The Phosphorylation and Distribution of Cortactin Downstream of Integrin α9β1 Affects Cancer Cell Behaviour

Anette M Høye,Ulla M Wewer,Atsuko Yoneda,John R Couchman

doi:10.1038/srep28529

Abstract

Integrins, a family of heterodimeric adhesion receptors are implicated in cell migration, development and cancer progression. They can adopt conformations that reflect their activation states and thereby impact adhesion strength and migration. Integrins in an intermediate activation state may be optimal for migration and we have shown previously that fully activated integrin α9β1 corresponds with less migratory behaviour in melanoma cells. Here, we aimed to identify components associated with the activation status of α9β1. Using cancer cell lines with naturally occuring high levels of this integrin, activation by α9β1-specific ligands led to upregulation of fibronectin matrix assembly and tyrosine phosphorylation of cortactin on tyrosine 470 (Y470). Specifically, cortactin phosphorylated on Y470, but not Y421, redistributed together with α9β1 to focal adhesions where active β1 integrin also localises, upon integrin activation. This was commensurate with reduced migration. The localisation and phosphorylation of cortactin Y470 was regulated by Yes kinase and PTEN phosphatase. Cortactin levels influenced fibronectin matrix assembly and active β1 integrin on the cell surface, being inversely correlated with migratory behaviour. This study underlines the complex interplay between cortactin and α9β1 integrin that regulates cell-extracellular matrix interactions.

Highlights

Integrins, a family of heterodimeric adhesion receptors are implicated in cell migration, development and cancer progression
Integrins in an intermediate activation state may be optimal for migration and we have shown previously that fully activated integrin α9β1 corresponds with less migratory behaviour in melanoma cells
We have previously reported that α9β1 likely exists in an intermediate activation state that can become fully activated upon treatment with Mn2+, a general integrin activator, or a β1-integrin activating antibody in G361 human malignant melanoma cells

Summary

Introduction

A family of heterodimeric adhesion receptors are implicated in cell migration, development and cancer progression. Cortactin phosphorylated on Y470, but not Y421, redistributed together with α9β1 to focal adhesions where active β1 integrin localises, upon integrin activation. But not all, of the integrin family have been extensively studied both at the conformational and the signalling level Those are integrins such as αIIbβ[3], αLβ2, and αXβ2, that are present on the surface of platelets or leukocytes where activation is important for platelet aggregation during hemostasis and thrombosis, or leukocyte migration and regulated immune response[6,7]. The multidomain protein cortactin was first discovered as a major substrate of Src kinase[14] and is important in actin cytoskeletal dynamics[15]

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