Endothelial Jag1-RBPJ signalling promotes inflammatory leucocyte recruitment and atherosclerosis

To determine the role of NOTCH during the arterial injury response and the subsequent chronic arterial-wall inflammation underlying atherosclerosis.

We have generated a mouse model of endothelial-specific (Cdh5-driven) depletion of the Notch effector recombination signal binding protein for immunoglobulin kappa J region (RBPJ) [(ApoE^−/−); homozygous RBPJk conditional mice (RBPJ^flox/flox); Cadherin 5-CreERT, tamoxifen inducible driver mice (Cdh5-Cre^ERT)]. Endothelial-specific deletion of RBPJ or systemic deletion of Notch1 in athero-susceptible ApoE^−/− mice fed a high-cholesterol diet for 6 weeks resulted in reduced atherosclerosis in the aortic arch and sinus. Intravital microscopy revealed decreased leucocyte rolling on the endothelium of ApoE^−/−; RBPJ^flox/flox; Cdh5-Cre^ERT mice, correlating with a lowered content of leucocytes and macrophages in the vascular wall. Transcriptome analysis revealed down-regulation of proinflammatory and endothelial activation pathways in atherosclerotic tissue of RBPJ-mutant mice. During normal Notch activation, Jagged1 signalling up-regulation in endothelial cells promotes nuclear translocation of the Notch1 intracellular domain (N1ICD) and its physical interaction with nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). This N1ICD–NF-κB interaction is required for reciprocal transactivation of target genes, including vascular cell adhesion molecule-1.

Notch signalling pathway inactivation decreases leucocyte rolling, thereby preventing endothelial dysfunction and vascular inflammation. Attenuation of Notch signalling might provide a treatment strategy for atherosclerosis.