神经纤维素2通过Hippo/YAP途径抑制VSMC增殖失调在血管再狭窄发生中的作用研究

The incidence of coronary artery restenosis after percutaneous coronary intervention(PCI) remains high. VSMC proliferation plays a vital role in this pathophysiological process. Neurofibromin 2 (NF2) regulates tumor angiogenesis, indicating that NF2 may be involved in the process of vascular remodeling. Our previous studies showed that the level of NF2 phosphorylation is up-regulating after vascular endothelium injury, and NF2 knockdown decreases the YAP phosphorylation, leading to VSMCs proliferation and restenosis. Thus, we infer that the increasing cytokines after endothelium injury up-regulates NF2 phosphorylation and results in NF2 inactivation; the inactivate NF2 decreases the phosphorylation of protein in Hippo pathway such as WST1/2、LATS1/2 and YAP, and decreases the suppression of NF2 to cell proliferation, leading to artery remodeling and restenosis. To verify the hypothesis, the wire-induced arterial injury mice model and carotid artery stenting VSMC-specific NF2 KO mice will be used to study the effects of NF2 in the VSMC proliferation and the underlying mechanisms, which may be an effective therapeutic target for prevention and treatment of restenosis.

冠状动脉介入治疗后血管再狭窄发生率较高，血管平滑肌细胞（VSMC）增殖在这个过程中发挥着关键作用。神经纤维素2（NF2）可调节肿瘤新生血管形成，提示其在血管重构中发挥重要作用。我们通过预实验发现，血管内皮损伤可促进新生内膜NF2磷酸化；NF2基因敲低后，Hippo通路中YAP磷酸化水平下调，VSMC增殖增加，提示NF2可能通过Hippo/YAP通路调节VSMC增殖，从而在血管再狭窄中发挥作用。据此推测：血管内皮损伤后，局部增加的细胞因子可促进NF2磷酸化，致其失活，Hippo通路蛋白WST1/2、LATS1/2及YAP磷酸化降低，引发NF2抑制VSMC增殖能力减弱，血管异常重构，从而导致血管再狭窄。为验证此假设，本项目拟用内皮机械损伤和颈动脉支架植入平滑肌细胞特异性NF2基因敲除小鼠，通过在体、离体实验研究VSMC增殖，探讨NF2对VSMC增殖的调控机制，为血管再狭窄防治提供新靶点。

据报道，神经纤维素2（NF2）是一种有效的肿瘤抑制因子，可抑制多种细胞的增殖。NF2在血管损伤后新生内膜增生中的作用尚不清楚。我们探讨了NF2在血管损伤后血管平滑肌细胞（VSMC）增殖、迁移和内膜增生中的作用。在接受血小板衍生生长因子（PDGF）-BB的VSMC和受到血管损伤的动脉中，NF2磷酸化升高。血管平滑肌细胞NF2缺乏的小鼠在损伤后表现为新生内膜增生增强，PDGF-BB治疗后血管平滑肌细胞增殖和迁移增加。在机制上，我们观察到PDGF-BB处理VSMC或血管受到损伤后，核p-NF2增加，p-Yes相关蛋白（YAP）下降，YAP核移位。NF2敲除或YAP过度表达在VSMC增殖、迁移和新生内膜增生中表现出相似的表型。YAP抑制消除了NF2敲除介导的上述效应。最后，在PDGF-BB治疗后，NF2敲除进一步促进了YAP-TEA域转录因子1（TEAD1）的相互作用。TEAD1的抑制阻断了PDGF-BB诱导的VSMC增殖和迁移，NF2基因敲除或YAP过表达均不能逆转这种现象。总之，NF2基因敲除通过诱导YAP-TEAD1相互作用促进血管损伤后VSMC增殖、迁移和新生内膜增生。