核糖核酸酶抑制因子对H_2O_2损伤的大鼠神经胶质瘤细胞系C6的影响

核糖核酸酶抑制因子 (ribonucleaseinhibitor,RI)是广泛存在于哺乳动物细胞浆中的一种酸性糖蛋白 .为了进一步了解RI的功能 ,根据RI分子结构富含巯基的特点 ,研究了RI对过氧化氢(H2 O2 )损伤的大鼠神经胶质瘤细胞 (C6 )的影响 .用不同浓度的H2 O2 分别作用于转染有RIcDNA并且RI过表达的C6细胞和正常C6细胞 ,对比损伤前后 2者的细胞存活率、LDH漏出量、细胞内GSH和MDA含量差别 ,以及细胞内抗氧化酶类GPX、CAT和GST活性的差别 .结果表明 ,与正常C6细胞相比 ,RI过表达的C6细胞在H2 O2 作用下存活率高 ,LDH漏出量、MDA含量明显减少 ,而细胞内GSH较多 ;RI过表达的C6细胞在损伤前后均表现出更强的CAT和GST活性 .提示RI具有抗氧化功能 ,能够减轻H2 O2 所致的细胞过氧化损伤 .

Effects of Ribonuclease Inhibitor on the Rat Glial Cell Line C6 Injured by H_2O_2

Ribonuclease inhibitor (RI) is an acidic cytosolic glycoprotein which molecular mass was estimated to be 50 kD.RI inhibits the activities of ribonuclease A (RNase A) and angiogenin by forming a very tight complex with a stoichiometry of 1∶1.RI contains 30 cysteine residues.In this sense,RI is a good candidate to be controlled in vivo by thiol\|disulfide exchange reaction in response to change in cellular redox status.Effects of RI on the rat glial cell line C6 injured with H\-2O\-2 were studied by the comparison between the transfected C6 cells with RI cDNA in which RI was overexpressed and the control C6 cells.The transfected C6 cells had higher viability,less LDH leakage and MDA contents,but more GSH contents.This result showed that RI had antioxidant activity and it was able to protect cells from peroxidative injuries.The antioxidant mechanism of RI was not only due to its multithiol group in a molecule,but also the transfected C6 cells showing more catalase and glutathione S\|transferase activities.Catalase activities in transfected C6 cells increased by 0 73 time than in the control C6 cells,and glutathione S\|transferase activities increased by 2 72 times.It is possible that RI may be as an antioxidant in tissues to inhibit the formation of tumor.The work may be a useful base for gene therapy of RI and others.