Response of VEGF expression to amino acid deprivation and inducers of endoplasmic reticulum stress.
Response of VEGF expression to amino acid deprivation and inducers of endoplasmic reticulum stress.
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发表时间：
2002-08
影响因子：
4.4
通讯作者：
S. Abcouwer;P. Marjon;R. Loper;D. V. Vander Jagt
中科院分区：
文献类型：
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作者：
S. Abcouwer;P. Marjon;R. Loper;D. V. Vander Jagt
目的 血管内皮生长因子 (VEGF) 在导致增殖性视网膜病的血管生成启动中发挥重要作用。影响 VEGF 表达的几种环境条件和化学试剂也会引起内质网 (ER) 应激。当前研究的假设是 VEGF 的表达对引起 ER 应激的条件（包括氨基酸剥夺）有反应。方法 人视网膜色素上皮细胞系 (ARPE-19) 的汇合培养物被去除氨基酸或用 ER 应激化学诱导剂处理。使用钴处理来模拟缺氧诱导的 VEGF 表达。 Northern blot分析用于测量细胞内VEGF mRNA，ELISA用于测量分泌的VEGF蛋白。将葡萄糖调节蛋白 78 (GRP78) mRNA 水平与 VEGF 进行比较。磷酸甘油醛脱氢酶 (GAPDH) mRNA 用作对照。结果 已知可激活 ER 应激反应 (ERSR) 途径的条件和化学试剂也会诱导 VEGF 的表达。培养基中氨基酸的缺失使 VEGF mRNA 表达增加 1.3 至 6 倍。葡萄糖剥夺或用衣霉素、布雷菲德菌素 A、钙离子载体 A23187 或毒胡萝卜素处理 ARPE-19 细胞可使这些细胞中 VEGF mRNA 的表达增加 8 至 10 倍。在所有条件下，GRP78 mRNA 的表达与 VEGF mRNA 的表达均呈良好相关性。这些治疗还使 VEGF 蛋白的分泌增加了两倍。谷氨酰胺剥夺后 VEGF mRNA 水平迅速增加（超过 10 倍），并且在生理相关的谷氨酰胺浓度范围内观察到。谷氨酰胺饥饿使 VEGF mRNA 的半衰期延长 2.5 倍。结论 这些结果表明 VEGF 是一种 ER 应激反应基因，并表明细胞可以通过转录和转录后机制增加 VEGF 表达来对营养缺乏做出反应。
PURPOSE Vascular endothelial growth factor (VEGF) plays an important role in initiation of the angiogenesis that leads to proliferative retinopathy. Several environmental conditions and chemical agents that influence the expression of VEGF can also cause endoplasmic reticulum (ER) stress. The hypothesis for the current study was that expression of VEGF is responsive to conditions that cause ER stress, including amino acid deprivation. METHODS Confluent cultures of a human retinal pigmented epithelial cell line (ARPE-19) were deprived of amino acids or treated with chemical inducers of ER stress. Treatment with cobalt was used to mimic hypoxia-induced expression of VEGF. Northern blot analysis was used to measure intracellular VEGF mRNA, and ELISA was used to measure secreted VEGF protein. Glucose-regulated protein 78 (GRP78) mRNA levels were compared with those of VEGF. Glyceraldehyde-phosphate dehydrogenase (GAPDH) mRNA was used as a control. RESULTS Conditions and chemical agents known to activate ER stress response (ERSR) pathways also induced the expression of VEGF. Deprivation of amino acids in the culture medium increased VEGF mRNA expression by 1.3- to 6-fold. Glucose deprivation or treatment of ARPE-19 cells with tunicamycin, brefeldin A, the calcium ionophore A23187, or thapsigargin increased the expression of VEGF mRNA in these cells by 8- to 10-fold. Expression of GRP78 mRNA was well correlated with that of VEGF mRNA under all conditions. These treatments also increased the secretion of VEGF protein by up to twofold. The increase in VEGF mRNA level in response to glutamine deprivation was rapid (greater than 10-fold) and was observed in a physiologically relevant range of glutamine concentrations. The half-life of VEGF mRNA was increased 2.5-fold by glutamine starvation. CONCLUSIONS These results indicate that VEGF is an ER stress-responsive gene and suggest that cells can respond to nutrient deprivation by increasing VEGF expression through both transcriptional and posttranscriptional mechanisms.