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Breunig K, Lei X, Montalbano M, Guardia GDA, Ostadrahimi S, Alers V, Kosti A, Chiou J, Klein N, Vinarov C, Wang L, Li M, Song W, Kraus WL, Libich DS, Tiziani S, Weintraub ST, Galante PAF, Penalva LOF. SERBP1 interacts with PARP1 and is present in PARylation-dependent protein complexes regulating splicing, cell division, and ribosome biogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.22.586270. [PMID: 38585848 PMCID: PMC10996453 DOI: 10.1101/2024.03.22.586270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
RNA binding proteins (RBPs) containing intrinsically disordered regions (IDRs) are present in diverse molecular complexes where they function as dynamic regulators. Their characteristics promote liquid-liquid phase separation (LLPS) and the formation of membraneless organelles such as stress granules and nucleoli. IDR-RBPs are particularly relevant in the nervous system and their dysfunction is associated with neurodegenerative diseases and brain tumor development. SERBP1 is a unique member of this group, being mostly disordered and lacking canonical RNA-binding domains. Using a proteomics approach followed by functional analysis, we defined SERBP1's interactome. We uncovered novel SERBP1 roles in splicing, cell division, and ribosomal biogenesis and showed its participation in pathological stress granules and Tau aggregates in Alzheimer's disease brains. SERBP1 preferentially interacts with other G-quadruplex (G4) binders, implicated in different stages of gene expression, suggesting that G4 binding is a critical component of SERBP1 function in different settings. Similarly, we identified important associations between SERBP1 and PARP1/polyADP-ribosylation (PARylation). SERBP1 interacts with PARP1 and its associated factors and influences PARylation. Moreover, protein complexes in which SERBP1 participates contain mostly PARylated proteins and PAR binders. Based on these results, we propose a feedback regulatory model in which SERBP1 influences PARP1 function and PARylation, while PARylation modulates SERBP1 functions and participation in regulatory complexes.
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2
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Grzybowska EA, Wakula M. Protein Binding to Cis-Motifs in mRNAs Coding Sequence Is Common and Regulates Transcript Stability and the Rate of Translation. Cells 2021; 10:2910. [PMID: 34831133 PMCID: PMC8616275 DOI: 10.3390/cells10112910] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 10/22/2021] [Accepted: 10/24/2021] [Indexed: 12/19/2022] Open
Abstract
Protein binding to the non-coding regions of mRNAs is relatively well characterized and its functionality has been described in many examples. New results obtained by high-throughput methods indicate that binding to the coding sequence (CDS) by RNA-binding proteins is also quite common, but the functions thereof are more obscure. As described in this review, CDS binding has a role in the regulation of mRNA stability, but it has also a more intriguing role in the regulation of translational efficiency. Global approaches, which suggest the significance of CDS binding along with specific examples of CDS-binding RBPs and their modes of action, are outlined here, pointing to the existence of a relatively less-known regulatory network controlling mRNA stability and translation on yet another level.
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Affiliation(s)
- Ewa A. Grzybowska
- Molecular and Translational Oncology, Maria Sklodowska-Curie National Research Institute of Oncology, Roentgena 5, 02-781 Warsaw, Poland;
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3
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Fielding-Gebhardt H, Warren SF, Brady NC. Child Challenging Behavior Influences Maternal Mental Health and Relationship Quality Over Time in Fragile X Syndrome. J Autism Dev Disord 2020; 50:779-797. [PMID: 31754947 PMCID: PMC7053402 DOI: 10.1007/s10803-019-04308-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Parenting children with neurodevelopmental disabilities is often challenging. Biological mothers of children with Fragile X Syndrome (FXS) may be susceptible to increased risk of mental health problems. This study examined the longitudinal relationships between maternal mental health, child challenging behaviors, and mother-child relationship quality in children and adolescents with FXS. Fifty-five mother-child dyads were followed from childhood into adolescence. The findings suggest that child challenging behaviors, maternal mental health, and mother-child relationship quality were stable during that period. Additionally, elevated levels of child challenging behaviors negatively impacted maternal mental health. Finally, child challenging behaviors, in combination with maternal mental health, influenced mother-child relationship quality. Clinical implications are discussed.
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Affiliation(s)
- Heather Fielding-Gebhardt
- Child Language Doctoral Program, University of Kansas, 1000 Sunnyside Avenue, Lawrence, KS, 66045, USA.
| | - Steven F Warren
- Department of Speech-Language-Hearing: Sciences and Disorders, University of Kansas, Lawrence, USA
| | - Nancy C Brady
- Department of Speech-Language-Hearing: Sciences and Disorders, University of Kansas, Lawrence, USA
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4
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Fielding-Gebhardt H, Warren SF. Early Predictors of Later Expressive Language in Boys With Fragile X Syndrome. AMERICAN JOURNAL ON INTELLECTUAL AND DEVELOPMENTAL DISABILITIES 2019; 124:11-24. [PMID: 30715922 PMCID: PMC6939380 DOI: 10.1352/1944-7558-124.1.11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The predictive ability of early consonant inventory and intentional communication on later expressive language was examined in 36 boys with fragile X syndrome (FXS). Autism symptom severity was included as a potential moderator. Participants were visited in their homes twice over a 6-year period, and mother-child interactions were videotaped, coded, and transcribed behavior by behavior. Consonant inventory and concurrent autism symptom severity were predictive of later number of different words, as was the interaction between the two. Intentional communication was not predictive of number of different words. These findings provide additional specific evidence for differences in foundational language abilities associated with autism symptom severity in boys with FXS. Clinical implications are discussed.
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Affiliation(s)
| | - Steven F Warren
- Heather Fielding-Gebhardt and Steven F. Warren, University of Kansas
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5
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Wang DO, Ninomiya K, Mori C, Koyama A, Haan M, Kitabatake M, Hagiwara M, Chida K, Takahashi SI, Ohno M, Kataoka N. Transport Granules Bound with Nuclear Cap Binding Protein and Exon Junction Complex Are Associated with Microtubules and Spatially Separated from eIF4E Granules and P Bodies in Human Neuronal Processes. Front Mol Biosci 2017; 4:93. [PMID: 29312956 PMCID: PMC5744441 DOI: 10.3389/fmolb.2017.00093] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 12/15/2017] [Indexed: 02/05/2023] Open
Abstract
RNA transport and regulated local translation play critically important roles in spatially restricting gene expression in neurons. Heterogeneous population of RNA granules serve as motile units to translocate, store, translate, and degrade mRNAs in the dendrites contain cis-elements and trans-acting factors such as RNA-binding proteins and microRNAs to convey stimulus-, transcript-specific local translation. Here we report a class of mRNA granules in human neuronal processes that are enriched in the nuclear cap-binding protein complex (CBC) and exon junction complex (EJC) core components, Y14 and eIF4AIII. These granules are physically associated with stabilized microtubules and are spatially segregated from eIF4E-enriched granules and P-bodies. The existence of mRNAs retaining both nuclear cap binding protein and EJC in the distal sites of neuronal processes suggests that some localized mRNAs have not yet undergone the “very first translation,” which contribute to the spatio-temporal regulation of gene expression.
