The chromosomal protein HMGN2 mediates the LPS-induced expression of β-defensins in mice

Human β-defensin-2 (HBD-2), an antimicrobial peptide produced by epithelial cells, plays an important role in the body's innate and adaptive immunity. High-mobility group N2 (HMGN2), a member of the HMG superfamily, binds to chromatin to modulate gene transcription. Previously, we have shown that HMGN2 acts as a positive modulator of the signal transduction cascade in the process of inducible human β-defensin expression. In our current study, we found that down-regulation of HMGN2 reduces the expression level of murine β-defensin-3 and -4 (mBD-3 and mBD-4), but not mBD-1 upon LPS stimulation in various tissues of pregnant ICR mice, as well as in embryonic and neonatal lungs and livers at different developmental time points. In the control group, murine HMGN2 expression decreased, while mBD-1 and mBD-4 expression increased slightly during development. In the LPS-treated groups, murine HMGN2 and mBD-1 expression did not change significantly, whereas mBD-3 and mBD-4 expression significantly increased in maternal, embryonic, and neonatal tissues, especially the mBD-3 expression. HMGN2 shRNA interference led to decreased mBD-3 and mBD-4 expression, while mBD-1 expression did not significantly change. These results demonstrate that HMGN2 is a component of the LPS-induced mouse β-defensin response.