A novel role for the glucocorticoid receptor in the regulation of monocyte chemoattractant protein-1 mRNA stability
A novel role for the glucocorticoid receptor in the regulation of monocyte chemoattractant protein-1 mRNA stability
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DOI：
10.1074/jbc.m605925200
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发表时间：
2007-04-06
影响因子：
4.8
通讯作者：
Taubman, Mark B.
中科院分区：
文献类型：
--
作者：
Dhawan, Latika;Liu, Bin;Taubman, Mark B.
单核细胞趋化蛋白-1 （MCP-1）在吸引单核细胞到炎症部位中起重要作用，是动脉粥样硬化斑块中巨噬细胞积聚的主要介质。我们之前的研究表明，糖皮质激素通过显著降低MCP-1 mRNA的稳定性来抑制动脉平滑肌细胞（SMC）中MCP-1的分泌。我们现在报道MCP-1 mRNA的不稳定是由糖皮质激素受体（GR）介导的。GR拮抗剂RU486阻断糖皮质激素地塞米松（Dex）对SMC培养中MCP-1 mRNA稳定性的影响。使用先前报道的体外mRNA凝胶转移和稳定性分析，GR抗体阻断了dex处理的SMC细胞质提取物衰变MCP-1 mRNA的能力。重组人GR （rhGR）以浓度依赖的方式结合体外转录MCP-1 mRNA，而其他类固醇激素受体家族成员则没有。GR与MCP-1 mRNA的结合是特异性的，因为没有发现它与其他mRNA结合。通过实时逆转录pcr对dex处理的SMC提取物中GR进行免疫沉淀，结果表明内源性GR与MCP-1 mRNA特异性结合。外源rhGR的加入阻断了dex处理的SMC提取物降解MCP-1 mRNA的能力，表明外源rhGR可以与内源性含有gr的降解复合物竞争。这些数据表明GR在结合和促进mRNA降解方面具有新的作用。这些结果为GR功能提供了新的见解，并可能为减轻MCP-1介导的炎症反应提供新的途径。
Monocyte chemoattractant protein-1 (MCP-1) plays an important role in attracting monocytes to sites of inflammation and is the dominant mediator of macrophage accumulation in atherosclerotic plaques. We have previously shown that glucocorticoids inhibit the secretion of MCP-1 in arterial smooth muscle cells (SMC) by markedly decreasing MCP-1 mRNA stability. We now report that the destabilization of MCP-1 mRNA is mediated by the glucocorticoid receptor (GR). The GR antagonist, RU486, blocked the effect of the glucocorticoid dexamethasone (Dex) on MCP-1 mRNA stability in SMC culture. Using a previously reported in vitro mRNA gel shift and stability assay, antibodies to the GR blocked the ability of cytoplasmic extracts from Dex-treated SMC to decay MCP-1 mRNA. Recombinant human GR (rhGR) bound in a concentration dependent manner to in vitro transcribed MCP-1 mRNA, whereas other members of the steroid hormone receptor family did not. Binding of GR to MCP-1 mRNA was specific as it was not found to bind other mRNAs. Immunoprecipitation of GR in extracts from Dex-treated SMC followed by real-time reverse transcription-PCR demonstrated that endogenous GR was bound specifically to MCP-1 mRNA. The addition of exogenous rhGR blocked the ability of extracts from Dex-treated SMC to degrade MCP-1 mRNA, suggesting that exogenous rhGR can compete with an endogenous GR-containing degradative complex. These data suggest a novel role for the GR in binding to and facilitating mRNA degradation. These results provide novel insights into GR function and may provide a new approach to attenuate the inflammatory response mediated by MCP-1.