151
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Reyes ST, Mohajeri S, Krasinska K, Guo SG, Gu M, Pisani L, Rosenberg J, Spielman DM, Chin FT. GABA Measurement in a Neonatal Fragile X Syndrome Mouse Model Using 1H-Magnetic Resonance Spectroscopy and Mass Spectrometry. Front Mol Neurosci 2020; 13:612685. [PMID: 33390902 PMCID: PMC7775297 DOI: 10.3389/fnmol.2020.612685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 11/20/2020] [Indexed: 11/20/2022] Open
Abstract
Fragile X syndrome (FXS) is the leading monogenetic cause of autism spectrum disorder and inherited cause of intellectual disability that affects approximately one in 7,000 males and one in 11,000 females. In FXS, the Fmr1 gene is silenced and prevents the expression of the fragile X mental retardation protein (FMRP) that directly targets mRNA transcripts of multiple GABAA subunits. Therefore, FMRP loss adversely impacts the neuronal firing of the GABAergic system which creates an imbalance in the excitatory/inhibitory ratio within the brain. Current FXS treatment strategies focus on curing symptoms, such as anxiety or decreased social function. While treating symptoms can be helpful, incorporating non-invasive imaging to evaluate how treatments change the brain's biology may explain what molecular aberrations are associated with disease pathology. Thus, the GABAergic system is suitable to explore developing novel therapeutic strategies for FXS. To understand how the GABAergic system may be affected by this loss-of-function mutation, GABA concentrations were examined within the frontal cortex and thalamus of 5-day-old wild type and Fmr1 knockout mice using both 1H magnetic resonance imaging (1H-MRS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Our objective was to develop a reliable scanning method for neonatal mice in vivo and evaluate whether 1H-MRS is suitable to capture regional GABA concentration differences at the front end of the critical cortical period where abnormal neurodevelopment occurs due to FMRP loss is first detected. 1H-MRS quantified GABA concentrations in both frontal cortex and thalamus of wild type and Fmr1 knockout mice. To substantiate the results of our 1H-MRS studies, in vitro LC-MS/MS was also performed on brain homogenates from age-matched mice. We found significant changes in GABA concentration between the frontal cortex and thalamus within each mouse from both wild type and Fmr1 knockout mice using 1H-MRS and LC-MS/MS. Significant GABA levels were also detected in these same regions between wild type and Fmr1 knockout mice by LC-MS/MS, validating that FMRP loss directly affects the GABAergic system. Thus, these new findings support the need to develop an effective non-invasive imaging method to monitor novel GABAergic strategies aimed at treating patients with FXS.
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Affiliation(s)
- Samantha T. Reyes
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Sanaz Mohajeri
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Karolina Krasinska
- Stanford University Mass Spectrometry Laboratory, Stanford University, Stanford, CA, United States
| | - Scarlett G. Guo
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Meng Gu
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Laura Pisani
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Jarrett Rosenberg
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Daniel M. Spielman
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Frederick T. Chin
- Department of Radiology, Stanford University, Stanford, CA, United States
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152
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Uhl M, Tran VD, Backofen R. Improving CLIP-seq data analysis by incorporating transcript information. BMC Genomics 2020; 21:894. [PMID: 33334306 PMCID: PMC7745353 DOI: 10.1186/s12864-020-07297-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 12/02/2020] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Current peak callers for identifying RNA-binding protein (RBP) binding sites from CLIP-seq data take into account genomic read profiles, but they ignore the underlying transcript information, that is information regarding splicing events. So far, there are no studies available that closer observe this issue. RESULTS Here we show that current peak callers are susceptible to false peak calling near exon borders. We quantify its extent in publicly available datasets, which turns out to be substantial. By providing a tool called CLIPcontext for automatic transcript and genomic context sequence extraction, we further demonstrate that context choice affects the performances of RBP binding site prediction tools. Moreover, we show that known motifs of exon-binding RBPs are often enriched in transcript context sites, which should enable the recovery of more authentic binding sites. Finally, we discuss possible strategies on how to integrate transcript information into future workflows. CONCLUSIONS Our results demonstrate the importance of incorporating transcript information in CLIP-seq data analysis. Taking advantage of the underlying transcript information should therefore become an integral part of future peak calling and downstream analysis tools.
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Affiliation(s)
- Michael Uhl
- Bioinformatics Group, Department of Computer Science, University of Freiburg, Georges-Köhler-Allee 106, Freiburg, 79110, Germany
| | - Van Dinh Tran
- Bioinformatics Group, Department of Computer Science, University of Freiburg, Georges-Köhler-Allee 106, Freiburg, 79110, Germany
| | - Rolf Backofen
- Bioinformatics Group, Department of Computer Science, University of Freiburg, Georges-Köhler-Allee 106, Freiburg, 79110, Germany. .,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Schaenzlestr. 18, Freiburg, 79104, Germany.
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153
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Casingal CR, Kikkawa T, Inada H, Sasaki Y, Osumi N. Identification of FMRP target mRNAs in the developmental brain: FMRP might coordinate Ras/MAPK, Wnt/β-catenin, and mTOR signaling during corticogenesis. Mol Brain 2020; 13:167. [PMID: 33323119 PMCID: PMC7739466 DOI: 10.1186/s13041-020-00706-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 11/23/2020] [Indexed: 01/18/2023] Open
Abstract
Corticogenesis is one of the most critical and complicated processes during embryonic brain development. Any slight impairment in corticogenesis could cause neurodevelopmental disorders such as Fragile X syndrome (FXS), of which symptoms contain intellectual disability (ID) and autism spectrum disorder (ASD). Fragile X mental retardation protein (FMRP), an RNA-binding protein responsible for FXS, shows strong expression in neural stem/precursor cells (NPCs) during corticogenesis, although its function during brain development remains largely unknown. In this study, we attempted to identify the FMRP target mRNAs in the cortical primordium using RNA immunoprecipitation sequencing analysis in the mouse embryonic brain. We identified 865 candidate genes as targets of FMRP involving 126 and 118 genes overlapped with ID and ASD-associated genes, respectively. These overlapped genes were enriched with those related to chromatin/chromosome organization and histone modifications, suggesting the involvement of FMRP in epigenetic regulation. We further identified a common set of 17 FMRP “core” target genes involved in neurogenesis/FXS/ID/ASD, containing factors associated with Ras/mitogen-activated protein kinase, Wnt/β-catenin, and mammalian target of rapamycin (mTOR) pathways. We indeed showed overactivation of mTOR signaling via an increase in mTOR phosphorylation in the Fmr1 knockout (Fmr1 KO) neocortex. Our results provide further insight into the critical roles of FMRP in the developing brain, where dysfunction of FMRP may influence the regulation of its mRNA targets affecting signaling pathways and epigenetic modifications.
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Affiliation(s)
- Cristine R Casingal
- Department of Developmental Neuroscience, United Center for Advanced Research and Translational Medicine (ART), Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8575, Japan
| | - Takako Kikkawa
- Department of Developmental Neuroscience, United Center for Advanced Research and Translational Medicine (ART), Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8575, Japan
| | - Hitoshi Inada
- Department of Developmental Neuroscience, United Center for Advanced Research and Translational Medicine (ART), Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8575, Japan.,Laboratory of Health and Sports Sciences, Division of Biomedical Engineering for Health and Welfare, Tohoku University Graduate School of Biomedical Engineering, 6-6-12, Aramaki Aza Aoba Aoba-ku, Sendai, Miyagi, 980-8579, Japan
| | - Yukio Sasaki
- Functional Structure Biology Laboratory, Department of Medical Life Science, Yokohama City University Graduate School of Medical Life Science, 1-7-29 Suehiro-cho, Tsumuri-ku, Yokohama, 230-0045, Japan
| | - Noriko Osumi
- Department of Developmental Neuroscience, United Center for Advanced Research and Translational Medicine (ART), Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8575, Japan.
