Mechanisms of Macrophage Activation

描述（由申请人提供）：单核吞噬细胞在宿主对癌症反应中的贡献在很大程度上是通过肿瘤微环境中遇到刺激时诱导的基因表达模式来决定的。巨噬细胞基因表达在对原始促炎剂（IFNgamma和LPS）或抗炎剂（IL-10和tgf - β）的反应中的控制来自于多种细胞内信号的整合，这些信号在转录和转录后水平上起作用。目前对特定mRNA稳定性的转录后调控的了解有限。许多细胞因子和趋化因子mRNA的3'非翻译区（UTRs）中的AU富序列元件（AREs）与are特异性RNA结合蛋白一起导致mRNA的快速衰变。我们和其他人已经表明，促炎或抗炎刺激分别可以稳定或破坏选定的趋化因子mrna，特别是KC（小鼠CXCL1）。这些发现导致了一种普遍的假设，即瞬时表达的炎症基因的转录后控制涉及通过以序列特定方式操作的过程诱导不稳定mrna的稳定。抗炎剂通过对抗这种反应而起作用。目前，该模型的多个特征仍未定义。这些包括(a)刺激依赖性反应的序列决定因素，(b)稳定和/或不稳定因子启动的信号通路如何整合并与mRNA稳定性控制耦合，(c)稳定或不稳定刺激改变mRNA衰变的哪些步骤，以及(d)结合蛋白如何将信号事件与负责mRNA衰变变化的效应机制偶联。我们现在建议通过以下具体实验目标的表现来解决这些问题，作为对假设的进一步检验。1. 评估依赖于are的序列基础，刺激介导的mRNA稳定性控制。2. 评估LPS、IL-10和tgf - β控制mRNA稳定性的信号通路。3. 确定受刺激依赖性调节的mRNA衰变机制。4. 确定已知的ARE/RNA结合蛋白在lps诱导的稳定和IL-10或tgf - β介导的不稳定中的作用

DESCRIPTION (provided by applicant): The contribution of mononuclear phagocytes in host response to cancer is determined in large part through the pattern of gene expression induced in response to stimuli encountered in the tumor microenvironment. Control of macrophage gene expression in response to prototypic pro-inflammatory (IFNgamma and LPS) or anti-inflammatory agents (IL-10 and TGFbeta) results from the integration of multiple intracellular signals that operate at both transcriptional and post-transcriptional levels. Current knowledge of post-transcriptional regulation of specific mRNA stability is limited. AU rich sequence elements (AREs) in the 3' untranslated regions (UTRs) of many cytokine and chemokine mRNAs in concert with ARE-specific RNA binding proteins lead to rapid mRNA decay. We and others have shown that pro-inflammatory or anti-inflammatory stimuli can stabilize or destabilize, respectively, selected chemokine mRNAs particularly KC (mouse CXCL1). These findings lead to the general hypothesis that post-transcriptional control of transiently expressed inflammatory genes involves the induced stabilization of unstable mRNAs through a process that operates in sequence specific fashion. Anti-inflammatory agents act by antagonizing this response. At present multiple features of this model remain undefined. These include (a) the sequence determinants for stimulus-dependent response, (b) how signaling pathways initiated by stabilizing and/or destabilizing agents are integrated and coupled with control of mRNA stability, (c) which steps in mRNA decay are altered by stabilizing or destabilizing stimuli and (d) how ARE-binding proteins couple signaling events to effector mechanisms responsible for the changes in mRNA decay. We now propose to address these issues as a further test of the hypothesis by performance of the following specific experimental aims. 1. Evaluate the sequence basis for ARE-dependent, stimulus-mediated control of mRNA stability. 2. Evaluate signaling pathways involved in the control of mRNA stability by LPS, IL-10 and TGFbeta. 3. Identify the mRNA decay mechanisms that are subject to stimulus-dependent modulation. 4. Determine the role of known ARE/RNA binding proteins in LPS-induced stabilization and IL-10 or TGFbeta-mediated destabilization