Unknown,Transcriptomics,Genomics,Proteomics

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Gene expression profiling in THP1 cells after PAPD5 or GLD2 knockdown

ABSTRACT: Next-generation sequencing experiments have shown that microRNAs are expressed in many different isoforms (isomiRs), whose biological relevance is often unclear. We found that mature miR-21, the most widely researched microRNA because of its importance in human disease, is produced in two prevalent isomiR forms that differ by one nucleotide at their 3M-bM-^@M-^Y end, and moreover that the 3M-bM-^@M-^Y end of miR-21 is post transcriptionally adenylated by the noncanonical poly(A) polymerase PAPD5. PAPD5 knockdown caused an increase in the miR-21 expression level, suggesting that PAPD5-mediated adenylation of miR-21 leads to its degradation. Exoribonuclease knockdown experiments followed by small RNA sequencing suggested that PARN degrades miR-21 in the 3M-bM-^@M-^Y-to-5M-bM-^@M-^Y direction. In accordance with this model, microarray expression profiling demonstrated that PAPD5 knockdown results in a downregulation of miR-21 target mRNAs. We found that disruption of the miR-21 adenylation and degradation pathway is a general feature in tumors across a wide range of tissues, as evidenced by data from The Cancer Genome Atlas, as well as in the non-cancerous proliferative disease psoriasis. We conclude that PAPD5 and PARN mediate degradation of oncomiR miR-21 through a tailing and trimming process, and that this pathway is disrupted in cancer and other proliferative diseases. Gene expression levels were profiled by Illumina microarrays using RNA produced previously (PMID 20719920). Briefly, total RNA was extracted from THP1 cells in four replicates 72 hours after transfection of siRNA against PAPD5 or GLD2, or of calibrator negative control siRNA. Gene expression levels were profiled in two of the PAPD5 knockdown replicates, two of the GLD2 knockdown replicates, and two of the negative control replicates.

ORGANISM(S): Homo sapiens

SUBMITTER: Michiel de Hoon

PROVIDER: E-GEOD-57939 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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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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Gene expression profiling in THP1 cells after PAPD5 or GLD2 knockdown

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