Key role of endothelial importin-α in VEGF expression and gastric angiogenesis: novel insight into aging gastropathy
Key role of endothelial importin-α in VEGF expression and gastric angiogenesis: novel insight into aging gastropathy
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DOI：
10.1152/ajpgi.00382.2013
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发表时间：
2014-02-01
影响因子：
4.5
通讯作者：
Tarnawski, Andrzej S.
中科院分区：
文献类型：
--
作者：
Ahluwalia, Amrita;Jones, Michael K.;Tarnawski, Andrzej S.
最近的体内研究表明，衰老的胃粘膜血管生成受损，血管内皮生长因子（VEGF）的表达减少。血管生成由缺氧和VEGF基因激活触发，并且后者需要将转录因子转运到内皮细胞核中。我们专注于胃粘膜内皮细胞（GMEC），这是胃血管生成的关键目标和效应器，并确定是否以及在何种程度上importin-α，核转运蛋白，调节VEGF基因激活和胃血管生成和importin-α在衰老胃病的可能作用。分别从3和24月龄大鼠、青年大鼠（YGEC）和老年大鼠（AGEC）中分离GMEC。我们在这些细胞中检测了1）体外血管生成，2）VEGF和importin-alpha的表达，3）通过importin-alpha对缺氧诱导因子（HIF）-1 alpha的核转运，4）HIF-1 alpha与VEGF基因启动子的结合，以及5）YGEC中importin-alpha沉默及其在AGEC中上调对血管生成和VEGF表达的影响。与YGEC相比，AGEC表现出显著的体外血管生成受损4倍，VEGF、importin-α和核HIF-1 α的表达分别降低1.4倍、1.6倍和2.9倍。AGEC中importin-alpha的上调显著逆转了所有这些异常。在YGEC中，敲低导入蛋白-α 1和-α 3分别显著降低了93%和73%的体外血管生成和48%和52%的VEGF表达。上述研究结果表明，importin-alpha是胃血管生成的一种新型且关键的调节因子。其在AGEC中的表达减少是血管生成受损和VEGF减少的关键机制。
Recent in vivo studies demonstrated that aging gastric mucosa has impaired angiogenesis and reduced expression of vascular endothelial growth factor (VEGF). Angiogenesis is triggered by hypoxia and VEGF gene activation, and the latter requires transport of transcription factor(s) into endothelial cell nuclei. We focused on gastric mucosal endothelial cells (GMEC), which are key targets and effectors of gastric angiogenesis, and determined whether and to what extent importin-alpha, a nuclear transport protein, regulates VEGF gene activation and gastric angiogenesis and the possible role of importin-alpha in aging gastropathy. GMEC were isolated from rats 3 and 24 mo of age, young (YGEC) and aging (AGEC), respectively. We examined in these cells 1) in vitro angiogenesis, 2) expression of VEGF and importin-alpha, 3) nuclear transport of hypoxia-inducible factor (HIF)-1 alpha by importin-alpha, 4) binding of HIF-1 alpha to the VEGF gene promoter, and 5) effects of importin-alpha silencing in YGEC and its upregulation in AGEC on angiogenesis and VEGF expression. AGEC exhibited significantly impaired in vitro angiogenesis by fourfold and decreased expression of VEGF, importin- alpha, and nuclear HIF-1 alpha by 1.4-fold, 1.6-fold, and 2.9-fold, respectively, vs. YGEC. Upregulation of importin-alpha in AGEC significantly reversed all these abnormalities. In YGEC, knockdown of importins- alpha 1 and -alpha 3 significantly reduced in vitro angiogenesis by 93% and 73% and VEGF expression by 48% and 52%, respectively. The above findings demonstrate that importin-alpha is a novel and critical regulator of gastric angiogenesis. Its reduced expression in AGEC is the key mechanism for impaired angiogenesis and reduced VEGF.