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Ghayour-Mobarhan M, Zangouei AS, Hosseinirad SM, Mojarrad M, Moghbeli M. Genetics of blood malignancies among Iranian population: an overview. Diagn Pathol 2020; 15:44. [PMID: 32375828 PMCID: PMC7201799 DOI: 10.1186/s13000-020-00968-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 04/29/2020] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Blood malignancies are among the leading causes of cancer related deaths in the world. Different environmental and genetic risk factors are involved in progression of blood malignancies. It has been shown that the lifestyle changes have affected the epidemiological patterns of these malignancies. Hematologic cancers are the 5th common cancer among Iranian population. It has been observed that there is a rising trend of blood malignancies incidences during the recent decades. Therefore, it is required to design novel diagnostic methods for the early detection of such malignancies in this population. MAIN BODY In present review we have summarized all of the significant genes which have been reported among Iranian patients with blood malignancies. The reported genes were categorized based on their cell and molecular functions to clarify the molecular biology and genetics of blood malignancies among Iranian patients. CONCLUSION It was observed that the epigenetic and immune response factors were the most frequent molecular processes associated with progression of blood malignancies among Iranian population. This review paves the way of introducing a population based panel of genetic markers for the early detection of blood malignancies in this population.
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Affiliation(s)
- Majid Ghayour-Mobarhan
- Metabolic Syndrome Research Center, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Amir Sadra Zangouei
- Student Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | | | - Majid Mojarrad
- Department of Medical Genetics and Molecular Medicine, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Meysam Moghbeli
- Department of Medical Genetics and Molecular Medicine, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
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2
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Paces J, Nic M, Novotny T, Svoboda P. Literature review of baseline information to support the risk assessment of RNAi‐based GM plants. ACTA ACUST UNITED AC 2017. [PMCID: PMC7163844 DOI: 10.2903/sp.efsa.2017.en-1246] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Jan Paces
- Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic (IMG)
| | | | | | - Petr Svoboda
- Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic (IMG)
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3
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Abstract
MicroRNAs (miRNAs) are small non-coding RNAs that function as guide molecules in RNA silencing. Targeting most protein-coding transcripts, miRNAs are involved in nearly all developmental and pathological processes in animals. The biogenesis of miRNAs is under tight temporal and spatial control, and their dysregulation is associated with many human diseases, particularly cancer. In animals, miRNAs are ∼22 nucleotides in length, and they are produced by two RNase III proteins--Drosha and Dicer. miRNA biogenesis is regulated at multiple levels, including at the level of miRNA transcription; its processing by Drosha and Dicer in the nucleus and cytoplasm, respectively; its modification by RNA editing, RNA methylation, uridylation and adenylation; Argonaute loading; and RNA decay. Non-canonical pathways for miRNA biogenesis, including those that are independent of Drosha or Dicer, are also emerging.
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4
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Nicholson AW. Ribonuclease III mechanisms of double-stranded RNA cleavage. WILEY INTERDISCIPLINARY REVIEWS-RNA 2013; 5:31-48. [PMID: 24124076 PMCID: PMC3867540 DOI: 10.1002/wrna.1195] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 08/09/2013] [Accepted: 08/10/2013] [Indexed: 12/22/2022]
Abstract
Double-stranded(ds) RNA has diverse roles in gene expression and regulation, host defense, and genome surveillance in bacterial and eukaryotic cells. A central aspect of dsRNA function is its selective recognition and cleavage by members of the ribonuclease III (RNase III) family of divalent-metal-ion-dependent phosphodiesterases. The processing of dsRNA by RNase III family members is an essential step in the maturation and decay of coding and noncoding RNAs, including miRNAs and siRNAs. RNase III, as first purified from Escherichia coli, has served as a biochemically well-characterized prototype, and other bacterial orthologs provided the first structural information. RNase III family members share a unique fold (RNase III domain) that can dimerize to form a structure that binds dsRNA and cleaves phosphodiesters on each strand, providing the characteristic 2 nt, 3′-overhang product ends. Ongoing studies are uncovering the functions of additional domains, including, inter alia, the dsRNA-binding and PAZ domains that cooperate with the RNase III domain to select target sites, regulate activity, confer processivity, and support the recognition of structurally diverse substrates. RNase III enzymes function in multicomponent assemblies that are regulated by diverse inputs, and at least one RNase III-related polypeptide can function as a noncatalytic, dsRNA-binding protein. This review summarizes the current knowledge of the mechanisms of catalysis and target site selection of RNase III family members, and also addresses less well understood aspects of these enzymes and their interactions with dsRNA. WIREs RNA 2014, 5:31–48. doi: 10.1002/wrna.1195
