Endothelial- specific Nck1 Deletion Reduces Proinflammatory Endothelial Activation And Atherosclerosis Without Affecting Ischemic Angiogenesis

The Nck family of signaling adaptors, including both Nck1 and Nck2, classically regulate cell motility during vascular development and postnatal angiogenesis. While Nck1 and Nck2 play redundant roles in this regard with deletion of both isoforms required to affect tissue remodeling, we demonstrated that global Nck1 deletion was sufficient to reduce atherosclerotic plaque formation and selective Nck1 inhibition reduces proinflammatory endothelial activation in response to oscillatory shear stress. Therefore, we sought to determine the role of endothelial Nck1 in atherosclerosis and ischemic angiogenesis using novel endothelial-specific Nck1 knockout mice. Endothelial-specific Nck1 inhibition significantly reduced Western dietinduced atherosclerotic plaque formation at multiple sites compared to mice expressing endothelial-specific Cre alone or to endothelial-specific Nck2 knockout mice. This reduced plaque formation was characterized by diminished macrophage and smooth muscle incorporation despite enhanced weight gain in endothelial Nck1 knockout mice. RNA Sequencing analysis of endothelial cells in culture showed that Nck1 depletion reduces the expression of a variety of proinflammatory pathways but enhances the expression of genes involved in central carbon metabolism and proliferation. In addition, mass spectrometry analysis of Nck1 interacting proteins showed overrepresentation in binding partners involved in cell metabolism, consistent with published GWAS associations between Nck1 and body mass index and circulating plasma lipids. In contrast, Nck1 inhibition did not affect angiogenesis or limb perfusion in the femoral artery ligation model of hind limb ischemia. Taken together, endothelial Nck1 inhibition reduces atherosclerotic plaque formation associated with diminished proinflammatory responses without limiting ischemic angiogenesis, suggesting that Nck1 inhibition could be utilized to reduce atherosclerosis without preventing ischemic angiogenesis in the affected tissue.