Starega-Roslan Julia, Witkos Tomasz M, Galka-Marciniak Paulina, Krzyzosiak Wlodzimierz J
Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14 Str., 61-704 Poznan, Poland.
Int J Mol Sci. 2015 Apr 10;16(4):8110-27. doi: 10.3390/ijms16048110.
The deep-sequencing of small RNAs has revealed that different numbers and proportions of miRNA variants called isomiRs are formed from single miRNA genes and that this effect is attributable mainly to imprecise cleavage by Drosha and Dicer. Factors that influence the degree of cleavage precision of Drosha and Dicer are under investigation, and their identification may improve our understanding of the mechanisms by which cells modulate the regulatory potential of miRNAs. In this study, we focused on the sequences and structural determinants of Drosha and Dicer cleavage sites, which may explain the generation of homogeneous miRNAs (in which a single isomiR strongly predominates) as well as the generation of heterogeneous miRNAs. Using deep-sequencing data for small RNAs, we demonstrate that the generation of homogeneous miRNAs requires more sequence constraints at the cleavage sites than the formation of heterogeneous miRNAs. Additionally, our results indicate that specific Drosha cleavage sites have more sequence determinants in miRNA precursors than specific cleavage sites for Dicer and that secondary structural motifs in the miRNA precursors influence the precision of Dicer cleavage. Together, we present the sequence and structural features of Drosha and Dicer cleavage sites that influence the heterogeneity of the released miRNAs.
小RNA的深度测序表明，单个miRNA基因可形成数量和比例各异的miRNA变体（称为isomiRs），且这种效应主要归因于Drosha和Dicer的切割不精确。影响Drosha和Dicer切割精确程度的因素正在研究中，其鉴定可能会增进我们对细胞调节miRNA调控潜能机制的理解。在本研究中，我们聚焦于Drosha和Dicer切割位点的序列和结构决定因素，这或许能解释均一性miRNA（其中单一isomiR占主导）的产生以及异质性miRNA的产生。利用小RNA的深度测序数据，我们证明，与异质性miRNA的形成相比，均一性miRNA的产生在切割位点需要更多的序列限制。此外，我们的结果表明，在miRNA前体中，特定的Drosha切割位点比Dicer的特定切割位点具有更多的序列决定因素，并且miRNA前体中的二级结构基序会影响Dicer切割的精确性。我们共同呈现了影响释放的miRNA异质性的Drosha和Dicer切割位点的序列和结构特征。