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Affiliation(s)
- Allen W Nicholson
- Department of Biology and Chemistry, College of Science & Technology, Temple University, Philadelphia, PA, USA
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5
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Wagner S, Willenbrock S, Nolte I, Murua Escobar H. Comparison of non-coding RNAs in human and canine cancer. Front Genet 2013; 4:46. [PMID: 23579348 PMCID: PMC3619122 DOI: 10.3389/fgene.2013.00046] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 03/13/2013] [Indexed: 12/21/2022] Open
Abstract
The discovery of the post-transcriptional gene silencing (PTGS) by small non-protein-coding RNAs is considered as a major breakthrough in biology. In the last decade we just started to realize the biologic function and complexity of gene regulation by small non-coding RNAs. PTGS is a conserved phenomenon which was observed in various species such as fungi, worms, plants, and mammals. Micro RNAs (miRNA) and small interfering RNAs (siRNAs) are two gene silencing mediators constituting an evolutionary conserved class of non-coding RNAs regulating many biological processes in eukaryotes. As this small RNAs appear to regulate gene expression at translational and transcriptional level it is not surprising that during the last decade many human diseases among them Alzheimer's disease, cardiovascular diseases, and various cancer types were associated with deregulated miRNA expression. Consequently small RNAs are considered to hold big promises as therapeutic agents. However, despite of the enormous therapeutic potential many questions remain unanswered. A major critical point, when evaluating novel therapeutic approaches, is the transfer of in vitro settings to an in vivo model. Classical animal models rely on the laboratory kept animals under artificial conditions and often missing an intact immune system. Model organisms with spontaneously occurring tumors as e.g., dogs provide the possibility to evaluate therapeutic agents under the surveillance of an in intact immune system and thereby providing an authentic tumor reacting scenario. Considering the genomic similarity between canines and humans and the advantages of the dog as cancer model system for human neoplasias the analyses of the complex role of small RNAs in canine tumor development could be of major value for both species. Herein we discuss comparatively the role of miRNAs in human and canine cancer development and highlight the potential and advantages of the model organism dog for tumor research.
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Affiliation(s)
- Siegfried Wagner
- Small Animal Clinic, University of Veterinary Medicine Hannover Hannover, Germany
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6
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Abstract
Micro-ribonucleic acids (miRNAs) are small (21-24 nucleotide), endogenously expressed, noncoding RNAs that have emerged as important posttranscriptional regulators of gene expression. MiRNAs have been identified and cloned from diverse eukaryotic organisms where they have been shown to control important physiological and developmental processes such as apoptosis, cell division, and differentiation. A high level of conservation of some miRNAs across phyla further emphasizes their importance as posttranscriptional regulators. Research in a variety of model systems has been instrumental in dissecting the biological functions of miRNAs. In this chapter, we discuss the current literature on the role of miRNAs as developmental regulators in Drosophila.
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7
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Polzikov MA, Veĭko NN, Zharskaia OO, Magoulas KB, Zatsepina OV. [Overexpression of the nucleolar protein SURF-6 in mouse fibroblasts NIH/3T3 leads to stabilisation of intragenic transcribed spacers of the pre-rRNA]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2010; 36:661-71. [PMID: 21063453 DOI: 10.1134/s1068162010050092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
SURF-6 is an evolutionary conserved nucleolar protein that is required for maintenance of cell viability, but its functional significance in mammals still remains illusive. In the present work we examined effects of SURF-6 overexpression in mouse NIH/3T3 fibroblasts transfected with two plasmids. The plasmid pUHrT62-1 encodes a tetracycline-dependant trans-activator, the protein rtTA, the plasmid pBI-SURF6--the genes of EGFP (enhanced green fluorescent protein) and of mouse SURF-6 which expression was controlled by the rtTA-responsive bi-directorial promoter. Western blot analysis showed that the SURF-6 level was severely augmented in cells transfected with pUHrT62-1 and pBI-SURF6 and incubated with the inducer--doxycycline opposed to the transfected but not-induced cells. The increase of SURF-6 was observed in 24 and 48 h after adding the inducer doxycycline. Dot-hybridization of isolated RNA with biotinilated oligonucleotide probes to various regions of mouse primarily pre-rRNA transcripts showed that overexpression of SURF-6 enhanced levels of the second intragenic transcribed spacer ITS2 in about seven folds and of the 5' external transcribed spacer 5'ETS in two folds. Amounts of fragments corresponding to 18S, 5.8S and 28S rRNA remained almost unchanged. These observations for the first time demonstrated that mammalian SURF-6 helps to stabilize or prevents premature cleavage of the pre-rRNA intragenic transcribed spacers, particularly of ITS2, similar to its homologue in S. cerevisiae the protein Rrp14. Today metazoan proteins that play a similar role in ribosome biogenesis, are not described.
