JNK1 and AP-1 regulate PMA-inducible squamous differentiation marker expression in Clara-like H441 cells
JNK1 and AP-1 regulate PMA-inducible squamous differentiation marker expression in Clara-like H441 cells
复制标题
DOI：
10.1152/ajplung.00125.2001
复制
发表时间：
2002-02-01
影响因子：
4.9
通讯作者：
Reddy, SPM
中科院分区：
文献类型：
--
作者：
Vuong, H;Patterson, T;Reddy, SPM
远端细支气管区暴露于各种毒物和污染物可抑制Clara细胞分化标志物的表达，并极大地促进鳞状细胞分化(SCD)的诱导。在这里，我们首次证明了佛波醇13-肉豆蔻酸酯(PMA)诱导的SCD标志物SPRR在Clara样H441细胞中的表达。对人SPRR1B表达的转录刺激主要由含有两个关键激活蛋白(AP)-1位点的-150-84-BP区域介导。在未经刺激的细胞中，-150-84-BP区域与AP-1蛋白结合较弱，主要是Jund和Fra1。而PMA显著诱导了JunB和Fra1的结合。与此一致，野生型Jun蛋白的过表达上调了SPRR1B启动子的活性。相反，c-jun突变体抑制了基础和PMA诱导的报告基因的表达。有趣的是，FRA2的过表达抑制了PMA诱导的报告活性，而FRA1显著增强了基础水平的活性，表明这些蛋白在SPRR1B表达中的相反作用与在近端气管支气管上皮细胞中观察到的类似(BEAS-2B克隆S6)。有趣的是，与S6细胞不同，c-Jun NH2末端激酶(JNK)1突变体显著降低了PMA诱导的H441细胞中SPRR1B启动子的活性。因此，JNK1对AP-1蛋白的时间表达和/或空间激活可能参与了Clara细胞SCD的诱导。
Exposure of distal bronchiolar region to various toxicants and pollutants suppresses Clara cell differentiation marker expression and greatly enhances the induction of squamous cell differentiation (SCD). Here, we demonstrate for the first time phorbol 13-myristate 12-acetate (PMA)-inducible expression of SCD markers, SPRRs, in Clara-like H441 cells. The transcriptional stimulation of human SPRR1B expression is mainly mediated by a -150- to -84-bp region that harbors two critical activator protein (AP)-1 sites. In unstimulated cells, the -150- to -84-bp region is weakly bound by AP-1 proteins, mainly JunD and Fra1. However, PMA prominently induced the binding of JunB and Fra1. Consistent with this, overexpression of wild-type Jun proteins upregulated the SPRR1B promoter activity. Conversely, a c-jun mutant suppressed both basal and PMA-inducible reporter gene expression. Intriguingly, overexpression of fra2 suppressed PMA-inducible reporter activity, whereas fra1 significantly enhanced basal level activity, indicating an opposing role for these proteins in SPRR1B expression in a manner similar to that observed in proximal tracheobronchial epithelial cells (BEAS-2B clone S6). Interestingly, unlike in S6 cells, a catalytically inactive c-Jun NH2-terminal kinase (JNK) 1 mutant significantly reduced the PMA-inducible SPRR1B promoter activity in H441 cells. Thus either temporal expression and/or spatial activation of AP-1 proteins by JNK1 might contribute to the induction of SCD in Clara cells.