Dataset Information

Small RNA profiling in human cell line following Dicer silencing

ABSTRACT: microRNAs (miRNAs) are a large class of small non-coding RNAs which post-transcriptionally regulate the expression of a large fraction of all animal genes and are important in a wide range of biological processes. Recent advances in high-throughput sequencing allow miRNA detection at unprecedented sensitivity, but the computational task of accurately identifying the miRNAs in the background of sequenced RNAs remains challenging. For this purpose we have designed miRDeep2, a substantially improved algorithm which identifies canonical and non-canonical miRNAs such as those derived from transposable elements and informs on high-confidence candidates that are detected in multiple independent samples. Analyzing data from seven animal species representing the major animal clades, miRDeep2 identified miRNAs with an accuracy of 98.6-99.9% and reported hundreds of novel miRNAs. To test the accuracy of miRDeep2, we knocked down the miRNA biogenesis pathway in a human cell line and sequenced small RNAs before and after. The vast majority of the >100 novel miRNAs expressed in this cell line were indeed specifically down-regulated, validating most miRDeep2 predictions. Last, a new miRNA expression profiling routine, low time and memory usage and user-friendly interactive graphic output can make miRDeep2 useful to a wide range of researchers."

ORGANISM(S): Homo sapiens

PROVIDER: GSE31069 | GEO | 2011/09/13

SECONDARY ACCESSION(S): PRJNA144843

REPOSITORIES: GEO

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Project description:Modification of microRNA sequences by the 3' addition of nucleotides to generate so-called M-bM-^@M-^\isomiRsM-bM-^@M-^] adds to the complexity of miRNA function, with recent reports showing that 3' modifications can influence miRNA stability and efficiency of target repression. Here we show that the 3' modification of miRNAs is a physiological and common post-transcriptional event that shows selectivity for specific miRNAs and is observed across species ranging from C. elegans to human. The modifications result predominantly from adenylation and uridylation, and are seen across tissue types, disease states, and developmental stages. To quantitatively profile 3' nucleotide additions, we developed and validated a novel assay based on NanoString Technologies' nCounter platform. For certain miRNAs, the frequency of modification was altered by processes such as cell differentiation, indicating that 3' modification is a biologically regulated process. To investigate the mechanism of 3' nucleotide additions, we used RNA interference to screen a panel of eight candidate miRNA nucleotidyl transferases for 3' miRNA modification activity in human cells. Multiple enzymes, including PAPD1, PAPD4, PAPD5, ZCCHC6, ZCCHC11, and TUT1, were found to govern 3' nucleotide addition to miRNAs in a miRNA-specific manner. Three of these enzymesM-bM-^@M-^SPAPD1, ZCCHC6 and TUT1M-bM-^@M-^Shave not previously been known to modify miRNAs. Collectively, our results indicate that 3' modification observed in next generation small RNA sequencing data is a biologically relevant process, and identify enzymatic mechanisms that may lead to new approaches for modulating miRNA activity in vivo. We validated the specificity of the platform by assaying three pools of synthetic RNA oligonucleotides representing canonical, variant 1, and variant 2 versions of 5 miRNAs (miR-15a, miR-15b, miR-125a-5p, miR-143 and miR-221).Each bridge pool (i.e., specific to canonical, variant 1 or variant 2) was used to assay the three mixtures of synthetic miRNA oligonucleotides. In order to assess accuracy, we also assayed mixtures of 5 synthetic miRNAs containing 60% canonical miRNA, 30% variant 1, and 10% variant 2. Triplicate technical replicates of each sample were performed.

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Small RNA profiling in human cell line following Dicer silencing

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