Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

C. elegans piRNAs are processed from capped-small RNAs transcribed at promoters throughout the genome

ABSTRACT: Piwi-interacting (pi) RNAs are a class of germline-expressed small RNAs that have been linked to epigenetic programming in metazoa. C. elegans piRNAs known as 21U-RNAs are defined by more than 15,000 genome-encoded species. To explore the origin of 21U-RNAs we employed methods to enrich the 5' ends of Pol II transcripts. We show that a species of capped-short (cs) RNA is frequently expressed bidirectionally at Pol II loci in C. elegans. Interestingly, at annotated 21U-RNA loci, csRNAs originate precisely 2 nt upstream of the mature piRNA species suggesting that csRNAs are piRNA precursors. In addition, we show that csRNAs associated with TS sites genome-wide define a previously overlooked class of 21U-RNA loci, and nearly double the number of piRNA species available for genome surveillance. Our methods should be of general utility in TS site identification and 5' anchored RNA-expression profiling. Identification of capped RNA including capped small RNA and long capped RNA in C. elegans. The mouse data are independent data to test the CapSeq sequencing protocol.

ORGANISM(S): Mus musculus

SUBMITTER: Weifeng Gu

PROVIDER: E-GEOD-40053 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

CapSeq and CIP-TAP identify Pol II start sites and reveal capped small RNAs as C. elegans piRNA precursors.

Gu Weifeng W Lee Heng-Chi HC Chaves Daniel D Youngman Elaine M EM Pazour Gregory J GJ Conte Darryl D Mello Craig C CC

Cell 20121201 7

Piwi-interacting (pi) RNAs are germline-expressed small RNAs linked to epigenetic programming. C. elegans piRNAs are thought to be transcribed as independent gene-like loci. To test this idea and to identify potential transcription start (TS) sites for piRNA precursors, we developed CapSeq, an efficient enzymatic method for 5' anchored RNA profiling. Using CapSeq, we identify candidate TS sites, defined by 70-90 nt sequence tags, for >50% of annotated Pol II loci. Surprisingly, however, these Ca ...[more]

PMID: 23260138

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Project description:Epigenetic inheritance is the transmission of information independently of the nucleotide sequence of the genome. A fundamental question in biology is to what extent does epigenetics contribute to trans-generational inheritance. Here we investigate the role of Argonaute-small-RNA pathways in epigenetic inheritance in the nematode C. elegans. Argonautes present their guide RNAs for base-pairing with target sequences and, upon binding, can cleave the target RNA and/or recruit cofactors that mediate post-transcriptional or transcriptional silencing 1,2. Previous studies have shown that Argonaute small-RNA pathways reinforce and maintain epigenetic silencing in C. elegans 3-5. For example, the conserved PIWI-related Argonaute PRG-1 initiates a remarkably stable mode of epigenetic silencing, termed RNA-induced epigenetic silencing (RNAe) 3. Alleles that are silenced by RNAe send trans-acting Argonaute-small-RNA signals that can act in a sequence-specific manner to induce the permanent Epigenetic inheritance is the transmission of information independently of the nucleotide sequence of the genome. A fundamental question in biology is to what extent does epigenetics contribute to trans-generational inheritance. Here we investigate the role of Argonaute-small-RNA pathways in epigenetic inheritance in the nematode C. elegans. Argonautes present their guide RNAs for base-pairing with target sequences and, upon binding, can cleave the target RNA and/or recruit cofactors that mediate post-transcriptional or transcriptional silencing 1,2. Previous studies have shown that Argonaute small-RNA pathways reinforce and maintain epigenetic silencing in C. elegans 3-5. For example, the conserved PIWI-related Argonaute PRG-1 initiates a remarkably stable mode of epigenetic silencing, termed RNA-induced epigenetic silencing (RNAe) 3. Alleles that are silenced by RNAe send trans-acting Argonaute-small-RNA signals that can act in a sequence-specific manner to induce the permanent silencing of homologous genes 3. Here we explore an opposite phenomenon, RNA-induced gene activation (RNAa), in which an expressed gene provides a sequence-specific signal that can activate a silent homologous gene. We provide evidence that the CSR-1 Argonaute is required for this trans-activating signal. CSR-1 engages antisense small RNAs complementary to most, if not all, germline-expressed mRNAs 6,7. Moreover, we show that the ability of a foreign sequence to mediate RNAa is correlated with acquisition of CSR-1-associated small RNAs targeting the foreign sequence. Thus CSR-1 small RNAs constitute a memory of previous germline-gene expression that protects endogenous genes from epigenetic silencing. These findings reveal a remarkably sophisticated epigenetic surveillance mechanism that monitors the flow of transgenerational information ensuring that progeny express only those genes also expressed in their parents. Examine small RNA population changes in different transgene lines

Dataset Information

C. elegans piRNAs are processed from capped-small RNAs transcribed at promoters throughout the genome

Publications

CapSeq and CIP-TAP identify Pol II start sites and reveal capped small RNAs as C. elegans piRNA precursors.

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