C型肝炎病毒非結構性蛋白質NS3對細胞貼附及移動能力的影響

The Effects of the Hepatitis C Virus NS3 Protein on Cell Adhesion and Migration Ability

吳雨柔(Yu-Rou Wu)

指導教授 ： 張鑫

國立臺灣大學/醫學院/微生物學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.01468

摘要

C型肝炎病毒的NS3為一多功能性之非結構性蛋白質，具有絲胺酸蛋白酶、核醣核酸水解酶和核醣核酸解旋酶的酵素活性。Integrin是一種位於細胞表面負責與細胞外基質交互作用的穿膜受器。目前研究顯示，integrin可以調控細胞生長、存活、分化和型態的改變等訊號。研究指出表現NS3可造成纖維母細胞在養分缺乏的環境下增生，NS3也被證明具有誘導細胞轉型的能力。本實驗室發現NS3在NS4A的輔助下會發生內部截切，且NS3蛋白酶活性對於細胞轉型扮演重要的角色；因此我們認為NS3蛋白質為肝癌形成的重要因子。實驗室結果指出NS3蛋白質和細胞內生性integrin β1有相互作用，本研究更進一步探討NS3是否影響細胞的貼附、移動能力和integrin下游訊號傳遞。利用不同的細胞外基質，進行細胞貼附實驗，結果發現細胞貼附能力隨著NS3蛋白質表現量而明顯下降；而在傷口癒合分析實驗中，表現NS3蛋白質的細胞移動能力有提升的趨勢。利用西方墨點法分析表現NS3蛋白質的細胞integrin及下游訊號paxillin活化的變化，結果顯示細胞不論貼附在poly-L-lysine、fibronectin和collagen的細胞外基質上時，NS3蛋白質的表現都會造成integrin β1總表現量下降；但貼附在fibronectin時，integrin β1活化程度的下降比較明顯。當表現NS3蛋白質的細胞貼附在collagen上時，其integrin β1下游訊號傳遞paxillin磷酸化比例有下降的趨勢。NS3是否藉由影響細胞integrin β1的表現量，並對於integrin辦認不同細胞外基質的形態(α2β1和α5β1)造成差異性影響，導致下游訊號有所改變，進而調控細胞貼附和移動有待進一步確認。本研究對NS3影響細胞貼附和移動之瞭解，提供了進一步探討NS3促使細胞癌化可能作用機制的一個方向。

關鍵字

C型肝炎病毒 ； 非結構性蛋白質NS3 ； 整合分子 ； 細胞移動 ； 細胞貼附

並列摘要

Hepatitis C virus (HCV) non-structural protein 3 (NS3) is a multiple functional protein that possesses serine protease, NTPase and RNA helicase activities. Integrins, which are heterodimeric membrane glycoproteins, are cell-surface receptors mediating cell-matrix adhesion and initiate multiple intracellular signal transductions in response to ligand occupancy. Through these signaling pathways, integrins play important roles in regulating cell proliferation, cell survival, cell morphological changes and cell differentiation. Previous studies have demonstrated the abilities of the HCV NS3 to enhance cell growth rate, to allow culture cells to grow in low serum condition, and to induce cell transformation. Therefore, NS3 was proposed to be an important factor in tumorigenesis. Studies in our laboratory have demonstrated that the NS3 has an NS4A-dependent internal NS3 cleavage activity, and the protease activity of the NS3 plays an important role in cell transforming activity. In addition, an interaction between the NS3 protein and endogenous integrin β1 was demonstrated. In this study, whether NS3 affects cell adhesion and migration was examined. A possible association of the effects with integrin signaling was further analyzed. Adhesion assay and wound healing assay were performed. The results showed that NS3 reduced cell adhesion and promoted cell migration. In addition, NS3 reduced the expression levels of total integrin β1 no matter poly-L-lysine, fibronectin, or collagen was used as the extracellular matrix, but showed a reduction in the active form integrin β1 only when fibronectin was used. In addition, the ratio of phosphorylated paxillin to total was reduced in NS3 expressing cells that were attached on collagen. Whether NS3 down-regulates integrin expression causing an inhibitory effect on cell adhesion needs to be further confirmed. In addition, the regulation can be complicated and depends on various integrin heterodimers. These results provide a possible direction in further studying the mechanisms of NS3 involved in HCV turmorigenesis.

並列關鍵字

hepatitis C virus ； NS3 ； integrin ； cell migration ； cell adhesion

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