A large portion of the genome is non-coding DNA, which frequently contains redundant microsatellite-like trinucleotide repeats with function not yet to be known. Recent studies have shown that many of these trinucleotide repeats are involved in triplet repeat expansion diseases (TREDs), such as fragile X syndrome (FXS), Huntington's disease (HD), myotonic dystrophy (DM), and a number of spinocerebellar ataxias (SCAs). The trinucleotide repeats can fold into RNA hairpins and are further processed by Dicer to form microRNA (miRNA)-like molecules, capable of triggering targeted gene-silencing effects in the TREDs; however, the pathogenic mechanism of these repeat-associated miRNAs (ramRNAs) is unclear. To resolve this question, we have identified the first native ramRNAs in FXS and successfully developed a ramRNA-mediated transgenic zebrafish model for studying the role of the ramRNAs in FXS-related neurodegeneration. Based on this model, we found that ramRNA-induced DNA methylation of the FMR1 5′-UTR CGG trinucleotide repeat expansion is central to FXS etiology. This epigenetic modification leads to physical, neurocognitive and emotional characteristics linked to the transcriptional FMR1 gene inactivation and the deficiency of its protein product. FMR1 deficiency often causes synapse deformity in the neurons essential for cognition and memory activities. Furthermore, the metabotropic glutamate receptor (mGluR)-activated long-term depression (LTD) is augmented after the FMR1 inactivation, suggesting that exaggerated LTD may be responsible for aspects of abnormal neuronal responses in FXS, such as autism. Therefore, the establishment of this ramRNA-mediated transgenic animal model provides a new avenue to dissect the physiopathological and epigenetic alterations of TREDs affected by the microsatellite-like trinucleotide repeat expansions, with the hope of providing insights into areas of opportunity for therapeutic intervention.
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References
Ambros V, Lee RC, Lavanway A, Williams PT, Jewell D. (2003). MicroRNAs and other tiny endogenous RNAs in C. elegans. Curr Biol 13:807-818.
Ambros V. (2004). The functions of animal microRNAs. Nature 431:350-355.
Bartel DP.(2004). MicroRNAs: genomics, biogenesis, mechanism, and function. Cell 116:281-297.
Brown V, Jin P, Ceman S, Darnell JC, et al. (2001). Microarray identification of FMRP-associated brain mRNAs and altered mRNA translational profiles in fragile X syndrome. Cell 107:477-487.
Chung KH, Hart CC, Al-Bassam S, et al. (2006). Polycistronic RNA polymerase II expression vectors for RNA interference based on BIC/miR-155. Nucleic Acid Res 34:e53.
Clement JQ, Qian L, Kaplinsky N, Wilkinson MF. (1999). The stability and fate of a spliced intron from vertebrate cells. RNA 5:206-220.
Eberhart DE, Malter HE, Feng Y, Warren ST. (1996). The fragile X mental retardation protein is a ribonucleoprotein containing both nuclear localization and nuclear export signals. Hum Mol Genet 5:1083-1091.
Galvez R, Gopal AR, Greenough WT. (2003). Somatosensory cortical barrel dendritic abnor-malities in a mouse model of the fragile X mental retardation syndrome. Brain Res 971:83-89.
Genc B, Muller-Hartmann H, Zeschnigk M, et al. (2000). Methylation mosaicism of 5′-(CGG)(n)-3′ repeats in fragile X, premutation and normal individuals. Nucleic Acids Res 28:2141-2152.
Gibbons RJ, McDowell TL, Raman S, et al. (2000). Mutations in ATRX, encoding a SWI/SNF-like protein, cause diverse changes in the pattern of DNA methylation. Nat Genet 24:368-371.
Godfraind JM, Reyniers E, De Boulle K, et al. (1996). Long-term potentiation in the hippoc-ampus of fragile X knockout mice. Am J Med Genet 64:246-251.
Grimm D, Streetz KL, Jopling CL, et al. (2006). Fatality in mice due to oversaturation of cel-lular microRNA/short hairpin RNA pathways. Nature 441:537-541.
Gunnery S, Ma Y, Mathews MB. (1999). Termination sequence requirements vary among genes transcribed by RNA polymerase III. J Mol Biol 286:745-757.
Hagerman RJ, Staley LW, O’Conner R, et al. (1996). Learning-disabled males with a fragile X CGG expansion in the upper premutation size range. Pediatrics 97:122-126.
Handa V, Saha T, Usdin K. (2003). The fragile X syndrome repeats form RNA hairpins that do not activate the interferon-inducible protein kinase, PKR, but are cut by Dicer. Nucleic Acids Res 31:6243-6248.
