Hepatocyte-Specific Deletion of Heme Oxygenase-1 Disrupts Redox Homeostasis in Basal and Oxidative Environments
Hepatocyte-Specific Deletion of Heme Oxygenase-1 Disrupts Redox Homeostasis in Basal and Oxidative Environments
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DOI：
10.1620/tjem.216.331
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发表时间：
2008-12-01
影响因子：
2.2
通讯作者：
Hosoya, Tomonori
中科院分区：
文献类型：
--
作者：
Mamiya, Takashi;Katsuoka, Fumiki;Hosoya, Tomonori
血红素加氧酶-1（HO-1）是血红素催化剂的限速酶，并且已经被认为通过将促氧化剂血红素修饰成毒性较小的催化剂（其表现为抗氧化剂）而在细胞对抗氧化应激的反应中起重要作用。然而，所涉及的确切机制和这种活动的生理意义仍有待澄清。为了阐明HO-1在体内的作用，利用白蛋白启动子驱动的Cre-loxP系统，通过定点重组技术建立了HO-1基因的肝细胞特异性条件性敲除（CKO）小鼠。在HO-1 CKO小鼠的肝脏中，HO-1蛋白水平降低至对照小鼠肝脏的约30%。HO-1 CKO小鼠存活，在6个月内表现出正常的生长曲线，并且没有显示出组织学和血清学异常。我们发现，一些细胞保护基因，如NAD（P）H脱氢酶醌1和谷胱甘肽S-转移酶P1，表现出显着的表达升高，表明HO-1 CKO小鼠的氧化应激增加，即使在静止条件下。体内电子顺磁共振研究表明，HO-1 CKO小鼠肝脏中硝酰基自由基的信号衰减时间显著长于对照小鼠，表明突变小鼠肝脏中的自由基清除活性显著受损。HO-1 CKO小鼠对四氯化碳肝毒性敏感。这些结果提供了第一个体内证据，即HO-1在基础条件下和化学损伤时都能保护细胞免受氧化应激。
Heme oxygenase-1 (HO-1) is the rate-limiting enzyme of heme catabolism and has been assumed to be important in cellular response against oxidative stress through modification of the pro-oxidant heme into less toxic catabolites that behave as antioxidants. However, the precise mechanisms involved and the physiological significance of such activity remain to be clarified. To elucidate roles HO-1 plays in vivo, hepatocyte-specific-conditional knockout (CKO)mice of HO-1 gene were generated by site-specific recombination using albumin-promoter-driven Cre-loxP system. In livers of HO-1 CKO mice HO-1 protein level decreased to approximately 30% of control mouse livers. The HO-1 CKO mice are viable, exhibit normal growth curves over six months, and show no histological and serological abnormalities. We found that several cytoprotective genes, such as NAD(P)H dehydrogenase quinone 1 and glutathione S-transferase P1, showed markedly elevated expression, Suggesting the increase of oxidative stress in HO-1 CKO mice even under quiescent conditions. hi vivo electron paramagnetic resonance Studies demonstrated that signal decay times of nitroxyl radicals were significantly longer in livers of HO-1 CKO mice than that of control mice, indicating that radical scavenging activity was significantly compromised in the Mutant liver. HO-1 CKO mice were Susceptible to carbon tetrachloride hepatotoxicity. These results provide the first in vivo evidence that HO-1 acts to protect cells against the oxidative stress in both basal conditions and upon chemical insult.