TRANSLATIONAL CONTROL OF THE ACUTE PHASE RESPONSE

来自巨噬细胞衍生的细胞因子如IL-1 β的炎症信号， IL-6和TNF在急性期重编程肝脏基因转录 响应（APR）。 然而，肝H-和L-的翻译效率 铁蛋白mRNAs（H-和L-mRNAs）也在IL-1 β刺激下增加， mRNA水平无变化。 这表明，炎症 细胞因子不仅可以抑制刺激增加的信号， 但也通过改变mRNA来改变基因表达 翻译. 铁蛋白的翻译和积累增加， 增加组织的铁储存能力，并从血清中去除铁。 这可能在APR期间提供保护性反应。 典型的人类肝脏APR基因，如血清淀粉样蛋白A（SAA）和α-1 酸性糖蛋白（AGP）在暴露于炎性细胞因子后增加。 然而，肝脏SAA和AGP基因的表达也受到后炎症反应的控制。 转录机制后，他们的外观作为稳定的mRNA在细胞中， 细胞质 这些蛋白质被翻译和输出作为另一部分， 一种适应性反应，以最大限度地减少炎症过程中的损伤。 以下 实验计划： A）检查IL-1 β、TNF和IL-6在H-和L-铁蛋白中的作用 在肝癌（HepG 2和Hep 3B）和内皮细胞中的基因翻译。 B）影响翻译控制的机制的分析， 急性期反应。 铁蛋白mRNA中的RNA序列， 将评估对IL-1 β、TNF和IL-6的免疫应答。 RNA H-和L-mRNA的5'非编码区中的元件显示序列 与其他APR基因5'非编码区中的基序相似，包括 AGP。 翻译调节可能通过这种方式起作用的假设 将测试“RNA增强剂”。 C）多聚（A）尾在肝脏mRNA的3'端延长或缩短， 这对AGP、SAA和铁蛋白翻译和RNA的影响 将在暴露于细胞因子的肝癌细胞中表征稳定性。

Inflammatory signals from macrophage derived cytokines such as Il-1beta, Il-6, and TNF reprogram liver gene transcription during the acute phase response (APR). However the translational efficiency of hepatic H- and L- ferritin mRNAs (H- and L-mRNAs) also increases in response to Il-1beta in the absence of changes in mRNA levels. This suggests that inflammatory cytokines may not only transduce signals which stimulate increased transcription of APR genes but also change gene expression by altering mRNA translation. Increased translation and accumulation of ferritin would increase the iron storage capacity of tissues, and remove iron from serum. This may afford a protective response during the APR. The transcription of typical human liver APR genes such as serum amyloid A (SAA) and alpha-1 acid glycoprotein (AGP) increases after exposure to inflammatory cytokines. However liver SAA and AGP gene expression is also controlled by post- transcriptional mechanisms after their appearance as stable mRNAs in the cytoplasm. These proteins are translated and exported as another part of an adaptive response to minimize damage during inflammation. The following experiments are planned: A)An examination of the role of Il-1beta, TNF, & Il-6 in H- & L- ferritin gene translation in hepatoma (HepG2 & Hep3B) and endothelial cells. B)An analysis of the mechanisms influencing translational control during the acute phase response. The RNA sequences in ferritin mRNAs which are translationally responsive to Il-1beta, TNF and Il-6 will be assessed. RNA elements in the 5' non coding regions of H- and L- mRNA exhibit sequence similarity with a motif in other APR gene 5' noncoding regions, including AGP. The hypothesis that translational regulation might act through such "RNA enhancers" will be tested. C)Poly(A) tails lengthen or shorten at the 3' of liver mRNAs during the APR. The effect of this on AGP, SAA, and ferritin translation and RNA stability will be characterized in hepatoma cells exposed to cytokines.