Regulation of mRNA stability in vascular smooth muscle

描述(申请人提供)：单核细胞趋化蛋白-1(MCP-1)是一种由内皮细胞、平滑肌细胞(SMC)和巨噬细胞分泌的趋化因子，在动脉粥样硬化发展过程中对巨噬细胞募集到动脉壁起关键作用。血小板衍生生长因子(PDGF)是SMC的激活剂，也是MCP-1的有效诱导剂。PDGF对SMC MCP-1mRNA水平的影响在很大程度上是由于其mRNA半衰期(tl/2)显著增加。相反，糖皮质激素地塞米松(Dex)抑制多种细胞中MCP-1mRNA的积累；在SMC中，这是由于mRNA t1/2的显著减少。Dex的作用似乎依赖于糖皮质激素受体(GR)，而不是新的转录，这表明GR有一个新的作用。尽管关于PDGF和Dex调控基因转录的机制有相当多的信息，但关于它们对mRNA稳定性的影响却知之甚少。这项建议将研究PDGF和Dex在细胞培养和体内调节MCP-1mRNA稳定性的机制。目的1鉴定MCP-1mRNA的地塞米松敏感区，阐明地塞米松破坏MCP-1mRNA稳定性的机制，并鉴定相关蛋白。重点还将放在确定GR在调节MCP-1mRNA稳定性方面的作用。同样，目标2将描述血小板衍生生长因子增强单核细胞趋化蛋白-1mRNA稳定性的机制，并确定涉及的蛋白质(S)。目的3将在动物模型中检测MCP-1mRNA稳定性的调节，并将在体内建立地塞米松对MCP-1介导的事件的影响。它还将开发动物模型来检测AIMS 1和AIMS 2中确定的MCP-1mRNA稳定性的介质。这些研究将为MCP-1的调节、PDGF和糖皮质激素的生物学以及动脉壁炎症反应的控制提供新的见解。它还可能通过模仿地塞米松的作用或通过阻断PDGF对MCP-1mRNA的影响来提供抑制MCP-1表达和巨噬细胞聚集的新方法。

DESCRIPTION (provided by applicant): Monocyte chemoattractant protein-1 (MCP-1) is a chemokine secreted by endothelial cells, smooth muscle cells (SMC), and macrophages that plays a key role in recruiting macrophages to the arterial wall during the development of atherosclerosis. Platelet-derived growth factor (PDGF) is an activator of SMC and a potent inducer of MCP-1. The effect of PDGF on MCP-1 mRNA levels in SMC is due largely to a marked increase in mRNA half-life (tl/2). In contrast, the glucocorticoid dexamethasone (Dex) inhibits the accumulation of MCP-1 mRNA in a variety of cell types; in SMC this is due to a marked decrease in mRNA tl/2. The Dex effect appears to be dependent upon the glucocorticoid receptor (GR), but not on new transcription, suggesting a novel role for the GR. Although there is considerable information concerning the mechanisms by which PDGF and Dex regulate gene transcription, far less is known about their effects on mRNA stability. This proposal will examine the mechanisms by which PDGF and Dex regulate MCP-1 mRNA stability in cell culture and in vivo. Aim 1 will characterize the Dex-sensitive region of the MCP-1 mRNA, elucidate the mechanisms by which Dex destabilizes MCP-1 mRNA, and identify the proteins involved. Emphasis will also be placed on establishing the role of the GR in regulating MCP-1 mRNA stability. Similarly, aim 2 will characterize the mechanism by which PDGF enhances MCP-1 mRNA stability and identify the protein(s) involved. Aim 3 will examine the regulation of MCP-1 mRNA stability in animal models and will establish the effect of Dex on MCP-1-mediated events in vivo. It will also develop animal models for examining mediators of MCP-1 mRNA stability identified in aims 1 and 2. These studies will provide new insights into the regulation of MCP-1, the biology of PDGF and glucocorticoids, and the control of the inflammatory response in the arterial wall. It may also provide novel approaches to inhibiting MCP-1 expression and macrophage accumulation by mimicking the effect of Dex or by blocking the effect of PDGF on MCP- 1 mRNA.