Gene Regulatory Regions Required for beta Defensin-2 Up-Regulation by Interleukin-1alpha in the Human Middle Ear Epithelial Cell Line

Abstract

BACKGROUND AND OBJECTIVES: Innate immunity is important in the middle ear because of the lack of immune cells in the region. Among innate immunities beta-defensin-2 is known to play an important role in the immune function of the middle ear. But we still do not understand well about the signal transduction pathway and gene regulatory region of beta-defensin-2 (hBD-2). MATERIALS AND METHOD: The expression of beta-defensin-2 (hBD-2) by IL-1alpha in HMEEC was detected by RT-PCR. The luciferase-expressing vector containing diverse lengths of the hBD-2 5' flanking region made by the progressive unidirectional deletion was transferred to HEEMC (Human Middle Ear Cell). We analyzed the function of 5' flanking region by luciferase activity measured using a luminometer after supplementing corresponding substrates to the cell lysate. RESULTS: hBD-2 was upregulated by IL-1alpha in HMEEC-1. The treatment of IL-1alpha up-regulated the activity of promoter by 7.60+/-1.45 (average+/-standard deviation) folds in 2.7 kpb sized 5' flanking region, 3.81+/-0.78 folds in 1.1 kbp, and 4.00+/-0.73 folds in 500 bp. CONCLUSION: These results indicate there are two effective gene regions that regulate the hBD-2 expression by IL-1alpha between 2.7 kbp and 1.1 kbp, and at 500 bp upstream of the translation starting point of hBD-2 in HMEEC-1.