Aims Proper arteriogenesis after tissue ischemia is necessary to rebuild stable blood circulation; nevertheless, this process is impaired in type-2 diabetes mellitus (T2DM). Raptor, is a scaffold protein and a component of mammalian target of rapamycin complex 1 (mTORC1). However, the role of the endothelial Raptor in arteriogenesis under the conditions of T2DM remains unknown. This study investigated the role of endothelial Raptor in ischemia-induced arteriogenesis during T2DM. Methods and Results Although endothelial mTORC1 is hyperactive in T2DM, we observed a marked reduction in the expression of endothelial Raptor in two mouse models and in human vessels. Inducible endothelial-specific Raptor knockout severely exacerbated impaired hindlimb perfusion and arteriogenesis after hindlimb ischemic injury in 12-week high-fat diet fed mice. Additionally, we found that Raptor deficiency dampened vascular endothelial growth factor receptor 2 (VEGFR2) signaling in endothelial cells and inhibited VEGF-induced cell migration and tube formation in a PTP1B-dependent manner. Furthermore, mass spectrometry analysis indicated that Raptor interacts with neuropilin 1 (NRP1), the co-receptor of VEGFR2, and mediates VEGFR2 trafficking by facilitating the interaction between NRP1 and Synectin. Finally, we found that endothelial cell-specific overexpression of the Raptor mutant (loss of mTOR binding) reversed impaired hindlimb perfusion and arteriogenesis induced by endothelial Raptor knockout in high-fat diet fed mice. Conclusions Collectively, our study demonstrated the crucial role of endothelial Raptor in promoting ischemia-induced arteriogenesis in T2DM by mediating VEGFR2 signaling. Thus, endothelial Raptor is a novel therapeutic target for promoting arteriogenesis and ameliorating perfusion in T2DM.

中文翻译：

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内皮猛禽在2型糖尿病下肢缺血后动脉生成异常中的作用

目的组织缺血后适当的动脉生成对于重建稳定的血液循环是必要的；然而，这一过程在 2 型糖尿病 (T2DM) 中受到损害。 Raptor 是一种支架蛋白，也是哺乳动物雷帕霉素靶点复合物 1 (mTORC1) 的组成部分。然而，内皮猛禽在 T2DM 条件下动脉生成中的作用仍不清楚。本研究调查了内皮猛禽在 T2DM 期间缺血诱导的动脉生成中的作用。方法和结果 尽管内皮 mTORC1 在 T2DM 中高度活跃，但我们在两种小鼠模型和人类血管中观察到内皮 Raptor 的表达显着减少。在 12 周高脂饮食喂养的小鼠中，后肢缺血性损伤后，诱导性内皮特异性 Raptor 敲除严重加剧了后肢灌注和动脉生成受损。此外，我们发现 Raptor 缺陷会抑制内皮细胞中的血管内皮生长因子受体 2 (VEGFR2) 信号传导，并以 PTP1B 依赖性方式抑制 VEGF 诱导的细胞迁移和管形成。此外，质谱分析表明，Raptor 与 VEGFR2 的共同受体神经毡蛋白 1 (NRP1) 相互作用，并通过促进 NRP1 和 Synectin 之间的相互作用来介导 VEGFR2 运输。最后，我们发现内皮细胞特异性过度表达 Raptor 突变体（mTOR 结合丧失）可逆转高脂饮食喂养小鼠内皮 Raptor 敲除引起的后肢灌注受损和动脉生成。结论 总的来说，我们的研究证明了内皮 Raptor 通过介导 VEGFR2 信号传导在 T2DM 中促进缺血诱导的动脉生成中发挥着至关重要的作用。因此，内皮 Raptor 是促进 T2DM 动脉生成和改善灌注的新治疗靶点。