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154
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Briševac D, Scholz R, Du D, Elagabani MN, Köhr G, Kornau HC. The small GTPase Arf6 is dysregulated in a mouse model for fragile X syndrome. J Neurochem 2020; 157:666-683. [PMID: 33125726 DOI: 10.1111/jnc.15230] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 10/09/2020] [Accepted: 10/27/2020] [Indexed: 11/29/2022]
Abstract
Fragile X syndrome (FXS), the most common inherited cause of intellectual disability, results from silencing of the fragile X mental retardation gene 1 (FMR1). The analyses of FXS patients' brain autopsies revealed an increased density of immature dendritic spines in cortical areas. We hypothesize that the small GTPase Arf6, an actin regulator critical for the development of glutamatergic synapses and dendritic spines, is implicated in FXS. Here, we determined the fraction of active, GTP-bound Arf6 in cortical neuron cultures and synaptoneurosomes from Fmr1 knockout mice, measured actin polymerization in neurons expressing Arf6 mutants with variant GTP- or GDP-binding properties, and recorded hippocampal long-term depression induced by metabotropic glutamate receptors (mGluR-LTD) in acute brain slices. We detected a persistently elevated Arf6 activity, a loss of Arf6 sensitivity to synaptic stimulation and an increased Arf6-dependent dendritic actin polymerization in mature Fmr1 knockout neurons. Similar imbalances in Arf6-GTP levels and actin filament assembly were caused in wild-type neurons by RNAi-mediated depletion of the postsynaptic Arf6 guanylate exchange factors IQSEC1 (BRAG2) or IQSEC2 (BRAG1). Targeted deletion of Iqsec1 in hippocampal neurons of 3-week-old mice interfered with mGluR-LTD in wild-type, but not in Fmr1 knockout mice. Collectively, these data suggest an aberrant Arf6 regulation in Fmr1 knockout neurons with consequences for the actin cytoskeleton, spine morphology, and synaptic plasticity. Moreover, FXS and syndromes caused by genetic variants in IQSEC1 and IQSEC2 share intellectual disabilities and developmental delay as main symptoms. Therefore, dysregulation of Arf6 may contribute to the cognitive impairment in FXS.
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Affiliation(s)
- Dušica Briševac
- Neuroscience Research Center (NWFZ), Charité - Universitätsmedizin Berlin, Berlin, Germany.,Department of Biology, Chemistry, and Pharmacy, Freie Universität Berlin, Berlin, Germany
| | - Ralf Scholz
- Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Dan Du
- Central Institute of Mental Health, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | | | - Georg Köhr
- Central Institute of Mental Health, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.,Department of Neurophysiology, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Hans-Christian Kornau
- Neuroscience Research Center (NWFZ), Charité - Universitätsmedizin Berlin, Berlin, Germany.,Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany.,German Center for Neurodegenerative Diseases (DZNE) Berlin, Berlin, Germany
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155
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Carbamazepine Restores Neuronal Signaling, Protein Synthesis, and Cognitive Function in a Mouse Model of Fragile X Syndrome. Int J Mol Sci 2020; 21:ijms21239327. [PMID: 33297570 PMCID: PMC7731004 DOI: 10.3390/ijms21239327] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 11/19/2020] [Accepted: 12/03/2020] [Indexed: 02/07/2023] Open
Abstract
Fragile X syndrome (FXS) is a leading genetic disorder of intellectual disability caused by the loss of the functional fragile X mental retardation protein (FMRP). To date, there is no efficacious mechanism-based medication for FXS. With regard to potential disease mechanisms in FXS, it is widely accepted that the lack of FMRP causes elevated protein synthesis and deregulation of neuronal signaling. Abnormal enhancement of the ERK½ (extracellular signal-regulated kinase ½) and PI3K-Akt (Phosphoinositide 3 kinase-protein kinase B) signaling pathways has been identified in both FXS patients and FXS mouse models. In this study, we show that carbamazepine, which is an FDA-approved drug and has been mainly used to treat seizure and neuropathic pain, corrects cognitive deficits including passive avoidance and object location memory in FXS mice. Carbamazepine also rescues hyper locomotion and social deficits. At the cellular level, carbamazepine dampens the elevated level of ERK½ and Akt signaling as well as protein synthesis in FXS mouse neurons. Together, these results advocate repurposing carbamazepine for FXS treatment.
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156
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Shu H, Donnard E, Liu B, Jung S, Wang R, Richter JD. FMRP links optimal codons to mRNA stability in neurons. Proc Natl Acad Sci U S A 2020; 117:30400-30411. [PMID: 33199649 PMCID: PMC7720238 DOI: 10.1073/pnas.2009161117] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Fragile X syndrome (FXS) is caused by inactivation of the FMR1 gene and loss of encoded FMRP, an RNA binding protein that represses translation of some of its target transcripts. Here we use ribosome profiling and RNA sequencing to investigate the dysregulation of translation in the mouse brain cortex. We find that most changes in ribosome occupancy on hundreds of mRNAs are largely driven by dysregulation in transcript abundance. Many down-regulated mRNAs, which are mostly responsible for neuronal and synaptic functions, are highly enriched for FMRP binding targets. RNA metabolic labeling demonstrates that, in FMRP-deficient cortical neurons, mRNA down-regulation is caused by elevated degradation and is correlated with codon optimality. Moreover, FMRP preferentially binds mRNAs with optimal codons, suggesting that it stabilizes such transcripts through direct interactions via the translational machinery. Finally, we show that the paradigm of genetic rescue of FXS-like phenotypes in FMRP-deficient mice by deletion of the Cpeb1 gene is mediated by restoration of steady-state RNA levels and consequent rebalancing of translational homeostasis. Our data establish an essential role of FMRP in codon optimality-dependent mRNA stability as an important factor in FXS.
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Affiliation(s)
- Huan Shu
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605;
| | - Elisa Donnard
- Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Botao Liu
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605
| | - Suna Jung
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605
| | - Ruijia Wang
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605
| | - Joel D Richter
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605
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157
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Gebauer F, Schwarzl T, Valcárcel J, Hentze MW. RNA-binding proteins in human genetic disease. Nat Rev Genet 2020; 22:185-198. [PMID: 33235359 DOI: 10.1038/s41576-020-00302-y] [Citation(s) in RCA: 294] [Impact Index Per Article: 73.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2020] [Indexed: 12/27/2022]
Abstract
RNA-binding proteins (RBPs) are critical effectors of gene expression, and as such their malfunction underlies the origin of many diseases. RBPs can recognize hundreds of transcripts and form extensive regulatory networks that help to maintain cell homeostasis. System-wide unbiased identification of RBPs has increased the number of recognized RBPs into the four-digit range and revealed new paradigms: from the prevalence of structurally disordered RNA-binding regions with roles in the formation of membraneless organelles to unsuspected and potentially pervasive connections between intermediary metabolism and RNA regulation. Together with an increasingly detailed understanding of molecular mechanisms of RBP function, these insights are facilitating the development of new therapies to treat malignancies. Here, we provide an overview of RBPs involved in human genetic disorders, both Mendelian and somatic, and discuss emerging aspects in the field with emphasis on molecular mechanisms of disease and therapeutic interventions.
