Abstract

While CANTOS established the role of treating inflammation in atherosclerosis, our understanding of endothelial activation at atherosclerosis-prone sites remains limited. Disturbed flow at atheroprone regions primes plaque inflammation by enhancing endothelial NF-{kappa}B signaling. Herein, we demonstrate a novel role for the Nck adaptor proteins in disturbed flow-induced endothelial activation. Although highly similar, only Nck1 deletion, but not Nck2 deletion, limits flow-induced NF-{kappa}B activation and proinflammatory gene expression. Nck1 knockout mice show reduced endothelial activation and inflammation in both models of disturbed flow and high fat diet-induced atherosclerosis. Bone marrow chimeras confirm that vascular Nck1, but not hematopoietic Nck1, mediates this effect. In contrast, endothelial Nck2 depletion does not affect endothelial activation or atherosclerosis. Domain swap experiments and point mutations identify the Nck1 SH2 domain and the first SH3 domain as critical for flow-induced endothelial activation. We further characterize Nck1s proinflammatory role by identifying interleukin-1 type I receptor kinase-1 (IRAK-1) as a Nck1-selective binding partner, demonstrating IRAK-1 activation by disturbed flow requires Nck1 in vitro and in vivo, showing endothelial Nck1 and IRAK-1 staining in early human atherosclerosis, and demonstrating that disturbed flow-induced endothelial activation requires IRAK-1. Taken together, our data reveal a hitherto unknown link between Nck1 and IRAK-1 in atherogenic inflammation.