探討TRIP6與IFIT5之交互作用於細胞中扮演之角色

Abstract

多型性神經膠質母細胞瘤（Glioblastoma multiforme, GBM）是惡性且侵潤性高的原發性腦瘤，目前臨床上仍無法完全根治。因此，瞭解其細胞遷移及浸潤機制，有助於透過有效抑制腫瘤浸潤能力，減少GBM侵襲正常腦組織而達到提高患者的存活率。細胞點狀黏著分子TRIP6（Thyroid receptor-interacting protein 6）和干擾素誘導蛋白質IFIT5（Interferon Induced Proteins with Tetratricopeptide Repeats 5），兩者都被研究出可調控肌動蛋白質及活化發炎因子NF-κB，而實驗室在之前的研究中已發現TRIP6和IFIT5之間會有交互作用。為深入了解此交互作用是否影響此二蛋白質在細胞中的功能，本研究首先探討TRIP6與IFIT5之結合位置。結果顯示TRIP6的C端負責與IFIT5進行交互作用並促進IFIT5共聚到肌動蛋白質形成之壓力絲上。我們進一步透過拍攝細胞移動變化影像得知，IFIT5與TRIP6皆會促進細胞的動態變化。利用傷口復原法檢測細胞移動之能力，發現IFIT5雖促進細胞之形變卻無法促進細胞移動，反而有抑制之趨勢，並抑制TRIP6促進之細胞移動現象。但若只有過表現TRIP6之C端與IFIT5，IFIT5抑制現象反而減弱，因此TRIP6之C端可能與內生的TRIP6競爭IFIT5，降低IFIT5抑制內生型TRIP6的作用。由這些結果可知，對GBM患者IFIT5可能具抑制細胞移動的作用，從而降低細胞的侵略性而使病人存活率增加。Glioblastoma, the most common primary brain tumors, are malignant and highly invasive tumors. There are many different treatments, glioblastoma patients can't be cure. Therefore, understanding its cell migration and infiltration mechanism may reduce the invasion of glioblastoma to normal brain tissue and improve patients’ survival. Focal adhesion molecule, TRIP6, and interferon induced protein, IFIT5, both have been reported to be involved in regulation of cell migration and activation of inflammatory factor, NF-κB. We had demonstrated that the TRIP6 interacted with IFIT5 in cells. To further investigate the physiological role of this interaction, we first identify the domain of TRIP6 responsible for this interaction. We found that the C-terminal 3 LIM domains of TRIP6 interacts with IFIT5. Furthermore, through the interaction with IFIT5, TRIP6 promoted the co-localization of IFIT5 and actin. We also demonstrated that overexpression IFIT5 and TRIP6 both enhanced the dynamic morphological changes of cells. We further examined cell migration ability by wound healing assay, and found that although IFIT5 promoted cell dynamic changes, it did not enhance cell migration. IFIT5 significantly inhibited TRIP6-promoted cell migration. This inhibitory effect is reduced when IFIT5 co-expressed with the C-terminal domain of TRIP6. The C-terminal domain of TRIP6 may compete with endogenous TRIP6 for the binding of IFIT5, therefore, it reduced the inhibitory effects of IFIT5 on TRIP6. In summary, IFIT5 may inhibit the migration of GBM cells and therefore increase the survival rate of patients.