14-3-3 gamma and zeta protein expression in active microglia Immune response mechanisms of Parkinson's disease

Jing He; Shenggang Sun; Xiaowu Chen

摘要：BACKGROUND: The progressive degeneration of dopaminergic neurons in Parkinson's disease is associated with an activated glial reaction, combined with an inflammatory process. These responses lead to the production of cytokines, such as interferon-γ, tumor necrosis factor-α(TNF-α), and interleukin-1β. In addition, 14-3-3 protein is a component of Lewy bodies in Parkinson's disease.OBJECTIVE: To observe the expression of 14-3-3 γ and ζ protein, as well as TNF-α, in mouse microglia, as well as changes after lipopolysaccharide (LPS) activation. To investigate possible mechanisms of dopaminergic neuronal injury due to activated microglia. To and clarify the immune response mechanisms of Parkinson's disease.DESIGN: Randomized controlled observation, cell study.SETTING: Laboratory of Department of Neurology, the Affiliated Union Hospital of Tongji Medical College, Huazhong University of Science and Technology.MATERIALS: The BV-2 immortalized murine microglia cell line was purchased from China Unit cell center. LPS was provided by Sigma Company. Cell cultures were purchased from Gibco. Phospho-(Ser) 14-3-3 binding motif antibody was purchased from Santa Cruz Biotechnologies. FITC was provided by Linfei Biotechnology, Wuhan, China. TNF-α ELISA was provided by Jingmei Biotech Co, Wuhan, China. The flow cytometer was provided by Becton Dickinson, Canada.METHODS: The present experiment was performed at the Laboratory of Department of Neurology, the Affiliated Union Hospital of Tongji Medical College, Huazhong University of Science and Technology from April to December 2006. The microglial cell line, BV-2, was cultured in vitro and stimulated with LPS for 2, 6, 12, and 24 hours. BV-2 cultures without LPS were used as controls.MAIN OUTCOME MEASURES: Expression of 14-3-3 γ protein was detected by flow cytometry. 14-3-3 ζ percentage expression and the mean fluorescence intensity was detected by immunofluorescence. TNF-αexpression was detected by ELISA.RESULTS: 14-3-3γ protein expression analysis: following LPS-induction in BV-2 cells, the fluorescence intensity of the 14-3-3γ proteins gradually decreased. The 12 and 24 hours groups exhibited significantly lower expression than the normal control group (P < 0.05). 14-3-3 ζ percentage expression and the mean fluorescence intensity: the percentage of 14-3-3ζ protein expression gradually decreased with LPS stimulation. The mean fluorescence intensity from the 6, 12, and 24 hours groups was significantly less than the control group (P < 0.05). TNF-α expression: resting BV-2 cells did not express TNF-α. Following 2 hours of LPS stimulation, TNF-α was highly expressed in BV-2 cells, but decreased again by 24 hours.CONCLUSION: Dopaminergic neuronal injury, due to activated microglial cells, might be related to the participation of 14-3-3 proteins and the release of TNF-α.