Influences of Mechanotransduction Through Integrin-Linked Kinase on Collective Cell Migration

Abstract

A thorough understanding of cell migration is necessary to fully realize its connection to the larger-scale processes that it modulates, such as cancer metastasis, wound healing, and tissue morphogenesis. The impact of mechanical cues on cell fate has appeared as a prominent theme at the interface of cell biology, physics, and engineering. Several studies have examined how mechanical stresses regulate epithelial-mesenchymal transition (EMT), a phenotypic process through which epithelial cells detach from their neighbors and become motile and invasive. Most recently, we found that EMT is regulated by the mechanical properties of the underlying substratum. Here, we examine how matrix signaling through integrin-linked kinase (ILK), a mechanosensor involved in the formation of cell-cell and cell-matrix contacts, affects EMT downstream of transforming growth factor-β1 (TGFβ1). We show that when integrin signaling is disrupted through knockdown of ILK, the migration rate of mouse mammary epithelial cells decreases relative to controls. However, treatment of the culture with TGFβ1 abolishes this difference, allowing ILK-depleted cells to migrate as fast as controls. We determined that ILK is involved in the formation of cytoskeletal and morphological structures that are critical to cell migration in wound healing, but TGFβ1 is capable of independently effecting these changes to a lesser extent even when ILK is depleted. Lastly, we describe a constraint-removal migration assay to analyze the impacts of TGFβ1 and mechanotransduction through ILK on cell migration at physiologically relevant matrix stiffnesses. Our work helps elucidate the ways in which the mechanical microenvironment induces phenotypic changes in cells that dramatically alter their fate.