Induction of murine interleukin-1 beta expression by water-soluble components from Hericium erinaceum

Abstract

Aim: To investigate the inductive effect of water extract from Hericium erinaceum (WEHE) on interleukin-1beta (IL-1beta) expression.

Methods: A murine macrophage cell-line, RAW 264.7 was stimulated with 1 to 10 mg/L WEHE and inductions of IL-1beta protein and its steady state mRNA were examined using a bioassay, Western blotting, and reverse transcription-polymerase chain reaction (RT-PCR) analysis. The inductive effect of WEHE on IL-1beta gene expression was further investigated by a chloramphenicol acetyltransferase (CAT) reporter gene assay using a transient transfection with pIL-1(870 bp)-CAT where the expression of the CAT gene was regulated by a IL-1beta promoter. An electrophoretic mobility shift assay (EMSA) was also performed to examine transcription factors, nuclear factor-kappa B (NF-kappaB), activator protein 1 (AP-1), nuclear factor interleukin-6 (NF-IL6), and cAMP response element (CRE)/activating transcription factor (ATF).

Results: WEHE induced IL-1beta production in both its mRNA and protein expression in a dose-dependent manner. The inductive effect of WEHE on IL-1beta gene expression was due to the augmentation of the IL-1beta transcription. Furthermore, EMSA showed that WEHE markedly increased the binding activities of NF-kappaB, and to a lesser extent, those of AP-1 and NF-IL6 to their cognate DNA recognition sites, whereas CRE/ATF binding remained constant, all of which are known to be involved in the regulation of IL-1beta gene expression.

Conclusion: WEHE induces IL-1kappa expression in macrophages at a transcriptional level by enhancing the activation of transcription factors, NF-kappaB, NF-IL6, and AP-1.