不完整大腸桿菌Thioredoxin對人類週邊血液單核球細胞PBMC及自然殺手細胞株YT之增殖作用的探討

Abstract

大腸桿菌的Thioredoxin E.coli Trx的結構與hTrx即為相似，都是由5個β-strand組成厭水性中心周圍則圍繞著四個α-helices。在本實驗中，我們利用基因deletion mutation 及site-directed mutagenesis的方式來改變E.coli Trx的結構，目前探究其中兩個結構不完整的蛋白質。（1）E.coli Trx83，去除掉84－108此段胺基酸序列，總胺基酸為83個，結構上則少掉C-terminal strand-helix motif，目的為仿照人類Trx80；（2）E.coli Trx96，去除掉97－108此段胺基酸序列，總胺基酸為96個，少掉C-terminal helix motif。本研究發現氧化態及還原態的E.coli Trx83和Trx96皆能刺激人類正常週邊血液的單核球細胞生長，E.coli Trx83的還原態活性較強，而E.coli Trx96還原態與氧化態差異不明顯，但人類及大腸桿菌Trx皆無顯著刺激。E.coli Trx83和Trx96可以刺激monocytes生長，且還原態大於氧化態。但E.coli Trx96無法顯著刺激lymphocytes，E.coli Trx83還原態卻能稍微刺激。因此E.coli Trx96功能與Trx80相似，但E.coli Trx83的氧化態與還原態對PBMC的增殖強度不同。E.coli Trx83和Trx96也可刺激人類自然殺手細胞株YT生長，還原態略大於氧化態蛋白質，然而增殖強度皆不如野生株Trx。故C-terminal strand-helix motif對於thioredoxin刺激YT細胞株的功能扮演重要的角色。

Trx is a key component of cellular redox biochemistry and regulation. We investigated function of C-terminally truncated E.coli Trx83 and Trx96, comprising the 83and 96 N-terminal amino acids, respectively, in the stimulation of cell growth. We discovered that they can stimulate the growth of resting human peripheral blood mononuclear cells (PBMCs). Moreover, Trx83 and Trx96 increased proliferation of monocyte. Trx83 also increased proliferation of lymphocyte a little, but Trx96 did not. In anothor investigation, the Trx83 and Trx96 both stimulated the proliferation of NK-like cell line YT proliferation. However, the activity of Trx83 and Trx96 are lower than E.coli and human full-length thioredoxin. Therefore, the C-terminal strand-helix motif may play the important part in growth stimulation of YT cell.