Silencing of Int6 Promotes Recovery of Blood Perfusion after Limb Ischemia via Stabilizing Hypoxia-Inducible Factor 2α

低氧诱导因子（Hypoxia-inducible factors，HIF）是低氧应答基因的关键调控因子。特别是，HIF-2α在血管重塑中起重要作用，通过转录几种血管生成因子导致成熟的血管生成。本研究的目的是验证Int 6沉默和伴随的HIF-2α稳定可能增强组织缺血中血流恢复的假设。对Int 6沉默在培养的肌肉细胞中的作用的分析表明，Int 6的沉默通过诱导和稳定HIF-2α导致与血管生成蛋白相对应的几个基因的上调，包括碱性成纤维细胞生长因子和血小板衍生生长因子-B。此外，内皮细胞的管形成分析揭示了对INT 6沉默的肌细胞的旁分泌反应的增加。在小鼠后肢缺血模型中，肌肉注射设计用于抑制Int 6的小干扰RNA质粒导致受损组织的灌注和功能恢复显著增强。肌肉中的Int 6沉默导致缺血肢体中血流的恢复增强。Int 6可能作为一个有价值的治疗靶点来控制缺血性疾病中的血管生成。

Hypoxia-inducible factors (HIFs) are the key regulators of hypoxia-responding genes. In particular, the HIF-2α plays an essential role in vascular remodeling, leading to mature angiogenesis by transcribing several angiogenic factors. The aim of current study is to test the hypothesis that silencing of Int6 and concomitant HIF-2α stabilization may enhance the recovery of blood flow in tissue ischemia. Analysis of the effect of Int6 silencing in cultured muscle cells implied that silencing of Int6 led to up-regulation of several genes corresponding to angiogenic proteins, including basic fibroblast growth factor and platelet-derived growth factor-B through induction and stabilization of HIF-2α. Moreover, tube formation analysis of endothelial cells revealed an increase in paracrine response to INT6-silenced muscle cells. In mouse models of hindlimb ischemia, intramuscular injection of small interfering RNA plasmid designed to inhibit Int6 led to significantly enhanced perfusion and functional recovery of damaged tissues. Int6 silencing in muscle leads to enhanced recovery of blood flow in ischemic limb. Int6 may serve as a valuable therapeutic target to control angiogenesis in ischemic diseases.