Endothelial Jag1-RBPJ signalling promotes inflammatory leucocyte recruitment and atherosclerosis

Abstract

Aim To determine the role of NOTCH during the arterial injury response and the subsequent chronic arterial-wall inflammation underlying atherosclerosis. Methods and results 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-Cre$^{ERT}$, 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. Conclusions 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.This study was funded by grants SAF2013-45543R, RD12/0042/0005 (RIC) and RD12/0019/0003 (TERCEL) from the Spanish Ministry of Economy and Competitiveness (MINECO) to J.L.dlP, RD12/0042/0028 (RIC) to V.A. and RD12/0042/0053 (RIC) and SAF2012-40127 to J.M.G. M.N. held a Sara Borrell post-doctoral contract (CD09/00452) and D.M. holds a post-doctoral contract associated with grant RD12/0042/0005, both awarded by The Instituto de Salud Carlos III; B.M.P. holds a Juan de la Cierva post-doctoral contract (JCI-2010-06343). The CNIC is supported by the Spanish Ministry of Economy and Competitiveness (MINECO) and the Pro CNIC Foundation, and is a ‘Severo Ochoa’ Center of Excellence (MINECO award SEV-2015-0505).This is the author accepted manuscript. The final version is available from Oxford University Press via http://dx.doi.org/10.1093/cvr/cvw19