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Affiliation(s)
- Dan O Wang
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, Japan.,K-CONNEX (Keihanshin Consortium for Fostering Next Generation of Global Leaders in Research), Kyoto, Japan
| | - Kensuke Ninomiya
- Institute for Virus research, Kyoto University, Kyoto, Japan.,Laboratory of Anatomy and Developmental Biology, Kyoto University School of Medicine, Kyoto, Japan
| | - Chihiro Mori
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, Japan
| | - Ayako Koyama
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, Japan
| | - Martine Haan
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, Japan
| | | | - Masatoshi Hagiwara
- Laboratory of Anatomy and Developmental Biology, Kyoto University School of Medicine, Kyoto, Japan
| | - Kazuhiro Chida
- Laboratory of Cell Regulation, Departments of Applied Animal Sciences and Applied Biological Chemistry Graduate School of Agriculture and Life Sciences, The University of Tokyo, Kyoto, Japan
| | - Shin-Ichiro Takahashi
- Laboratory of Cell Regulation, Departments of Applied Animal Sciences and Applied Biological Chemistry Graduate School of Agriculture and Life Sciences, The University of Tokyo, Kyoto, Japan
| | - Mutsuhito Ohno
- Institute for Virus research, Kyoto University, Kyoto, Japan
| | - Naoyuki Kataoka
- Institute for Virus research, Kyoto University, Kyoto, Japan.,Laboratory of Anatomy and Developmental Biology, Kyoto University School of Medicine, Kyoto, Japan.,Laboratory of Cell Regulation, Departments of Applied Animal Sciences and Applied Biological Chemistry Graduate School of Agriculture and Life Sciences, The University of Tokyo, Kyoto, Japan.,Medical Innovation Center, Laboratory for Malignancy Control Research, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Medical Top Track Program, Medical Research Institute, Tokyo Dental and Medical University, Tokyo, Japan
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6
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Suhl JA, Chopra P, Anderson BR, Bassell GJ, Warren ST. Analysis of FMRP mRNA target datasets reveals highly associated mRNAs mediated by G-quadruplex structures formed via clustered WGGA sequences. Hum Mol Genet 2014; 23:5479-91. [PMID: 24876161 DOI: 10.1093/hmg/ddu272] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Fragile X syndrome, a common cause of intellectual disability and a well-known cause of autism spectrum disorder, is the result of loss or dysfunction of fragile X mental retardation protein (FMRP), a highly selective RNA-binding protein and translation regulator. A major research priority has been the identification of the mRNA targets of FMRP, particularly as recent studies suggest an excess of FMRP targets among genes implicated in idiopathic autism and schizophrenia. Several large-scale studies have attempted to identify mRNAs bound by FMRP through several methods, each generating a list of putative target genes, leading to distinct hypotheses by which FMRP recognizes its targets; namely, by RNA structure or sequence. However, no in depth analyses have been performed to identify the level of consensus among the studies. Here, we analyze four large FMRP target datasets to generate high-confidence consensus lists, and examine all datasets for sequence elements within the target RNAs to validate reported FMRP binding motifs (GACR, ACUK and WGGA). We found GACR to be highly enriched in FMRP datasets, while ACUK was not. The WGGA pattern was modestly enriched in several, but not all datasets. The previous association between FMRP and G-quadruplexes prompted the analysis of the distribution of WGGA in the target genes. Consistent with the requirements for G-quadruplex formation, we observed highly clustered WGGA motifs in FMRP targets compared with other genes, implicating both RNA structure and sequence in the recognition motif of FMRP. In addition, we generate a list of the top 40 FMRP targets associated with FXS-related phenotypes.
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Affiliation(s)
| | | | | | | | - Stephen T Warren
- Department of Human Genetics, Departments of Biochemistry and Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
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7
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Zhang Y, Park S, Blaser S, Sheets MD. Determinants of RNA binding and translational repression by the Bicaudal-C regulatory protein. J Biol Chem 2014; 289:7497-504. [PMID: 24478311 DOI: 10.1074/jbc.m113.526426] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bicaudal-C (Bic-C) RNA binding proteins function as important translational repressors in multiple biological contexts within metazoans. However, their RNA binding sites are unknown. We recently demonstrated that Bic-C functions in spatially regulated translational repression of the xCR1 mRNA during Xenopus development. This repression contributes to normal development by confining the xCR1 protein, a regulator of key signaling pathways, to specific cells of the embryo. In this report, we combined biochemical approaches with in vivo mRNA reporter assays to define the minimal Bic-C target site within the xCR1 mRNA. This 32-nucleotide Bic-C target site is predicted to fold into a stem-loop secondary structure. Mutational analyses provided evidence that this stem-loop structure is important for Bic-C binding. The Bic-C target site was sufficient for Bic-C mediated repression in vivo. Thus, we describe the first RNA binding site for a Bic-C protein. This identification provides an important step toward understanding the mechanisms by which evolutionarily conserved Bic-C proteins control cellular function in metazoans.
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Affiliation(s)
- Yan Zhang
- From the Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53706
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Zamiri B, Reddy K, Macgregor RB, Pearson CE. TMPyP4 porphyrin distorts RNA G-quadruplex structures of the disease-associated r(GGGGCC)n repeat of the C9orf72 gene and blocks interaction of RNA-binding proteins. J Biol Chem 2013; 289:4653-9. [PMID: 24371143 DOI: 10.1074/jbc.c113.502336] [Citation(s) in RCA: 164] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Certain DNA and RNA sequences can form G-quadruplexes, which can affect genetic instability, promoter activity, RNA splicing, RNA stability, and neurite mRNA localization. Amyotrophic lateral sclerosis and frontotemporal dementia can be caused by expansion of a (GGGGCC)n repeat in the C9orf72 gene. Mutant r(GGGGCC)n- and r(GGCCCC)n-containing transcripts aggregate in nuclear foci, possibly sequestering repeat-binding proteins such as ASF/SF2 and hnRNPA1, suggesting a toxic RNA pathogenesis, as occurs in myotonic dystrophy. Furthermore, the C9orf72 repeat RNA was recently demonstrated to undergo the noncanonical repeat-associated non-AUG translation (RAN translation) into pathologic dipeptide repeats in patient brains, a process that is thought to depend upon RNA structure. We previously demonstrated that the r(GGGGCC)n RNA forms repeat tract length-dependent G-quadruplex structures that bind the ASF/SF2 protein. Here we show that the cationic porphyrin (5,10,15,20-tetra(N-methyl-4-pyridyl) porphyrin (TMPyP4)), which can bind some G-quadruplex-forming sequences, can bind and distort the G-quadruplex formed by r(GGGGCC)8, and this ablates the interaction of either hnRNPA1 or ASF/SF2 with the repeat. These findings provide proof of concept that nucleic acid binding small molecules, such as TMPyP4, can distort the secondary structure of the C9orf72 repeat, which may beneficially disrupt protein interactions, which may ablate either protein sequestration and/or RAN translation into potentially toxic dipeptides. Disruption of secondary structure formation of the C9orf72 RNA repeats may be a viable therapeutic avenue, as well as a means to test the role of RNA structure upon RAN translation.
