Abstract
Dehydrotrametenolic acid (DTA) is a lanostane-type triterpene acid isolated from Poria cocos Wolf (Polyporaceae). Several studies have reported the anti-inflammatory and antidiabetic effects of DTA; however, its effects on the skin are poorly understood. In this study, we investigated the effects of DTA on skin barrier function in vitro and its regulatory mechanism in human keratinocyte cell line HaCaT cells. DTA increased the microRNA (mRNA) expression of natural moisturizing factor-related genes, such as HAS-2, HAS-3, and AQP3 in HaCaT cells. DTA also upregulated the mRNA expression of various keratinocyte differentiation markers, including TGM-1, involucrin, and caspase-14. Moreover, the protein expression of HAS-2, HAS-3, and TGM-2 were significantly increased by DTA. To examine the regulatory mechanisms of DTA, Western blotting, luciferase-reporter assays, and RT-PCR were conducted. The phosphorylation of mitogen-activated protein kinases (MAPKs) and IκBα were increased in DTA-treated HaCaT cells. In addition, AP-1 and NF-κB transcriptional factors were dose-dependently activated by DTA. Taken together, our in vitro mechanism studies indicate that the regulatory effects of DTA on skin hydration and keratinocyte differentiation are mediated by the MAPK/AP-1 and IκBα/NF-κB pathways. In addition, DTA could be a promising ingredient in cosmetics for moisturizing and increased skin barrier function.