NOX1/NADPH oxidase is involved in endotoxin-induced cardiomyocyte apoptosis

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• 作者：Kuniharu Matsuno ; Kazumi Iwata ; Misaki Matsumoto ; Masato Katsuyama ; Wenhao Cui ; Ayumi Murata ; Hideo Nakamura ; Masakazu Ibi ; Kanako Ikami ; Jia Zhang ; Satoaki Matoba ; Denan Jin ; Shinji Takai ; Hiroaki Matsubara ; Naoyuki Matsuda ; Chihiro Yabe-Nishimura
• 关键词：Cardiomyocyte apoptosis ; NADPH oxidase ; Protein kinase B (Akt) ; Protein phosphatase 2A (PP2A) ; Sepsis
• 刊名：Free Radical Biology and Medicine
• 出版年：2012
• 出版时间：1 November, 2012
• 年：2012
• 卷：53
• 期：9
• 页码：1718-1728
• 全文大小：1363 K

文摘

The functional significance of NOX1/NADPH oxidase in the heart has not been explored due to its low expression relative to other NOX homologs identified so far. We aimed to clarify the role of NOX1/NADPH oxidase in the septic heart by utilizing mice deficient in the Nox1 gene (Nox1^?/Y). Sepsis was induced by intraperitoneal administration of lipopolysaccharides (LPS: 25 mg/kg) or cecal ligation and puncture (CLP) surgery. A marked elevation of NOX1 mRNA was demonstrated in cardiac tissue, which was accompanied by increased production of reactive oxygen species (ROS). In Nox1^?/Y treated with LPS, cardiac dysfunction and survival were significantly improved compared with wild-type mice (Nox1^+/Y) treated with LPS. Concomitantly, LPS-induced cardiomyocyte apoptosis and activation of caspase-3 were alleviated in Nox1^?/Y. The level of phosphorylated Akt in cardiac tissue was significantly lowered in Nox1^+/Y but not in Nox1^?/Y treated with LPS or that underwent CLP surgery. Increased oxidation of cysteine residues of Akt and enhanced interaction of Akt with protein phosphatase 2A (PP2A), a major phosphatase implicated in the dephosphorylation of Akt, were demonstrated in LPS-treated Nox1^+/Y. These responses to LPS were significantly attenuated in Nox1^?/Y. Taken together, ROS derived from NOX1/NADPH oxidase play a pivotal role in endotoxin-induced cardiomyocyte apoptosis by increasing oxidation of Akt and subsequent dephosphorylation by PP2A. Marked up-regulation of NOX1 may affect the risk of mortality under systemic inflammatory conditions.