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Affiliation(s)
- Bita Zamiri
- From the Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario M5S 3M2
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9
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Language dysfluencies in females with the FMR1 premutation. Brain Cogn 2013; 82:84-9. [PMID: 23523717 DOI: 10.1016/j.bandc.2013.02.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 02/17/2013] [Accepted: 02/18/2013] [Indexed: 11/21/2022]
Abstract
Recent evidence suggests that there are age-related neurocognitive implications for fragile X premutation carriers, including deficits in executive function, and that such deficits are more common in male than female premutation carriers. The purpose of the current study is to examine one aspect of executive function, language dysfluencies, in a group of 193 women with the premutation, and to contrast them with a comparison group (mothers of children with autism spectrum disorders). Our results demonstrate a linguistic profile in the female premutation carriers characterized by dysfluencies associated with deficits in organization and planning, with a clear impact of age. The comparison group, matched on both age and education level, did not demonstrate the age effect. Our results suggest dysfluencies could be an early indicator of cognitive aging in some female premutation carriers, and could be used to target early intervention.
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10
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Sterling A, Abbeduto L. Language development in school-age girls with fragile X syndrome. JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2012; 56:974-83. [PMID: 22676254 PMCID: PMC3627376 DOI: 10.1111/j.1365-2788.2012.01578.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
BACKGROUND Girls with fragile X syndrome (FXS) have a wide range of cognitive and language abilities. The range of language outcomes experienced by girls with FXS, however, has been relatively unexplored. The purpose of this exploratory study was to examine receptive and expressive language, with a focus on vocabulary and syntax, in a group of school-age girls with FXS. METHOD Twenty-one girls with FXS aged 7-15 years participated in the study. The girls completed a receptive vocabulary test, non-verbal IQ test and an expressive language sample. RESULTS The mean IQ for this group of girls was at the cut-off for intellectual disability. Vocabulary was an area of strength relative to non-verbal cognition. Age and non-verbal IQ were significant predictors of vocabulary performance. CONCLUSIONS The data suggest that a substantial portion of the sample would qualify for speech and language services. This study highlights the need for continued research in the area of language and cognitive development in girls with the full mutation of fragile X.
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Affiliation(s)
- A Sterling
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705-2280, USA.
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11
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Darnell JC, Richter JD. Cytoplasmic RNA-binding proteins and the control of complex brain function. Cold Spring Harb Perspect Biol 2012; 4:a012344. [PMID: 22723494 DOI: 10.1101/cshperspect.a012344] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The formation and maintenance of neural circuits in the mammal central nervous system (CNS) require the coordinated expression of genes not just at the transcriptional level, but at the translational level as well. Recent evidence shows that regulated messenger RNA (mRNA) translation is necessary for certain forms of synaptic plasticity, the cellular basis of learning and memory. In addition, regulated translation helps guide axonal growth cones to their targets on other neurons or at the neuromuscular junction. Several neurologic syndromes have been correlated with and indeed may be caused by aberrant translation; one important example is the fragile X mental retardation syndrome. Although translation in the CNS is regulated by multiple mechanisms and factors, we focus this review on regulatory mRNA-binding proteins with particular emphasis on fragile X mental retardation protein (FMRP) and cytoplasmic polyadenylation element binding (CPEB) because they have been shown to be at the nexus of translational control and brain function in health and disease.
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Affiliation(s)
- Jennifer C Darnell
- Department of Molecular Neuro-Oncology, Rockefeller University, New York, New York 10065, USA.
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12
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Blackwell E, Ceman S. Arginine methylation of RNA-binding proteins regulates cell function and differentiation. Mol Reprod Dev 2012; 79:163-75. [PMID: 22345066 DOI: 10.1002/mrd.22024] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Accepted: 12/26/2011] [Indexed: 12/13/2022]
Abstract
Arginine methylation is a post-translational modification that regulates protein function. RNA-binding proteins are an important class of cell-function mediators, some of which are methylated on arginine. Early studies of RNA-binding proteins and arginine methylation are briefly introduced, and the enzymes that mediate this post-translational modification are described. We review the most common RNA-binding domains and briefly discuss how they associate with RNAs. We address the following groups of RNA-binding proteins: hnRNP, Sm, Piwi, Vasa, FMRP, and HuD. hnRNPs were the first RNA-binding proteins found to be methylated on arginine. The Sm proteins function in RNA processing and germ cell specification. The Piwi proteins are largely germ cell specific and are also required for germ cell production, as is Vasa. FMRP participates in germ cell formation in Drosophila, but is more widely known for its neuronal function. Similarly, HuD plays a role in nervous system development and function. We review the effects of arginine methylation on the function of each protein, then conclude by addressing remaining questions and future directions of arginine methylation as an important and emerging area of regulation.
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Affiliation(s)
- Ernest Blackwell
- Department of Cell and Developmental Biology, Neuroscience Program and College of Medicine, University of Illinois, Urbana-Champaign, Illlinois, USA
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13
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Till SM, Li HL, Miniaci MC, Kandel ER, Choi YB. A presynaptic role for FMRP during protein synthesis-dependent long-term plasticity in Aplysia. Learn Mem 2010; 18:39-48. [PMID: 21177378 DOI: 10.1101/lm.1958811] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Loss of the Fragile X mental retardation protein (FMRP) is associated with presumed postsynaptic deficits in mouse models of Fragile X syndrome. However, the possible presynaptic roles of FMRP in learning-related plasticity have received little attention. As a result, the mechanisms whereby FMRP influences synaptic function remain poorly understood. To investigate the cellular locus of the effects of FMRP on synaptic plasticity, we cloned the Aplysia homolog of FMRP and find it to be highly expressed in neurons. By selectively down-regulating FMRP in individual Aplysia neurons at the sensory-to-motor neuron synapse reconstituted in co-cultures, we demonstrate that FMRP functions both pre- and postsynaptically to constrain the expression of long-term synaptic depression induced by repeated pulses of FMRF-amide. In contrast, FMRP has little to no effect on long-term synaptic facilitation induced by repeated pulses of serotonin. Since other components of signaling pathways involved in plasticity appear to be conserved between Aplysia and mammalian neurons, our findings suggest that FMRP can participate in both pre- and postsynaptic regulation of enduring synaptic plasticity that underlies the storage of certain types of long-term memory.
