Induction of apoptosis by cigarette smoke via ROS-dependent endoplasmic reticulum stress and CCAAT/enhancer-binding protein-homologous protein (CHOP)

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• 作者：Yasuhiro Tagawa ; Nobuhiko Hiramatsu ; Ayumi Kasai ; Kunihiro Hayakawa ; Maro Okamura ; Jian Yao ; Masanori Kitamura
• 关键词：Cigarette smoke ; Bronchial epithelial cell ; Apoptosis ; Endoplasmic reticulum stress ; Reactive oxygen species
• 刊名：Free Radical Biology and Medicine
• 出版年：2008
• 期刊代码：105_08915849
• 类别：med
• 出版时间：1 July 2008
• 卷：45
• 期：1
• 页码：50-59
• 文件大小：1310 K

摘要

In this report, we investigated a role of endoplasmic reticulum (ER) stress in cigarette smoke (CS)-induced apoptosis of human bronchial epithelial cells (hBEC). Exposure of hBEC to CS or CS extract (CSE) caused expression of endogenous ER stress markers GRP78 and CHOP and induction of apoptosis evidenced by nuclear condensation, membrane blebbing, and activation of caspase-3 and caspase-4. In vivo exposure of mice to CS also caused induction of GRP78 and CHOP in the lung. Attenuation of ER stress by overexpression of ER chaperone GRP78 or ORP150 significantly attenuated CSE-triggered apoptosis. Exposure of hBEC to CSE caused generation of reactive oxygen species, and treatment with antioxidants inhibited CSE-induced apoptosis. Interestingly, antioxidants including a scavenger of O₂^- blunted induction of CHOP by CSE without affecting the level of GRP78, and dominant-negative inhibition of CHOP abolished CSE-induced apoptosis. Furthermore, a generator of O₂^- selectively induced CHOP and apoptosis in hBEC. Our results revealed that: (1) CS induces ER stress in vitro and in vivo, (2) ER stress mediates CS-triggered apoptosis downstream of oxidative stress, (3) CS-initiated apoptosis is caused through oxidative stress-dependent induction of CHOP, (4) O₂^- may play a dominant role in this process, and (5) oxidative stress-independent induction of GRP78 counterbalances the proapoptotic action of CHOP.