Department of Cell Biochemistry, Jagiellonian University, Krakow, Poland.
FEBS J. 2009 Dec;276(24):7386-99. doi: 10.1111/j.1742-4658.2009.07452.x.
In human monocyte-derived macrophages, the MCPIP gene (monocyte chemoattractant protein-induced protein) is strongly activated by interleukin-1beta (IL-1beta). Using bioinformatics, a PIN domain was identified, spanning amino acids 130-280; such domains are known to possess structural features of RNases. Recently, RNase properties of MCPIP were confirmed on transcripts coding for interleukins IL-6 and IL-12p40. Here we present evidence that siRNA-mediated inhibition of the MCPIP gene expression increases the level of the IL-1beta transcript in cells stimulated with LPS, whereas overexpression of MCPIP exerts opposite effects. Cells with an increased level of wild-type MCPIP showed lower levels of IL-1beta mRNA. However, this was not observed when mutant forms of MCPIP, either entirely lacking the PIN domain or with point mutations in this domain, were used. The results of experiments with actinomycin D indicate that lower levels of IL-1beta mRNA are due to shortening of the IL-1beta transcript half-life, and are not related to the presence of AU-rich elements in the 3' UTR. The interaction of the MCPIP with transcripts of both IL-1beta and MCPIP observed in an RNA immunoprecipitation assay suggests that this novel RNase may be involved in the regulation of expression of several genes.
在人类单核细胞衍生的巨噬细胞中，MCPIP 基因（单核细胞趋化蛋白诱导蛋白）被白细胞介素-1β（IL-1β）强烈激活。通过生物信息学，鉴定出一个 PIN 结构域，跨越氨基酸 130-280；这种结构域具有 RNase 的结构特征。最近，MCPIP 的 RNase 性质在编码白细胞介素 IL-6 和 IL-12p40 的转录本上得到了证实。在这里，我们提供的证据表明，用 siRNA 抑制 MCPIP 基因的表达会增加 LPS 刺激细胞中 IL-1β 转录本的水平，而 MCPIP 的过表达则会产生相反的效果。具有较高水平野生型 MCPIP 的细胞显示出较低水平的 IL-1β mRNA。然而，当使用完全缺乏 PIN 结构域或该结构域存在点突变的 MCPIP 突变体时，并未观察到这种情况。用放线菌素 D 进行的实验结果表明，IL-1β mRNA 水平较低是由于 IL-1β 转录本半衰期缩短所致，与 3'UTR 中存在富含 AU 的元件无关。在 RNA 免疫沉淀测定中观察到的 MCPIP 与 IL-1β 和 MCPIP 的转录本的相互作用表明，这种新型 RNase 可能参与了几个基因表达的调控。