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Affiliation(s)
- Sally M Till
- Department of Neuroscience, College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA
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14
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Eadie BD, Cushman J, Kannangara TS, Fanselow MS, Christie BR. NMDA receptor hypofunction in the dentate gyrus and impaired context discrimination in adult Fmr1 knockout mice. Hippocampus 2010; 22:241-54. [PMID: 21049485 DOI: 10.1002/hipo.20890] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2010] [Indexed: 12/21/2022]
Abstract
Fragile X syndrome (FXS) is the most common form of inherited intellectual disability in humans. This X-linked disorder is caused by the transcriptional repression of a single gene, Fmr1. The loss of Fmr1 transcription prevents the production of Fragile X mental retardation protein (FMRP) which in turn disrupts the expression of a variety of key synaptic proteins that appear to be important for intellectual ability. A clear link between synaptic dysfunction and behavioral impairment has been elusive, despite the fact that several animal models of FXS have been generated. Here we report that Fmr1 knockout mice exhibit impaired bidirectional synaptic plasticity in the dentate gyrus (DG) of the hippocampus. These deficits are associated with a novel decrease in functional NMDARs (N-methyl-D-aspartate receptors). In addition, mice lacking the Fmr1 gene show impaired performance in a context discrimination task that normally requires functional NMDARs in the DG. These data indicate that Fmr1 deletion results in significant NMDAR-dependent electrophysiological and behavioral impairments specific to the DG.
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Affiliation(s)
- Brennan D Eadie
- MD/PhD Program, University of British Columbia, Vancouver, BC, Canada
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McDuffie A, Abbeduto L, Lewis P, Kover S, Kim JS, Weber A, Brown WT. Autism spectrum disorder in children and adolescents with fragile X syndrome: within-syndrome differences and age-related changes. AMERICAN JOURNAL ON INTELLECTUAL AND DEVELOPMENTAL DISABILITIES 2010; 115:307-26. [PMID: 20567604 PMCID: PMC2887668 DOI: 10.1352/1944-7558-115.4.307] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The Autism Diagnostic Interview-Revised (ADI-R) was used to examine diagnostic profiles and age-related changes in autism symptoms for a group of verbal children and adolescents who had fragile X syndrome, with and without autism. After controlling for nonverbal IQ, we found statistically significant between-group differences for lifetime and current autism symptoms for the Communication and Restricted Interests/Repetitive Behaviors domains, but not the Reciprocal Social Interaction domain. Effect sizes for differences in Reciprocal Social Interaction also were smaller than effect sizes for the other domains, with one exception. Overall, severity of autism symptoms improved with age for all participants, with the least improvement noted for Restricted Interests and Repetitive Behaviors. FMRP did not account for unique variance in autism symptoms over and above nonverbal IQ.
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Affiliation(s)
- Andrea McDuffie
- University of Wisconsin, Waisman Center, Madison, WI 53705, USA.
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Plante I, Provost P. Hypothesis: a role for fragile X mental retardation protein in mediating and relieving microRNA-guided translational repression? J Biomed Biotechnol 2010; 2006:16806. [PMID: 17057359 PMCID: PMC1559909 DOI: 10.1155/jbb/2006/16806] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
MicroRNA (miRNA)-guided messenger RNA (mRNA) translational
repression is believed to be mediated by effector miRNA-containing
ribonucleoprotein (miRNP) complexes harboring fragile X mental
retardation protein (FMRP). Recent studies documented the nucleic
acid chaperone properties of FMRP and characterized its role and
importance in RNA silencing in mammalian cells. We propose a model
in which FMRP could facilitate miRNA assembly on target mRNAs in a
process involving recognition of G quartet structures. Functioning
within a duplex miRNP, FMRP may also mediate mRNA targeting
through a strand exchange mechanism, in which the miRNA* of the
duplex is swapped for the mRNA. Furthermore, FMRP may contribute
to the relief of miRNA-guided mRNA repression through a reverse
strand exchange reaction, possibly initiated by a specific
cellular signal, that would liberate the mRNA for translation.
Suboptimal utilization of miRNAs may thus account for some of the
molecular defects in patients with the fragile X syndrome.
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Affiliation(s)
- Isabelle Plante
- Centre de Recherche en Rhumatologie et Immunologie,
Centre de Recherche du CHUL (CHUQ), 2705 Boulevard, Laurier, Sainte-Foy, Québec, Canada G1V 4G2
- Department of Anatomy and physiology, Faculty of
Medicine, Laval University, Québec, Canada G1K 7P4
| | - Patrick Provost
- Centre de Recherche en Rhumatologie et Immunologie,
Centre de Recherche du CHUL (CHUQ), 2705 Boulevard, Laurier, Sainte-Foy, Québec, Canada G1V 4G2
- Department of Anatomy and physiology, Faculty of
Medicine, Laval University, Québec, Canada G1K 7P4
- *Patrick Provost:
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Plante I, Davidovic L, Ouellet DL, Gobeil LA, Tremblay S, Khandjian EW, Provost P. Dicer-derived microRNAs are utilized by the fragile X mental retardation protein for assembly on target RNAs. J Biomed Biotechnol 2010; 2006:64347. [PMID: 17057366 PMCID: PMC1698263 DOI: 10.1155/jbb/2006/64347] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In mammalian cells, fragile X mental retardation protein (FMRP)
has been reported to be part of a microRNA (miRNA)-containing
effector ribonucleoprotien (RNP) complex believed to mediate
translational control of specific mRNAs. Here, using recombinant
proteins, we demonstrate that human FMRP can act as a miRNA
acceptor protein for the ribonuclease Dicer and facilitate the
assembly of miRNAs on specific target RNA sequences. The miRNA
assembler property of FMRP was abrogated upon deletion of its
single-stranded (ss) RNA binding K-homology domains. The
requirement of FMRP for efficient RNA interference (RNAi) in vivo
was unveiled by reporter gene silencing assays using various small
RNA inducers, which also supports its involvement in an ss small
interfering RNA (siRNA)-containing RNP (siRNP) effector complex in
mammalian cells. Our results define a possible role for FMRP in
RNA silencing and may provide further insight into the molecular
defects in patients with the fragile X syndrome.