Huber KM, Gallagher SM, Warren ST, Bear MF. (2002). Altered synaptic plasticity in a mouse model of fragile X mental retardation. Proc Natl Acad Sci USA 99:7746-7750.
Irwin SA, Patel B, Idupulapati M, et al. (2001). Abnormal dendritic spine characteristics in the temporal and visual cortices of patients with fragile-X syndrome: a quantitative examina-tion. Am J Med Genet 98:161-167.
Irwin SA, Christmon CA, Grossman AW, et al. (2005). Fragile X mental retardation protein levels increase following complex environment exposure in rat brain regions undergoing active synaptogenesis. Neurobiol Learn Mem 83:180-187.
Jin P, Zarnescu DC, Zhang F, et al. (2003). RNA-mediated neurodegeneration caused by the fragile X premutation rCGG repeats in Drosophila. Neuron 39:739-747.
Jin P, Zarnescu DC, Ceman S, et al. (2004a). Biochemical and genetic interaction between the fragile X mental retardation protein and the microRNA pathway. Nat Neurosci 7:113-117.
Jin P, Alisch RS, Warren ST. (2004b). RNA and microRNAs in fragile X mental retardation. Nat Cell Biol 6:1048-1053.
Khvorova A, Reynolds A, Jayasena SD. (2003). Functional siRNAs and miRNAs exhibit strand bias. Cell 115:209-216.
Danin-Kreiselman M, Lee CY, Chanfreau G. (2003). RNAse III-mediated degradation of unspliced pre-mRNAs and lariat introns. Mol. Cell 11:1279-1289.
Kimmel CB, Ballard WW, Kimmel SR, et al. (1995). Stages of embryonic development of the zebrafish. Dev Dyn 203:253-310.
Koekkoek SK, Yamaguchi K, Milojkovic BA, et al. (2005). Deletion of FMR1 in Purkinje cells enhances parallel fiber LTD, enlarges spines, and attenuates cerebellar eyelid condition-ing in Fragile X syndrome. Neuron 47:339-352.
Krol J, Fiszer A, Mykowska A, et al. (2007). Ribonuclease dicer cleaves triplet repeat hairpins into shorter repeats that silence specific targets. Mol Cell 25:575-586.
Lee YS, Nakahara K, Pham JW, et al. (2004). Distinct roles for Drosophila Dicer-1 and Dicer-2 in the siRNA/miRNA silencing pathways. Cell 117:69-81.
Lewis BP, Green RE, Brenner SE. (2003). Evidence for the widespread coupling of alternative splicing and nonsense-mediated mRNA decay in humans. Proc Natl Acad Sci USA 100:189-192.
Li Z, Zhang Y, Ku L, et al. (2001). The fragile X mental retardation protein inhibits translation via interacting with mRNA. Nucleic Acids Res 29:2276-2283.
Lin SL, Chang D, Wu DY, Ying SY. (2003). A novel RNA splicing-mediated gene silencing mechanism potential for genome evolution. Biochem Biophys Res Commun 310:754-760.
Lin SL, Ying SY. (2004a). New drug design for gene therapy - taking advantage of introns. Lett Drug Design Discov 1:256-262.
Lin SL, Ying SY. (2004b). Novel RNAi therapy - intron-derived microRNA drugs. Drug Design Rev 1:247-255.
Lin SL and Ying SY. (2004c). Combinational therapy for HIV-1 eradication and vaccination. Int J Oncol 24:81-88.
Lin SL, Chang D, Ying SY (2005). Asymmetry of intronic pre-microRNA structures in functional RISC assembly. Gene 356:32-38.
Lin SL, Chang D, Ying SY. (2006a). Isolation and identification of gene-specific microRNAs. Methods Mol Biol 342:313-320.
Lin SL, Chang SJE, Ying SY. (2006b). First in vivo evidence of microRNA-induced fragile X mental retardation syndrome. Mol Psychiatr 11:616-617.
Lin SL, Chang SJE, Ying SY. (2006c). Transgene-like animal model using intronic microRNAs. Methods Mol Biol 342:321-334.
Lin SL, Ying SY. (2006d). Gene silencing in vitro and in vivo using intronic microRNAs. Methods Mol Biol 342:295-312.
Lin SL, Chang D, Ying SY. (2007). Hyaluronan stimulates transformation of androgen-independent prostate cancer. Carcinogenesis 28:310-320.
Lopez-Bendito G, Shigemoto R, Kulik A, et al. (2004). Distribution of metabotropic GABA receptor subunits GABAB1a/b and GABAB2 in the rat hippocampus during prenatal and postnatal development. Hippocampus 14:836-848.
Lund E, Guttinger S, Calado A, et al. (2004). Nuclear export of microRNA precursors. Science 303:95-98.
