ABSTRACT: Small RNAs in plants are protected by 2'-O-methylation at 3' terminal nucleotide by HEN1. In hen1 mutant, small RNAs lacking 3' methylation are truncated and tailed at 3' end. We identified a nucleotidyltransferase gene HESO1 in Arabidopsis that tails small RNAs in hen1. In order to study the small RNA tailing and truncation in detail in wild type Col, heso1-1, hen1-8 and hen1-8 heso1-1 double mutant, we constructed small RNA libraries for these four genotypes and we found heso1-1 mutation reduces small RNA tailing in hen1-8 background, however, the 3' truncation is not significantly affected.
Project description:Small RNAs in plants are protected by 2'-O-methylation at 3' terminal nucleotide by HEN1. In hen1 mutant, small RNAs lacking 3' methylation are truncated and tailed at 3' end. We identified a nucleotidyltransferase gene HESO1 in Arabidopsis that tails small RNAs in hen1. In order to study the small RNA tailing and truncation in detail in wild type Col, heso1-1, hen1-8 and hen1-8 heso1-1 double mutant, we constructed small RNA libraries for these four genotypes and we found heso1-1 mutation reduces small RNA tailing in hen1-8 background, however, the 3' truncation is not significantly affected. 8 samples examined: wild-type Col (replicate 1), heso1-1 (replicate 1), hen1-8(replicate 1), hen1-8 heso1-1 (replicate 1), wild-type Col (replicate 2), heso1-1 (replicate 2), hen1-8(replicate 2) and hen1-8 heso1-1 (replicate 2).
Project description:3’ uridylation is increasingly recognized as a conserved RNA modification process associated with RNA turnover in eukaryotes. 2’-O-methylation on the 3’ terminal ribose protects micro(mi)RNAs from 3’ truncation and 3’ uridylation in Arabidopsis. Previously, we identified HESO1 as the nucleotidyl transferase that uridylates most unmethylated miRNAs in vivo, but substantial 3’ tailing of miRNAs still remains in heso1 loss-of-function mutants. In this study, we found that among nine HESO1 paralogs, UTP:RNA URIDYLYLTRANSFERASE 1 (URT1) is the single most predominant nucleotidyl transferase that tails miRNAs. URT1 and HESO1 prefer substrates with different 3’ end nucleotides in vitro and act cooperatively to tail different forms of the same miRNAs in vivo. Moreover, both HESO1 and URT1 exhibit nucleotidyl transferase activity on AGO1-bound miRNAs. Although these enzymes are able to add long tails to AGO1-bound miRNAs, the tailed miRNAs remain associated with AGO1. In fact, we show that a tailed miRNA acquires the ability to trigger the production of secondary siRNAs. Therefore, 3’ uridylation could endow new properties to miRNAs in addition to its known effects in miRNA degradation.
Project description:Small silencing RNAs are key regulators of gene expression in both plants and animals. HEN1-mediated 3’ terminal 2’-O-methylation plays a crucial role in small RNA stability control. In the absence of HEN1, small RNAs are frequently uridylated (untemplated uridine addition) and trimmed, a phenomenon that is conserved across species. However, the underlying molecular mechanism is largely unknown. In this study, we have discovered UTP: RNA uridylyltransferase (URT1) acts redundantly with HESO1 in the uridylation of miRNAs, in addition to its role in oligo-adenylated mRNA uridylation. We show both common and distinctive features of URT1 and HESO1 in catalyzing miRNA uridylation. non coding RNA deep sequencing
Project description:Small silencing RNAs are key regulators of gene expression in both plants and animals. HEN1-mediated 3’ terminal 2’-O-methylation plays a crucial role in small RNA stability control. In the absence of HEN1, small RNAs are frequently uridylated (untemplated uridine addition) and trimmed, a phenomenon that is conserved across species. However, the underlying molecular mechanism is largely unknown. In this study, we have discovered UTP: RNA uridylyltransferase (URT1) acts redundantly with HESO1 in the uridylation of miRNAs, in addition to its role in oligo-adenylated mRNA uridylation. We show both common and distinctive features of URT1 and HESO1 in catalyzing miRNA uridylation.