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Affiliation(s)
- Isabelle Plante
- Centre de Recherche en Rhumatologie et Immunologie, Centre de Recherche du CHUL-CHUQ, 2705 Blvd. Laurier, Sainte-Foy, QC, Canada, G1V 4G2
- Department of Anatomy and Physiology, Faculty of Medicine, Laval University, Quebec, QC, Canada, G1K 7P4
| | - Laetitia Davidovic
- Department of Anatomy and Physiology, Faculty of Medicine, Laval University, Quebec, QC, Canada, G1K 7P4
- Unité de Recherche en Génétique Humaine et Moléculaire, Centre de Recherche Hôpital St-Francois d’Assise-CHUQ, QC, Canada, G1L 3L5
| | - Dominique L. Ouellet
- Centre de Recherche en Rhumatologie et Immunologie, Centre de Recherche du CHUL-CHUQ, 2705 Blvd. Laurier, Sainte-Foy, QC, Canada, G1V 4G2
- Department of Anatomy and Physiology, Faculty of Medicine, Laval University, Quebec, QC, Canada, G1K 7P4
| | - Lise-Andrée Gobeil
- Centre de Recherche en Rhumatologie et Immunologie, Centre de Recherche du CHUL-CHUQ, 2705 Blvd. Laurier, Sainte-Foy, QC, Canada, G1V 4G2
- Department of Anatomy and Physiology, Faculty of Medicine, Laval University, Quebec, QC, Canada, G1K 7P4
| | - Sandra Tremblay
- Department of Anatomy and Physiology, Faculty of Medicine, Laval University, Quebec, QC, Canada, G1K 7P4
- Unité de Recherche en Génétique Humaine et Moléculaire, Centre de Recherche Hôpital St-Francois d’Assise-CHUQ, QC, Canada, G1L 3L5
| | - Edouard W. Khandjian
- Department of Anatomy and Physiology, Faculty of Medicine, Laval University, Quebec, QC, Canada, G1K 7P4
- Unité de Recherche en Génétique Humaine et Moléculaire, Centre de Recherche Hôpital St-Francois d’Assise-CHUQ, QC, Canada, G1L 3L5
| | - Patrick Provost
- Centre de Recherche en Rhumatologie et Immunologie, Centre de Recherche du CHUL-CHUQ, 2705 Blvd. Laurier, Sainte-Foy, QC, Canada, G1V 4G2
- Department of Anatomy and Physiology, Faculty of Medicine, Laval University, Quebec, QC, Canada, G1K 7P4
- *Patrick Provost:
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18
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Abstract
The machinery required for the replication of eukaryotic chromosomal DNA is made up of proteins whose function, structure and main interaction partners are evolutionarily conserved. Several new cases have been reported recently, however, in which non-coding RNAs play additional and specialised roles in the initiation of eukaryotic DNA replication in different classes of organisms. These non-coding RNAs include Y RNAs in vertebrate somatic cells, 26T RNA in somatic macronuclei of the ciliate Tetrahymena, and G-rich RNA in the Epstein-Barr DNA tumour virus and its human host cells. Here, I will give an overview of the experimental evidence in favour of roles for these non-coding RNAs in the regulation of eukaryotic DNA replication, and compare and contrast their biosynthesis and mechanisms of action.
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19
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TERRA RNA binding to TRF2 facilitates heterochromatin formation and ORC recruitment at telomeres. Mol Cell 2009; 35:403-13. [PMID: 19716786 DOI: 10.1016/j.molcel.2009.06.025] [Citation(s) in RCA: 408] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 03/10/2009] [Accepted: 06/23/2009] [Indexed: 12/30/2022]
Abstract
Telomere-repeat-encoding RNA (referred to as TERRA) has been identified as a potential component of yeast and mammalian telomeres. We show here that TERRA RNA interacts with several telomere-associated proteins, including telomere repeat factors 1 (TRF1) and 2 (TRF2), subunits of the origin recognition complex (ORC), heterochromatin protein 1 (HP1), histone H3 trimethyl K9 (H3 K9me3), and members of the DNA-damage-sensing pathway. siRNA depletion of TERRA caused an increase in telomere dysfunction-induced foci, aberrations in metaphase telomeres, and a loss of histone H3 K9me3 and ORC at telomere repeat DNA. Previous studies found that TRF2 amino-terminal GAR domain recruited ORC to telomeres. We now show that TERRA RNA can interact directly with the TRF2 GAR and ORC1 to form a stable ternary complex. We conclude that TERRA facilitates TRF2 interaction with ORC and plays a central role in telomere structural maintenance and heterochromatin formation.
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20
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Abstract
Recent genome-wide interrogations of transcribed RNA have yielded compelling evidence for pervasive and complex transcription throughout a large majority of the human genome. Tens of thousands of noncoding RNA transcripts have been identified, most of which have yet to be functionally characterized. Along with the revelation that noncoding RNAs in the human genome are surprisingly abundant, there has been a surge in molecular and genetic data showing important and diverse regulatory roles for noncoding RNA. In this report, we summarize the potential roles that noncoding RNAs may play in the molecular pathogenesis of different mental retardation disorders. We suspect that these findings are just the tip of the iceberg, with noncoding RNAs possibly being involved in disease pathogenesis at different levels and through multiple distinct mechanisms.
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Affiliation(s)
- K E Szulwach
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
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21
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Corley SM, Gready JE. Identification of the RGG box motif in Shadoo: RNA-binding and signaling roles? Bioinform Biol Insights 2008; 2:383-400. [PMID: 19812790 PMCID: PMC2735946 DOI: 10.4137/bbi.s1075] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Using comparative genomics and in-silico analyses, we previously identified a new member of the prion-protein (PrP) family, the gene SPRN, encoding the protein Shadoo (Sho), and suggested its functions might overlap with those of PrP. Extended bioinformatics and conceptual biology studies to elucidate Sho’s functions now reveal Sho has a conserved RGG-box motif, a well-known RNA-binding motif characterized in proteins such as FragileX Mental Retardation Protein. We report a systematic comparative analysis of RGG-box containing proteins which highlights the motif’s functional versatility and supports the suggestion that Sho plays a dual role in cell signaling and RNA binding in brain. These findings provide a further link to PrP, which has well-characterized RNA-binding properties.
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Affiliation(s)
- Susan M Corley
- Computational Proteomics and Therapy Design Group, Division of Molecular Bioscience, John Curtin School of Medical Research, Australian National University, PO Box 334, Canberra ACT 2601, Australia
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22
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Norseen J, Thomae A, Sridharan V, Aiyar A, Schepers A, Lieberman PM. RNA-dependent recruitment of the origin recognition complex. EMBO J 2008; 27:3024-35. [PMID: 18946490 DOI: 10.1038/emboj.2008.221] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Accepted: 09/23/2008] [Indexed: 12/13/2022] Open
Abstract
The origin recognition complex (ORC) has an important function in determining the initiation sites of DNA replication. In higher eukaryotes, ORC lacks sequence-specific DNA binding, and the mechanisms of ORC recruitment and origin determination are poorly understood. ORC is recruited with high efficiency to the Epstein-Barr virus origin of plasmid replication (OriP) through a complex mechanism involving interactions with the virus-encoded EBNA1 protein. We present evidence that ORC recruitment to OriP and DNA replication function depends on RGG-like motifs, referred to as LR1 and LR2, in the EBNA1 amino-terminal domain. Moreover, we show that LR1 and LR2 recruitment of ORC is RNA dependent. HMGA1a, which can functionally substitute for LR1 and LR2 domain, can also recruit ORC in an RNA-dependent manner. EBNA1 and HMGA1a RGG motifs bound to structured G-rich RNA, as did ORC1 peptides, which interact with EBNA1. RNase A treatment of cellular chromatin released a fraction of the total ORC, suggesting that ORC association with chromatin, and possibly cellular origins, is stabilized by RNA. We propose that structural RNA molecules mediate ORC recruitment at some cellular and viral origins, similar to OriP.
