Abstract
In this study, we report the role of DNA methyltransferase 1 (DNMT1) in ultraviolet A (UVA)-induced senescence in human dermal fibroblasts (HDFs). We show that DNMT1 expression was significantly reduced during UVA-induced senescence, and this senescence could be alleviated or aggravated by the up- or down-regulation of DNMT1, respectively. Expression of the transcription factor zinc finger E-box binding homeobox 1(ZEB1) also decreased after UVA irradiation, following a UVA-induced increase of intracellular reactive oxygen species (ROS). We show that ZEB1 binds to the DMNT1 promoter and regulates its transcription, which, in turn, affects cellular senescence. These changes in DMNT1 and ZEB1 expression following UVA exposure were confirmed in matched skin specimens that had or had not been sun-exposed. On analyzing the promoter methylation of 24 senescence associated genes in these matched skin specimens, we discovered that p53 promoter methylation was significantly reduced in sun-exposed skin. In vitro experiments confirmed that UVA irradiation reduced p53 promoter methylation, and DNMT1 up-regulation could reverse this effect. Collectively, down-regulation of ZEB1 caused by UVA induced ROS could transcriptionally inhibit DNMT1, leading to low methylation level of senescence related proteins p53 and increase its expression, eventually result in cellar senescence.
Highlights
Chronic exposure to solar ultraviolet (UV) radiation is a major cause of premature skin aging, known as photoaging
Expression of the transcription factor zinc finger E‐box binding homeobox 1(ZEB1) decreased after ultraviolet A (UVA) irradiation, following a UVA‐induced increase of intracellular reactive oxygen species (ROS).We show that zinc finger E-box-binding homeobox 1 (ZEB1) binds to the DMNT1 promoter and regulates its transcription, which, in turn, affects cellular senescence
We have shown that DNA methyltransferase 1 (DNMT1) attenuated UVA-induced cellular senescence in human dermal fibroblasts (HDFs) by maintaining p53 promoter methylation, suppressing its expression
Summary
Chronic exposure to solar ultraviolet (UV) radiation is a major cause of premature skin aging, known as photoaging. UV induces responses such as oxidative stress, inflammatory responses, DNA damage and immune suppression, significantly affects epigenetic regulation, altering the gene expression programs that contribute to aging. Epigenetic features such as DNA methylation patterns and histone modifications are altered by exposure to UV radiation [4, 5]. Sun exposure induced an epigenetic shift towards DNA hypomethylation in human skin, and the degree of hypomethylation correlated with clinical photoaging measures [6]. Increases in histone H3-K9/14 acetylation within the promoter regions of ATF3, COX2, IL-8, MKP1, and MnSOD have been reported in UV-irradiated human keratinocytes [8]
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