Selective role of Nck1 in atherogenic inflammation and plaque formation

Area of Science:

• Cardiovascular Biology
• Molecular Medicine
• Atherosclerosis Research

Background:

• Endothelial activation at atherosclerosis-prone sites is key to plaque inflammation.
• Disturbed blood flow enhances endothelial NF-κB signaling, promoting inflammation.
• The role of Nck adaptor proteins in this process is not well understood.

Purpose of the Study:

• To investigate the role of Nck adaptor proteins (Nck1 and Nck2) in disturbed flow-induced endothelial activation.
• To elucidate the specific domains and binding partners of Nck1 involved in atherogenic inflammation.
• To determine whether vascular or hematopoietic Nck1 mediates the observed effects.

Main Methods:

• Utilized Nck1 and Nck2 knockout mouse models under disturbed flow and high-fat diet conditions.
• Employed bone marrow chimera experiments to differentiate vascular versus hematopoietic roles.
• Performed domain-swap experiments and point mutations to identify critical Nck1 domains.
• Identified and validated IRAK-1 as a Nck1-binding partner using in vitro and in vivo assays.
• Examined human atherosclerotic lesions for Nck1 and IRAK-1 expression.

Main Results:

• Nck1 deletion, but not Nck2 deletion, significantly reduced NF-κB activation and inflammatory gene expression.
• Nck1-knockout mice exhibited decreased endothelial activation and atherosclerosis development.
• Vascular Nck1, not hematopoietic Nck1, was responsible for mediating these effects.
• The Nck1 SH2 and first SH3 domains were critical for flow-induced activation.
• Nck1 selectively binds to IRAK-1, and IRAK-1 activation by disturbed flow requires Nck1.
• Endothelial Nck1 and IRAK-1 were found in early human atherosclerosis.

Conclusions:

• Nck1 plays a critical, vascular-specific role in disturbed flow-induced endothelial activation and atherogenic inflammation.
• The Nck1-IRAK-1 interaction is a key pathway linking disturbed flow to endothelial inflammation.
• These findings reveal a novel mechanism in atherosclerosis and suggest Nck1 as a potential therapeutic target.