Ang II–stimulated migration of vascular smooth muscle cells is dependent on LR11 in mice
Meizi Jiang, … , Wolfgang J. Schneider, Yasushi Saito
Meizi Jiang, … , Wolfgang J. Schneider, Yasushi Saito
Published July 10, 2008
Citation Information: J Clin Invest. 2008;118(8):2733-2746. https://doi.org/10.1172/JCI32381.
View: Text | PDF
Research Article Cardiology

Ang II–stimulated migration of vascular smooth muscle cells is dependent on LR11 in mice

Abstract

Medial-to-intimal migration of SMCs is critical to atherosclerotic plaque formation and remodeling of injured arteries. Considerable amounts of the shed soluble form of the LDL receptor relative LR11 (sLR11) produced by intimal SMCs enhance SMC migration in vitro via upregulation of urokinase-type plasminogen activator receptor (uPAR) expression. Here, we show that circulating sLR11 is a novel marker of carotid intima-media thickness (IMT) and that targeted disruption of the LR11 gene greatly reduces intimal thickening of arteries through attenuation of Ang II–induced migration of SMCs. Serum concentrations of sLR11 were positively correlated with IMT in dyslipidemic subjects, and multivariable regression analysis suggested sLR11 levels as an index of IMT, independent of classical atherosclerosis risk factors. In Lr11–/– mice, femoral artery intimal thickness after cuff placement was decreased, and Ang II–stimulated migration and attachment of SMCs from these mice were largely abolished. In isolated murine SMCs, sLR11 caused membrane ruffle formation via activation of focal adhesion kinase/ERK/Rac1 accompanied by complex formation between uPAR and integrin αvβ3, a process accelerated by Ang II. Overproduction of sLR11 decreased the sensitivity of Ang II–induced activation pathways to inhibition by an Ang II type 1 receptor blocker in mice. Thus, we demonstrate a requirement for sLR11 in Ang II–induced SMC migration and propose what we believe is a novel role for sLR11 as a biomarker of carotid IMT.

Authors

Meizi Jiang, Hideaki Bujo, Kenji Ohwaki, Hiroyuki Unoki, Hiroyuki Yamazaki, Tatsuro Kanaki, Manabu Shibasaki, Kazuhiko Azuma, Kenichi Harigaya, Wolfgang J. Schneider, Yasushi Saito

×

Figure 1

Intimal thickness of arteries after cuff placement in Lr11–/– mice.

Options: View larger image (or click on image) Download as PowerPoint
Intimal thickness of arteries after cuff placement in Lr11–/– mice. ...
(A) Targeted disruption strategy of the murine LR11 gene, consisting of 49 exons. The targeting vector (bold line) contains 3.3 kb (5′) and 4.4 kb (3′) of genomic DNA flanking the neomycin-resistance cassette (Neor). After homologous recombination, Neor replaced exon 1 (Ex1, gray box), which contained the initiation codon of the LR11 gene. The location of the probe used for Southern blot analysis is shown. RV, EcoRV; X, XbaI; H, HindIII; E, EcoRI. (B) Southern blot analysis of murine-tail DNA from heterozygous intercrosses digested with EcoRV using the probe (see Figure 1A) that detects 17-kb and 6.8-kb fragments in the WT and knockout allele, respectively. (C) Immunodetection of LR11 protein. Total protein (100 μg) extracted from brain and kidney were separated by electrophoresis, blotted on a membrane, and incubated with antibody against LR11 (~250 kDa) or LRP1(~85 kDa). The samples were loaded on the same gel but not on immediately neighboring lanes. (D) Upper panels show sections of femoral artery of Lr11+/+ or Lr11–/– mouse after cuff placement, subjected to elastica van Gieson staining. Arrowheads indicate the internal elastic layers. Scale bar: 50 μm. Lower panel shows I/M ratio of arteries presented as mean ± SD (n = 15). *P < 0.05.