ROLE OF A TRANSCRIPTION FACTOR FAMILY IN LUNG DEVELOPMENT

这一提议背后的假设是，转录家族 因素方面，最初从肝脏分离的C/EBP家族起着关键作用 肺上皮细胞的分化。C/EBP家族的成员 已知在显示特化脂肪的细胞中起重要作用 新陈代谢。除肝脏外，C/EBPs的α、β和增量 研究表明，它在脂肪细胞分化中起作用。这些C/EBP的RNA是 也存在于肺中。初步数据表明，在成年大鼠中 肺、C/EBPSα和βmRNA及C/EBPSα、β和Delta蛋白 在II型细胞中大量富含。当单元格被移除时 从肺中提取和纯化后，蛋白质水平迅速下降。然而， 当细胞被电镀在修复SP-B、C/EBPalpha的基质上时 表达式也返回。在胎鼠中，C/EBPalpha的mRNA成为 可在怀孕18天至20天之间检测到，与 表面活性剂体系的成熟和可检测物质的出现 SP-A信使核糖核酸含量。C/EBPalpha蛋白水平也增加 基本上是在怀孕第19天左右。C/EBPalpha蛋白是 免疫斑点印迹法检测肺源性细胞株NCI-H441 它表达SP-A和SP-B，但不表达A549，它不表达 表面活性蛋白质。C？EBPalpha基因导入A549细胞的研究 反义基因转染NCI-H441细胞过程中SP-A基因的表达 针对C/E，PBPalpha可降低SP-A基因的表达。在人胎肺中 外植体培养，用cAMP和地塞米松处理似乎增加 胞核中C/EBPSβ，尤其是Delta的水平 肺泡。这些数据表明C/EBP家族参与了肺部 上皮细胞分化。拟议的实验将：1) C/EBP蛋白在发育正常人群中的表达特征 肺和支气管肺发育不良肺；2)评估疗效， C/EBP蛋白，加速处理(环磷酸腺苷、地塞米松、 T3)或减速(佛波酯，缺氧)肺发育；3)研究 调节C/EBP水平对培养肺和40细胞发育的影响 分析C/EBP蛋白在激活P-B转录中的作用 基因启动子。

The hypothesis underlying this proposal is that a family of transcription factors, the C/EBP family, originally isolated from liver has a key role int he differentiation of the lung epithelium. Members of the C/EBP family are known to play an important part in cells exhibiting specialized lipid metabolism. In addition to liver, C/EBPs alpha, beta and delta have been shown to have a role in adipocyte differentiation. RNA for these C/EBPs is also present int he lung. Preliminary data indicates that, in adult rat lung, C/EBPs alpha and beta mRNA and C/EBPs alpha, beta and delta protein are substantially enriched in type II cells. When the cells are removed from the lung and purified, the protein level rapidly declines. However, when the cells are plated on a matrix which restores SP-B, C/EBPalpha expression also returns. In fetal rats, mRNA for C/EBPalpha becomes detectable between days 18 and 20 of gestation, correlating with the maturation of the surfactant system and the appearance of detectable amounts of SP-A mRNA. Levels of C/EBPalpha protein also increase substantially at about day 19 of gestation. C/EBPalpha protein is detectable by immunodot blotting in NCI-H441, a lung-derived cell line which expresses SP-A and SP-B, but not in A549, which does not express the surfactant proteins. Transfection of A549 cells with C?EBPalpha induces SP-A gene expression while transfection of NCI-H441 cells with antisense against C/E PBPalpha reduces SP-A gene expression. In human fetal lung explant culture, treatment with cAMP and dexamethasone appeared to increase levels of C/EBPs beta and especially delta in nuclei of cells lining the alveoli. These data suggest the involvement of the C/EBP family in lung epithelial cell differentiation. The proposed experiments will: 1) characterize athe expression of C/EBP proteins in the developing normal lung and in the bronchopulmonary dysplasic lung; 2) evaluate the effect, on C/EBP proteins, of treatments which accelerate (cyclic AMP, dexamethasone, T3) or decelerate (phorbol ester, hypoxia) lung development; 3) study the effect of modulating C/EBP levels on development of cultured lung and 40 analyze the role of C/EBP proteins in activating transcription of the P-B gene promoter.