McCaffrey AP, Meuse L, Pham TT, et al. (2002). RNA interference in adult mice. Nature 418:38-39.
Miyagishi M, Taira K. (2002). U6 promoter-driven siRNAs with four uridine 3′ overhangs efficiently suppress targeted gene expression in mammalian cells. Nat Biotechnol 20:497-500.
Paul CP, Good PD, Winer I, Engelke DR. (2002). Effective expression of small interfering RNA in human cells. Nat Biotechnol 20:505-508.
Rodriguez, A, Griffiths-Jones, S, Ashurst JL, Bradley A. (2004). Identification of mammalian microRNA host genes and transcription units. Genome Res 14:1902-1910.
Ruby JG, Jan CH, Bartel DP. (2007). Intronic microRNA precursors that bypass Drosha processing. Nature 448:83-86.
Schwarz DS, Hutvagner G, Du T, et al. (2003). Asymmetry in the assembly of the RNAi enzyme complex. Cell 115:199-208.
Schramm L, Hernandez N. (2002). Recruitment of RNA polymerase III to its target promot-ers. Genes Dev 16:2593-2620.
Selby L, Zhang C, Sun QQ. (2007). Major defects in neocortical GABAergic inhibitory circuits in mice lacking the fragile X mental retardation protein. Neurosci Lett 412:227-232.
Sheth U, Parker R. (2006) Targeting of aberrant mRNAs to cytoplasmic processing bodies. Cell 125:1095-1109.
Sledz, CA, Holko M, de Veer MJ, et al. (2003). Activation of the interferon system by short-interfering RNAs. Nat Cell Biol 5:834-839.
Tamanini F, Van Unen L, Bakker C, et al. (1999). Oligomerization properties of fragile-X mental-retardation protein (FMRP) and the fragile-X-related proteins FXR1P and FXR2P. Biochem J 343 Pt 3:517-523.
Tang G. (2005). siRNA and miRNA: an insight into RISCs. Trends Biochem Sci 30:106-114.
Tropepe V, Sive HL. (2003). Can zebrafish be used as a model to study the neurodevelopmen-tal causes of autism? Genes Brain Behav 2:268-281.
Tucker B, Richards R, Lardelli M. (2004). Expression of three zebrafish orthologs of human FMR1-related genes and their phylogenetic relationships. Dev Genes Evol 214:567-574.
Tuschl, T, Borkhardt, A. (2002). Small interfering RNAs: a revolutionary tool for the analysis of gene function and gene therapy. Mol Interv 2:158-167.
Weiler IJ, Greenough WT. (1999). Synaptic synthesis of the Fragile X protein: possible involvement in synapse maturation and elimination. Am J Med Genet 83:248-252.
Westerfield M. (2003). The Zebrafish Book. Sprague J, Clements D, Conlin T, et al. The Zebrafish Information Network (ZFIN): the zebrafish model organism database. Nucleic Acids Res. 31:241-243.
Wullimann MF. (1998). The central nerve system. In Evans DH (Ed) The physiology of fishes, 2nd. CRC press, New York, pp. 245-281.
van ‘t Padje S, Engels B, Blonden L, et al. (2005). Characterization of Fmrp in zebrafish: evolutionary dynamics of the fmr1 gene. Dev Genes Evol 215:198-206.
Xia H, Mao Q, Paulson HL, Davidson BL. (2002). siRNA-mediated gene silencing in vitro and in vivo. Nat Biotechnol. 20:1006-1010.
Xia XG, Zhou H, Samper E, Melov S and Xu Z. (2006). Pol II-expressed shRNA knocks down Sod2 gene expression and causes phenotypes of the gene knockout in mice. PLoS Genet 2:e10.
Yi R, Qin Y, Macara IG, Cullen BR. (2003). Exportin-5 mediates the nuclear export of pre-microRNAs and short hairpin RNAs. Genes Dev. 17:3011-3016.
Ying SY, Lin, SL. (2004). Intron-derived microRNAs-fine tuning of gene functions. Gene 342:25-28.
Zhang G., Taneja KL, Singer RH, Green MR. (1994). Localization of pre-mRNA splicing in mammalian nuclei. Nature 372:809-812.
Zhou HSL, Xia XG, Xu Z. (2005). An RNA polymerase II construct synthesizes short hairpin RNA with a quantitative indicator and mediates high efficient RNAi. Nucleic Acid Res. 33:e62.
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Lin, SL., Ying, SY. (2008). Role of Repeat-Associated MicroRNA (ramRNA) in Fragile X Syndrome (FXS). In: Ying, SY. (eds) Current Perspectives in microRNAs (miRNA). Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-8533-8_14
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