Protective role of HMGB1 in keratinocytes in skin inflammation

ABSTRACT: Dysregulation and abnormal expression of inflammatory mediators by keratinocytes promote the pathogenesis of the skin inflammation such as allergic contact dermatitis (ACD). High-mobility group box 1 (HMGB1) protein, a prototypical damage-associated molecular pattern (DAMP), that is expressed in the nucleus but released extracellularly upon inflammation has gained attention as an accelerator for skin inflammation. However, in vivo role of HMGB1 in ACD and other skin disorders remains to be elusive. In this study, we generated conditional knockout mice in which HMGB1 is deleted in keratinocytes and examined its role in skin inflammation models including 2,4-dinitrofluorobenezene (DNFB)-induced ACD. Unexpectedly, deletion of HMGB1 in keratinocytes exacerbated skin inflammation, accompanied by increased ear thickening. Elevated mRNA expression of interleukin-24 (IL-24), a known cytokine which promotes the pathogenesis of ACD, was also observed in the skin lesion of the mice. In accordance with above observations, both constitutive and IL-4-induced Il24 mRNA expression in vitro was augmented in hmgb1-deficient primary mouse keratinocytes and keratinocyte cell line PAM212 cells. Chromatin immunoprecipitation (ChIP) analysis revealed increased binding of tri-methyl histone H3 (lys4) (H3K4me3), a well-known histone mark for transcription active genes, to the promoter region of the Il24 gene in the hmgb1-deficient cells. ChIP-sequencing data also showed broad changes of H3K4me3 mark in the cells. Thus, HMGB1 in the nucleus dictates histone modifications. In conclusion, our study demonstrated a key role for HMGB1 in keratinocytes in the maintenance of chromatin modification status to protect from exuberant skin inflammation.

ORGANISM(S): Mus musculus

PROVIDER: GSE159695 | GEO | 2021/01/01

REPOSITORIES: GEO