Tae Ryong Lee

Dehydroabietic acid (DAA) is a naturally occurring diterpene resin acid derived from coniferous plants such as Pinus and Picea. Various bioactive effects of DAA have been studied including antibacterial, antifungal, and anticancer activities. However, the anti-inflammatory mechanism of DAA remains unclear. We evaluated the anti-inflammatory effect of DAA in macrophage cell lines. Dehydroabietic acid clearly reduced nitric oxide (NO) production and inflammatory gene expression decreased according to RT-PCR results. Dehydroabietic acid displayed anti-inflammatory activity at the transcriptional level in results from NF-κB- or AP-1-mediated luciferase assays. To identify the DAA target protein, we investigated NF-κB and AP-1 pathways by Western blotting analysis. Dehydroabietic acid suppressed the activity of proto-oncogene tyrosine protein kinase (Src) and spleen tyrosine kinase (Syk) in the NF-κB cascade and transforming growth factor beta-activated kinase 1 (TAK1) in the AP-1 cascade. Using overexpression strategies, we confirmed that DAA targeted these kinases. Our findings demonstrate the anti-inflammatory effects and molecular mechanism of DAA. This suggests that DAA has potential as a drug or supplement to ameliorate inflammation.

8-Hydroxydaidzein (8-HD) is a daidzein metabolite isolated from soybeans. This compound has been studied for its anti-proliferation, depigmentation, and antioxidant activities. However, the anti-inflammatory activities of 8-HD are not well-understood. Through its antioxidant effects in ABTS and DPPH assays, 8-HD reduces the production of sodium nitroprusside (SNP)-induced radical oxygen species (ROS). By triggering various Toll-like receptors (TLRs), 8-HD suppresses the inflammatory mediator nitric oxide (NO) without cytotoxicity. We examined the regulatory mechanism of 8-HD in lipopolysaccharide (LPS)-induced conditions. We found that 8-HD diminishes inflammatory gene expression (e.g., inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, and tumor necrosis factor (TNF)-α) by regulating the transcriptional activities of nuclear factor (NF)-κB and activator protein 1 (AP-1). To find the potential targets of 8-HD, signaling pathways were investigated by immunoblotting analyses. These analyses revealed that 8-HD inhibits the activation of TAK1 and that phosphorylated levels of downstream molecules decrease in sequence. Together, our results demonstrate the antioxidant and anti-inflammatory actions of 8-HD and suggest its potential use in cosmetics or anti-inflammatory drugs.

As the outermost physical barrier of an organism, the skin is diurnally exposed to UV radiation (UVR). Recent studies have revealed that the skin exhibits a circadian rhythm in various functions, and this oscillation is disturbed and reset via a strong environmental cue, the UVR. However, a molecular link between circadian perturbation by UVR and UVR‐induced cellular responses has not been investigated. We identified tissue inhibitor of metalloproteinase ( TIMP)‐3 as a novel circadian locomotor output cycles kaput (CLOCK)‐dependent diurnal gene by using a CLOCK ‐knockdown strategy in human keratinocytes. Among dozens of identified transcripts down‐regulated by CLOCK knockdown, TIMP3 displayed a rhythmic expression in a CLOCK‐dependent manner, in which the expression of matrix metalloproteinase (MMP)‐1 and inflammatory cytokines, such as TNF‐α, chemokine (C‐X‐C motif) ligand (CXCL)‐1, and IL‐8, were inversely regulated. Upon UVB exposure, the expression of CLOCK and TIMP3 was down‐regulated, which led to an up‐regulation of secretion of MMP1 and TNF‐α proteins and in the transcription of CXCL1 and IL‐8 via CCAAT‐enhancer binding protein (C/EBP)‐α. UVB‐induced TNF‐α secretion increased further or decreased by knockdown or overexpression of TIMP3 , respectively, as well as by CLOCK . As a novel CLOCK‐dependent diurnal gene, TIMP3 inhibits the expression of inflammatory cytokines that are up‐regulated by UV irradiation in human keratinocytes. Thus, our work suggests a molecular link between circadian perturbation by UVR and UVR‐induced inflammation.— Park, S., Kim, K., Bae, I.‐H., Lee, S. H., Jung, J., Lee, T. R., Cho, E.‐G. TIMP3 is a CLOCK‐dependent diurnal gene that inhibits the expression of UVB‐induced inflammatory cytokines in human keratinocytes. FASEB J. 32, 1510‐1523 (2018). www.fasebj.org

Our previous work has identified miR-125b as a negative regulator of melanogenesis. However, the specific melanogenesis-related genes targeted by this miRNA had not been identified. In this study, we established a screening strategy involving three consecutive analytical approaches—analysis of target genes of miR-125b, expression correlation analysis between each target gene and representative pigmentary genes, and functional analysis of candidate genes related to melanogenesis—to discover melanogenesis-related genes targeted by miR-125b. Through these analyses, we identified SRC homology 3 domain-binding protein 4 (SH3BP4) as a novel pigmentation gene. In addition, by combining bioinformatics analysis and experimental validation, we demonstrated that SH3BP4 is a direct target of miR-125b. Finally, we found that SH3BP4 is transcriptionally regulated by microphthalmia-associated transcription factor as its direct target. These findings provide important insights into the roles of miRNAs and their targets in melanogenesis.