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8
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Wahid F, Shehzad A, Khan T, Kim YY. MicroRNAs: synthesis, mechanism, function, and recent clinical trials. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1803:1231-43. [PMID: 20619301 DOI: 10.1016/j.bbamcr.2010.06.013] [Citation(s) in RCA: 571] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 06/30/2010] [Accepted: 06/30/2010] [Indexed: 12/19/2022]
Abstract
MicroRNAs (miRNAs) are a class of small, endogenous RNAs of 21-25 nucleotides (nts) in length. They play an important regulatory role in animals and plants by targeting specific mRNAs for degradation or translation repression. Recent scientific advances have revealed the synthesis pathways and the regulatory mechanisms of miRNAs in animals and plants. miRNA-based regulation is implicated in disease etiology and has been studied for treatment. Furthermore, several preclinical and clinical trials have been initiated for miRNA-based therapeutics. In this review, the existing knowledge about miRNAs synthesis, mechanisms for regulation of the genome, and their widespread functions in animals and plants is summarized. The current status of preclinical and clinical trials regarding miRNA therapeutics is also reviewed. The recent findings in miRNA studies, summarized in this review, may add new dimensions to small RNA biology and miRNA therapeutics.
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Affiliation(s)
- Fazli Wahid
- School of life Sciences and Biotechnology, College of Natural sciences, Kyungpook National University, Buk-ku, Taegu, Korea
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9
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Abstract
Small RNAs of 20-30 nucleotides can target both chromatin and transcripts, and thereby keep both the genome and the transcriptome under extensive surveillance. Recent progress in high-throughput sequencing has uncovered an astounding landscape of small RNAs in eukaryotic cells. Various small RNAs of distinctive characteristics have been found and can be classified into three classes based on their biogenesis mechanism and the type of Argonaute protein that they are associated with: microRNAs (miRNAs), endogenous small interfering RNAs (endo-siRNAs or esiRNAs) and Piwi-interacting RNAs (piRNAs). This Review summarizes our current knowledge of how these intriguing molecules are generated in animal cells.
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Affiliation(s)
- V Narry Kim
- School of Biological Sciences and Center for National Creative Research, Seoul National University, Seoul, 151-742, Korea.
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10
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11
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Abstract
RNA interference is involved in many aspects of cell biology, and the recent identification of germ-cell specific small RNAs has led to speculation that RNAi might also be involved in gametogenesis. Work in yeast indicates that RNAi is involved in establishing and maintaining heterochromatin at centromeres, an important component of yeast and mammalian meiosis. Here we review developments in the field of RNAi and relate these to possible roles in mammalian gametogenesis.
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Affiliation(s)
- Rebecca J Holmes
- Department of Biomedical Sciences, Cornell University, Ithaca, NY 14853, USA.
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12
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Lee Y, Han J, Yeom KH, Jin H, Kim VN. Drosha in primary microRNA processing. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2007; 71:51-7. [PMID: 17381280 DOI: 10.1101/sqb.2006.71.041] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
MicroRNA (miRNA)-mediated gene silencing is one of the major regulatory pathways in eukaryotes. Much effort has been made to identify the factors involved in the pathway, and our understanding of RNA silencing has significantly advanced in recent years. Our group has been working on some of the issues regarding miRNA biogenesis and, in this paper, we summarize what we and other workers in the field have learned thus far. The focus remains on the role of Drosha and DGCR8 in the early events of miRNA biogenesis in animals.
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Affiliation(s)
- Y Lee
- School of Biological Sciences, Seoul National University, Seoul, Korea
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13
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Abstract
MicroRNA (miRNA) genes are transcribed into long primary transcripts (pri-miRNAs) that get processed into mature miRNAs of about 22 nt in length by two different ribonuclease (RNase) III enzymes, Drosha and Dicer. Various experimental protocols have been developed and modified for genetic and biochemical analyses for microRNA processing. Here we describe the methods for the analysis of pri-miRNA processing that is mediated by Drosha and its cofactor, DiGeorge Syndrome Critical Region Gene 8 (DGCR8).