Project description:miRNA levels depend on both biogenesis and turnover. The methyltransferase HEN1 stabilizes plant miRNAs, animal piRNAs, and siRNAs in both kingdoms via 3' terminal methylation. Loss of HEN1 in plants results in non-templated oligo-uridylation and accelerated degradation of miRNAs. In hen1 mutants from Arabidopsis and rice, we found that the patterns of miRNA truncation and uridylation differ substantially among miRNA families, but such patterns for the same miRNA are conserved between species. miR166 and miR163 are truncated predominantly to ~17 and ~16 nt, and subsequently recover via uridylation to approximately their original sizes, 21 and 24 nt, suggesting that in these cases miRNA truncation triggers uridylation. miR171 is untruncated but uridylated to 22 nt in hen1 mutants, gaining the ability to trigger production of phased, secondary siRNAs. Truncated and tailed variants were bound by ARGONAUTE1 (AGO1) in hen1, implying that these events occur while miRNAs are still bound by AGO1. Unexpectedly, a portion of miR158 in wildtype remains unmethylated and thus subject to uridylation and destabilization, suggesting that plants naturally utilize miRNA methylation to modulate miRNA accumulation. Our results suggest that the AGO1-containing RISC complex may undergo programming to reflect each bound miRNA, determining a defined, distinct decay destiny. In this analysis, we sequenced sRNAs from two hen1 mutant alleles in Arabidopsis and three hen1 alleles in rice. In Arabidopsis, the strong hen1-1 allele in the Landsberg erecta (Ler) ecotype is the first hen1 mutant and emerged from an enhancer screen in the hua1-1/hua2-1 background, and hen1-8 in the Columbia (Col) background is a weak allele. In rice, WAVY LEAF1 (WAF1) is the ortholog of Arabidopsis HEN1, and two mutant alleles waf1-1 and waf1-2 each bear a single-base substitution leading to a premature stop codon in the second exon and a non-functional splicing site of the fourth intron, respectively. We identified a third mutant allele of the rice HEN1 gene (Oshen1-3 from the Korean (POSTEC) rice T-DNA mutant population).
Project description:small RNA libraries from wild-type and Hen1 mutant testes were made with either polyA tailing (VASAGFPHen1minus/plus) or adapter ligation (Hen1Testis and WTTestis) and sequenced on an Illumina GAII platform. RNA was isolated from total testis tissue of both Hen1 wildtype and Hen1 mutant animals. After size selection from gel, the small RNA libraries wre made.
Project description:small RNA libraries from wild-type and Hen1 mutant testes were made with either polyA tailing (VASAGFPHen1minus/plus) or adapter ligation (Hen1Testis and WTTestis) and sequenced on an Illumina GAII platform.
Project description:miRNA levels depend on both biogenesis and turnover. The methyltransferase HEN1 stabilizes plant miRNAs, animal piRNAs, and siRNAs in both kingdoms via 3' terminal methylation. Loss of HEN1 in plants results in non-templated oligo-uridylation and accelerated degradation of miRNAs. In hen1 mutants from Arabidopsis and rice, we found that the patterns of miRNA truncation and uridylation differ substantially among miRNA families, but such patterns for the same miRNA are conserved between species. miR166 and miR163 are truncated predominantly to ~17 and ~16 nt, and subsequently recover via uridylation to approximately their original sizes, 21 and 24 nt, suggesting that in these cases miRNA truncation triggers uridylation. miR171 is untruncated but uridylated to 22 nt in hen1 mutants, gaining the ability to trigger production of phased, secondary siRNAs. Truncated and tailed variants were bound by ARGONAUTE1 (AGO1) in hen1, implying that these events occur while miRNAs are still bound by AGO1. Unexpectedly, a portion of miR158 in wildtype remains unmethylated and thus subject to uridylation and destabilization, suggesting that plants naturally utilize miRNA methylation to modulate miRNA accumulation. Our results suggest that the AGO1-containing RISC complex may undergo programming to reflect each bound miRNA, determining a defined, distinct decay destiny.
Project description:HUA ENHANCER 1 (Hen1) is a RNA 2'-O-methyltransferase that modifies small non-coding RNAs (sncRNAs) by adding a methyl group to the 2'-OH of 3'-terminal nucleotides, thereby protecting them from other modifications and degradation. The molecular mechanism underlying the methylation of small RNA duplexes has been revealed by the crystal structure of Hen1 in Arabidopsis (AtHen1). However, the molecular basis of single-stranded RNA methylation by mammalian Hen1 homologues, especially p-element-induced wimpy testis (PIWI)-interacting RNAs (piRNAs), remains elusive. Here we show that mouse Hen1 (mHen1) is responsive for the 3’ end methylation of classical piRNAs, as well as for the non-canonical piRNAs derived from ribosomal RNA (rRNAs), small nuclear RNAs (snRNAs) and transfer RNAs (tRNAs) in mouse spermatogonial stem cells (SSCs). Moreover, we identified a class of transfer RNA (tRNA)-derived sncRNAs as novel substrates of mHen1, which we refer to as Hen1-methylated tRNA-derived small RNAs. We determined the crystal structure of the catalytic domain of human Hen1 (HsHen1) in complex with its cofactor AdoMet at 1.8 Å resolution. Comparisons of the structures of HsHen1 and AtHen1 reveal a similar active site for binding a divalent cation and AdoMet. An in vitro methyltransferase assay indicated that the complete catalytic domain of HsHen1 is sufficient to methylate a specific length of single-stranded RNAs in a manganese-dependent manner. In conclusion, our functional and structural findings provide important insights into the methylation details of sncRNAs in mouse SSCs, and the catalytic mechanism of mammalian Hen1