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Abstract：
Endothelial nitric-oxide synthase (eNOS) and its bioactive product, nitric oxide (NO), mediate many endothelial cell functions, including angiogenesis and vascular permeability. For example, vascular endothelial growth factor (VEGF)-mediated angiogenesis is inhibited upon reduction of NO bioactivity both in vitro and in vivo Moreover, genetic disruption or pharmacological inhibition of eNOS attenuates angiogenesis during tissue repair, resulting in delayed wound closure. These observations emphasize that eNOS-derived NO can promote angiogenesis. Intriguingly, eNOS activity is regulated by nitric-oxide synthase trafficking inducer (NOSTRIN), which sequesters eNOS, thereby attenuating NO production. This has prompted significant interest in NOSTRIN\'s function in endothelial cells. We show here that NOSTRIN affects the functional transcriptome of endothelial cells by down-regulating several genes important for invasion and angiogenesis. Interestingly, the effects of NOSTRIN on endothelial gene expression were independent of eNOS activity. NOSTRIN also affected the expression of secreted cytokines involved in inflammatory responses, and ectopic NOSTRIN overexpression functionally restricted endothelial cell proliferation, invasion, adhesion, and VEGF-induced capillary tube formation. Furthermore, NOSTRIN interacted directly with TNF receptor-associated factor 6 (TRAF6), leading to the suppression of NFκB activity and inhibition of AKT activation via phosphorylation. Interestingly, TNF-α-induced NFκB pathway activation was reversed by NOSTRIN. We found that the SH3 domain of NOSTRIN is involved in the NOSTRIN-TRAF6 interaction and is required for NOSTRIN-induced down-regulation of endothelial cell proteins. These results have broad biological implications, as aberrant NOSTRIN expression leading to deactivation of the NFκB pathway, in turn triggering an anti-angiogenic cascade, might inhibit tumorigenesis and cancer progression.
摘要：
内皮型一氧化氮合酶(eNOS)及其生物活性产物,一氧化氮（NO），介导许多内皮细胞功能，包括血管生成和血管通透性。例如,血管内皮生长因子（VEGF）介导的血管生成在体外和体内NO生物活性降低后受到抑制。eNOS的遗传破坏或药理学抑制减弱组织修复过程中的血管生成，导致伤口闭合延迟。这些观察结果强调了eNOS来源的NO可以促进血管生成。有趣的是，eNOS活性受一氧化氮合酶运输诱导剂（NOSTRIN）调节，隔离eNOS，从而减少NO的产生。这促使人们对NOSTRIN在内皮细胞中的功能产生了极大的兴趣。我们在此表明，NOSTRIN通过下调对侵袭和血管生成重要的几个基因来影响内皮细胞的功能转录组。有趣的是,NOSTRIN对内皮基因表达的影响与eNOS活性无关。NOSTRIN还影响炎症反应中分泌的细胞因子的表达，和异位NOSTRIN过表达功能性限制内皮细胞增殖，入侵,附着力,和VEGF诱导的毛细管形成。此外，NOSTRIN与TNF受体相关因子6（TRAF6）直接相互作用，导致NFκB活性的抑制和通过磷酸化抑制AKT激活。有趣的是,TNF-α诱导的NFκB通路激活被NOSTRIN逆转。我们发现NOSTRIN的SH3结构域参与NOSTRIN-TRAF6相互作用，并且是NOSTRIN诱导的内皮细胞蛋白下调所必需的。这些结果具有广泛的生物学意义，由于NOSTRIN异常表达导致NFκB途径失活，进而引发抗血管生成级联反应，可能抑制肿瘤发生和癌症进展。