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Affiliation(s)
- Fátima Gebauer
- Gene Regulation, Stem Cells and Cancer Program, Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Barcelona, Spain. .,University Pompeu Fabra (UPF), Barcelona, Spain.
| | - Thomas Schwarzl
- European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Juan Valcárcel
- Gene Regulation, Stem Cells and Cancer Program, Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Barcelona, Spain.,University Pompeu Fabra (UPF), Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
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158
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Brašić JR, Nandi A, Russell DS, Jennings D, Barret O, Mathur A, Slifer K, Sedlak T, Martin SD, Brinson Z, Vyas P, Seibyl JP, Berry-Kravis EM, Wong DF, Budimirovic DB. Reduced Expression of Cerebral Metabotropic Glutamate Receptor Subtype 5 in Men with Fragile X Syndrome. Brain Sci 2020; 10:E899. [PMID: 33255214 PMCID: PMC7760509 DOI: 10.3390/brainsci10120899] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 11/07/2020] [Accepted: 11/14/2020] [Indexed: 12/28/2022] Open
Abstract
Glutamatergic receptor expression is mostly unknown in adults with fragile X syndrome (FXS). Favorable behavioral effects of negative allosteric modulators (NAMs) of the metabotropic glutamate receptor subtype 5 (mGluR5) in fmr1 knockout (KO) mouse models have not been confirmed in humans with FXS. Measurement of cerebral mGluR5 expression in humans with FXS exposed to NAMs might help in that effort. We used positron emission tomography (PET) to measure the mGluR5 density as a proxy of mGluR5 expression in cortical and subcortical brain regions to confirm target engagement of NAMs for mGluR5s. The density and the distribution of mGluR5 were measured in two independent samples of men with FXS (N = 9) and typical development (TD) (N = 8). We showed the feasibility of this complex study including MRI and PET, meaning that this challenging protocol can be accomplished in men with FXS with an adequate preparation. Analysis of variance of estimated mGluR5 expression showed that mGluR5 expression was significantly reduced in cortical and subcortical regions of men with FXS in contrast to age-matched men with TD.
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Affiliation(s)
- James R. Brašić
- Section of High Resolution Brain Positron Emission Tomography Imaging, Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (A.N.); (A.M.); (T.S.); (S.D.M.); (Z.B.); (P.V.); (D.F.W.)
| | - Ayon Nandi
- Section of High Resolution Brain Positron Emission Tomography Imaging, Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (A.N.); (A.M.); (T.S.); (S.D.M.); (Z.B.); (P.V.); (D.F.W.)
| | - David S. Russell
- Clinical Research, Institute for Neurodegenerative Disorders, New Haven, CT 06510, USA; (D.S.R.); (D.J.); (O.B.); (J.P.S.)
- Research Clinic, Invicro LLC, New Haven, CT 06510, USA
| | - Danna Jennings
- Clinical Research, Institute for Neurodegenerative Disorders, New Haven, CT 06510, USA; (D.S.R.); (D.J.); (O.B.); (J.P.S.)
- Research Clinic, Invicro LLC, New Haven, CT 06510, USA
- Denali Therapeutics, Inc., South San Francisco, CA 94080, USA
| | - Olivier Barret
- Clinical Research, Institute for Neurodegenerative Disorders, New Haven, CT 06510, USA; (D.S.R.); (D.J.); (O.B.); (J.P.S.)
| | - Anil Mathur
- Section of High Resolution Brain Positron Emission Tomography Imaging, Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (A.N.); (A.M.); (T.S.); (S.D.M.); (Z.B.); (P.V.); (D.F.W.)
| | - Keith Slifer
- Department of Psychiatry and Behavioral Sciences-Child Psychiatry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA;
- Department of Behavioral Psychology, Kennedy Krieger Institute, Baltimore, MD 21205, USA
| | - Thomas Sedlak
- Section of High Resolution Brain Positron Emission Tomography Imaging, Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (A.N.); (A.M.); (T.S.); (S.D.M.); (Z.B.); (P.V.); (D.F.W.)
- Department of Psychiatry and Behavioral Sciences-General Psychiatry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Samuel D. Martin
- Section of High Resolution Brain Positron Emission Tomography Imaging, Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (A.N.); (A.M.); (T.S.); (S.D.M.); (Z.B.); (P.V.); (D.F.W.)
- Department of Neuroscience, Zanvyl Krieger School of Arts and Sciences, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Zabecca Brinson
- Section of High Resolution Brain Positron Emission Tomography Imaging, Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (A.N.); (A.M.); (T.S.); (S.D.M.); (Z.B.); (P.V.); (D.F.W.)
| | - Pankhuri Vyas
- Section of High Resolution Brain Positron Emission Tomography Imaging, Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (A.N.); (A.M.); (T.S.); (S.D.M.); (Z.B.); (P.V.); (D.F.W.)
| | - John P. Seibyl
- Clinical Research, Institute for Neurodegenerative Disorders, New Haven, CT 06510, USA; (D.S.R.); (D.J.); (O.B.); (J.P.S.)
- Research Clinic, Invicro LLC, New Haven, CT 06510, USA
| | - Elizabeth M. Berry-Kravis
- Departments of Pediatrics, Neurological Sciences, and Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA;
| | - Dean F. Wong
- Section of High Resolution Brain Positron Emission Tomography Imaging, Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (A.N.); (A.M.); (T.S.); (S.D.M.); (Z.B.); (P.V.); (D.F.W.)
- Precision Radio-Theranostics Translational Laboratories, Mallinckrodt Institute of Radiology, School of Medicine, Washington University, Saint Louis, MO 63110, USA
| | - Dejan B. Budimirovic
- Department of Psychiatry and Behavioral Sciences-Child Psychiatry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA;
- Departments of Psychiatry and Neurogenetics, Kennedy Krieger Institute, Baltimore, MD 21205, USA
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159
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Li J, Jiang RY, Arendt KL, Hsu YT, Zhai SR, Chen L. Defective memory engram reactivation underlies impaired fear memory recall in Fragile X syndrome. eLife 2020; 9:61882. [PMID: 33215988 PMCID: PMC7679137 DOI: 10.7554/elife.61882] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 11/13/2020] [Indexed: 11/25/2022] Open
Abstract
Fragile X syndrome (FXS) is an X chromosome-linked disease associated with severe intellectual disabilities. Previous studies using the Fmr1 knockout (KO) mouse, an FXS mouse model, have attributed behavioral deficits to synaptic dysfunctions. However, how functional deficits at neural network level lead to abnormal behavioral learning remains unexplored. Here, we show that the efficacy of hippocampal engram reactivation is reduced in Fmr1 KO mice performing contextual fear memory recall. Experiencing an enriched environment (EE) prior to learning improved the engram reactivation efficacy and rescued memory recall in the Fmr1 KO mice. In addition, chemogenetically inhibiting EE-engaged neurons in CA1 reverses the rescue effect of EE on memory recall. Thus, our results suggest that inappropriate engram reactivation underlies cognitive deficits in FXS, and enriched environment may rescue cognitive deficits by improving network activation accuracy.
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Affiliation(s)
- Jie Li
- Department of Neurosurgery, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, United States
| | - Rena Y Jiang
- Department of Neurosurgery, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, United States
| | - Kristin L Arendt
- Department of Neurosurgery, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, United States
| | - Yu-Tien Hsu
- Department of Neurosurgery, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, United States
| | - Sophia R Zhai
- Department of Neurosurgery, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, United States
| | - Lu Chen
- Department of Neurosurgery, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, United States
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160
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Ryder PV, Fang J, Lerit DA. centrocortin RNA localization to centrosomes is regulated by FMRP and facilitates error-free mitosis. J Cell Biol 2020; 219:211538. [PMID: 33196763 PMCID: PMC7716377 DOI: 10.1083/jcb.202004101] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 09/12/2020] [Accepted: 10/14/2020] [Indexed: 02/06/2023] Open
Abstract
Centrosomes are microtubule-organizing centers required for error-free mitosis and embryonic development. The microtubule-nucleating activity of centrosomes is conferred by the pericentriolar material (PCM), a composite of numerous proteins subject to cell cycle-dependent oscillations in levels and organization. In diverse cell types, mRNAs localize to centrosomes and may contribute to changes in PCM abundance. Here, we investigate the regulation of mRNA localization to centrosomes in the rapidly cycling Drosophila melanogaster embryo. We find that RNA localization to centrosomes is regulated during the cell cycle and developmentally. We identify a novel role for the fragile-X mental retardation protein in the posttranscriptional regulation of a model centrosomal mRNA, centrocortin (cen). Further, mistargeting cen mRNA is sufficient to alter cognate protein localization to centrosomes and impair spindle morphogenesis and genome stability.
