17β-estradiol attenuates homocysteine-induced oxidative stress and inflammatory response as well as MAPKs cascade via activating PI3-K/Akt signal transduction pathway in Raw 264,7 cells

• Published in: 生物化学与生物物理学报：英文版 2015 (2), p.65-72
• Main Author: Ying Zhang Ying He Yi Zong Jiazhi Guo Lin Sun Yunbing Ma Wei Dong Li Gui
• Format: Article
• Language: English
• Subjects: MAPKs; PI3-K; 信号转导途径; 氧化应激; 炎症反应; 细胞因子; 雌二醇; 高半胱氨酸
• ISSN: 1672-9145; 1745-7270

Oxidative stress, inflammatory response, and mitogen-activated protein kinases （MAPKs） cascade are significant pathogenic factors of osteoporosis. It has been reported that elevated homocysteine （Hcy） may activate oxidative stress and reduce bone mineral density in post-menopausal osteopor- osis. Moreover, hormone replacement therapy has been widely used in clinic to prevent and treat post-menopausal women with osteoporosis and osteoporotic fracture, but the molecular mechan- isms and relevant signal transduction pathways underlying the action of Hcy remain unclear. In this study, we investigated the effects of 17β-estradiol （17β-E2） on the Hcy-induced oxidative stress, inflammatory response and MAPKs cascade, as well as the underlying signal transduction pathway in murine Raw 264.7 cells. The reactive oxygen species （ROS） was assessed by fluorospectrophoto- metry. The proinflammatory cytokines tumor necrosis factor-α （TNF-α） and interleukin （IL）-1β were analyzed by double-immunofluorescence labeling and reverse transcriptase polymerase chain reac- tion assay, respectively. Furthermore, phosphorylation levels of MAPKs cascade were measured by western blot analysis. A specific phosphatidylinositol 3-kinase （PI3-K） inhibitor, Wortmannin （1 μM） was employed to determine whether PI3-K/Akt signaling pathway mediated the 17β-E2＇s effect on Raw 264.7 cells. 171β-E2 markedly decreased the ROS production induced by Hcy, the expression of TNF-α and IL-1β at protein and mRNA levels, and down-regulated the phosphorylation of MAPKs （ERK1/2, JNK and p38）. These suppressing effects of 17β-E2 on Hcy-induced changes were reversed by pretreatment with PI3-K inhibitor Wortmannin. The results indicate that 17β-estradiol may attenu- ate Hcy-induced oxidative stress, inflammatory response and up-regulation of MAPKs in Raw 264.7 cells via PI3-K/Akt signal transduction pathway.