Heterogeneity of transcription factor expression and regulation in human airway epithelial and smooth muscle cells

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Abstract
Transcription factors represent a major mechanism by which cells establish basal and conditional expression of proteins, the latter potentially being adaptive or maladaptive in disease. The complement of transcription factors in two major structural cells of the lung relevant to asthma, airway epithelial and smooth muscle cells, is not known. A plate-based platform using nuclear extracts from these cells was used to assess potential expression by binding to oligonucleotide consensus sequences representing >300 transcription factors. Four conditions were studied: basal, β-agonist exposure, culture under proasthmatic conditions (IL-13, IL-4, TGF-β, and leukotriene D4), and the dual setting of β-agonist with proasthmatic culture. Airway epithelial cells expressed 70 transcription factors, whereas airway smooth muscle expressed 110. High levels of multiple transcription factors not previously recognized as being expressed in these cells were identified. Moreover, expression/ binding patterns under these conditions revealed extreme discordance in the direction and magnitude of change between the cell types. Singular (one cell type displayed regulation) and antithetic (both cell types underwent expression changes but in opposite directions) regulation dominated these patterns, with concomitant regulation in both cell types being rare (<10%). β-Agonist evoked up- and downregulation of transcription factors, which was highly influenced by the proasthmatic condition, with little overlap of factors regulated by β-agonists under both conditions. Together, these results reveal complex, cell type-dependent networks of transcription factors in human airway epithelium and smooth muscle that are dynamically regulated in unique ways by β-agonists and inflammation. These factors may represent additional components in asthma pathophysiology or potential new drug targets.