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Affiliation(s)
- Julie Norseen
- Program in Gene Expression and Regulation, The Wistar Institute, Philadelphia, PA 19104, USA
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23
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Armas P, Agüero TH, Borgognone M, Aybar MJ, Calcaterra NB. Dissecting CNBP, a zinc-finger protein required for neural crest development, in its structural and functional domains. J Mol Biol 2008; 382:1043-56. [PMID: 18703071 DOI: 10.1016/j.jmb.2008.07.079] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2008] [Revised: 07/25/2008] [Accepted: 07/28/2008] [Indexed: 01/18/2023]
Abstract
Cellular nucleic-acid-binding protein (CNBP) plays an essential role in forebrain and craniofacial development by controlling cell proliferation and survival to mediate neural crest expansion. CNBP binds to single-stranded nucleic acids and displays nucleic acid chaperone activity in vitro. The CNBP family shows a conserved modular organization of seven Zn knuckles and an arginine-glycine-glycine (RGG) box between the first and second Zn knuckles. The participation of these structural motifs in CNBP biochemical activities has still not been addressed. Here, we describe the generation of CNBP mutants that dissect the protein into regions with structurally and functionally distinct properties. Mutagenesis approaches were followed to generate: (i) an amino acid replacement that disrupted the fifth Zn knuckle; (ii) N-terminal deletions that removed the first Zn knuckle and the RGG box, or the RGG box alone; and (iii) a C-terminal deletion that eliminated the three last Zn knuckles. Mutant proteins were overexpressed in Escherichia coli, purified, and used to analyze their biochemical features in vitro, or overexpressed in Xenopus laevis embryos to study their function in vivo during neural crest cell development. We found that the Zn knuckles are required, but not individually essential, for CNBP biochemical activities, whereas the RGG box is essential for RNA-protein binding and nucleic acid chaperone activity. Removal of the RGG box allowed CNBP to preserve a weak single-stranded-DNA-binding capability. A mutant mimicking the natural N-terminal proteolytic CNBP form behaved as the RGG-deleted mutant. By gain-of-function and loss-of-function experiments in Xenopus embryos, we confirmed the participation of CNBP in neural crest development, and we demonstrated that the CNBP mutants lacking the N-terminal region or the RGG box alone may act as dominant negatives in vivo. Based on these data, we speculate about the existence of a specific proteolytic mechanism for the regulation of CNBP biochemical activities during neural crest development.
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Affiliation(s)
- Pablo Armas
- División Biología del Desarrollo, Instituto de Biología Molecular y Celular de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina
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24
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de Vrij FMS, Levenga J, van der Linde HC, Koekkoek SK, De Zeeuw CI, Nelson DL, Oostra BA, Willemsen R. Rescue of behavioral phenotype and neuronal protrusion morphology in Fmr1 KO mice. Neurobiol Dis 2008; 31:127-32. [PMID: 18571098 DOI: 10.1016/j.nbd.2008.04.002] [Citation(s) in RCA: 217] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 04/01/2008] [Accepted: 04/17/2008] [Indexed: 10/22/2022] Open
Abstract
Lack of fragile X mental retardation protein (FMRP) causes Fragile X Syndrome, the most common form of inherited mental retardation. FMRP is an RNA-binding protein and is a component of messenger ribonucleoprotein complexes, associated with brain polyribosomes, including dendritic polysomes. FMRP is therefore thought to be involved in translational control of specific mRNAs at synaptic sites. In mice lacking FMRP, protein synthesis-dependent synaptic plasticity is altered and structural malformations of dendritic protrusions occur. One hypothesized cause of the disease mechanism is based on exaggerated group I mGluR receptor activation. In this study, we examined the effect of the mGluR5 antagonist MPEP on Fragile X related behavior in Fmr1 KO mice. Our results demonstrate a clear defect in prepulse inhibition of startle in Fmr1 KO mice, that could be rescued by MPEP. Moreover, we show for the first time a structural rescue of Fragile X related protrusion morphology with two independent mGluR5 antagonists.
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Affiliation(s)
- Femke M S de Vrij
- Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands
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25
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Bhattacharyya A, McMillan E, Wallace K, Tubon TC, Capowski EE, Svendsen CN. Normal Neurogenesis but Abnormal Gene Expression in Human Fragile X Cortical Progenitor Cells. Stem Cells Dev 2008; 17:107-17. [PMID: 18225979 DOI: 10.1089/scd.2007.0073] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Human stem and progenitor cells offer an innovative way to study early events in development. An exciting new opportunity for these cells is their application to study the underlying developmental consequences of genetic diseases. Because many diseases, ranging from leukemias to developmental disorders, are caused by single-gene defects, stem and progenitor cells that carry disease-causing genetic mutations are invaluable in understanding and treating disease. We have characterized human neural progenitor (hNPCs) cells that carry a single-gene defect that leads to the neurodevelopmental disorder Fragile X syndrome (FX). A loss-of-function mutation in the FMR1 gene leads to subtle changes in neural development and subsequent mental impairment characteristic of FX. hNPCs were isolated from fetal cortex carrying the FMR1 mutation to determine whether aberrations occur in their proliferation and differentiation. As expected, FX hNPCs have reduced expression of the FMR1 gene product Fragile X mental retardation protein (FMRP), and this decrease is maintained in culture and following differentiation. In contrast to a previously published report, the proliferation of FX hNPCs and their differentiation into neurons is not different from unaffected controls. Although the early development of FX hNPCs is essentially normal, microarray analysis reveals novel changes in the expression of signal transduction genes in FX hNPCs. Therefore, hNPCs have intrinsic characteristics that can be investigated to further our understanding and potential treatment of developmental disorders such as FX.
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26
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Zhang M, Wang Q, Huang Y. Fragile X mental retardation protein FMRP and the RNA export factor NXF2 associate with and destabilize Nxf1 mRNA in neuronal cells. Proc Natl Acad Sci U S A 2007; 104:10057-62. [PMID: 17548835 PMCID: PMC1891223 DOI: 10.1073/pnas.0700169104] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Indexed: 11/18/2022] Open
Abstract
Fragile X syndrome is caused by the inactivation of the X-linked FMR1 gene, leading to the loss of its encoded protein FMRP. Although macroorchidism and defects in neuronal architecture and function have been associated with lack of FMRP, the exact molecular mechanism underlying this disease remains unclear. We have reported previously that in the brain and testis of mice, FMRP specifically interacts with a distinct mRNA nuclear export factor NXF2 but not with its close relative NXF1, a ubiquitously expressed essential mRNA nuclear export factor. This interaction marked NXF2 as a putative functional partner of FMRP. Here, we demonstrate by immunoprecipitation and quantitative real-time RT-PCR that, in cultured mouse neuronal cells, both FMRP and NXF2 are present in Nxf1 mRNA-containing ribonucleoprotein particles. Further, we show that expression of NXF2 leads to the destabilization of Nxf1 mRNA and that this effect is abolished when Fmr1 expression is reduced by siRNA, arguing that both proteins collaborate to exert this effect. Importantly, these findings correlate well with our observations that in both mouse hippocampal neurons and male germ cells where the expression of FMRP and NXF2 is most prominent, the expression of NXF1 is relatively poorly expressed. Our studies thus identify Nxf1 mRNA as a likely biologically relevant in vivo target of both FMRP and NXF2 and implicate FMRP, in conjunction with NXF2, as a posttranscriptional regulator of a major mRNA export factor. Such regulation may prove important in the normal development and function of neurons as well as of male germ cells.
