Plasma selenium-dependent glutathione peroxidase. Cell of origin and secretion.
Plasma selenium-dependent glutathione peroxidase. Cell of origin and secretion.
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发表时间：
1989-09
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通讯作者：
N. Avissar;J. Whitin;P. Allen;D. Wagner;P. Liegey;H. Cohen
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作者：
N. Avissar;J. Whitin;P. Allen;D. Wagner;P. Liegey;H. Cohen
人血浆谷胱甘肽过氧化物酶（GSHPx）已被证明是一种糖基化硒蛋白，在酶促、结构和抗原性上与已知的细胞谷胱甘肽过氧化物酶不同。该酶的胞外位置和它被糖基化的事实表明它是一种分泌蛋白。利用对人细胞和血浆GSHPx的相互非交叉反应性抗体，我们进行了一项研究，以确定血浆GSHPx的来源组织。筛选的细胞是内皮细胞，因为它们是细胞外超氧化物歧化酶的主要来源，HL-60细胞（髓样细胞系），因为它们是细胞外H2 O2的主要来源，和Hep G2细胞（肝细胞系），因为它们是许多血浆蛋白的来源。用[~（35）S]蛋氨酸或[~（75）Se]亚硒酸代谢标记人脐静脉内皮细胞，用[~（75）Se]亚硒酸代谢标记HL-60细胞和Hep G2细胞。用抗红细胞（RBC）GSHPx IgG或抗血浆GSHPx IgG从标记细胞及其培养基中免疫纯化蛋白质。利用抗RBC GSHPx IgG，仅从所有测试的细胞中沉淀酶的细胞形式，而不是从其培养基中沉淀。当抗血浆GSHPx IgG应用于细胞及其培养基时，硒蛋白仅从Hep G2细胞的培养基中沉淀。当Hep G2细胞在存在羧基离子载体莫能菌素的情况下孵育时，可以使用抗血浆GSHPx IgG检测到细胞内硒蛋白。抗RBC GSHPx IgG与纯化RBC GSHPx预孵育可部分抑制所有三种细胞类型的细胞形式沉淀，而抗血浆GSHPx IgG从Hep G2细胞培养基中沉淀硒蛋白可通过抗体与纯化血浆GSHPx预孵育来防止。我们认为血浆GSHPx是由肝细胞合成和分泌的。据我们所知，这是唯一已知的硒蛋白，具有明确的功能，已被证明是由哺乳动物细胞分泌合成的。
Human plasma glutathione peroxidase (GSHPx) has been shown to be a glycosylated selenoprotein distinct enzymatically, structurally, and antigenically from known cellular glutathione peroxidases. The extracellular location of the enzyme and the fact that it is glycosylated suggested that it is a secreted protein. Utilizing mutually non-cross-reactive antibodies to human cellular and plasma GSHPx, we conducted a search to determine the tissue of origin for plasma GSHPx. The cells screened were endothelial cells because they are the main source of extracellular superoxide dismutase, HL-60 cells (myeloid cell line) because they are the main source of extracellular H2O2, and Hep G2 cells (hepatic cell line) because they are the source of many plasma proteins. Human umbilical vein endothelial cells were metabolically labeled with either [35S]methionine or [75Se]selenious acid, and HL-60 cells and Hep G2 cells were metabolically labeled with [75Se]selenious acid. Proteins were immunopurified from the labeled cells and their media with either anti-red blood cell (RBC) GSHPx IgG or with anti-plasma GSHPx IgG. Utilizing anti-RBC GSHPx IgG, only the cellular form of the enzyme was precipitated from all the cells tested but not from their media. When anti-plasma GSHPx IgG was applied to the cells and their media, a selenoprotein was precipitated only from the media of Hep G2 cells. When Hep G2 cells were incubated in the presence of the carboxylic ionophore monensin, an intracellular selenoprotein could be detected using anti-plasma GSHPx IgG. The precipitation of the cellular form from all three cell types was partially inhibited by preincubation of the anti-RBC GSHPx IgG with purified RBC GSHPx while the precipitation of the selenoprotein from the medium of Hep G2 cells by anti-plasma GSHPx IgG was prevented by preincubation of the antibody with purified plasma GSHPx. We suggest that plasma GSHPx is synthesized by and secreted from hepatic cells. This is, to the best of our knowledge, the only known selenoprotein with a defined function that has been shown to be synthesized for secretion by mammalian cells.