ROLE OF A TRANSCRIPTION FACTOR FAMILY IN LUNG DEVELOPMENT

这一提议背后的假设是， 最初从肝脏分离的C/EBP家族因子具有关键作用， 在肺上皮分化过程中。 C/EBP家族成员 在细胞中发挥重要作用， 新陈代谢. 除肝脏外，C/EBP α、β和δ也被 显示在脂肪细胞分化中具有作用。 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/EBP α和β mRNA以及C/EBP α、β和δ蛋白 基本上富含II型细胞。 当细胞被移除时 从肺中分离并纯化后，蛋白质水平迅速下降。 然而，在这方面， 当将细胞接种在恢复SP-B、C/EB α的基质上时， 表达式也返回。 在胎鼠中，C/EBPalpha的mRNA变得 在妊娠第18天至第20天之间可检测到， 表面活性剂体系的成熟和可检测的 SP-A mRNA的量。 C/EBPalpha蛋白水平也增加 基本上在妊娠第19天左右。 C/EBPalpha蛋白是 在NCI-H441（一种肺源性细胞系）中通过免疫斑点印迹法可检测到 其表达SP-A和SP-B，但不在A549中，A549不表达 表面活性剂蛋白。 用C？EBPalpha诱导 反义核酸转染NCI-H441细胞后SP-A基因的表达 针对C/E的PBPalpha降低SP-A基因表达。 人胚肺 外植体培养，用cAMP和地塞米松处理似乎增加 内衬细胞核中的C/EBP β水平，尤其是δ水平 肺泡 这些数据表明，C/EBP家族参与肺 上皮细胞分化 拟议的实验将：1） C/EBP蛋白在发育正常人中的特异性表达 肺和支气管肺发育不良肺; 2）评估效果， C/EBP蛋白，加速治疗（环AMP，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.