Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, Ohio.
Am J Physiol Lung Cell Mol Physiol. 2020 Jul 1;319(1):L126-L136. doi: 10.1152/ajplung.00023.2020. Epub 2020 May 20.
The differentiated functions of the human airway epithelium are coordinated by a complex network of transcription factors. These include the pioneer factors Forkhead box A1 and A2 (FOXA1 and FOXA2), which are well studied in several tissues, but their role in airway epithelial cells is poorly characterized. Here, we define the cistrome of FOXA1 and FOXA2 in primary human bronchial epithelial (HBE) cells by chromatin immunoprecipitation with deep-sequencing (ChIP-seq). Next, siRNA-mediated depletion of each factor is used to investigate their transcriptome by RNA-seq. We found that, as predicted from their DNA-binding motifs, genome-wide occupancy of the two factors showed substantial overlap; however, their global impact on gene expression differed. FOXA1 is an abundant transcript in HBE cells, while FOXA2 is expressed at low levels, and both these factors likely exhibit autoregulation and cross-regulation. FOXA1 regulated loci are involved in cell adhesion and the maintenance of epithelial cell identity, particularly through repression of genes associated with epithelial to mesenchymal transition (EMT). FOXA1 also directly targets other transcription factors with a known role in the airway epithelium such as SAM-pointed domain-containing Ets-like factor (SPDEF). The intersection of the cistrome and transcriptome for FOXA1 revealed enrichment of genes involved in epithelial development and tissue morphogenesis. Moreover, depletion of FOXA1 was shown to reduce the transepithelial resistance of HBE cells, confirming the role of this factor in maintaining epithelial barrier integrity.
人类气道上皮细胞的分化功能由转录因子的复杂网络协调。这些转录因子包括叉头框 A1 和 A2(FOXA1 和 FOXA2)等先驱因子,它们在许多组织中都得到了深入研究,但在气道上皮细胞中的作用却知之甚少。在这里,我们通过染色质免疫沉淀测序(ChIP-seq)来定义原代人支气管上皮(HBE)细胞中 FOXA1 和 FOXA2 的顺式作用元件。接下来,我们通过 siRNA 介导的两种因子耗竭,通过 RNA-seq 来研究它们的转录组。我们发现,正如其 DNA 结合基序所预测的那样,两种因子的全基因组占据存在显著重叠;然而,它们对基因表达的整体影响却不同。FOXA1 在 HBE 细胞中是一种丰富的转录本,而 FOXA2 的表达水平较低,这两种因子可能都表现出自身调控和相互调控。FOXA1 调控的基因座参与细胞黏附和上皮细胞身份的维持,特别是通过抑制与上皮间质转化(EMT)相关的基因。FOXA1 还直接靶向其他已知在气道上皮中发挥作用的转录因子,如 SAM 点样域包含 Ets 样因子(SPDEF)。FOXA1 的顺式作用元件和转录组的交集揭示了参与上皮发育和组织形态发生的基因富集。此外,FOXA1 的耗竭被证明降低了 HBE 细胞的跨上皮电阻,证实了该因子在维持上皮屏障完整性中的作用。