Yi Na Wang1, Wei Wu, Hong Chao Chen, Hong Fang. 1. Department of Dermatology, 1st Affiliated Hospital, Zhejiang University School of Medicine, 79# Qing Chun Road, Hangzhou 310003, China.
Abstract
BACKGROUND: Genistein, as an active compound of dietary antioxidants, has shown considerable promise as an effective agent against aging process. However, the effect of genistein on skin photoaging and the associated mechanism remain unclear. OBJECTIVE: To delineate the effect of genistein on UVB-induced senescence in human dermal fibroblasts (HDFs) with emphasis on the mechanism of oxidative pathway regulated by p66Shc involved in the events. METHODS: HDFs were induced to premature senescence by repetitive subcytotoxic doses of UVB irradiation. Cellular apoptosis and DNA cell cycle were analyzed using flow cytometry. Intracellular levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were detected by ELISA. Mutation levels of two large deletions of mitochondrial DNA, 4977bp and 3895bp deletion, were determined by quantitative PCR. Western blot was applied to detect the expression and activation of p66Shc (the 66-kilodalton isoform of the growth factor adapter Shc) and FKHRL1 (a forkhead protein that is intimately linked with intracellular oxidation). RESULTS: Strong activity of senescence-associated beta-galactosidase (SA-beta-gal), high percent of cell apoptosis as well as cell cycle arrest in G0/G1 phase, and increased intracellular oxidative stress were observed in HDFs irradiated by UVB. Genistein exerted dramatically protective effects on HDFs in a dose-dependent manner. Elevated copy numbers of large deletions in mitochondrial DNA were also inhibited by genistein. Down-regulation of total and phosphorylated p66Shc on Ser36, as well as FKHRL1 and its phosphorylation on Thr32, were observed after genistein treatment. CONCLUSION: The results indicate that genistein protects UVB-induced senescence-like characteristics in HDFs via maintenance of antioxidant enzyme activities and modulation of mitochondrial oxidative stress through down-regulation of a p66Shc-dependent signaling pathway, which may provide potential prevention against skin aging and even photoaging. (c) 2010 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.
BACKGROUND:Genistein, as an active compound of dietary antioxidants, has shown considerable promise as an effective agent against aging process. However, the effect of genistein on skin photoaging and the associated mechanism remain unclear. OBJECTIVE: To delineate the effect of genistein on UVB-induced senescence in human dermal fibroblasts (HDFs) with emphasis on the mechanism of oxidative pathway regulated by p66Shc involved in the events. METHODS: HDFs were induced to premature senescence by repetitive subcytotoxic doses of UVB irradiation. Cellular apoptosis and DNA cell cycle were analyzed using flow cytometry. Intracellular levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were detected by ELISA. Mutation levels of two large deletions of mitochondrial DNA, 4977bp and 3895bp deletion, were determined by quantitative PCR. Western blot was applied to detect the expression and activation of p66Shc (the 66-kilodalton isoform of the growth factor adapter Shc) and FKHRL1 (a forkhead protein that is intimately linked with intracellular oxidation). RESULTS: Strong activity of senescence-associated beta-galactosidase (SA-beta-gal), high percent of cell apoptosis as well as cell cycle arrest in G0/G1 phase, and increased intracellular oxidative stress were observed in HDFs irradiated by UVB. Genistein exerted dramatically protective effects on HDFs in a dose-dependent manner. Elevated copy numbers of large deletions in mitochondrial DNA were also inhibited by genistein. Down-regulation of total and phosphorylated p66Shc on Ser36, as well as FKHRL1 and its phosphorylation on Thr32, were observed after genistein treatment. CONCLUSION: The results indicate that genistein protects UVB-induced senescence-like characteristics in HDFs via maintenance of antioxidant enzyme activities and modulation of mitochondrial oxidative stress through down-regulation of a p66Shc-dependent signaling pathway, which may provide potential prevention against skin aging and even photoaging. (c) 2010 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.