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Affiliation(s)
- Yoontae Lee
- School of Biological Sciences, Seoul National University, Seoul, Korea
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14
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Abstract
Discovered just over a decade ago, microRNA (miRNA) is now recognized as one of the major regulatory gene families in eukaryotic cells. Hundreds of miRNAs have been found in animals, plants and viruses, and there are certainly more to come. Through specific base-pairing with mRNAs, these tiny approximately 22-nt RNAs induce mRNA degradation or translational repression, or both. Because a miRNA can target numerous mRNAs, often in combination with other miRNAs, miRNAs operate highly complex regulatory networks. In this article, we summarize the current status of miRNA gene mining and miRNA expression profiling. We also review up-to-date knowledge of miRNA gene structure and the biogenesis mechanism. Our focus is on animal miRNAs.
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Affiliation(s)
- V Narry Kim
- Department of Biological Sciences and Research Center for Functional Cellulomics, Seoul National University, Seoul, 151-742, Korea.
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15
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Ouellet DL, Perron MP, Gobeil LA, Plante P, Provost P. MicroRNAs in gene regulation: when the smallest governs it all. J Biomed Biotechnol 2006; 2006:69616. [PMID: 17057368 PMCID: PMC1559927 DOI: 10.1155/jbb/2006/69616] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2006] [Accepted: 04/17/2006] [Indexed: 12/19/2022] Open
Abstract
Encoded by the genome of most eukaryotes examined so far, microRNAs (miRNAs) are small approximately 21-nucleotide (nt) noncoding RNAs (ncRNAs) derived from a biosynthetic cascade involving sequential processing steps executed by the ribonucleases (RNases) III Drosha and Dicer. Following their recent identification, miRNAs have rapidly taken the center stage as key regulators of gene expression. In this review, we will summarize our current knowledge of the miRNA biosynthetic pathway and its protein components, as well as the processes it regulates via miRNAs, which are known to exert a variety of biological functions in eukaryotes. Although the relative importance of miRNAs remains to be fully appreciated, deregulated protein expression resulting from either dysfunctional miRNA biogenesis or abnormal miRNA-based gene regulation may represent a key etiologic factor in several, as yet unidentified, diseases. Hence is our need to better understand the complexity of the basic mechanisms underlying miRNA biogenesis and function.
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Affiliation(s)
- Dominique L. Ouellet
- Centre de Recherche en Rhumatologie et Immunologie,
Centre de Recherche du CHUL, 2705 Boulevard Laurier, Ste-Foy, Quebec, Canada G1V 4G2
- Faculté de Médecine, Université Laval, Quebec, Canada G1K 7P4
| | - Marjorie P. Perron
- Centre de Recherche en Rhumatologie et Immunologie,
Centre de Recherche du CHUL, 2705 Boulevard Laurier, Ste-Foy, Quebec, Canada G1V 4G2
- Faculté de Médecine, Université Laval, Quebec, Canada G1K 7P4
| | - Lise-Andrée Gobeil
- Centre de Recherche en Rhumatologie et Immunologie,
Centre de Recherche du CHUL, 2705 Boulevard Laurier, Ste-Foy, Quebec, Canada G1V 4G2
- Faculté de Médecine, Université Laval, Quebec, Canada G1K 7P4
| | - Pierre Plante
- Centre de Recherche en Rhumatologie et Immunologie,
Centre de Recherche du CHUL, 2705 Boulevard Laurier, Ste-Foy, Quebec, Canada G1V 4G2
- Faculté de Médecine, Université Laval, Quebec, Canada G1K 7P4
| | - Patrick Provost
- Centre de Recherche en Rhumatologie et Immunologie,
Centre de Recherche du CHUL, 2705 Boulevard Laurier, Ste-Foy, Quebec, Canada G1V 4G2
- Faculté de Médecine, Université Laval, Quebec, Canada G1K 7P4
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16
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Murchison EP, Hannon GJ. miRNAs on the move: miRNA biogenesis and the RNAi machinery. Curr Opin Cell Biol 2005; 16:223-9. [PMID: 15145345 DOI: 10.1016/j.ceb.2004.04.003] [Citation(s) in RCA: 278] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Recent advances have led to a more detailed understanding of RNA interference and its role in microRNA biogenesis and function. Primary microRNA transcripts are processed by the RNaseIII nuclease, Drosha, and are exported from the nucleus by Exportin-5. Dicer cleaves microRNAs into their mature forms, which can be incorporated into effector complexes that mediate gene silencing activities. The 3' two-nucleotide overhang structure, a signature of RNaseIII cleavage, has been identified as a critical specificity determinant in targeting and maintaining small RNAs in the RNA interference pathway. MicroRNA functional analyses and genetic and biochemical interrogation of components of the pathway are starting to provide a glimpse at the range of biological processes and phenomena regulated by RNA interference.
