The ERI-6/7 helicase acts at the first stage of an siRNA amplification pathway that targets recent gene duplications.
Endogenous small interfering RNAs (siRNAs) are a class of naturally occuring regulatory RNAs found in fungi, plants, and animals. Some endogenous siRNAs are required to silence transposons or function in chromosome segregation; however, the specific roles of most endogenous siRNAs are unclear. The h...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2011-11-01
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| Series: | PLoS Genetics |
| Online Access: | http://europepmc.org/articles/PMC3213143?pdf=render |
| _version_ | 1828516101116395520 |
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| author | Sylvia E J Fischer Taiowa A Montgomery Chi Zhang Noah Fahlgren Peter C Breen Alexia Hwang Christopher M Sullivan James C Carrington Gary Ruvkun |
| author_facet | Sylvia E J Fischer Taiowa A Montgomery Chi Zhang Noah Fahlgren Peter C Breen Alexia Hwang Christopher M Sullivan James C Carrington Gary Ruvkun |
| author_sort | Sylvia E J Fischer |
| collection | DOAJ |
| description | Endogenous small interfering RNAs (siRNAs) are a class of naturally occuring regulatory RNAs found in fungi, plants, and animals. Some endogenous siRNAs are required to silence transposons or function in chromosome segregation; however, the specific roles of most endogenous siRNAs are unclear. The helicase gene eri-6/7 was identified in the nematode Caenorhabditis elegans by the enhanced response to exogenous double-stranded RNAs (dsRNAs) of the null mutant. eri-6/7 encodes a helicase homologous to small RNA factors Armitage in Drosophila, SDE3 in Arabidopsis, and Mov10 in humans. Here we show that eri-6/7 mutations cause the loss of 26-nucleotide (nt) endogenous siRNAs derived from genes and pseudogenes in oocytes and embryos, as well as deficiencies in somatic 22-nucleotide secondary siRNAs corresponding to the same loci. About 80 genes are eri-6/7 targets that generate the embryonic endogenous siRNAs that silence the corresponding mRNAs. These 80 genes share extensive nucleotide sequence homology and are poorly conserved, suggesting a role for these endogenous siRNAs in silencing of and thereby directing the fate of recently acquired, duplicated genes. Unlike most endogenous siRNAs in C. elegans, eri-6/7-dependent siRNAs require Dicer. We identify that the eri-6/7-dependent siRNAs have a passenger strand that is ∼19 nt and is inset by ∼3-4 nts from both ends of the 26 nt guide siRNA, suggesting non-canonical Dicer processing. Mutations in the Argonaute ERGO-1, which associates with eri-6/7-dependent 26 nt siRNAs, cause passenger strand stabilization, indicating that ERGO-1 is required to separate the siRNA duplex, presumably through endonucleolytic cleavage of the passenger strand. Thus, like several other siRNA-associated Argonautes with a conserved RNaseH motif, ERGO-1 appears to be required for siRNA maturation. |
| first_indexed | 2024-12-11T18:22:24Z |
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| id | doaj.art-51e9ea26caa74dd09c4adc58ba7a5093 |
| institution | Directory Open Access Journal |
| issn | 1553-7390 1553-7404 |
| language | English |
| last_indexed | 2024-12-11T18:22:24Z |
| publishDate | 2011-11-01 |
| publisher | Public Library of Science (PLoS) |
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| series | PLoS Genetics |
| spelling | doaj.art-51e9ea26caa74dd09c4adc58ba7a50932022-12-22T00:55:12ZengPublic Library of Science (PLoS)PLoS Genetics1553-73901553-74042011-11-01711e100236910.1371/journal.pgen.1002369The ERI-6/7 helicase acts at the first stage of an siRNA amplification pathway that targets recent gene duplications.Sylvia E J FischerTaiowa A MontgomeryChi ZhangNoah FahlgrenPeter C BreenAlexia HwangChristopher M SullivanJames C CarringtonGary RuvkunEndogenous small interfering RNAs (siRNAs) are a class of naturally occuring regulatory RNAs found in fungi, plants, and animals. Some endogenous siRNAs are required to silence transposons or function in chromosome segregation; however, the specific roles of most endogenous siRNAs are unclear. The helicase gene eri-6/7 was identified in the nematode Caenorhabditis elegans by the enhanced response to exogenous double-stranded RNAs (dsRNAs) of the null mutant. eri-6/7 encodes a helicase homologous to small RNA factors Armitage in Drosophila, SDE3 in Arabidopsis, and Mov10 in humans. Here we show that eri-6/7 mutations cause the loss of 26-nucleotide (nt) endogenous siRNAs derived from genes and pseudogenes in oocytes and embryos, as well as deficiencies in somatic 22-nucleotide secondary siRNAs corresponding to the same loci. About 80 genes are eri-6/7 targets that generate the embryonic endogenous siRNAs that silence the corresponding mRNAs. These 80 genes share extensive nucleotide sequence homology and are poorly conserved, suggesting a role for these endogenous siRNAs in silencing of and thereby directing the fate of recently acquired, duplicated genes. Unlike most endogenous siRNAs in C. elegans, eri-6/7-dependent siRNAs require Dicer. We identify that the eri-6/7-dependent siRNAs have a passenger strand that is ∼19 nt and is inset by ∼3-4 nts from both ends of the 26 nt guide siRNA, suggesting non-canonical Dicer processing. Mutations in the Argonaute ERGO-1, which associates with eri-6/7-dependent 26 nt siRNAs, cause passenger strand stabilization, indicating that ERGO-1 is required to separate the siRNA duplex, presumably through endonucleolytic cleavage of the passenger strand. Thus, like several other siRNA-associated Argonautes with a conserved RNaseH motif, ERGO-1 appears to be required for siRNA maturation.http://europepmc.org/articles/PMC3213143?pdf=render |
| spellingShingle | Sylvia E J Fischer Taiowa A Montgomery Chi Zhang Noah Fahlgren Peter C Breen Alexia Hwang Christopher M Sullivan James C Carrington Gary Ruvkun The ERI-6/7 helicase acts at the first stage of an siRNA amplification pathway that targets recent gene duplications. PLoS Genetics |
| title | The ERI-6/7 helicase acts at the first stage of an siRNA amplification pathway that targets recent gene duplications. |
| title_full | The ERI-6/7 helicase acts at the first stage of an siRNA amplification pathway that targets recent gene duplications. |
| title_fullStr | The ERI-6/7 helicase acts at the first stage of an siRNA amplification pathway that targets recent gene duplications. |
| title_full_unstemmed | The ERI-6/7 helicase acts at the first stage of an siRNA amplification pathway that targets recent gene duplications. |
| title_short | The ERI-6/7 helicase acts at the first stage of an siRNA amplification pathway that targets recent gene duplications. |
| title_sort | eri 6 7 helicase acts at the first stage of an sirna amplification pathway that targets recent gene duplications |
| url | http://europepmc.org/articles/PMC3213143?pdf=render |
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