Cyclic stretch-induced Crp3 sensitizes vascular smooth muscle cells to apoptosis during vein arterialization remodeling

Abstract

Vein graft failure limits the long-term patency of the saphenous vein used as a conduit for coronary artery bypass graft. Early graft adaptation involves some degree of intima hyperplasia to sustain the hemodynamic stress, but the progress to occlusion in some veins remains unclear. We have demonstrated that stretch-induced up-regulation of cysteine and glycine-rich protein 3 (Crp3) in rat jugular vein and human saphenous vein in response to arterialization. Here, we developed a Crp3-knockout (KO) rat to investigate the role of Crp3 in vascular remodeling. After 28 days of jugular vein arterialization, the intima layer was three-fold thicker in the Crp3-KO that showed comparable smooth muscle cells (SMC) proliferation but an absence of early apoptosis observed in the wild-type (WT) rat. We then investigated the role of Crp3 in early integrin-mediated signaling apoptosis in isolated jugular SMC. Interestingly, under basal conditions, ceramide treatment failed to induce apoptosis in both WT and Crp3-KO SMC. Under stretch, Crp3 expression increased in WT SMC and ceramide-induced apoptosis. Immunoblotting analysis indicated that ceramide stretch-induced apoptosis in SMC is accompanied by a decrease in the phosphorylation status of both focal adhesion kinase (Fak) and protein kinase B (Akt), leading to an increase in Bax expression and caspase-3 cleavage. In contrast, ceramide failed to decrease Fak and Akt phosphorylation in Crp3-KO SMC and, therefore, there was no downstream induction of Bax expression and effector caspase-3 cleavage. Taken together, we provide evidence that stretch-induced Crp3 modulates vein remodeling in response to arterialization by sensitizing SMC to apoptosis.