Oxidative stress mediates the apoptosis and epigenetic modification of the Bcl-2 promoter via DNMT1 in a cigarette smoke
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RESEARCH
Open Access
Oxidative stress mediates the apoptosis and epigenetic modification of the Bcl-2 promoter via DNMT1 in a cigarette smokeinduced emphysema model Huihui Zeng1,2,3, Tiao Li1,2,3, Xue He1,2,3, Shan Cai1,2,3, Hong Luo1,2,3, Ping Chen1,2,3 and Yan Chen1,2,3*
Abstract Background: Emphysema is a crucial pathological characteristic of chronic obstructive pulmonary disease (COPD). Oxidative stress, apoptosis and epigenetic mechanisms contribute to the pathogenesis of emphysema. However, an attempt to accurately identify whether these mechanisms interact with each other and how they are triggered has never been conducted. Method: The total reactive oxygen species (ROS) level, pulmonary apoptosis and B-cell lymphoma/leukemia-2 (Bcl2) expression, an apoptosis regulator, were detected in samples from COPD patients. Bisulfite sequencing PCR (BSP) was conducted to observe the alterations in the methylation of the Bcl-2 promoter in specimens. The dysregulation of DNA methyltransferase enzyme 1 (DNMT1), a vital DNA methyltransferase enzyme, in the lungs of patients was confirmed through western blotting. To find out interactions between oxidative stress and DNA methylation in emphysema, mouse models were built with antioxidant treatment and DNMT1 silencing, and were examined with the pulmonary apoptosis, Bcl-2 and DNMT1 levels, and epigenetic alterations of Bcl-2. Results: Higher ROS levels and pulmonary apoptosis were observed in COPD patients than in healthy controls. Downregulated Bcl-2 expression with increased promoter methylation and DNMT1 protein expression was found in COPD patients. Antioxidant treatment reduced the level of ROS, DNMT1 protein and emphysematous progression in the smoking models. Following DNMT1 blockade, smoking models showed improved lung function, pulmonary apoptosis, emphysematous progression, and increased Bcl-2 protein level with less promoter methylation than emphysema mice. Conclusion: Cigarette-induced oxidative stress mediates pulmonary apoptosis and hypermethylation of the Bcl-2 promoter in emphysema models through DNMT1. Keywords: Oxidative stress, Apoptosis, Hypermethylation, Bcl-2, DNMT1
* Correspondence: [email protected] 1 Department of Pulmonary and Critical Care Medicine, the Second Xiangya Hospital, Central South University, No. 139 Renmin Road, Changsha 410011, Hunan, China 2 Research Unit of Respiratory Diseases, Central South University, No. 139 Renmin Road, Changsha 410011, Hunan, China Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indica
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