Nocturnin, a deadenylase in Xenopus laevis retina:: A mechanism for posttranscriptional control of circadian-related mRNA
Nocturnin, a deadenylase in Xenopus laevis retina:: A mechanism for posttranscriptional control of circadian-related mRNA
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DOI：
10.1016/s0960-9822(03)00014-9
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发表时间：
2003-02-04
期刊：
影响因子：
9.2
通讯作者：
Green, CB
中科院分区：
文献类型：
--
作者：
Baggs, JE;Green, CB
背景资料：利用不同类型的调节来产生稳健的生物钟，包括在转录、转录后和翻译水平的调节。对可能参与这种昼夜节律控制的节律信息进行筛选，确定了一种新的基因，在非洲爪蟾视网膜中显示高幅度的昼夜节律表达，mRNA水平在深夜达到峰值。retinalturnin mRNA的表达仅限于含时钟的感光细胞层内retina.Results：在这些研究中，我们表明，retinalturnin删除聚（A）尾从合成RNA底物的过程中被称为deadenylation。夜曲蛋白核酸酶活性是镁依赖性的，因为EDTA的添加或预测结合镁的残基的突变破坏去腺苷化。底物偏好性研究表明，转铁蛋白是一种特异性降解3' poly（A）尾的核酸外切酶。虽然turnin是有节奏地表达在视网膜感光细胞的细胞质中，只有其他描述的脊椎动物deadenylase，PARN，是组成性存在于大多数视网膜细胞，包括photoreceptors.Conclusions：不同的空间和时间表达的turnin和PARN表明，可能有特定的mRNA的目标，每个deadenylase。由于去腺苷化调节mRNA的衰减和/或翻译沉默，我们建议，在一个新的机制，生物钟或其输出的转录后调节，去腺苷化的时钟相关的成绩单。
Background: Different types of regulation are utilized to produce a robust circadian clock, including regulation at the transcriptional, posttranscriptional, and translational levels. A screen for rhythmic messages that may be involved in such circadian control identified nocturnin, a novel gene that displays high-amplitude circadian expression in the Xenopus laevis retina, with peak mRNA levels in the early night. Expression of nocturnin mRNA is confined to the clock-containing photoreceptor cell layer within the retina.Results: In these studies, we show that nocturnin removes the poly(A) tail from a synthetic RNA substrate in a process known as deadenylation. Nocturnin nuclease activity is magnesium dependent, as the addition of EDTA or mutation of the residue predicted to bind magnesium disrupts deadenylation. Substrate preference studies show that nocturnin is an exonuclease that specifically degrades the 3' poly(A) tail. While nocturnin is rhythmically expressed in the cytoplasm of the retinal photoreceptor cells, the only other described vertebrate deadenylase, PARN, is constitutively present in most retinal cells, including the photoreceptors.Conclusions: The distinct spatial and temporal expression of nocturnin and PARN suggests that there may be specific mRNA targets of each deadenylase. Since deadenylation regulates mRNA decay and/or translational silencing, we propose that nocturnin deadenylates clock-related transcripts in a novel mechanism for posttranscriptional regulation in the circadian clock or its outputs.