Hirano Takeshi, Kudo Hideaki, Doi Yoshiaki, Nishino Tomoko, Fujimoto Sunao, Tsurudome Yosuke, Ootsuyama Yuko, Kasai Hiroshi
Department of Environmental Oncology, University of Occupational and Environmental Health, Yahatanishi-ku, Kitakyushu, Fukuoka 807-8555, Japan.
Cancer Sci. 2004 Feb;95(2):118-22. doi: 10.1111/j.1349-7006.2004.tb03191.x.
We previously reported that 3'-methyl-4-dimethylaminoazobenzene (3'-MeDAB) increased the 8-hydroxyguanine (8-OH-Gua) content in nuclear DNA and the base excision repair activity in mouse liver. However, to understand the mechanism of 3'-MeDAB carcinogenesis, a further investigation of the 8-OH-Gua repair systems was necessary. In this report, we examined the expression of the repair enzyme, 8-oxoguanine DNA glycosylase 1 (OGG1), in 3'-MeDAB-treated mouse liver. We prepared four kinds of anti-peptide polyclonal antibodies raised against mouse OGG1 (mOGG1). The sequences used as epitopes were designed from positions located close to the N-terminus, the nuclear localization signal (NLS), and the regions containing Lys(249) and Asp(267), which are involved in the catalytic mechanisms of mOGG1 (glycosylase and lyase, respectively). Immunoblotting, using all four antibodies, revealed a 32-kDa protein (mOGG1-32) in addition to the 38-kDa mOGG1 in the 3'-MeDAB-treated mouse liver. Moreover, immunostaining with mOGG1 antibody yielded strong, positive signals in the 3'-MeDAB-treated mouse liver nuclei. However, we could not detect any difference in the Ogg1 mRNA expression pattern. Although the function of mOGG1-32 remains unclear, these findings suggest that 3'-MeDAB may alter the function of the DNA repair protein, and this action may be related to 3'-MeDAB carcinogenesis.
我们之前报道过，3'-甲基-4-二甲基氨基偶氮苯（3'-MeDAB）会增加小鼠肝脏细胞核DNA中的8-羟基鸟嘌呤（8-OH-Gua）含量以及碱基切除修复活性。然而，为了了解3'-MeDAB致癌的机制，有必要对8-OH-Gua修复系统进行进一步研究。在本报告中，我们检测了经3'-MeDAB处理的小鼠肝脏中修复酶8-氧代鸟嘌呤DNA糖基化酶1（OGG1）的表达。我们制备了四种针对小鼠OGG1（mOGG1）的抗肽多克隆抗体。用作表位的序列是从靠近N端、核定位信号（NLS）以及包含Lys(249)和Asp(267)的区域设计的，这两个区域分别参与mOGG1的催化机制（糖基化酶和裂解酶）。使用所有四种抗体进行免疫印迹分析，结果显示在经3'-MeDAB处理的小鼠肝脏中，除了38 kDa的mOGG1外，还存在一种32 kDa的蛋白质（mOGG1-32）。此外，用mOGG1抗体进行免疫染色在经3'-MeDAB处理的小鼠肝脏细胞核中产生了强烈的阳性信号。然而，我们未检测到Ogg1 mRNA表达模式有任何差异。尽管mOGG1-32的功能尚不清楚，但这些发现表明3'-MeDAB可能会改变DNA修复蛋白的功能，并且这种作用可能与3'-MeDAB致癌有关。
