蛋白酶體調節閉合蛋白的降解在廣東住血線蟲引起腦膜腦炎之研究

Degradation of occludin by proteasome modulation in angiostrongyliasis meningoencephalitis

林毅傑(Yi-Chieh Lin)

指導教授 ： 蔡崇弘 ； 賴世展

中山醫學大學/醫學院/醫學研究所/碩士(2011年)

https://doi.org/10.6834/CSMU.2011.00004

摘要

脈絡叢上皮細胞（choroid plexus epithelial cells）間的緊密連結蛋白（tight junctions）是構成血液-腦脊髓液障壁（blood-cerebrospinal fluid barrier, BCB）的主要結構。蛋白酶體（proteasome）主要作用是降解細胞中不需要的或受到損傷的蛋白質。當廣東住血線蟲（Angiostrongylus cantonensis）感染非適宜宿主，會引起腦膜腦炎及BCB 的瓦解。本研究以廣東住血線蟲感染鼷鼠為模型，觀察到蛋白酶體的表現量在感染期間明顯增加。以免疫螢光染色法發現緊密連結蛋白閉合蛋白（occludin）和基質金屬蛋白酶-9（matrix　metalloproteinase-9, MMP-9） 在脈絡叢有相同的分布，並以共同免疫沉澱法證明閉合蛋白和MMP-9 有交互作用。並分別給予蛋白酶體活性抑制劑MG132 1.5 及3.0mg/kg/day，觀察到磷酸化的IκBα 及NF-κB減少。除此之外，MMP-9 的活性及閉合蛋白的降解也因為MG132 的作用而減少。綜合上述，當鼷鼠受到廣東住血線蟲感染而引發嗜伊紅性腦膜腦炎時，蛋白酶體是透過降解磷酸化的IκBα 來調節NF-κB 的活化，進而來調控下游MMP-9 的作用及閉合蛋白的降解。

關鍵字

廣東住血線蟲 ； 蛋白酶體 ； 閉合蛋白

並列摘要

The tight junctions in the epithelial cell of the choroids are the major structures of the blood-cerebrospinal fluid barrier (BCB). The major function of proteasome is to degrade unneeded or damage proteins by proteolysis. Disruption of BCB and resulted in meningoencephalitis are
important pathological events in non-permissive hosts caused by Angiostrongylus cantonensis. In this study, five-week BALB/c mice were infected with the third-stage larvae of A. cantonensis. The results showed the protein levels of proteasome were increased during A. cantonensis infection. Occludin was co-locolized with matrix metalloproteinase-9(MMP-9) by confocal immunoflourescence microscopy. Further, we demonstrated that occludin interacted with MMP-9 in brain tissue of infected-mice by co-immunoprecipitation. The
infected-mice were treated with proteasomal activity inhibitor MG132 in 1.5 and 3.0 mg/kg/day, respectively. The protein levels of phosphorylated IκBα were significantly decreased (P<0.05) as compared with untreated control. Also, phosphorylated nuclear factor kappa-light-chain-nhancer of activated B cells (NF-κB) has similar result. In addition, activity of MMP-9 and occludin degradation were reduced because of MG132. The role of proteasome in A. cantonensis infection is to degrade phosphorylated IκBα, and modulate phosphorylated NF-κB, and then regulate the activation of MMP-9 and occludin degradation.

並列關鍵字

Angiostrongylus cantonensisl ； proteasome ； occludin

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