中文摘要
人類血管靜止蛋白及血纖維蛋白溶酶原kringle片段已被證實可以藉由影響內皮細胞的爬行與增生而抑制血管新生。我們實驗室先前的研究中發現，kringle1-5 (K1-5)蛋白會引發人類凝血酶調節素(TM)內吞並分解，且TM可能在細胞與細胞間及細胞與基質間的連結中扮演重要的角色。然而，K1-5干擾內皮細胞爬行的機制尚不清楚。在本論文中，我們利用酵母菌表現的kringle蛋白來探討這個機制。根據長時間活細胞螢光影像擷取所得到的數據發現，牛動脈內皮細胞經K1-5處理之後其能動性上升，但傷口閉合的速率減慢。這個有趣的現象促使我們想要更進一步探討K1-5是如何去影響內皮細胞的爬行。首先我們發現K1-5會引起黏著斑激酶(FAK)在Y397及Y576這兩個胺基酸位置上的磷酸化，這暗示著FAK訊息傳遞路徑的活化。接著我們也證明FAK訊息傳遞路徑下游影響黏著斑拆解的paxillin及ERK亦被活化。根據這些結果我們認為K1-5藉由活化FAK訊息傳遞路徑而提高內皮細胞的能動性，同時卻又引發TM內吞而阻礙了細胞具有方向性的移動。另一方面我們也發現FAK訊息傳遞路徑下游的Akt與IκB-α磷酸化，並連同ERK一起調控細胞生存。

Abstract
The angiostatin and kringles fragments of plasminogen have been identified as an inhibitor of angiogenesis by suppressing endothelial cell migration and proliferation. In our previous studies, we found that kringle1-5 (K1-5) induced thrombomodulin (TM) internalization and degradation while TM might play an important role in the cell-cell and cell-matrix adhesion. However, the mechanism of K1-5 interfering endothelial cell migration still remained unclear. In this study, we used Pichia pastoris expressed kringle protein to verify the mechanism. According to data captured by time lapse video-microscopy, we found that the motility of bovine aortic endothelial cell treated with recombinant K1-5 protein increased, but the rate of wound closure decreased. This interesting phenomenon prompted us to investigate how K1-5 influenced endothelial cell migration. First, we found that K1-5 induced phosphorylation of focal adhesion kinase (FAK) on residues Y397 and Y576 which implicated the activation of FAK signal pathway. Then we illustrated the activation of paxillin and ERK which had been identified as downstream of FAK signal pathway that regulate focal adhesion disassembly. Based on these results, we suggested that K1-5 enhanced endothelial cell motility by activating FAK signaling pathway while impeded directional cell migration by inducing TM internalization. On the other hand, we also found that the phosphorylation of FAK downstream, Akt and IκB-α, along with ERK modulated cell survival.

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