Processing bodies are not required for mammalian nonsense-mediated mRNA decay
Processing bodies are not required for mammalian nonsense-mediated mRNA decay
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DOI：
10.1261/rna.1672509
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发表时间：
2009-07-01
期刊：
影响因子：
4.5
通讯作者：
Muehlemann, Oliver
中科院分区：
文献类型：
--
作者：
Stalder, Lukas;Muehlemann, Oliver
无义介导的mRNA衰变（NMD）是真核生物识别和降解具有提前终止密码子（PTC）的mRNA的质量控制机制。在酵母中，含有PTC的mRNA靶向加工体（P体），表达ATP酶缺陷型Upf 1 p突变体的酵母菌株积累P体。在这里，我们表明，在人类细胞中，ATP酶缺陷的UPF 1突变体和一部分的UPF 2和UPF 3b积累在细胞质病灶，共定位与P-体。耗尽的P-体组件Ge-1，这将阻止显微镜下可检测的P-体的形成，也损害了定位的突变体UPF 1，UPF 2，和UPF 3b的细胞质病灶。然而，ATP酶缺陷型UPF 1突变体在P体中的积累不依赖于UPF 2、UPF 3b或SMG 1，并且ATP酶缺陷型UPF 1突变体可以定位于P体中，不依赖于其磷酸化状态。最重要的是，破坏的P-体的Ge-1的耗尽既不影响含PTC的报告基因的mRNA水平，也不内源性NMD底物。与最近报道的人类无义mRNA的不依赖于SMG 6介导的核酸内切衰变一致，我们的研究结果表明，哺乳动物NMD不需要显微镜下可检测到的P-体。
Nonsense-mediated mRNA decay (NMD) is a eukaryotic quality-control mechanism that recognizes and degrades mRNAs with premature termination codons (PTCs). In yeast, PTC-containing mRNAs are targeted to processing bodies (P-bodies), and yeast strains expressing an ATPase defective Upf1p mutant accumulate P-bodies. Here we show that in human cells, an ATPase-deficient UPF1 mutant and a fraction of UPF2 and UPF3b accumulate in cytoplasmic foci that co-localize with P-bodies. Depletion of the P-body component Ge-1, which prevents formation of microscopically detectable P-bodies, also impairs the localization of mutant UPF1, UPF2, and UPF3b in cytoplasmic foci. However, the accumulation of the ATPase-deficient UPF1 mutant in P-bodies is independent of UPF2, UPF3b, or SMG1, and the ATPase-deficient UPF1 mutant can localize into the P-bodies independent of its phosphorylation status. Most importantly, disruption of P-bodies by depletion of Ge-1 affects neither the mRNA levels of PTC-containing reporter genes nor endogenous NMD substrates. Consistent with the recently reported decapping-independent SMG6-mediated endonucleolytic decay of human nonsense mRNAs, our results imply that microscopically detectable P-bodies are not required for mammalian NMD.