EB病毒第一型潛伏膜蛋白抑制旋轉肌球素1可促進人類上皮細胞的侵襲能力

Repression of TPM1 by EBV latent membrane protein 1 contributes to the invasiveness of human epithelial cells

黃馪珽(Ping-Ting Huang)

指導教授 ： 陳振陽 教授

國立臺灣大學/醫學院/微生物學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.00603

摘要

旋轉肌球素( Tropomyosin )是一種會與肌動蛋白結合( actin – binding )的蛋白質，具有穩定肌動蛋白絲( actin filament )的功能，過去研究發現，高分子量旋轉肌球素( HMW tropomyosin )的減少，可能與癌細胞轉移有關。高分子量旋轉肌球素是由TPM1及TPM2基因所產生，根據先前DNA微陣列晶片分析結果發現，表現EB病毒第一型潛伏膜蛋白( LMP1 )的細胞株中，TPM1 mRNA有減少的情況，先前研究已知LMP1會促進細胞侵襲能力，因此本研究欲進一步探討LMP1是否會藉由抑制TPM1- encoded 高分子量旋轉肌球素的產生，促進細胞的侵襲能力。
實驗結果發現，不管是利用短暫轉染( transient transfection )或者穩定表現LMP1的細胞株，與控制組比較，都有TPM1 mRNA及高分子量旋轉肌球素表現量減少的現象，而藉由啟動子活性試驗發現，LMP1的CTAR1和CTAR2兩個區域，對於LMP1抑制TPM1啟動子活性是必須的。將表現TPM1高分子量旋轉肌球素( TPM1-encoded HMW tropomyosins )的質體送入LMP1表現的細胞株，可以減少細胞侵襲能力。此外，將LMP1短暫轉染進入載體控制組及會表現TPM1的高分子量旋轉肌球素( TPM1- encoded HMW tropomyosins )的細胞株，發現載體控制組細胞侵襲能力增加約1.8倍，而表現高分子量旋轉肌球素的細胞株僅增加1.2倍左右。此結果顯示高分子量旋轉肌球素的減少，可能是LMP1促進細胞侵襲能力的諸多因素之一。至於LMP1透過那個訊息傳遞路徑減少TPM1的高分子量旋轉肌球素的產生，以及高分子量旋轉肌球素的減少造成促進細胞侵襲能力的機制，則需要進一步的實驗證明。

關鍵字

旋轉肌球素 ； 第一型潛伏膜蛋白 ； 細胞侵襲性 ； 肌動蛋白絲

並列摘要

Tropomyosins are a family of actin-binding proteins that stabilize actin microfilament. High-molecular-weight (HMW) tropomyosins are encoded by TPM1 and TPM2 genes. Reduced HMW tropomyosin levels have been suggested to be associated with metastatic potential in cancer cell lines. Early studies have shown that the Epstein-Barr virus latent membrane protein 1 (LMP1) is correlated with promotion of cell invasion. TPM1 mRNA was found to be down-regulated in LMP1-expressing cell line as compared with control by cDNA microarray. In this study, we investigated whether down-regulation of TPM1-encoded HMW tropomyosin by LMP1 could promote cell invasion.
We demonstrated that TPM1 mRNA level and HMW tropomyosins were suppressed in LMP1-expressing cell lines. LMP1 could repress TPM1 gene expression through inhibition of TPM1 promoter activity. CTAR1 and CTAR2 domains were essential for repression of TPM1 promoter activity by LMP1. Forced expression of TPM1-encoded HMW tropomyosins in LMP1-expressing cells reverted LMP1-induced cell invasion. Transient expression of LMP1 in vector control cells, cell invasive ability increased approximately 2-fold. However, invasive ability was only up-regulated to 1.2-fold by LMP1 in TPM1-encoded HMW tropomyosin-expressing cells. These results suggested that LMP1 could down-regulate TPM1-encoded HMW tropomyosin, and reduction of HMW tropomyosin levels was associated with promotion of cell invasion. The mechanisms of repression of TPM1-encoded HMW tropomyosins by LMP1 and inhibition of cell invasion by HMW tropomyosins require further investigation.

並列關鍵字

tropomyosin ； latent membrane protein 1 ； cell invasion ； actin filament

參考文獻

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