LPS刺激对TACE基因表达和对TNF-α前体加工的影响

The influence and function of LPS on the TACE gene expression

目的 :研究LPS刺激对肿瘤坏死因子转换酶 (TACE)基因转录和表达的影响及其与TNF α前体加工的关系。方法 :采用Dot blotting、Dot ELISA、间接免疫荧光和FACS等方法分别检测HL 6 0细胞在LPS刺激的不同时间段TACE、TNF α基因转录表达和膜分子分布情况。结果 :①HL 6 0细胞构成性高表达有活性TACE ,主要分布于细胞膜和核周边。②LPS刺激TNF α基因转录表达 ,但由于TACE的作用 ,膜TNF α(TM TNF α)下降 ,而分泌型TNF(sTNF α)增加 ;TACE的反义寡核苷酸 (ODN)显著抑制TNF α这种前体转换作用。③LPS同样刺激TACE基因表达增加 ,而且TACE酶解作用增强 ,但其蛋白表达和膜分子分布反而下降 ,推测TACE在发挥其催化膜蛋白作用后 ,其分子结构形式发生改变。结论 :炎症时分泌型TNF α增加不仅是该细胞因子基因表达增高所致 ,更受到TACE基因表达水平和活性状态的约束。

Objective:To study the influence of LPS on the Tumor Necrosis Factor alpha converting Enzyme(TACE) gene transcription and expression and its regulating effect on the TM TNF α secretion Methods:In vitro studies were carried out on HL 60 cells stimulated by LPS TACE?TNF α mRNA levels were measured by Dot blotting Expression of TACE?TNF α proteins was determined by Dot ELISA and the distribution of membrane molecules were determined by FACS and indirect immunofluorescence method Results:① TACE was detected in or on HL 60 cells and it is predomainantly localized on cell surface and to a perinuclear compartment ② LPS induced a time dependant increasement of TNF α mRNA and enhanced TNF α convertion with decreasing distribution of TNF α in cell surface and increasing secretion of TNF α protein Such convertion can be inhibited by TACE ODN ③ LPS also induced time dependant increase in expression of TACE gene and activation of its function On the other hand, TACE protein in cell lysates and on cell surface decreased These results suggested that molecular structure of TACE maybe change Conclusion:The increasement of the secreted TNF α is not only controlled in the level of itself gene transcription,but also affected by TACE enzymatice activity which is belongs to posteranslation level regulations.