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Chopra VS Mishra RK 《BioEssays : news and reviews in molecular, cellular and developmental biology》2006,28(5):445-448
Micro RNAs (miRNAs) have been shown to control many cellular processes including developmental timing in different organisms. The prediction that miRNAs are involved in regulating hox genes of flies and mouse is quite a recent idea and is supported by the finding that mir-196 represses Hoxb8 gene expression. The non-coding regions that encode these miRNAs are also conserved across species in the same way as other mechanisms that regulate expression of hox genes. On the contrary, until now no homeotic phenotype, a hallmark of any hox gene mutation, had been associated with any hox miRNA. Recent work on bithorax complex miRNA (miR-iab-4-5p) shows, for the first time, that miRNAs can lead to homeotic transformation. This miRNA regulates Ultrabithorax (Ubx) and results in the transformation of haltere to wing. This study unveils a new complexity and finesse to the regulation of hox gene expression pattern that is needed for determining the anteroposterior body axis in all bilaterians. 相似文献
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siRNA和miRNA的沉默机制是生物基因调控的重要手段之一. 小干扰RNA(small interfering RNA,siRNA)是RNA干扰的引发物,激发与之互补的目标mRNA沉默. 非编码RNA中的微小RNA(microRNA,miRNA),能够识别特定的目标mRNA,通过与mRNAs的3′ 非翻译区结合,影响该目标蛋白的翻译水平. siRNA和miRNA的基因调控机制对生物学研究及疾病的病因和治疗等有直接影响. 本文主要对siRNAs和miRNAs的生物起源及沉默机制进行比较性论述:提出Dicers酶蛋白、Ago蛋白以及20 nt~25 nt的双链RNAs的 3类大分子是RNA沉默的特征结构,并进行了说明性论述|总结性叙述了siRNA和miRNA的2类小分子经典沉默机制,并提出其异同点. 最后,本文根据近期研究进展,对siRNA和miRNA的生物起源及沉默机制提出了新的疑问. 相似文献
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microRNA(miRNA)是一类细胞内源性的小片段非编码RNA家族,通过与靶基因3′非翻译区(3′untranslated region,3′UTR)结合,对基因表达进行转录后水平的负性调控,参与多种生理和病理学过程。对细胞内成熟体miRNA的功能抑制机制之一是抑制物与miRNA互补结合,从而阻止其与靶基因的结合。这类抑制物主要包括细胞内天然存在的竞争性内源RNA(competing endogenous RNA,ce RNA),以及人工合成或载体表达的外源性miRNA吸附物。本文分别对这两种机制的作用方式进行综述,并对二者的相似点和不同点进行总结。 相似文献
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