A network of noncoding regulatory RNAs acts in the mammalian brain I

Noncoding RNAs (ncRNAs) play increasingly appreciated gene-regulatory roles. Here, we describe a regulatory network centered on four ncRNAs--a long ncRNA, a circular RNA, and two microRNAs--using gene editing in mice to probe the molecular consequences of disrupting key components of this network. The long ncRNA Cyrano uses an extensively paired site to miR-7 to trigger destruction of this microRNA. Cyrano-directed miR-7 degradation is much more efficient than previously described examples of target-directed microRNA degradation, which come primarily from studies of artificial and viral RNAs. By reducing miR-7 levels, Cyrano prevents repression of miR-7 targeted mRNAs and enables the accumulation of Cdr1as, a circular RNA known to regulate neuronal activity. Without Cyrano, excess miR-7 causes cytoplasmic destruction of Cdr1as, in part through enhanced slicing of Cdr1as by a second miRNA, miR-671. Thus, several types of ncRNAs can collaborate to establish a sophisticated regulatory network. mRNA expression profiling by RNA-seq of 10 tissues from wild-type (WT) and Cyrano-/- (CyrKO) mice. This study consists of 96 polyA-selected unstranded Tru-seq libraries prepared from 4-6 biological replicates per genotype for each tissue.非编码RNA（noncoding RNAs，ncRNAs）在基因调控中发挥的作用正日益得到学界的广泛认可。本研究构建了以四类非编码RNA为核心的调控网络——包含一条长链非编码RNA、一条环状RNA以及两种微小RNA（microRNAs，miRNAs），并通过在小鼠体内开展基因编辑实验，探究该网络关键组分被破坏后产生的分子效应。长链非编码RNA Cyrano通过一段与miR-7广泛互补配对的位点，介导该微小RNA的降解。Cyrano介导的miR-7降解效率，远高于此前已报道的靶向介导微小RNA降解案例——此类案例大多基于人工合成RNA与病毒RNA的研究。Cyrano通过降低miR-7的表达水平，解除其对靶标mRNA的抑制作用，从而促进已知可调控神经元活动的环状RNA Cdr1as的积累。在缺失Cyrano的情况下，过量的miR-7会引发Cdr1as在细胞质中的降解，其中部分原因是第二种微小RNA miR-671对Cdr1as的剪切作用增强。由此可见，多种类型的非编码RNA可协同作用，构建出一套精密复杂的基因调控网络。本研究通过RNA测序（RNA-seq）对野生型（wild-type，WT）与Cyrano基因敲除（Cyrano-/-，CyrKO）小鼠的10种组织进行mRNA表达谱分析。本研究共构建96个经polyA富集的非链特异性Tru-seq文库，每个组织的每种基因型均设置4至6个生物学重复。