Integrin α5β1 and ADAM-17 interact in vitro and co-localize in migrating HeLa cells

Tumor necrosis factor (TNF) α-converting enzyme (TACE/ADAM-17) has diverse roles in the proteolytic processing of cell surface molecules and, due to its ability to process TNFα, is a validated therapeutic target for anti-inflammatory therapies. Unlike a number of other ADAM proteins, which interact with integrin receptors via their disintegrin domains, there is currently no evidence for an ADAM-17-integrin association. By analyzing the adhesion of a series of cell lines with recombinant fragments of the extracellular domain of ADAM-17, we now demonstrate a functional interaction between ADAM-17 and α5β1 integrin in a trans orientation. Because ADAM-17-mediated adhesion was sensitive to RGD peptides and EDTA, and the integrin-binding site within ADAM-17 was narrowed down to the disintegrin/ cysteine-rich region, the two molecules appear to have a ligand-receptor relationship mediated by the α5β 1 ligand binding pocket. Intriguingly, ADAM-17 and α 5β1 were found to co-localize in both membrane ruffles and focal adhesions in HeLa cells. When confluent HeLa cell monolayers were wounded, ADAM-17 and α5β1 redistributed to the leading edge and co-localized, which is suggestive of a cis orientation. We postulate that the interaction of ADAM-17 with α5β 1 may target or modulate its metalloproteolytic activity.