Soy isoflavone daidzein에 의한 레티노이드 수용체 활성화 연구

Abstract

Retinoids modulate keratinocyte proliferation, differentiation, collagen synthesis and degradation, inflammatory response, and reduce sebum production in the skin. They have been used as therapeutic agents for diverse skin diseases such as aged skin, acne and skin cancer. Retinoids actions are mediated by retinoic acid receptors (RARs). Among the three isotypes, RARα,β and γ, RARα and RARγ are expressed and regulate retinoid target genes in the skin. Here, we found that extracts of two different soy beans, Glycine max and Rhynchosia Nulubilis increased transcriptional activity of RARα and RARγ. Further fractionation revealed that among the fractions, ethyl acetate fractions up-regulated transcriptional activity of RARs. HPLC analysis of the extracts and ethyl acetate fractions showed that daidzin and genistin are the major constituents of the fractions. Daidzin and its aglycone form, daidzein induce RAR transcriptional activity in dose-dependent manner. Genistin and genistein also up-regulated RAR transcriptional activity but their effects were weaker than that of daidzin and daidzein. Time resolved-fluorescence resonance energy transfer (TR-FRET) analysis demonstrated that daidzein bound both RARα and RARγ ligand binding domains and recruited co-activators. Daidzein increased RAR target genes, RARα and RARγ mRNA in time dependent manner in the keratinocyte, HaCaT. ChIP analysis showed that daidein treatment enhanced recruitment of RARα, RARγ, and p300 on functional RARE in the RARγ2 promoter. Protein levels of RARα and RARγ were reduced by daidzein, similar to the reduction by all-trans retinoic acid. Matrix metallopeptidase-9, which degrades collagen and enhances skin aging, was up-regulated by TNFα treatment, and its mRNA level and gelatinolytic activity were reduced by daidzein. Together, these results suggest that daidzein may be a functional ligand of retinoic acid receptors and it could be a therapeutic candidate for skin diseases as an alternative of retinoid. Also, these findings could explain a new mechanism of anti-skin aging effects of daidzein