MicroRNA-206 colocalizes with ribosome-rich regions in both the nucleolus and cytoplasm of rat myogenic cells
MicroRNA-206 colocalizes with ribosome-rich regions in both the nucleolus and cytoplasm of rat myogenic cells
复制标题
DOI：
10.1073/pnas.0609466103
复制
发表时间：
2006-12-12
影响因子：
11.1
通讯作者：
Pederson, Thoru
中科院分区：
文献类型：
--
作者：
Politz, Joan C. Ritland;Zhang, Fan;Pederson, Thoru
MicroRNA 很小，大约为 21 至 24 nt RNA，已被发现可调节基因表达。 miR-206 是一种在果蝇、斑马鱼和小鼠骨骼肌中高水平表达的 microRNA，被认为参与分化状态的实现和/或维持。我们使用锁核酸探针对大鼠肌原细胞分化过程中 miR-206 的细胞内定位进行原位杂交分析。与大多数被认为抑制靶mRNA翻译的microRNA一样，我们发现miR-206在培养的成肌细胞和分化的肌管中占据细胞质位置，并且其水平在分化过程中在肌管中增加，这与之前在体内肌肉组织中的发现一致。然而，令我们惊讶的是，我们还观察到 miR-206 集中在核仁中。设计为与 miR-206 前体形式互补的探针没有给出核仁信号。我们以更高的空间分辨率表征了 miR-206 的细胞内定位，发现很大一部分与 28S rRNA 在细胞质和核仁中共定位。 miR-206 并不集中在核仁的纤维中心或致密纤维成分（核糖体 RNA 转录和早期加工发生的地方），而是定位在颗粒成分（核糖体最终组装发生的地方）。这些结果表明 miR-206 可能与核仁中的新生核糖体以及细胞质中输出的功能性核糖体相关。
MicroRNAs are small, approximate to 21- to 24-nt RNAs that have been found to regulate gene expression. miR-206 is a microRNA that is expressed at high levels in Drosophila, zebrafish, and mouse skeletal muscle and is thought to be involved in the attainment and/or maintenance of the differentiated state. We used locked nucleic acid probes for in situ hybridization analysis of the intracellular localization of miR-206 during differentiation of rat myogenic cells. Like most microRNAs, which are presumed to suppress translation of target mRNAs, we found that miR-206 occupies a cytoplasmic location in cultured myoblasts and differentiated myotubes and that its level increases in myotubes over the course of differentiation, consistent with previous findings in muscle tissue in vivo. However, to our surprise, we also observed miR-206 to be concentrated in nucleoli. A probe designed to be complementary to the precursor forms of miR-206 gave no nucleolar signal. We characterized the intracellular localization of miR-206 at higher spatial resolution and found that a substantial fraction colocalizes with 28S rRNA in both the cytoplasm and the nucleolus. miR-206 is not concentrated in either the fibrillar centers of the nucleolus or the dense fibrillar component, where ribosomal RNA transcription and early processing occur, but rather is localized in the granular component, the region of the nucleolus where final ribosome assembly takes place. These results suggest that miR-206 may associate both with nascent ribosomes in the nucleolus and with exported, functional ribosomes in the cytoplasm.