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Affiliation(s)
- Meiqin Zhang
- *Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine, 300 George Street, New Haven, CT 06511; and
- Department of Gynecologic Oncology, Tumor Hospital, Fudan University, 270 Dongan Road, Shanghai 200032, China
| | - Qiaoqiao Wang
- *Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine, 300 George Street, New Haven, CT 06511; and
| | - Yingqun Huang
- *Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine, 300 George Street, New Haven, CT 06511; and
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27
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Abstract
The interaction of RNA-binding proteins (RBPs) with RNA is a crucial aspect of normal cellular metabolism. Yet, the diverse number of RBPs and RNA motifs to which they bind, the wide range of interaction strengths and the fact that RBPs associate in dynamic complexes have made it challenging to determine whether a particular RNA-binding protein binds a particular RNA. Recent work by three different laboratories has led to the development of new tools to query such interactions in the more physiological environs of cultured cells. The use of these methods has led to insights into (1) the networks of RNAs regulated by a particular protein, (2) the identification of new protein partners within messenger ribonucleoprotein particles and (3) the flux of RNA-binding proteins on an mRNA throughout its lifecycle. Here, I examine these new methods and discuss their relative strengths and current limitations.
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Affiliation(s)
- Robert B Denman
- Department of Molecular Biology, Laboratory of Biochemical Molecular Neurobiology, New York State Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island, NY 10314, USA.
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28
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Davidovic L, Bechara E, Gravel M, Jaglin XH, Tremblay S, Sik A, Bardoni B, Khandjian EW. The nuclear MicroSpherule protein 58 is a novel RNA-binding protein that interacts with fragile X mental retardation protein in polyribosomal mRNPs from neurons. Hum Mol Genet 2006; 15:1525-38. [PMID: 16571602 DOI: 10.1093/hmg/ddl074] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The fragile X syndrome, the leading cause of inherited mental retardation, is due to the inactivation of the fragile mental retardation 1 gene (FMR1) and the subsequent absence of its gene product FMRP. This RNA-binding protein is thought to control mRNA translation and its absence in fragile X cells leads to alteration in protein synthesis. In neurons, FMRP is thought to repress specific mRNAs during their transport as silent ribonucleoparticles (mRNPs) from the cell body to the distant synapses which are the sites of local synthesis of neuro-specific proteins. The mechanism by which FMRP sorts out its different mRNAs targets might be tuned by the intervention of different proteins. Using a yeast two-hybrid system, we identified MicroSpherule Protein 58 (MSP58) as a novel FMRP-cellular partner. In cell cultures, we found that MSP58 is predominantly present in the nucleus where it interacts with the nuclear isoform of FMRP. However, in neurons but not in glial cells, MSP58 is also present in the cytoplasmic compartment, as well as in neurites, where it co-localizes with FMRP. Biochemical evidence is given that MSP58 is associated with polyribosomal poly(A)+ mRNPs. We also show that MSP58, similar to FMRP, is present on polyribosomes prepared from synaptoneurosomes and that it behaves as an RNA-binding protein with a high affinity to the G-quartet structure. We propose that this novel cellular partner for FMRP escorts FMRP-containing mRNP from the nucleus and nucleolus to the somato-dendritic compartment where it might participate in neuronal translation regulation.
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Affiliation(s)
- Laetitia Davidovic
- Unité de Recherche en Génétique Humaine et Moléculaire, Centre de recherche Hôpital Saint-François d'Assise, le CHUQ, Québec, Canada G1L 3L5
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29
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Restifo LL. Mental retardation genes in drosophila: New approaches to understanding and treating developmental brain disorders. ACTA ACUST UNITED AC 2006; 11:286-94. [PMID: 16240406 DOI: 10.1002/mrdd.20083] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Drosophila melanogaster is emerging as a valuable genetic model system for the study of mental retardation (MR). MR genes are remarkably similar between humans and fruit flies. Cognitive behavioral assays can detect reductions in learning and memory in flies with mutations in MR genes. Neuroanatomical methods, including some at single-neuron resolution, are helping to reveal the cellular bases of faulty brain development caused by MR gene mutations. Drosophila fragile X mental retardation 1 (dfmr1) is the fly counterpart of the human gene whose malfunction causes fragile X syndrome. Research on the fly gene is leading the field in molecular mechanisms of the gene product's biological function and in pharmacological rescue of brain and behavioral phenotypes. Future work holds the promise of using genetic pathway analysis and primary neuronal culture methods in Drosophila as tools for drug discovery for a wide range of MR and related disorders.
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Affiliation(s)
- Linda L Restifo
- ARL Division of Neurobiology, University of Arizona, and Department of Neurology, Arizona Health Sciences Center, Tucson Arizona 85721-0077, USA.
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30
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Abstract
The fragile X mental retardation 1 gene (FMR1) mutation causes two disorders: fragile X syndrome (FXS) in those with the full mutation and the fragile X-associated tremor/ataxia syndrome (FXTAS) in some older individuals with the premutation. FXS is caused by a deficiency of the FMR1 protein (FMRP) leading to dysregulation of many genes that create a phenotype with ADHD, anxiety, and autism. FXTAS is caused by the elevation of FMR1-mRNA to levels 2 to 8 times normal in the premutation. This causes an RNA gain of function toxicity leading to brain atrophy, white matter disease, neuronal and astrocytic inclusion formation, and subsequent ataxia, intention tremor, peripheral neuropathy, and cognitive decline. The neurobiology and pathophysiology of FXS and FXTAS are described in detail.
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Affiliation(s)
- Randi J Hagerman
- Department of Pediatrics, M.I.N.D. Institute, University of California Davis Health System, Sacramento, California 95817, USA.
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31
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Abstract
The inflammatory response is a complex physiologic process that requires the coordinate induction of cytokines, chemokines, angiogenic factors, effector-enzymes, and proteases. Although transcriptional activation is required to turn on the inflammatory response, recent studies have revealed that posttranscriptional mechanisms play an important role by determining the rate at which mRNAs encoding inflammatory effector proteins are translated and degraded. Most posttranscriptional control mechanisms function to dampen the expression of pro-inflammatory proteins to ensure that potentially injurious proteins are not overexpressed during an inflammatory response. Here we discuss the factors that regulate the stability and translation of mRNAs encoding pro-inflammatory proteins.
