Blog
About

  • Record: found
  • Abstract: found
  • Article: not found

Genetic and Functional Diversification of Small RNA Pathways in Plants

Read this article at

ScienceOpenPublisherPMC
Bookmark
      There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

      Abstract

      Multicellular eukaryotes produce small RNA molecules (approximately 21–24 nucleotides) of two general types, microRNA (miRNA) and short interfering RNA (siRNA). They collectively function as sequence-specific guides to silence or regulate genes, transposons, and viruses and to modify chromatin and genome structure. Formation or activity of small RNAs requires factors belonging to gene families that encode DICER (or DICER-LIKE [DCL]) and ARGONAUTE proteins and, in the case of some siRNAs, RNA-dependent RNA polymerase (RDR) proteins. Unlike many animals, plants encode multiple DCL and RDR proteins. Using a series of insertion mutants of Arabidopsis thaliana, unique functions for three DCL proteins in miRNA (DCL1), endogenous siRNA (DCL3), and viral siRNA (DCL2) biogenesis were identified. One RDR protein (RDR2) was required for all endogenous siRNAs analyzed. The loss of endogenous siRNA in dcl3 and rdr2 mutants was associated with loss of heterochromatic marks and increased transcript accumulation at some loci. Defects in siRNA-generation activity in response to turnip crinkle virus in dcl2 mutant plants correlated with increased virus susceptibility. We conclude that proliferation and diversification of DCL and RDR genes during evolution of plants contributed to specialization of small RNA-directed pathways for development, chromatin structure, and defense.

      Abstract

      In plants, RNA-mediated silencing pathways have diversified in unique ways. This study elucidates the specific functions of some of the key regulators in development, chromatin structure, and pathogen defense

      Related collections

      Most cited references 88

      • Record: found
      • Abstract: found
      • Article: not found

      The 21-nucleotide let-7 RNA regulates developmental timing in Caenorhabditis elegans.

      The C. elegans heterochronic gene pathway consists of a cascade of regulatory genes that are temporally controlled to specify the timing of developmental events. Mutations in heterochronic genes cause temporal transformations in cell fates in which stage-specific events are omitted or reiterated. Here we show that let-7 is a heterochronic switch gene. Loss of let-7 gene activity causes reiteration of larval cell fates during the adult stage, whereas increased let-7 gene dosage causes precocious expression of adult fates during larval stages. let-7 encodes a temporally regulated 21-nucleotide RNA that is complementary to elements in the 3' untranslated regions of the heterochronic genes lin-14, lin-28, lin-41, lin-42 and daf-12, indicating that expression of these genes may be directly controlled by let-7. A reporter gene bearing the lin-41 3' untranslated region is temporally regulated in a let-7-dependent manner. A second regulatory RNA, lin-4, negatively regulates lin-14 and lin-28 through RNA-RNA interactions with their 3' untranslated regions. We propose that the sequential stage-specific expression of the lin-4 and let-7 regulatory RNAs triggers transitions in the complement of heterochronic regulatory proteins to coordinate developmental timing.
        Bookmark
        • Record: found
        • Abstract: found
        • Article: not found

        RNA interference.

        A conserved biological response to double-stranded RNA, known variously as RNA interference (RNAi) or post-transcriptional gene silencing, mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes. RNAi has been cultivated as a means to manipulate gene expression experimentally and to probe gene function on a whole-genome scale.
          Bookmark
          • Record: found
          • Abstract: found
          • Article: not found

          A cellular function for the RNA-interference enzyme Dicer in the maturation of the let-7 small temporal RNA.

          The 21-nucleotide small temporal RNA (stRNA) let-7 regulates developmental timing in Caenorhabditis elegans and probably in other bilateral animals. We present in vivo and in vitro evidence that in Drosophila melanogaster a developmentally regulated precursor RNA is cleaved by an RNA interference-like mechanism to produce mature let-7 stRNA. Targeted destruction in cultured human cells of the messenger RNA encoding the enzyme Dicer, which acts in the RNA interference pathway, leads to accumulation of the let-7 precursor. Thus, the RNA interference and stRNA pathways intersect. Both pathways require the RNA-processing enzyme Dicer to produce the active small-RNA component that represses gene expression.
            Bookmark

            Author and article information

            Affiliations
            1simpleCenter for Gene Research and Biotechnology and Department of Botany and Plant Pathology, Oregon State University Corvallis, OregonUnited States of America
            2simpleDepartment of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CaliforniaUnited States of America
            3simpleMolecular Biology Institute, University of California Los Angeles, Los Angeles, CaliforniaUnited States of America
            Contributors
            Journal
            PLoS Biol
            pbio
            PLoS Biology
            Public Library of Science (San Francisco, USA )
            1544-9173
            1545-7885
            May 2004
            24 February 2004
            : 2
            : 5
            350667
            15024409
            10.1371/journal.pbio.0020104
            Copyright: ©2004 Xie et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
            Categories
            Research Article
            Evolution
            Genetics/Genomics/Gene Therapy
            Plant Science
            Arabidopsis

            Life sciences

            Comments

            Comment on this article