title: Dermato-protective properties of ergothioneine through induction of Nrf2/ARE-mediated antioxidant genes in UVA-irradiated Human keratinocytes.
abstract: UVA irradiation-induced skin damage and redox imbalance have been shown to be ameliorated by ergothioneine (EGT), a naturally occurring sulfur-containing amino acid. However, the responsible molecular mechanism with nanomolar concentrations of EGT remains unclear. We investigated the dermato protective efficacies of EGT (125-500nM) against UVA irradiation (15J/cm(2)), and elucidated the underlying molecular mechanism in human keratinocyte-derived HaCaT cells. We found that EGT treatment prior to UVA exposure significantly increased the cell viability and prevented lactate dehydrogenase release into the medium. UVA-induced ROS and comet-like DNA formation were remarkably suppressed by EGT with a parallel inhibition of apoptosis, as evidenced by reduced DNA fragmentation (TUNEL), caspase-9/-3 activation, and Bcl-2/Bax dysregulation. Furthermore, EGT alleviated UVA-induced mitochondrial dysfunction. Dose-dependent increases of antioxidant genes, HO-1, NQO-1, and γ-GCLC and glutathione by EGT were associated with upregulated Nrf2 and downregulated Keap-1 expressions. This was confirmed by increased nuclear accumulation of Nrf2 and inhibition of Nrf2 degradation. Notably, augmented luciferase activity of ARE may explain Nrf2/ARE-mediated signaling pathways behind EGT dermato-protective properties. We further demonstrated that Nrf2 translocation was mediated by PI3K/AKT, PKC, or ROS signaling cascades. This phenomenon was confirmed with suppressed nuclear Nrf2 activation, and consequently diminished antioxidant genes in cells treated with respective pharmacological inhibitors (LY294002, GF109203X, and N-acetylcysteine). Besides, increased basal ROS by EGT appears to be crucial for triggering the Nrf2/ARE signaling pathways. Silencing of Nrf2 or OCTN1 (EGT carrier protein) signaling with siRNA showed no such protective effects of EGT against UVA-induced cell death, ROS, and apoptosis, which is evidence of the vitality of Nrf2 translocation and protective efficacy of EGT in keratinocytes. Our findings conclude that EGT at nanomolar concentrations effectively ameliorated UVA-induced skin damage, and may be considered as a desirable food supplement for skin protection and/or preparation of skin care products.
authors.affiliation: Department of Cosmeceutics, College of Pharmacy, China Medical University, Taichung 40402, Taiwan; Department of Health and Nutrition Biotechnology, Asia University, Taichung 41354, Taiwan.
authors.forename: You-Cheng
authors.initials: YC
authors.lastname: Hseu
authors.affiliation: Department of Cosmeceutics, College of Pharmacy, China Medical University, Taichung 40402, Taiwan.
authors.forename: Heng-Wei
authors.initials: HW
authors.lastname: Lo
authors.affiliation: Institute of Nutrition, China Medical University, Taichung 40402, Taiwan.
authors.forename: Mallikarjuna
authors.initials: M
authors.lastname: Korivi
authors.affiliation: Department of Cosmeceutics, College of Pharmacy, China Medical University, Taichung 40402, Taiwan.
authors.forename: Yu-Cheng
authors.initials: YC
authors.lastname: Tsai
authors.affiliation: Department of Cosmeceutics, College of Pharmacy, China Medical University, Taichung 40402, Taiwan.
authors.forename: Meng-Ju
authors.initials: MJ
authors.lastname: Tang
authors.affiliation: Institute of Nutrition, China Medical University, Taichung 40402, Taiwan. Electronic address: hlyang@mail.cmu.edu.tw.
authors.forename: Hsin-Ling
authors.initials: HL
authors.lastname: Yang
mesh_terms: D021581:Active Transport, Cell Nucleus; D061745:Antioxidant Response Elements; D000975:Antioxidants / Q000494:pharmacology; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D002460:Cell Line; D004880:Ergothioneine / Q000494:pharmacology*; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D053078:Membrane Potential, Mitochondrial; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D027701:Organic Cation Transport Proteins / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D015398:Signal Transduction; D027981:Symporters; D015533:Transcriptional Activation / Q000187:drug effects; D014466:Ultraviolet Rays
chemical_list: D000975:Antioxidants; D051017:Apoptosis Regulatory Proteins; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D027701:Organic Cation Transport Proteins; D011837:Radiation-Protective Agents; C109807:SLC22A4 protein, human; D027981:Symporters; D004880:Ergothioneine
keywords: Apoptosis; Ergothioneine; Free radicals; Heme oxygenase-1; Nrf2; Skin damage; Ultraviolet A