Induction of membrane circular dorsal ruffles requires co-signalling of integrin-ILK-complex and EGF receptor

Integrin and receptor tyrosine kinase signalling networks cooperate to regulate various biological functions. The molecular details underlying the integration of both signalling networks remain largely uncharacterized. Here we identify a signalling module composed of a fibronectin-alpha 5 beta 1-integrin-integrin-linked-kinase (ILK) complex that, in concert with epidermal growth factor (EGF) cues, cooperatively controls the formation of transient actin-based circular dorsal ruffles (DRs) in fibroblasts. DR formation depends on the precise spatial activation of Src at focal adhesions by integrin and EGF receptor signals, in an ILK-dependent manner. In a SILAC-based phosphoproteomics screen we identified the tumour-suppressor Cyld as being required for DR formation induced by alpha 5 beta 1 integrin and EGF receptor co-signalling. Furthermore, EGF-induced Cyld tyrosine phosphorylation is controlled by integrin ILK and Src as a prerequisite for DR formation. This study provides evidence for a novel function of integrin ILK and EGF signalling crosstalk in mediating Cyld tyrosine phosphorylation and fast actin-based cytoskeletal rearrangements.