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Affiliation(s)
- Elizabeth P Murchison
- Cold Spring Harbor Laboratory, Watson School of Biological Sciences, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
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17
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Abstract
The recent discovery of microRNAs (miRNAs) took many by surprise because of their unorthodox features and widespread functions. These tiny, approximately 22-nucleotide, RNAs control several pathways including developmental timing, haematopoiesis, organogenesis, apoptosis, cell proliferation and possibly even tumorigenesis. Among the most pressing questions regarding this unusual class of regulatory miRNA-encoding genes is how miRNAs are produced in cells and how the genes themselves are controlled by various regulatory networks.
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Affiliation(s)
- V Narry Kim
- Department of Biological Sciences and Institute of Molecular Biology and Genetics, Seoul National University, Seoul, 151-742, Korea.
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18
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Jaronczyk K, Carmichael J, Hobman T. Exploring the functions of RNA interference pathway proteins: some functions are more RISCy than others? Biochem J 2005; 387:561-71. [PMID: 15845026 PMCID: PMC1134985 DOI: 10.1042/bj20041822] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2004] [Revised: 12/23/2004] [Accepted: 02/22/2005] [Indexed: 01/21/2023]
Abstract
PPD (PAZ Piwi domain) proteins and the Dicer family have been the subjects of intense study over the last 6 years. These proteins have well-established roles in RNAi (RNA interference), a process that relies on siRNAs (small interfering RNAs) or miRNAs (microRNAs) to mediate specificity. The development of techniques for applying RNAi as a laboratory tool and a molecular therapeutic technique has rapidly outpaced our understanding of the biology of this process. However, over the last 2 years, great strides have been made towards elucidating how PPD proteins and Dicer regulate gene-silencing at the pre- and post-transcriptional levels. In addition, evidence is beginning to emerge that suggests that these proteins have additional siRNA-independent roles as cell-cycle regulators. In the present review, we summarize the well-known roles of these two classes of proteins in gene-silencing pathways, as well as explore the evidence for novel roles of PPD and Dicer proteins.
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Key Words
- dicer
- gene expression
- gene silencing
- paz piwi domain protein (ppd protein)
- rna-induced silencing complex (risc)
- rna interference (rnai)
- ds, double-stranded
- fxr, fragile x mental retardation protein
- gfp, green fluorescent protein
- mirna, microrna
- mirnp, mirna-containing ribonucleoprotein
- mvh, mammalian vasa homologue
- ppd, paz piwi domain
- risc, rna-induced silencing complex
- rits, rna-induced initiation of transcriptional gene silencing
- rnai, rna interference
- sirna, small interfering rna
- ss, single-stranded
- utr, untranslated region
- vig, vasa intronic gene protein
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Affiliation(s)
- Katarzyna Jaronczyk
- *Department of Cell Biology, University of Alberta, Edmonton, AB, Canada T6G 2H7
| | - Jon B. Carmichael
- *Department of Cell Biology, University of Alberta, Edmonton, AB, Canada T6G 2H7
| | - Tom C. Hobman
- *Department of Cell Biology, University of Alberta, Edmonton, AB, Canada T6G 2H7
- †Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada T6G 2H7
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Basyuk E, Suavet F, Doglio A, Bordonné R, Bertrand E. Human let-7 stem-loop precursors harbor features of RNase III cleavage products. Nucleic Acids Res 2004; 31:6593-7. [PMID: 14602919 PMCID: PMC275551 DOI: 10.1093/nar/gkg855] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The bidentate RNase III Dicer cleaves microRNA precursors to generate the 21-23 nt long mature RNAs. These precursors are 60-80 nt long, they fold into a characteristic stem-loop structure and they are generated by an unknown mechanism. To gain insights into the biogenesis of microRNAs, we have characterized the precise 5' and 3' ends of the let-7 precursors in human cells. We show that they harbor a 5'-phosphate and a 3'-OH and that, remarkably, they contain a 1-4 nt 3' overhang. These features are characteristic of RNase III cleavage products. Since these precursors are present in both the nucleus and the cytoplasm of human cells, our results suggest that they are generated in the nucleus by the nuclear RNase III. Additionally, these precursors fit the minihelix export motif and are thus likely exported by this pathway.
