NF-κB-mediated transcriptional regulation of human β-defensin-2 gene following lipopolysaccharide stimulation

Abstract

Abstract β-Defensins are cationic peptides with broad-spectrum antimicrobialactivities that contribute to innate host defense. Among humanβ-defensins (hBDs), hBD-2 is up-regulated in epithelial tissues andmononuclear phagocytes in response to bacterial infection andproinflammatory cytokines. However, little is known about the molecularmechanism of hBD-2 gene regulation. Here, we investigatedlipopolysaccharide (LPS)-mediated transcriptional regulation of thehBD-2 gene by focusing on the roles of NF-κB, STAT, and NF-IL-6 sitesin mononuclear phagocytes using RAW264.7 cells, which are sensitive to LPS. Luciferase reporter analyses demonstrated that two NF-κB siteswere essential for full LPS responsiveness of the hBD-2 gene. Further, both NF-κB sites were also crucial for basal transcriptionalactivity. In contrast, neither the NF-IL-6 nor STAT binding site wasrequired for LPS-induced hBD-2 transcription. Electrophoretic mobilityshift assay indicated that in unstimulated cells, NF-κB p50 homodimerbound to both NF-κB sites, whereas the p65-p50 heterodimer formedcomplexes with these sites following LPS stimulation. Together, theseobservations indicate that NF-κB plays an important role in theregulation of hBD-2 gene expression in response to LPS.