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Affiliation(s)
- Georg Stoecklin
- Division of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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32
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Darnell JC, Mostovetsky O, Darnell RB. FMRP RNA targets: identification and validation. GENES BRAIN AND BEHAVIOR 2005; 4:341-9. [PMID: 16098133 DOI: 10.1111/j.1601-183x.2005.00144.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Fragile X Syndrome is caused by the loss of function of the FMR1 gene (Pieretti et al. 1991. Cell 66, 817-822; O'Donnell & Warren 2002. Annu Rev Neurosci 25, 315-338]. Identification of the RNA targets to which FMRP binds is a key step in understanding the function of the protein and the cellular defects caused by its absence (Darnell et al. 2004 Ment Retard Dev Disabil Res Rev 10, 49-52). Here we discuss the current understanding of FMRP as an RNA-binding protein, the different approaches that have been taken to identify FMRP RNA targets and the relevance of some of these approaches to FMRP biology. In addition, we present evidence that point mutations in the K-homology (KH)1 or KH2 domains of FMRP abrogate its polyribosome association in transfected neuroblastoma cells but that the deletion of the RGG box does not. This suggests that RNA binding by the RGG box of FMRP may mediate other aspects of cellular mRNA metabolism such as mRNA localization or that it may have a role downstream of polyribosome association.
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Affiliation(s)
- J C Darnell
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY, USA
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33
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Gantois I, Vandesompele J, Speleman F, Reyniers E, D'Hooge R, Severijnen LA, Willemsen R, Tassone F, Kooy RF. Expression profiling suggests underexpression of the GABA(A) receptor subunit delta in the fragile X knockout mouse model. Neurobiol Dis 2005; 21:346-57. [PMID: 16199166 DOI: 10.1016/j.nbd.2005.07.017] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2005] [Revised: 07/05/2005] [Accepted: 07/28/2005] [Indexed: 11/29/2022] Open
Abstract
It is still unclear why absence of the fragile X protein (FMRP) leads to mental retardation and specific behavioral problems. In neurons, the protein transports specific mRNAs towards the actively translating ribosomes near the synapses. To unravel the mechanism leading to the disorder, we performed global gene expression analysis by means of the differential display method using the fragile X mouse model. To verify differential expression, we used microarray technology and real-time PCR. Three differentially expressed cDNAs showed consistent underexpression in the fragile X knockout mouse, including a GABA(A) receptor subunit delta, a Rho guanine exchange factor 12 and an EST BU563433. In addition, we identified 5 genes that showed differential expression dependent on the sample of RNA analysis. We consider their differential expression as provisional. It is possible that these differentially expressed genes play an important role in the cognitive and behavioral problems observed in the fragile X syndrome.
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Affiliation(s)
- Ilse Gantois
- Department of Medical Genetics, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium
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34
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Abstract
The Epstein-Barr virus (EBV) SM protein is a member of a highly conserved family of proteins present in most mammalian herpes viruses. There is a significant amount of functional and sequence divergence among the homologs encoded by the human herpes viruses, including differences in mechanism of action and varying effects on splicing and transcription. Nevertheless, in those cases where it has been studied, these proteins are essential for lytic replication of the virus. The mechanism by which SM regulates gene expression operates at the level of mRNA stability, processing, and export. SM enhances expression of EBV lytic genes and has both positive and negative effects on cellular gene expression. In addition to enhancing accumulation of EBV gene mRNAs, SM has important effects on cellular mRNAs, altering the host cell gene expression profile to facilitate viral replication. This article describes the current state of knowledge regarding the role of EBV SM in cellular and viral gene regulation and summarizes some of the similarities and differences with the ORF57 homolog from Kaposi's sarcoma-associated herpes virus (KSHV/HHV8).
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Affiliation(s)
- Sankar Swaminathan
- Department of Medicine, University of Florida Shands Cancer Center, Gainesville, Florida 32610, USA.
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35
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Abstract
PURPOSE OF REVIEW This review will describe recent developments in the neurobiology of fragile X syndrome (FXS), the association between FXS and autism, and involvement in premutation carriers. RECENT FINDINGS Metabotropic glutamate receptor 5 (mGluR5)-coupled pathways are dysregulated in individuals with FXS and this is thought to relate to the FXS phenotype. The mGluR5 model suggests that mGluR5 antagonists, including downstream effectors such as lithium, could be useful for treating FXS. Two forms of clinical involvement associated with the fragile X mental retardation 1 (FMR1) gene, autism and fragile X-associated tremor/ataxia syndrome (FXTAS), have received additional attention during the past year. One study has found that approximately 30% of individuals with FXS have autism; those with autism have lowered cognitive abilities, language problems, and behavioral difficulties compared to those with FXS alone. Furthermore, evidence is mounting that autism also occurs in some young males who have premutation alleles. Finally, males and occasional females with premutation alleles may develop a neurological syndrome with aging that consists of tremor, ataxia, peripheral neuropathy, and cognitive deficits. Significant brain atrophy and white-matter disease is usually seen. This new disorder (FXTAS) is thought to be related to elevated levels of abnormal FMR1 mRNA. SUMMARY Full-mutation forms of the gene (> 200 repeats) can cause autism, learning disabilities, anxiety disorders, and mental retardation. Disorders associated with premutation forms of the gene (55-200 repeats) include, in addition to autism, FXTAS in older males and females, and premature ovarian failure.
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Affiliation(s)
- Randi J Hagerman
- Department of Pediatrics, University of California at Davis Medical Center, M.I.N.D. Institute, Sacramento, CA 95817, USA.
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Abstract
Advances in defining mechanisms of cortical development have been paralleled in recent years by an intense interest in translating these findings into greater insight of both childhood- and adult-onset cognitive and mental health disorders of developmental etiology. Successful integration of basic and clinical findings have been applied to monogenic disorders. The greater challenge lies in studying cortical development in the context of gene x environment interactions, which underlie the pathogenesis of the most common neurodevelopmental disorders. This can occur through an improved delineation of pathophysiological characteristics unique to specific complex disorders and the application of this information to the refinement of the most relevant model systems.
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Affiliation(s)
- Pat Levitt
- Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37203, USA.
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Hazel P, Huppert J, Balasubramanian S, Neidle S. Loop-length-dependent folding of G-quadruplexes. J Am Chem Soc 2005; 126:16405-15. [PMID: 15600342 DOI: 10.1021/ja045154j] [Citation(s) in RCA: 382] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Guanine-rich DNA sequences can form a large number of structurally diverse quadruplexes. These vary in terms of strand polarity, loop composition, and conformation. We have derived guidelines for understanding the influence of loop length on the structure adopted by intramolecular quadruplex-forming sequences, using a combination of experimental (using CD and UV melting data) and molecular modeling and simulation techniques. We find that a parallel-stranded intramolecular quadruplex structure is the only possible fold when three single residue loops are present. When single thymine loops are present in combination with longer length loops, or when all loops are longer than two residues, both parallel- and antiparallel-folded structures are able to form. Multiple conformations of each structure are likely to coexist in solution, as they were calculated to have very similar free energies.
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Affiliation(s)
- Pascale Hazel
- Cancer Research UK Biomolecular Structure Group, The School of Pharmacy, University of London, 29-39 Brunswick Square, London WC1N 1AX, UK
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