period, and adhesion immobilization occurs at a constant tension. CONCLUSIONS:We have identified a tension-dependent, extracellular "clutch" between integrins and the extracellular matrix; this clutch stabilizes adhesions under myosin II driven tension. The current work elucidates a mechanism by which force transmission is modulated during focal adhesion maturation.

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Translocation of CrkL to focal adhesions mediates integrin-induced migration downstream of Src family kinases.

Project description:The adapter protein Crk-Like (CrkL) can associate with the Src substrate p130(Cas) (Cas). The biological role of CrkL downstream of Cas, however, has been largely obscure. Consistent with the ability of CrkL to biochemically associate with Cas, we found that Src triggers translocation of CrkL to focal adhesions (FAs) in a manner dependent on Cas. Forced localization of CRKL to FAs (FA-CRKL) by itself was sufficient to induce activation of Rac1 and Cdc42 and rescued haptotaxis defects of mouse embryonic fibroblasts (MEFs) lacking Src, Yes, and Fyn, three broadly expressed Src family members required for integrin-induced migration. Consistent with Rac1 activation, FA-CRKL induced cotranslocation of a Rac1 activator, Dock1, to focal adhesions. These results therefore indicate a role for CrkL in mediating Src signaling by activating small G proteins at focal adhesions. Furthermore, MEFs lacking CrkL show impaired integrin-induced migration despite expression of a closely related protein, Crk-II, in these cells. These results therefore provide formal evidence that CrkL plays a specific role in integrin-induced migration as a downstream mediator of Src.

| S-EPMC152569 | biostudies-literature

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