Mechanisms of Macrophage Activation

描述（由申请方提供）：单核吞噬细胞在宿主对癌症反应中的作用在很大程度上是通过对肿瘤微环境中遇到的刺激物的反应诱导的基因表达模式来确定的。响应于原型促炎剂（IFN γ和LPS）或抗炎剂（IL-10和TGF β）的巨噬细胞基因表达的控制由在转录和转录后水平上操作的多种细胞内信号的整合引起。目前对特定mRNA稳定性的转录后调控的认识是有限的。许多细胞因子和趋化因子mRNA的3'非翻译区（UTR）中富含Au的序列元件（战神）与ARE特异性RNA结合蛋白一起导致mRNA快速衰减。我们和其他人已经表明，促炎或抗炎刺激可以分别稳定或不稳定选定的趋化因子mRNA，特别是KC（小鼠CXCL 1）。这些发现导致了一般假设，即瞬时表达的炎症基因的转录后控制涉及通过以序列特异性方式操作的过程诱导不稳定mRNA的稳定。抗炎剂通过拮抗这种反应起作用。目前，该模型的多个特征仍未确定。这些包括（a）刺激依赖性反应的序列决定子，（B）由稳定和/或去稳定剂引发的信号传导途径如何整合并与mRNA稳定性的控制偶联，（c）稳定或去稳定刺激改变了mRNA衰变中的哪些步骤，以及（d）ARE结合蛋白如何将信号传导事件偶联到负责mRNA衰变变化的效应器机制。我们现在提出解决这些问题作为进一步的测试的假设，通过以下具体的实验目的的性能。1.评估ARE依赖性、刺激介导的mRNA稳定性控制的序列基础。2.评价LPS、IL-10和TGF β控制mRNA稳定性的信号通路。3.识别受刺激依赖性调节的mRNA衰变机制。4.确定已知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