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Affiliation(s)
- Eugenia Basyuk
- IGMM-CNRS UMR 5535, IFR 24, 1919 Route de Mende, F-34293 Montpellier Cedex, France
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20
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Abstract
Our understanding of RNA interference has been enhanced by new data concerning RNase III molecules. The role of Dicer has previously been established in RNAi as the originator of 22-mers characteristic of silencing phenomena. Recently, a related RNAse III enzyme, Drosha, has surfaced as another component of the RNAi pathway. In addition to biochemistry, protein structures have proven to be helpful in deciphering the enzymology of RNase III molecules.
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Affiliation(s)
- Michelle A Carmell
- Cold Spring Harbor Laboratory, Watson School of Biological Sciences, 1 Bungtown Road, Cold Spring Harbor, New York 11724, USA
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Zhang Y, Calin-Jageman I, Gurnon JR, Choi TJ, Adams B, Nicholson AW, Van Etten JL. Characterization of a chlorella virus PBCV-1 encoded ribonuclease III. Virology 2004; 317:73-83. [PMID: 14675626 DOI: 10.1016/j.virol.2003.08.044] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Sequence analysis of the 330-kb genome of chlorella virus PBCV-1 revealed an open reading frame, A464R, which encodes a protein with 30-35% amino acid identity to ribonuclease III (RNase III) from many bacteria. The a464r gene was cloned and the protein was expressed in Escherichia coli using the chitin-binding intein system. The recombinant PBCV-1 RNase III cleaves model dsRNA substrates, in a Mg(2+)-dependent manner, into a defined set of products. The substrate cleavage specificity overlaps, but is nonidentical to that of E. coli RNase III. The a464r gene is expressed very early during PBCV-1 infection, within 5-10 min p.i. The RNase III protein appears at 15 min p.i. and disappears by 120 min p.i. The a464r gene is highly conserved among the chlorella viruses. Phylogenetic analyses indicate that the PBCV enzyme is most closely related to Mycoplasma pneumoniae RNase III.
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Affiliation(s)
- Yuanzheng Zhang
- Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583-0722, USA
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22
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Lee Y, Ahn C, Han J, Choi H, Kim J, Yim J, Lee J, Provost P, Rådmark O, Kim S, Kim VN. The nuclear RNase III Drosha initiates microRNA processing. Nature 2003; 425:415-9. [PMID: 14508493 DOI: 10.1038/nature01957] [Citation(s) in RCA: 3534] [Impact Index Per Article: 168.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2003] [Accepted: 07/25/2003] [Indexed: 02/07/2023]
Abstract
Hundreds of small RNAs of approximately 22 nucleotides, collectively named microRNAs (miRNAs), have been discovered recently in animals and plants. Although their functions are being unravelled, their mechanism of biogenesis remains poorly understood. miRNAs are transcribed as long primary transcripts (pri-miRNAs) whose maturation occurs through sequential processing events: the nuclear processing of the pri-miRNAs into stem-loop precursors of approximately 70 nucleotides (pre-miRNAs), and the cytoplasmic processing of pre-miRNAs into mature miRNAs. Dicer, a member of the RNase III superfamily of bidentate nucleases, mediates the latter step, whereas the processing enzyme for the former step is unknown. Here we identify another RNase III, human Drosha, as the core nuclease that executes the initiation step of miRNA processing in the nucleus. Immunopurified Drosha cleaved pri-miRNA to release pre-miRNA in vitro. Furthermore, RNA interference of Drosha resulted in the strong accumulation of pri-miRNA and the reduction of pre-miRNA and mature miRNA in vivo. Thus, the two RNase III proteins, Drosha and Dicer, may collaborate in the stepwise processing of miRNAs, and have key roles in miRNA-mediated gene regulation in processes such as development and differentiation.
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Affiliation(s)
- Yoontae Lee
- Institute of Molecular Biology and Genetics and School of Biological Sciences, Seoul National University, Seoul 151-742, Korea
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