Identification of Novel Inducible Genes in Airway Epithelium

DNA differential display analysis (DD-PCR) was utilized to identify genes that are expressed in airway epithelium and are relevant to airway inflammation; cytokine-mediated induction of gene expression and inhibition of that induction by glucocorticoids were the criteria for selection. The IB3-1 cell line was cultured in the presence of tumor necrosis factor-α (TNF-α), dexamethasone, or dimethyl sulfoxide (DMSO) as a control, and analyzed via DD-PCR and Northern blot analyses. With this approach, two TNF-α-inducible and dexamethasone (DEX)-sensitive expressed sequence tags (EST8 and EST19) were identified. In IB3-1 cells, TNF-α increased messenger RNA (mRNA) expression of EST8 (34%, P ≤ 0.005) and EST19 (41%, P ≤ 0.01), whereas dexamethasone reduced this expression to resting levels. This pattern of mRNA expression was also observed in normal human bronchial epithelial cells (EST8: 21%, P ≤ 0.009; EST19: 11%, P ≤ 0.02) and in the basophil leukemia cell line KU812 (EST8: 34%, P ≤ 0.01). Through basic local alignment search tool (BLAST) analysis, it was determined that these ESTs exhibited significant homology with the monomeric G protein rhoC (EST8: 100% homology, P = 1.6 × 10^-100) and the UFO tyrosine kinase receptor (EST19: 86% homology, 5.3 × 10^-28).