Expression of ABCA3, a causative gene for fatal surfactant deficiency, is up-regulated by glucocorticoids in lung alveolar type II cells
Expression of ABCA3, a causative gene for fatal surfactant deficiency, is up-regulated by glucocorticoids in lung alveolar type II cells
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DOI：
10.1016/j.bbrc.2004.08.133
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发表时间：
2004-10-15
影响因子：
3.1
通讯作者：
Inagaki, N
中科院分区：
文献类型：
--
作者：
Yoshida, I;Ban, N;Inagaki, N
我们以前已经证明，ATP结合盒转运体ABCA3主要表达在肺泡II型细胞板层小体的限制膜上。最近，ABCA3基因突变在患有致命性表面活性物质缺乏的新生儿中被报道。在目前的研究中，我们已经在大鼠肺中表明，ABCA3蛋白的表达在出生前20.5天的胚胎后显著增加。即使在胚胎18.5天，当地塞米松(Dex)从胚胎15.5开始给怀孕的雌性大鼠连续3天给予表面活性物质加速形成时，也显著地诱导了表达。由于地塞米松使人肺泡II型细胞系A549细胞中ABCA3基因的表达水平提高了4倍，因此我们克隆并鉴定了人ABCA3基因的启动子区域。ABCA3基因5‘侧翼区含有潜在的糖皮质激素反应元件(GRE)，启动子活性上调约2倍。当含有GRE的区域被删除或在GRE中引入点突变时，地塞米松并没有上调GRE的表达，使用地塞米松处理的A549核提取物的凝胶迁移率改变分析表明，糖皮质激素受体与GRE特异性结合。这些结果表明，糖皮质激素诱导的ABCA3在体内的表达上调是通过启动子中的GRE介导的转录激活，并提示ABCA3在肺表面活性物质的形成中发挥重要作用，可能是通过运输胆固醇等脂类。(C)2004 Elsevier Inc.保留所有权利。
We have shown previously that the ATP-binding cassette transporter ABCA3 is expressed predominantly at the limiting membrane of the lamellar bodies in lung alveolar type II cells. Very recently, an ABCA3 gene mutation was reported in human newborns with fatal surfactant deficiency. In the present study, we have shown in rat lung that expression of the ABCA3 protein is dramatically increased after embryonic day (E) 20.5 just before birth. Expression was also markedly induced even at E18.5 when dexamethasone (Dex), which is known to accelerate surfactant formation, was administered to pregnant female rats for 3 days from E15.5. Since Dex increased the ABCA3 mRNA expression level in human alveolar type II cell line A549 cells 4-fold, we cloned and characterized the promoter region of the human ABCA3 gene. Promoter activity of the 5'-flanking region of the ABCA3 gene, which contains a potential glucocorticoid-responsive element (GRE), was up-regulated about 2-fold. Up-regulation by Dex was not observed when the GRE-containing region was deleted or when a point mutation was introduced into the GRE, and electrophoretic mobility shift assay using Dex-treated A549 nuclear extracts demonstrated specific binding of the glucocorticoid receptor to the GRE. These findings demonstrate that glucocorticoid-induced up-regulation of ABCA3 expression in vivo is mediated by transcriptional activation through the GRE in the promoter, and suggest that ABCA3 plays an important role in the formation of pulmonary surfactant, probably by transporting lipids such as cholesterol. (C) 2004 Elsevier Inc. All rights reserved.