Translational Regulation by the TNF Alpha AU-rich Element

TNFalpha是一种促炎细胞因子，由几种细胞类型在对感染或损伤的反应中短暂产生。TNFalpha的产生受到转录、mRNA衰变和翻译水平的严格调控，这种强效分子的异常表达与自身免疫性疾病、类风湿性关节炎、克罗恩病和其他炎症有关。TNFalpha的翻译调控是由位于mRNA 3'-UTR的富au元件（AREs）介导的。ARE参与静息细胞的翻译抑制以及刺激条件下的翻译激活。已经鉴定了几种are结合蛋白，其中TIA-1和TIAR与翻译抑制有关。然而，参与TNFalpha翻译上调的因素尚不清楚。研究这一现象的系统已经在酿酒酵母中建立起来。ARE结合蛋白tristetrprolin （TTP）的酵母同源物和TIA-1/TIAR的酵母同源物被发现是ARE翻译调控的关键介质。本研究的目的是利用酵母系统表征TNFalpha are的翻译调控机制，并进行遗传筛选以识别反式作用

TNFalpha is a pro-inflammatory cytokine produced transiently by several cell types in response to infection or injury. Production of TNFalpha is tightly regulated at the levels of transcription, mRNA decay and translation and aberrant expression of this potent molecule has been linked to autoimmune disorders, rheumatoid arthritis, Crohn's disease and other inflammatory conditions. The translational regulation of TNFalpha is mediated by AU-rich elements (AREs) located in the 3'-UTR of the mRNA. The ARE is involved in translational repression in resting cells as well as in activation of translation under stimulatory conditions. Several ARE-binding proteins have been identified and, of these, TIA-1 and TIAR have been implicated in translational repression. However, the factors involved in up-regulation of TNFalpha translation are not known. A system for studying this phenomenon has been developed in the yeast Saccharomyces cerevisiae. The yeast homologues of the ARE-binding protein Tristetraprolin (TTP) and a yeast homologue of TIA-1/TIAR were found to be key mediators of translation regulation by the ARE. The goals of this proposal are to utilize the yeast system to characterize the mechanism of translational regulation by the TNFalpha ARE, and to perform a genetic screen to identify the trans-acting factors required for accurate regulation. In addition, the role of TTP and its murine homologues (Tis 11 b and Tis 11 d) in modulating TNFalpha translation in mouse macrophages will be investigated. The experiments described here aim to increase our understanding of both general ARE function and regulation of TNFalpha expression.