RESUMO
Adenosine-to-inosine (A-to-I) RNA editing targets double-stranded RNA stem-loop structures in the mammalian brain. It has previously been shown that miRNAs are substrates for A-to-I editing. For the first time, we show that for several definitions of edited miRNA, the level of editing increases with development, thereby indicating a regulatory role for editing during brain maturation. We use high-throughput RNA sequencing to determine editing levels in mature miRNA, from the mouse transcriptome, and compare these with the levels of editing in pri-miRNA. We show that increased editing during development gradually changes the proportions of the two miR-376a isoforms, which previously have been shown to have different targets. Several other miRNAs that also are edited in the seed sequence show an increased level of editing through development. By comparing editing of pri-miRNA with editing and expression of the corresponding mature miRNA, we also show an editing-induced developmental regulation of miRNA expression. Taken together, our results imply that RNA editing influences the miRNA repertoire during brain maturation.
Assuntos
Adenosina/metabolismo , Encéfalo/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Inosina/metabolismo , MicroRNAs/metabolismo , Edição de RNA , Adenosina/genética , Animais , Sequência de Bases , Encéfalo/embriologia , Encéfalo/crescimento & desenvolvimento , Biologia Computacional , Dendritos/genética , Dendritos/metabolismo , Embrião de Mamíferos/metabolismo , Desenvolvimento Embrionário/genética , Sequenciamento de Nucleotídeos em Larga Escala , Inosina/genética , Camundongos , MicroRNAs/genética , Isoformas de RNA/genética , Isoformas de RNA/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , TranscriptomaRESUMO
Transcripts have been found to be site selectively edited from adenosine-to-inosine (A-to-I) in the mammalian brain, mostly in genes involved in neurotransmission. While A-to-I editing occurs at double-stranded structures, other structural requirements are largely unknown. We have investigated the requirements for editing at the I/M site in the Gabra-3 transcript of the GABA(A) receptor. We identify an evolutionarily conserved intronic duplex, 150 nt downstream of the exonic hairpin where the I/M site resides, which is required for its editing. This is the first time a distant RNA structure has been shown to be important for A-to-I editing. We demonstrate that the element also can induce editing in related but normally not edited RNA sequences. In human, thousands of genes are edited in duplexes formed by inverted repeats in non-coding regions. It is likely that numerous such duplexes can induce editing of coding regions throughout the transcriptome.