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The role of reactive oxygen species in adipocytes and obesity: with special reference to extracellular SOD

活性氧在脂肪细胞和肥胖中的作用：特别参考细胞外 SOD

基本信息

批准号：
13470084
负责人：
OHNO Hideki
金额：
$ 9.15万
依托单位：
Kyorin University, School of Medicine
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

Extracellular superoxide dismutase (EC-SOD) is a copper- and zinc-containing secretary glycoprotein, located in extracellular fluids including plasma and the extracellular matrix of tissues. The primary structure of EC-SOD indicates that the enzyme consists of an N-terminal hydrophobic signal peptide for secretion, a Cu, Zn-SOD-like domain in the middle portion, and a heparin-binding region, which contains clusters of positively charged amino acids in the C-terminal portion, as well as one potential site for N-linked gycosylation. Histochemical examination of mouse tissues showed nuclear staining of EC-SOD, and the nuclear translocation of EC-SOD was also confirmed in cultured cells. The EC-SOD which wa secreted into the medium was incorporated into 3T3-L1 preadipocytes and a significant fraction of the material taken up was localized in the mucleus. Site-directed mutagenesis indicated that the heparin-binding domain of EC-SOD functions as the nuclear localization signal. Moreover, EC-SOD was incorporated from conditioned medium of stable EC-SOD expressing CHO-EK cells into 3T3-L1 cells within 15 min. The uptake was clearly inhibited by the addition of heparin at a concentration of 0.4 μg/ml. Nuclear translocation of the incorporated EC-SOD was markedly enhanced by H_2O_2 treatment following incubation with the CHO-EK medium. The results obtained here suggest that the upregulation of the nuclear translocation of EC-SOD by oxidative stress might play a role in the mechanism by which the nucleus is protected against oxidative damage of genomic DNA, possibly leading to a low incidence of lifestyle related diseases such as cancer.

细胞外超氧化物歧化酶（EC-SOD）是一种含铜和锌的秘书糖蛋白，存在于包括血浆和组织的细胞外基质在内的细胞外液中。EC-SOD的初级结构表明，该酶由一个用于分泌的n端疏水信号肽，中间部分的Cu， zn - sod样结构域，c端部分的肝素结合区（包含带正电的氨基酸簇）以及一个n键糖基化的潜在位点组成。小鼠组织的组织化学检查显示EC-SOD有核染色，培养细胞也证实EC-SOD有核易位。分泌到培养基中的EC-SOD被合并到3T3-L1前脂肪细胞中，被吸收的物质中有很大一部分定位于细胞核。定点突变表明，EC-SOD的肝素结合结构域作为核定位信号。将EC-SOD从稳定表达CHO-EK细胞的条件培养基中掺入3T3-L1细胞，时间为15 min。添加浓度为0.4 μg/ml的肝素可明显抑制其摄取。在CHO-EK培养基中孵育后，H_2O_2处理显著增强了EC-SOD的核易位。本研究结果提示氧化应激对EC-SOD核易位的上调可能在保护细胞核免受基因组DNA氧化损伤的机制中发挥作用，可能导致癌症等生活方式相关疾病的低发病率。