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161
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Feuge J, Scharkowski F, Michaelsen-Preusse K, Korte M. FMRP Modulates Activity-Dependent Spine Plasticity by Binding Cofilin1 mRNA and Regulating Localization and Local Translation. Cereb Cortex 2020; 29:5204-5216. [PMID: 30953439 DOI: 10.1093/cercor/bhz059] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 02/14/2019] [Accepted: 02/27/2019] [Indexed: 11/13/2022] Open
Abstract
Multiple variants of intellectual disability, e.g., the Fragile X Syndrome are associated with alterations in dendritic spine morphology, thereby pointing to dysregulated actin dynamics during development and processes of synaptic plasticity. Surprisingly, although the necessity of spine actin remodeling was demonstrated repeatedly, the importance and precise role of actin regulators is often undervalued. Here, we provide evidence that structural and functional plasticity are severely impaired after NMDAR-dependent LTP in the hippocampus of Fmr1 KO mice. We can link these defects to an aberrant activity-dependent regulation of Cofilin 1 (cof1) as activity-dependent modulations of local cof1 mRNA availability, local cof1 translation as well as total cof1 expression are impaired in the absence of FMRP. Finally, we can rescue activity-dependent structural plasticity in KO neurons by mimicking the regulation of cof1 observed in WT cells, thereby illustrating the potential of actin modulators to provide novel treatment strategies for the Fragile X Syndrome.
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Affiliation(s)
- Jonas Feuge
- Division of Cellular Neurobiology, Zoological Institute, TU Braunschweig, Germany
| | | | | | - Martin Korte
- Division of Cellular Neurobiology, Zoological Institute, TU Braunschweig, Germany.,Helmholtz Center for Infection Research, Research group Neuroinflammation and Neurodegeneration, Braunschweig, Germany
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162
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Khlghatyan J, Evstratova A, Bozoyan L, Chamberland S, Chatterjee D, Marakhovskaia A, Soares Silva T, Toth K, Mongrain V, Beaulieu J. Fxr1 regulates sleep and synaptic homeostasis. EMBO J 2020; 39:e103864. [PMID: 32893934 PMCID: PMC7604579 DOI: 10.15252/embj.2019103864] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 08/01/2020] [Accepted: 08/06/2020] [Indexed: 12/22/2022] Open
Abstract
The fragile X autosomal homolog 1 (Fxr1) is regulated by lithium and has been GWAS-associated with schizophrenia and insomnia. Homeostatic regulation of synaptic strength is essential for the maintenance of brain functions and involves both cell-autonomous and system-level processes such as sleep. We examined the contribution of Fxr1 to cell-autonomous homeostatic synaptic scaling and neuronal responses to sleep loss, using a combination of gene overexpression and Crispr/Cas9-mediated somatic knockouts to modulate gene expression. Our findings indicate that Fxr1 is downregulated during both scaling and sleep deprivation via a glycogen synthase kinase 3 beta (GSK3β)-dependent mechanism. In both conditions, downregulation of Fxr1 is essential for the homeostatic modulation of surface AMPA receptors and synaptic strength. Preventing the downregulation of Fxr1 during sleep deprivation results in altered EEG signatures. Furthermore, sequencing of neuronal translatomes revealed the contribution of Fxr1 to changes induced by sleep deprivation. These findings uncover a role of Fxr1 as a shared signaling hub between cell-autonomous homeostatic plasticity and system-level responses to sleep loss, with potential implications for neuropsychiatric illnesses and treatments.
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Affiliation(s)
- Jivan Khlghatyan
- Department of Pharmacology & ToxicologyUniversity of TorontoTorontoONCanada
- Department of Psychiatry and NeuroscienceFaculty of MedicineUniversité LavalQuébec‐CityQCCanada
- Present address:
Department of NeuroscienceNovartis Institutes for Biomedical ResearchCambridgeMAUSA
| | - Alesya Evstratova
- Department of Pharmacology & ToxicologyUniversity of TorontoTorontoONCanada
| | - Lusine Bozoyan
- Department of Pharmacology & ToxicologyUniversity of TorontoTorontoONCanada
| | - Simon Chamberland
- Department of Psychiatry and NeuroscienceFaculty of MedicineUniversité LavalQuébec‐CityQCCanada
- Present address:
NYU Neuroscience InstituteLangone Medical CenterNew York UniversityNew YorkNYUSA
| | | | | | - Tiago Soares Silva
- Department of Pharmacology & ToxicologyUniversity of TorontoTorontoONCanada
| | - Katalin Toth
- Department of Cellular and Molecular MedicineFaculty of MedicineUniversity of OttawaOttawaONCanada
| | - Valerie Mongrain
- Department of NeuroscienceUniversité de Montréal and Center for Advanced Research in Sleep MedicineHôpital du Sacré‐Coeur de Montréal (CIUSSS‐NIM)MontrealQCCanada
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163
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Arsenault J, Hooper AWM, Gholizadeh S, Kong T, Pacey LK, Koxhioni E, Niibori Y, Eubanks JH, Wang LY, Hampson DR. Interregulation between fragile X mental retardation protein and methyl CpG binding protein 2 in the mouse posterior cerebral cortex. Hum Mol Genet 2020; 29:3744-3756. [PMID: 33084871 PMCID: PMC7861017 DOI: 10.1093/hmg/ddaa226] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 09/28/2020] [Accepted: 10/12/2020] [Indexed: 12/31/2022] Open
Abstract
Several X-linked neurodevelopmental disorders including Rett syndrome, induced by mutations in the MECP2 gene, and fragile X syndrome (FXS), caused by mutations in the FMR1 gene, share autism-related features. The mRNA coding for methyl CpG binding protein 2 (MeCP2) has previously been identified as a substrate for the mRNA-binding protein, fragile X mental retardation protein (FMRP), which is silenced in FXS. Here, we report a homeostatic relationship between these two key regulators of gene expression in mouse models of FXS (Fmr1 Knockout (KO)) and Rett syndrome (MeCP2 KO). We found that the level of MeCP2 protein in the cerebral cortex was elevated in Fmr1 KO mice, whereas MeCP2 KO mice displayed reduced levels of FMRP, implicating interplay between the activities of MeCP2 and FMRP. Indeed, knockdown of MeCP2 with short hairpin RNAs led to a reduction of FMRP in mouse Neuro2A and in human HEK-293 cells, suggesting a reciprocal coupling in the expression level of these two regulatory proteins. Intra-cerebroventricular injection of an adeno-associated viral vector coding for FMRP led to a concomitant reduction in MeCP2 expression in vivo and partially corrected locomotor hyperactivity. Additionally, the level of MeCP2 in the posterior cortex correlated with the severity of the hyperactive phenotype in Fmr1 KO mice. These results demonstrate that MeCP2 and FMRP operate within a previously undefined homeostatic relationship. Our findings also suggest that MeCP2 overexpression in Fmr1 KO mouse posterior cerebral cortex may contribute to the fragile X locomotor hyperactivity phenotype.
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Affiliation(s)
- Jason Arsenault
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada.,Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.,Program in Neurosciences and Mental Health, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Alexander W M Hooper
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - Shervin Gholizadeh
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - Tian Kong
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.,Program in Neurosciences and Mental Health, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Laura K Pacey
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - Enea Koxhioni
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - Yosuke Niibori
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - James H Eubanks
- Division of Genetics and Development, Krembil Research Institute, University Health Network, Toronto, ON M5T 0S8, Canada.,Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.,Department of Surgery, Division of Neurosurgery, University of Toronto, Toronto, ON M5T 1P5, Canada
| | - Lu-Yang Wang
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.,Program in Neurosciences and Mental Health, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - David R Hampson
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada.,Department of Pharmacology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
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164
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The Fragile X Mental Retardation Protein Regulates RIPK1 and Colorectal Cancer Resistance to Necroptosis. Cell Mol Gastroenterol Hepatol 2020; 11:639-658. [PMID: 33091622 PMCID: PMC7806864 DOI: 10.1016/j.jcmgh.2020.10.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 10/15/2020] [Accepted: 10/16/2020] [Indexed: 12/23/2022]
Abstract
BACKGROUND & AIMS The fragile X mental retardation protein (FMRP) affects multiple steps of the mRNA metabolism during brain development and in different neoplastic processes. However, the contribution of FMRP in colon carcinogenesis has not been investigated. METHODS FMR1 mRNA transcript and FMRP protein expression were analyzed in human colon samples derived from patients with sporadic colorectal cancer (CRC) and healthy subjects. We used a well-established mouse model of sporadic CRC induced by azoxymethane to determine the possible role of FMRP in CRC. To address whether FMRP controls cancer cell survival, we analyzed cell death pathway in CRC human epithelial cell lines and in patient-derived colon cancer organoids in presence or absence of a specific FMR1 antisense oligonucleotide or siRNA. RESULTS We document a significant increase of FMRP in human CRC relative to non-tumor tissues. Next, using an inducible mouse model of CRC, we observed a reduction of colonic tumor incidence and size in the Fmr1 knockout mice. The abrogation of FMRP induced spontaneous cell death in human CRC cell lines activating the necroptotic pathway. Indeed, specific immunoprecipitation experiments on human cell lines and CRC samples indicated that FMRP binds receptor-interacting protein kinase 1 (RIPK1) mRNA, suggesting that FMRP acts as a regulator of necroptosis pathway through the surveillance of RIPK1 mRNA metabolism. Treatment of human CRC cell lines and patient-derived colon cancer organoids with the FMR1 antisense resulted in up-regulation of RIPK1. CONCLUSIONS Altogether, these data support a role for FMRP in controlling RIPK1 expression and necroptotic activation in CRC.
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165
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Li D, Choque-Olsson N, Jiao H, Norgren N, Jonsson U, Bölte S, Tammimies K. The influence of common polygenic risk and gene sets on social skills group training response in autism spectrum disorder. NPJ Genom Med 2020; 5:45. [PMID: 33083014 PMCID: PMC7550579 DOI: 10.1038/s41525-020-00152-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 09/15/2020] [Indexed: 12/14/2022] Open
Abstract
Social skills group training (SSGT) is a frequently used behavioral intervention in autism spectrum disorder (ASD), but the effects are moderate and heterogeneous. Here, we analyzed the effect of polygenic risk score (PRS) and common variants in gene sets on the intervention outcome. Participants from the largest randomized clinical trial of SSGT in ASD to date were selected (N = 188, 99 from SSGT, 89 from standard care) to calculate association between the outcomes in the SSGT trial and PRSs for ASD, attention-deficit hyperactivity disorder (ADHD), and educational attainment. In addition, specific gene sets were selected to evaluate their role on intervention outcomes. Among all participants in the trial, higher PRS for ADHD was associated with significant improvement in the outcome measure, the parental-rated Social Responsiveness Scale. The significant association was due to better outcomes in the standard care group for individuals with higher PRS for ADHD (post-intervention: β = −4.747, P = 0.0129; follow-up: β = −5.309, P = 0.0083). However, when contrasting the SSGT and standard care group, an inferior outcome in the SSGT group was associated with higher ADHD PRS at follow-up (β = 6.67, P = 0.016). Five gene sets within the synaptic category showed a nominal association with reduced response to interventions. We provide preliminary evidence that genetic liability calculated from common variants could influence the intervention outcomes. In the future, larger cohorts should be used to investigate how genetic contribution affects individual response to ASD interventions.
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Affiliation(s)
- Danyang Li
- Center of Neurodevelopmental Disorders (KIND), Centre for Psychiatry Research, Department of Women's and Children's Health, Karolinska Institutet, Stockholm County Council, Stockholm, Sweden.,Astrid Lindgren Children's Hospital, Karolinska University Hospital, Region Stockholm, Stockholm, Sweden.,Child and Adolescent Psychiatry, Stockholm Health Care Services, Region Stockholm, Stockholm, Sweden
| | - Nora Choque-Olsson
- Center of Neurodevelopmental Disorders (KIND), Centre for Psychiatry Research, Department of Women's and Children's Health, Karolinska Institutet, Stockholm County Council, Stockholm, Sweden.,Child and Adolescent Psychiatry, Stockholm Health Care Services, Region Stockholm, Stockholm, Sweden.,Center for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet and Stockholm Health Care Services, Region Stockholm, Stockholm, Sweden
| | - Hong Jiao
- Department of Biosciences and Nutrition, Karolinska Institutet, and Clinical Research Centre, Karolinska University Hospital, Huddinge, Sweden
| | - Nina Norgren
- Department of Molecular Biology, National Bioinformatics Infrastructure Sweden (NBIS), Science for Life Laboratory, Umeå University, 901 87 Umeå, Sweden
| | - Ulf Jonsson
- Center of Neurodevelopmental Disorders (KIND), Centre for Psychiatry Research, Department of Women's and Children's Health, Karolinska Institutet, Stockholm County Council, Stockholm, Sweden.,Child and Adolescent Psychiatry, Stockholm Health Care Services, Region Stockholm, Stockholm, Sweden.,Department of Neuroscience, Child and Adolescent Psychiatry, Uppsala University, Uppsala, Sweden
| | - Sven Bölte
- Center of Neurodevelopmental Disorders (KIND), Centre for Psychiatry Research, Department of Women's and Children's Health, Karolinska Institutet, Stockholm County Council, Stockholm, Sweden.,Child and Adolescent Psychiatry, Stockholm Health Care Services, Region Stockholm, Stockholm, Sweden.,Curtin Autism Research Group, School of Occupational Therapy, Social Work and Speech Pathology, Curtin University, Perth, WA Australia
| | - Kristiina Tammimies
- Center of Neurodevelopmental Disorders (KIND), Centre for Psychiatry Research, Department of Women's and Children's Health, Karolinska Institutet, Stockholm County Council, Stockholm, Sweden.,Astrid Lindgren Children's Hospital, Karolinska University Hospital, Region Stockholm, Stockholm, Sweden.,Child and Adolescent Psychiatry, Stockholm Health Care Services, Region Stockholm, Stockholm, Sweden
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166
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Clifton NE, Thomas KL, Wilkinson LS, Hall J, Trent S. FMRP and CYFIP1 at the Synapse and Their Role in Psychiatric Vulnerability. Complex Psychiatry 2020; 6:5-19. [PMID: 34883502 PMCID: PMC7673588 DOI: 10.1159/000506858] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 02/27/2020] [Indexed: 12/23/2022] Open
Abstract
There is increasing awareness of the role genetic risk variants have in mediating vulnerability to psychiatric disorders such as schizophrenia and autism. Many of these risk variants encode synaptic proteins, influencing biological pathways of the postsynaptic density and, ultimately, synaptic plasticity. Fragile-X mental retardation 1 (FMR1) and cytoplasmic fragile-X mental retardation protein (FMRP)-interacting protein 1 (CYFIP1) contain 2 such examples of highly penetrant risk variants and encode synaptic proteins with shared functional significance. In this review, we discuss the biological actions of FMRP and CYFIP1, including their regulation of (i) protein synthesis and specifically FMRP targets, (ii) dendritic and spine morphology, and (iii) forms of synaptic plasticity such as long-term depression. We draw upon a range of preclinical studies that have used genetic dosage models of FMR1 and CYFIP1 to determine their biological function. In parallel, we discuss how clinical studies of fragile X syndrome or 15q11.2 deletion patients have informed our understanding of FMRP and CYFIP1, and highlight the latest psychiatric genomic findings that continue to implicate FMRP and CYFIP1. Lastly, we assess the current limitations in our understanding of FMRP and CYFIP1 biology and how they must be addressed before mechanism-led therapeutic strategies can be developed for psychiatric disorders.
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Affiliation(s)
- Nicholas E. Clifton
- Neuroscience & Mental Health Research Institute, Cardiff University, Cardiff, United Kingdom
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Kerrie L. Thomas
- Neuroscience & Mental Health Research Institute, Cardiff University, Cardiff, United Kingdom
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Lawrence S. Wilkinson
- Neuroscience & Mental Health Research Institute, Cardiff University, Cardiff, United Kingdom
- School of Psychology, Cardiff University, Cardiff, United Kingdom
| | - Jeremy Hall
- Neuroscience & Mental Health Research Institute, Cardiff University, Cardiff, United Kingdom
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, United Kingdom
- Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Simon Trent
- Neuroscience & Mental Health Research Institute, Cardiff University, Cardiff, United Kingdom
- School of Life Sciences, Faculty of Natural Sciences, Keele University, Keele, United Kingdom
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167
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Budimirovic DB, Schlageter A, Filipovic-Sadic S, Protic DD, Bram E, Mahone EM, Nicholson K, Culp K, Javanmardi K, Kemppainen J, Hadd A, Sharp K, Adayev T, LaFauci G, Dobkin C, Zhou L, Brown WT, Berry-Kravis E, Kaufmann WE, Latham GJ. A Genotype-Phenotype Study of High-Resolution FMR1 Nucleic Acid and Protein Analyses in Fragile X Patients with Neurobehavioral Assessments. Brain Sci 2020; 10:E694. [PMID: 33008014 PMCID: PMC7601415 DOI: 10.3390/brainsci10100694] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/25/2020] [Accepted: 09/25/2020] [Indexed: 01/04/2023] Open
Abstract
Fragile X syndrome (FXS) is caused by silencing of the FMR1 gene, which encodes a protein with a critical role in synaptic plasticity. The molecular abnormality underlying FMR1 silencing, CGG repeat expansion, is well characterized; however, delineation of the pathway from DNA to RNA to protein using biosamples from well characterized patients with FXS is limited. Since FXS is a common and prototypical genetic disorder associated with intellectual disability (ID) and autism spectrum disorder (ASD), a comprehensive assessment of the FMR1 DNA-RNA-protein pathway and its correlations with the neurobehavioral phenotype is a priority. We applied nine sensitive and quantitative assays evaluating FMR1 DNA, RNA, and FMRP parameters to a reference set of cell lines representing the range of FMR1 expansions. We then used the most informative of these assays on blood and buccal specimens from cohorts of patients with different FMR1 expansions, with emphasis on those with FXS (N = 42 total, N = 31 with FMRP measurements). The group with FMRP data was also evaluated comprehensively in terms of its neurobehavioral profile, which allowed molecular-neurobehavioral correlations. FMR1 CGG repeat expansions, methylation levels, and FMRP levels, in both cell lines and blood samples, were consistent with findings of previous FMR1 genomic and protein studies. They also demonstrated a high level of agreement between blood and buccal specimens. These assays further corroborated previous reports of the relatively high prevalence of methylation mosaicism (slightly over 50% of the samples). Molecular-neurobehavioral correlations confirmed the inverse relationship between overall severity of the FXS phenotype and decrease in FMRP levels (N = 26 males, mean 4.2 ± 3.3 pg FMRP/ng genomic DNA). Other intriguing findings included a significant relationship between the diagnosis of FXS with ASD and two-fold lower levels of FMRP (mean 2.8 ± 1.3 pg FMRP/ng genomic DNA, p = 0.04), in particular observed in younger age- and IQ-adjusted males (mean age 6.9 ± 0.9 years with mean 3.2 ± 1.2 pg FMRP/ng genomic DNA, 57% with severe ASD), compared to FXS without ASD. Those with severe ID had even lower FMRP levels independent of ASD status in the male-only subset. The results underscore the link between FMR1 expansion, gene methylation, and FMRP deficit. The association between FMRP deficiency and overall severity of the neurobehavioral phenotype invites follow up studies in larger patient cohorts. They would be valuable to confirm and potentially extend our initial findings of the relationship between ASD and other neurobehavioral features and the magnitude of FMRP deficit. Molecular profiling of individuals with FXS may have important implications in research and clinical practice.
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Affiliation(s)
- Dejan B. Budimirovic
- Departments of Psychiatry and Neurogenetics, Fragile X Clinic, Kennedy Krieger Institute, Baltimore, MD 21205, USA;
- Department of Psychiatry & Behavioral Sciences-Child Psychiatry, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Annette Schlageter
- Asuragen, Inc., Austin, TX 78744, USA; (A.S.); (S.F.-S.); (E.B.); (K.N.); (K.C.); (K.J.); (J.K.); (A.H.)
| | - Stela Filipovic-Sadic
- Asuragen, Inc., Austin, TX 78744, USA; (A.S.); (S.F.-S.); (E.B.); (K.N.); (K.C.); (K.J.); (J.K.); (A.H.)
| | - Dragana D. Protic
- Departments of Psychiatry and Neurogenetics, Fragile X Clinic, Kennedy Krieger Institute, Baltimore, MD 21205, USA;
- School of Medicine, University of Belgrade, 11000 Belgrade, Serbia
| | - Eran Bram
- Asuragen, Inc., Austin, TX 78744, USA; (A.S.); (S.F.-S.); (E.B.); (K.N.); (K.C.); (K.J.); (J.K.); (A.H.)
| | - E. Mark Mahone
- Department of Neuropsychology, Kennedy Krieger Institute, Baltimore, MD 21205, USA;
| | - Kimberly Nicholson
- Asuragen, Inc., Austin, TX 78744, USA; (A.S.); (S.F.-S.); (E.B.); (K.N.); (K.C.); (K.J.); (J.K.); (A.H.)
| | - Kristen Culp
- Asuragen, Inc., Austin, TX 78744, USA; (A.S.); (S.F.-S.); (E.B.); (K.N.); (K.C.); (K.J.); (J.K.); (A.H.)
| | - Kamyab Javanmardi
- Asuragen, Inc., Austin, TX 78744, USA; (A.S.); (S.F.-S.); (E.B.); (K.N.); (K.C.); (K.J.); (J.K.); (A.H.)
| | - Jon Kemppainen
- Asuragen, Inc., Austin, TX 78744, USA; (A.S.); (S.F.-S.); (E.B.); (K.N.); (K.C.); (K.J.); (J.K.); (A.H.)
| | - Andrew Hadd
- Asuragen, Inc., Austin, TX 78744, USA; (A.S.); (S.F.-S.); (E.B.); (K.N.); (K.C.); (K.J.); (J.K.); (A.H.)
| | - Kevin Sharp
- Department of Pediatrics, Rush University Medical Center, Chicago, IL 60612, USA; (K.S.); (L.Z.); (E.B.-K.)
| | - Tatyana Adayev
- Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA; (T.A.); (G.L.); (C.D.); (W.T.B.)
| | - Giuseppe LaFauci
- Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA; (T.A.); (G.L.); (C.D.); (W.T.B.)
| | - Carl Dobkin
- Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA; (T.A.); (G.L.); (C.D.); (W.T.B.)
| | - Lili Zhou
- Department of Pediatrics, Rush University Medical Center, Chicago, IL 60612, USA; (K.S.); (L.Z.); (E.B.-K.)
| | - William Ted Brown
- Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA; (T.A.); (G.L.); (C.D.); (W.T.B.)
| | - Elizabeth Berry-Kravis
- Department of Pediatrics, Rush University Medical Center, Chicago, IL 60612, USA; (K.S.); (L.Z.); (E.B.-K.)
- Departments of Pediatrics, Neurological Sciences and Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA
| | - Walter E. Kaufmann
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA;
- Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Gary J. Latham
- Asuragen, Inc., Austin, TX 78744, USA; (A.S.); (S.F.-S.); (E.B.); (K.N.); (K.C.); (K.J.); (J.K.); (A.H.)
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168
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Athar YM, Joseph S. The Human Fragile X Mental Retardation Protein Inhibits the Elongation Step of Translation through Its RGG and C-Terminal Domains. Biochemistry 2020; 59:3813-3822. [PMID: 32945655 DOI: 10.1021/acs.biochem.0c00534] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The fragile X mental retardation protein (FMRP) is an RNA-binding protein that regulates the translation of numerous mRNAs in neurons. The precise mechanism of translational regulation by FMRP is unknown. Some studies have indicated that FMRP inhibits the initiation step of translation, whereas other studies have indicated that the elongation step of translation is inhibited by FMRP. To determine whether FMRP inhibits the initiation or the elongation step of protein synthesis, we investigated m7G-cap-dependent and IRES-driven, cap-independent translation of several reporter mRNAs in vitro. Our results show that FMRP inhibits both m7G-cap-dependent and cap-independent translation to similar degrees, indicating that the elongation step of translation is inhibited by FMRP. Additionally, we dissected the RNA-binding domains of hFMRP to determine the essential domains for inhibiting translation. We show that the RGG domain, together with the C-terminal domain (CTD), is sufficient to inhibit translation, while the KH domains do not inhibit mRNA translation. However, the region between the RGG domain and the KH2 domain may contribute as NT-hFMRP shows more potent inhibition than the RGG-CTD tail alone. Interestingly, we see a correlation between ribosome binding and translation inhibition, suggesting the RGG-CTD tail of hFMRP may anchor FMRP to the ribosome during translation inhibition.
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Affiliation(s)
- Youssi M Athar
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0314, United States
| | - Simpson Joseph
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0314, United States
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169
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A simple procedure for bacterial expression and purification of the fragile X protein family. Sci Rep 2020; 10:15858. [PMID: 32985615 PMCID: PMC7522082 DOI: 10.1038/s41598-020-72984-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 09/07/2020] [Indexed: 11/23/2022] Open
Abstract
The fragile X protein family consists of three RNA-binding proteins involved in translational regulation. Fragile X mental retardation protein (FMRP) is well-studied, as its loss leads to fragile X syndrome, a neurodevelopmental disorder which is the most prevalent form of inherited mental retardation and the primary monogenetic cause of autism. Fragile X related proteins 1 and 2 (FXR1P and FXR2P) are autosomal paralogs of FMRP that are involved in promoting muscle development and neural development, respectively. There is great interest in studying this family of proteins, yet researchers have faced much difficulty in expressing and purifying the full-length versions of these proteins in sufficient quantities. We have developed a simple, rapid, and inexpensive procedure that allows for the recombinant expression and purification of full-length human FMRP, FXR1P, and FXR2P from Escherichia coli in high yields, free of protein and nucleic acid contamination. In order to assess the proteins’ function after purification, we confirmed their binding to pseudoknot and G-quadruplex forming RNAs as well as their ability to regulate translation in vitro.
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170
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Russo A, DiAntonio A. Wnd/DLK Is a Critical Target of FMRP Responsible for Neurodevelopmental and Behavior Defects in the Drosophila Model of Fragile X Syndrome. Cell Rep 2020; 28:2581-2593.e5. [PMID: 31484070 PMCID: PMC6746345 DOI: 10.1016/j.celrep.2019.08.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 07/02/2019] [Accepted: 07/30/2019] [Indexed: 01/23/2023] Open
Abstract
Fragile X syndrome (FXS) is the leading heritable cause of intellectual disability and commonly co-occurs with autism spectrum disorder. Silencing of the Fmr1 gene leads to the absence of the protein product, fragile X mental retardation protein (FMRP), which represses translation of many target mRNAs. Excess translation of these targets is one cause of neuronal dysfunction in FXS. Utilizing the Drosophila model of FXS, we identified the mitogen-activated protein kinase kinase kinase (MAP3K) Wallenda/dual leucine zipper kinase (DLK) as a critical target of FMRP. dFMRP binds Wallenda mRNA and is required to limit Wallenda protein levels. In dFmr1 mutants, Wallenda signaling drives defects in synaptic development, neuronal morphology, and behavior. Pharmacological inhibition of Wallenda in larvae suppresses dFmr1 neurodevelopmental phenotypes, while adult administration prevents dFmr1 behavioral defects. We propose that in dFmr1 mutants chronic Wallenda/DLK signaling disrupts nervous system development and function and that inhibition of this kinase cascade might be a candidate therapeutic intervention for the treatment of FXS. Russo and DiAntonio identify a dysregulated MAPK signaling pathway in the fly model of fragile X syndrome. MAP3K Wnd/DLK drives dFmr1 mutant phenotypes, and pharmacological inhibition of Wnd/DLK prevents neural dysfunction in this model, thus highlighting a possible role for Wnd/DLK in the pathophysiology of fragile X syndrome.
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Affiliation(s)
- Alexandra Russo
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Aaron DiAntonio
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA; Needleman Center for Neurometabolism and Axonal Therapeutics, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA.
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171
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Luu S, Province H, Berry-Kravis E, Hagerman R, Hessl D, Vaidya D, Lozano R, Rosselot H, Erickson C, Kaufmann WE, Budimirovic DB. Response to Placebo in Fragile X Syndrome Clinical Trials: An Initial Analysis. Brain Sci 2020; 10:E629. [PMID: 32932789 PMCID: PMC7563217 DOI: 10.3390/brainsci10090629] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 09/03/2020] [Accepted: 09/07/2020] [Indexed: 12/16/2022] Open
Abstract
Fragile X syndrome (FXS) is the leading cause of inherited intellectual disability and autism spectrum disorder. Individuals with FXS often present with a wide range of cognitive deficits and problem behaviors. Educational, behavioral and pharmacological interventions are used to manage these and other complex issues affecting individuals with FXS. Despite the success of preclinical models and early-phase drug clinical studies in FXS, large-scale randomized-controlled trials have failed to meet primary endpoints. Currently, no targeted or disease-modifying treatments for FXS have received regulatory approval. Here, we examined the placebo response in FXS clinical trials conducted between 2006 and 2018. Specifically, we performed a meta-analysis of placebo-treated groups in eight double-blind, randomized controlled trials. Placebo groups demonstrated significant improvements on caregiver-rated efficacy endpoints, which were greater in adolescents and adults than in children. Among the latter measures, the Visual Analog Scale scores displayed the greatest improvements, whereas the positive effects on the Vineland-II Adaptive Behavior Composite and the Aberrant Behavior Checklist-Community/fragile X version were statistically significant in both children and adolescents/adults. Although the Clinical Global Impression scale Improvement appears to have exhibited a substantial placebo effect in multiple clinical trials in FXS, limited data availability for meta-analysis, prevented us from drawing conclusions. No placebo-related improvements were observed in performance-rated measures. These findings raise substantial concerns about placebo effects in outcome measures commonly used in the randomized-controlled trials in FXS and suggest several potential improvements in the study design and implementation of such trials. Considering the small number of trials available for this study, larger and more detailed follow up meta-analyses are needed. Meanwhile, efforts to improve the measurement properties of endpoints and rater training in drug trials in FXS should be prioritized.
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Affiliation(s)
- Skylar Luu
- Albany Medical Center, Albany Medical College, 43 New Scotland Ave, Albany, NY 12208, USA;
| | - Haley Province
- Feinberg School of Medicine, Northwestern University, 420 E. Superior St, Chicago, IL 60611, USA;
| | - Elizabeth Berry-Kravis
- Departments of Pediatrics, Neurological Sciences, Biochemistry, Rush University Medical Center, 1725 West Harrison, Suite 718, Chicago, IL 60612, USA;
| | - Randi Hagerman
- MIND Institute and the Department of Pediatrics, University of California Davis Medical Center, 2825 50th Street, Sacramento, CA 95817, USA;
| | - David Hessl
- MIND Institute and the Department of Psychiatry and Behavioral Sciences, University of California Davis Medical Center, 2825 50th Street, Sacramento, CA 95817, USA;
| | - Dhananjay Vaidya
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21218, USA;
| | - Reymundo Lozano
- Departments of Genetics and Genomic Sciences, Pediatrics and Psychiatry, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Pl, New York, NY 10029, USA;
| | | | - Craig Erickson
- Division of Child and Adolescent Psychiatry, Cincinnati Children’s Hospital Medical Center and the University of Cincinnati College of Medicine, 3333 Burnet Avenue, MLC 4002, Cincinnati, OH 45229, USA;
| | - Walter E. Kaufmann
- Boston Children’s Hospital and Department of Human Genetics, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, USA
| | - Dejan B. Budimirovic
- Kennedy Krieger Institute/The Johns Hopkins Medical Institutions, Department of Psychiatry & Behavioral Sciences-Child Psychiatry, the Johns Hopkins University School of Medicine, 1741 Ashland Ave, Rm 241, Baltimore, MD 21205, USA
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172
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Huebschman JL, Corona KS, Guo Y, Smith LN. The Fragile X Mental Retardation Protein Regulates Striatal Medium Spiny Neuron Synapse Density and Dendritic Spine Morphology. Front Mol Neurosci 2020; 13:161. [PMID: 33013316 PMCID: PMC7511717 DOI: 10.3389/fnmol.2020.00161] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 08/05/2020] [Indexed: 01/23/2023] Open
Abstract
The fragile X mental retardation protein (FMRP), an RNA-binding protein that mediates the transport, stability, and translation of hundreds of brain RNAs, is critically involved in regulating synaptic function. Loss of FMRP, as in fragile X syndrome (FXS), is a leading monogenic cause of autism and results in altered structural and functional synaptic plasticity, widely described in the hippocampus and cortex. Though FXS is associated with hyperactivity, impaired social interaction, and the development of repetitive or stereotyped behaviors, all of which are influenced by striatal activity, few studies have investigated the function of FMRP here. Utilizing a cortical-striatal co-culture model, we find that striatal medium spiny neurons (MSNs) lacking FMRP fail to make normal increases in PSD95 expression over a short time period and have significant deficits in dendritic spine density and colocalized synaptic puncta at the later measured time point compared to wildtype (WT) MSNs. Acute expression of wtFMRP plasmid in Fmr1 KO co-cultures results in contrasting outcomes for these measures on MSNs at the more mature time point, reducing spine density across multiple spine types but making no significant changes in colocalized puncta. FMRP’s KH2 and RGG RNA-binding domains are required for normal elimination of PSD95, and interruption of these domains slightly favors elimination of immature spine types. Further, KH2 is required for normal levels of colocalized puncta. Our data are largely consistent with a basal role for FMRP and its RNA-binding domains in striatal synapse stabilization on developing MSNs, and in light of previous findings, suggest distinct regional and/or cell type-specific roles for FMRP in regulating synapse structure.
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Affiliation(s)
- Jessica L Huebschman
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center, Bryan, TX, United States.,Texas A&M Institute for Neuroscience, Texas A&M University, College Station, TX, United States
| | - Kitzia S Corona
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Yuhong Guo
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Laura N Smith
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center, Bryan, TX, United States.,Texas A&M Institute for Neuroscience, Texas A&M University, College Station, TX, United States
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173
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Turner-Bridger B, Caterino C, Cioni JM. Molecular mechanisms behind mRNA localization in axons. Open Biol 2020; 10:200177. [PMID: 32961072 PMCID: PMC7536069 DOI: 10.1098/rsob.200177] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 09/01/2020] [Indexed: 12/12/2022] Open
Abstract
Messenger RNA (mRNA) localization allows spatiotemporal regulation of the proteome at the subcellular level. This is observed in the axons of neurons, where mRNA localization is involved in regulating neuronal development and function by orchestrating rapid adaptive responses to extracellular cues and the maintenance of axonal homeostasis through local translation. Here, we provide an overview of the key findings that have broadened our knowledge regarding how specific mRNAs are trafficked and localize to axons. In particular, we review transcriptomic studies investigating mRNA content in axons and the molecular principles underpinning how these mRNAs arrived there, including cis-acting mRNA sequences and trans-acting proteins playing a role. Further, we discuss evidence that links defective axonal mRNA localization and pathological outcomes.
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Affiliation(s)
- Benita Turner-Bridger
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, UK
| | - Cinzia Caterino
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milan, Italy
| | - Jean-Michel Cioni
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milan, Italy
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174
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Abstract
RNA-binding proteins are a critical group of multifunctional proteins that precisely regulate all aspects of gene expression, from alternative splicing to mRNA trafficking, stability, and translation. Converging evidence highlights aberrant RNA metabolism as a common pathogenic mechanism in several neurodevelopmental and neurodegenerative diseases. However, dysregulation of disease-linked RNA-binding proteins results in widespread, often tissue-specific and/or pleiotropic effects on the transcriptome, making it challenging to determine the underlying cellular and molecular mechanisms that contribute to disease pathogenesis. Understanding how splicing misregulation as well as alterations of mRNA stability and localization impact the activity and function of neuronal proteins is fundamental to addressing neurodevelopmental defects and synaptic dysfunction in disease. Here we highlight recent exciting studies that use high-throughput transcriptomic analysis and advanced genetic, cell biological, and imaging approaches to dissect the role of disease-linked RNA-binding proteins on different RNA processing steps. We focus specifically on efforts to elucidate the functional consequences of aberrant RNA processing on neuronal morphology, synaptic activity and plasticity in development and disease. We also consider new areas of investigation that will elucidate the molecular mechanisms RNA-binding proteins use to achieve spatiotemporal control of gene expression for neuronal homeostasis and plasticity.
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Affiliation(s)
- Shavanie Prashad
- Department of Pathology, Yale University School of Medicine, Yale University, New Haven, CT, USA.,Experimental Pathology Graduate Group, Yale University School of Medicine, Yale University, New Haven, CT, USA
| | - Pallavi P Gopal
- Department of Pathology, Yale University School of Medicine, Yale University, New Haven, CT, USA.,Experimental Pathology Graduate Group, Yale University School of Medicine, Yale University, New Haven, CT, USA.,Yale Center for RNA Science and Medicine, Yale University School of Medicine, Yale University, New Haven, CT, USA
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175
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Hooshmandi M, Wong C, Khoutorsky A. Dysregulation of translational control signaling in autism spectrum disorders. Cell Signal 2020; 75:109746. [PMID: 32858122 DOI: 10.1016/j.cellsig.2020.109746] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/17/2020] [Accepted: 08/18/2020] [Indexed: 11/27/2022]
Abstract
Deviations from the optimal level of mRNA translation are linked to disorders with high rates of autism. Loss of function mutations in genes encoding translational repressors such as PTEN, TSC1, TSC2, and FMRP are associated with autism spectrum disorders (ASDs) in humans and their deletion in animals recapitulates many ASD-like phenotypes. Importantly, the activity of key translational control signaling pathways such as PI3K-mTORC1 and ERK is frequently dysregulated in autistic patients and animal models and their normalization rescues many abnormal phenotypes, suggesting a causal relationship. Mutations in several genes encoding proteins not directly involved in translational control have also been shown to mediate ASD phenotypes via altered signaling upstream of translation. This raises the possibility that the dysregulation of translational control signaling is a converging mechanism not only in familiar but also in sporadic forms of autism. