MACROPHAGE ENDOGENOUS FACTOR THAT SUPPRESSES ANABOLISM

我们一直在研究肿瘤坏死因子-α(TNF)的作用。 3T3-L1分解代谢状态的诱导与调节 成纤维细胞。我们的兴趣一直集中在对 葡萄糖进入细胞的关键阶段的细胞营养。 我们的数据支持这样一种假设，即让人想起血清的肿瘤坏死因子源自 生长因子，提高葡萄糖转运活性以及 联合作用对3T3-L1细胞转运蛋白(GLUT1)mRNA的影响 固有的供过于求活动，先前存在的转运蛋白的移位 以及GLUT1基因的稳定作用。GLUT1基因的稳定结果 在没有GLUT1的情况下，GLUT1的mRNA大量积累 抄写。GLUT1 mRNA含量的增加促进了合成和 结果观察到进入细胞的葡萄糖显著增加。 我们建议研究肿瘤坏死因子诱导GLUT1基因稳定性的机制。 我们的研究集中在广泛的3‘非翻译区(UTR) Glut1 mRNA，包含一系列序列基序，可能发挥一种 在决定稳定性方面的作用。我们的初步数据表明 肿瘤坏死因子诱导一种蛋白的活性，该蛋白与人乳头瘤病毒3‘端非编码区结合 GLUT1信使核糖核酸，可能影响消息的稳定性。我们 建议纯化并鉴定3‘端非编码区结合蛋白(S)； 确定其结合的要求和对mRNA的贡献 无细胞检测系统的稳定性。在完好的细胞中，使用 针对纯化的蛋白制备抗体，我们将对其进行鉴定 蛋白的合成、周转和激活，以响应肿瘤坏死因子。 上述研究将在3T3-L1前脂肪细胞中进行。 成纤维细胞和GLUT1基因表达调控的研究 稳定性。当这些细胞在培养中分化为脂肪细胞时 表达第二个转运蛋白GLUT4(胰岛素反应葡萄糖 传送器)我们将检查差异对稳定性的影响 两个运输机都有。我们的研究解决了肿瘤坏死因子干扰的能力 在多种疾病中具有细胞营养和葡萄糖动态平衡 处于葡萄糖进入细胞的临界水平的状态。

We have been investigating the role of tumor necrosis factor-alpha (TNF) on the induction and regulation of the catabolic state in 3T3-Ll fibroblasts. Our interest has been focused on the regulation of cellular nutrition at the critical step of glucose entry into the cell. Our data supports the hypothesis that TNF, reminiscent of serum derived growth factors, elevates glucose transport activity as well as transporter (GLUT1) mRNA in 3T3-L1 cells by combined effects on intrinsic GLUT activity, translocation of preexisting transporters as well as GLUT1 mRNA stabilization. The GLUT1 mRNA stabilization results in a major accumulation of GLUT1 mRNA in the absence of increased transcription. The increased content of GLUT1 mRNA fuels synthesis and results in the observed major increase in glucose entry into the cell. We propose to examine mechanisms of TNF-induced stability of GLUT1 mRNA. Our studies focus on the extensive 3'-untranslated region (UTR) of the GLUT1 mRNA which contains a series of sequence motifs that may play a role in determining stability. Our preliminary data demonstrates that TNF induces the activity of a protein that binds to the 3' UTR region of the GLUT1 mRNA, which may effect the stability of the message. We propose to purify and characterize the 3'UTR binding protein(s); determine its requirements for binding and contribution to mRNA stability in a cell-free assay system. In the intact cells, using antibody prepared against the purified protein, we will characterize the synthesis, turnover and activation of the protein in response to TNF. The described studies will be performed in the 3T3-L1 preadipocytes/ fibroblasts and thoroughly characterize the regulation of GLUT1 mRNA stability. As these cells differentiate in culture to adipocytes and express a second transporter, GLUT4 (insulin responsive glucose transporter) we will examine for differential effect on the stability of both transporters. Our studies address the ability of TNF to interfere with cellular nutrition and glucose homeostasis in numerous disease states at the critical level of glucose entry into the cell.