Department of Cardiology, Cardiovascular Research Institute, Shenyang Northern Hospital, Shenyang, China.
Atherosclerosis. 2011 Oct;218(2):543-51. doi: 10.1016/j.atherosclerosis.2011.08.002. Epub 2011 Aug 10.
Cellular repressor of E1A-stimulated genes (CREG) is a homeostasis-modulating gene abundantly expressed in adult artery endothelium. Previous studies have demonstrated a protective effect of CREG against atherosclerosis through prevention of vascular smooth muscle cell apoptosis. However, the role of CREG in endothelial cells (ECs) apoptosis and the underlying signaling mechanisms are unknown.
We ascertained that CREG expression was decreased in atherogenesis-prone endothelium in apolipoprotein E-null (apoE(-/-)) mice compared with their wild-type littermates using in situ immunofluorescent staining. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) staining and caspase-3 activity assays determined that treatment of apoE(-/-) mice arteries with staurosporine (STS) significantly induced endothelial apoptosis associated with a reduction of CREG expression. Gain- and loss-of-function analyses revealed that silencing CREG expression significantly enhanced ECs apoptosis, whereas CREG overexpression abrogated apoptosis stimulated by STS or etoposide (VP-16). Blocking assays using the neutralizing antibody for vascular endothelial growth factor (VEGF) and the specific inhibitor of phosphoinositide 3-kinase (PI3K), such as LY294002 or wortmannin, demonstrated that the protective effect of CREG on ECs apoptosis was mainly mediated by activation of the VEGF/PI3K/AKT signaling pathway.
These data demonstrate that CREG plays a critical role in protecting the vascular endothelium from apoptosis, and the protective effort of CREG against ECs apoptosis is through the activation of the VEGF/PI3K/AKT signaling pathway.
E1A 刺激基因的细胞抑制剂（CREG）是一种在成人动脉内皮细胞中大量表达的维持内环境稳定的基因。先前的研究表明，CREG 通过防止血管平滑肌细胞凋亡对动脉粥样硬化起到保护作用。然而，CREG 在血管内皮细胞（EC）凋亡中的作用及其潜在的信号机制尚不清楚。
我们通过原位免疫荧光染色确定，载脂蛋白 E 基因敲除（apoE(-/-)）小鼠的动脉粥样硬化易发生部位内皮细胞的 CREG 表达降低，与野生型同窝仔相比。末端脱氧核苷酸转移酶介导的 dUTP-生物素缺口末端标记（TUNEL）染色和 caspase-3 活性测定表明，用司他丁（STS）处理 apoE(-/-) 小鼠的动脉会显著诱导内皮细胞凋亡，同时伴有 CREG 表达减少。基因沉默和过表达分析表明，沉默 CREG 表达会显著增强 ECs 凋亡，而 CREG 过表达则可阻断 STS 或依托泊苷（VP-16）诱导的凋亡。使用血管内皮生长因子（VEGF）的中和抗体和磷脂酰肌醇 3-激酶（PI3K）的特异性抑制剂，如 LY294002 或wortmannin 的阻断实验表明，CREG 对 ECs 凋亡的保护作用主要是通过激活 VEGF/PI3K/AKT 信号通路介导的。
这些数据表明，CREG 在保护血管内皮细胞免于凋亡方面发挥着关键作用，CREG 对 ECs 凋亡的保护作用是通过激活 VEGF/PI3K/AKT 信号通路实现的。
