A MicroRNA Processing Defect in Smokers' Macrophages Is Linked to SUMOylation of the Endonuclease DICER
A MicroRNA Processing Defect in Smokers' Macrophages Is Linked to SUMOylation of the Endonuclease DICER
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DOI：
10.1074/jbc.m114.565473
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发表时间：
2014-05-02
影响因子：
4.8
通讯作者：
Monick, Martha M.
中科院分区：
文献类型：
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作者：
Gross, Thomas J.;Powers, Linda S.;Monick, Martha M.
背景：吸烟导致肺泡巨噬细胞 miRNA 表达整体下调。结果：香烟烟雾暴露会改变 RNA 核酸内切酶 DICER，导致 microRNA 加工缺陷。结论：香烟烟雾部分通过 DICER 的 SUMO 化改变肺泡巨噬细胞 microRNA 表达。意义：这是首次描述环境暴露通过 DICER 翻译后修饰引起 microRNA 表达变化。尽管肺泡巨噬细胞在吸烟相关疾病中发挥着重要作用，但人们对调节其病理生理表型的因素知之甚少。通过评估吸烟者巨噬细胞，我们发现多种 microRNA (miRNA) 显着下调。这项工作研究了以下假设：香烟烟雾通过抑制初级 miRNA 转录物的加工来改变肺巨噬细胞中成熟 miRNA 的表达。对吸烟者肺泡巨噬细胞的研究表明 miRNA 成熟存在缺陷。对 miRNA 生物发生机制的研究使我们关注胞质 RNA 核酸内切酶 DICER。 DICER 从 pre-miRNA 上切割茎环结构，使它们解离成成熟的 20-22 核苷酸单链形式。 DICER 活性测定证实接触香烟烟雾后 DICER 活性受损。进一步的蛋白质研究表明，随着香烟烟雾的暴露，DICER 的天然 217-kDa 形式的表达降低，并且高分子量形式的积累。这种分子质量变化被证明含有 SUMO 部分，并且可以通过沉默针对初级 SUMO 化连接酶 Ubc9 的 RNA 来阻断。在确定导致 DICER 变化的香烟烟雾成分时，我们发现 N-乙酰半胱氨酸（一种抗氧化剂和抗醛剂）可以保护香烟烟雾提取物中的 DICER 蛋白和活性。这种 miRNA 的大量下调（部分由 DICER 的改变驱动）可能是吸烟者肺部发现的促进疾病的巨噬细胞表型的重要调节因子。
Background: Smoking causes a global down-regulation in alveolar macrophage miRNA expression. Results: Cigarette smoke exposure modifies the RNA endonuclease DICER, resulting in a microRNA processing defect. Conclusion: Cigarette smoke alters alveolar macrophage microRNA expression, in part, by SUMOylation of DICER. Significance: This is the first description of an environmental exposure causing changes in microRNA expression via post-translational modification of DICER.Despite the fact that alveolar macrophages play an important role in smoking-related disease, little is known about what regulates their pathophysiologic phenotype. Evaluating smoker macrophages, we found significant down-regulation of multiple microRNAs (miRNAs). This work investigates the hypothesis that cigarette smoke alters mature miRNA expression in lung macrophages by inhibiting processing of primary miRNA transcripts. Studies on smoker alveolar macrophages showed a defect in miRNA maturation. Studies on the miRNA biogenesis machinery led us to focus on the cytosolic RNA endonuclease, DICER. DICER cleaves the stem-loop structure from pre-miRNAs, allowing them to dissociate into their mature 20-22-nucleotide single-stranded form. DICER activity assays confirmed impaired DICER activity following cigarette smoke exposure. Further protein studies demonstrated a decreased expression of the native 217-kDa form of DICER and an accumulation of high molecular weight forms with cigarette smoke exposure. This molecular mass shift was shown to contain SUMO moieties and could be blocked by silencing RNA directed at the primary SUMOylating ligase, Ubc9. In determining the cigarette smoke components responsible for changes in DICER, we found that N-acetylcysteine, an antioxidant and anti-aldehyde, protected DICER protein and activity from cigarette smoke extract. This massive down-regulation of miRNAs (driven in part by alterations in DICER) may be an important regulator of the disease-promoting macrophage phenotype found in the lungs of smokers.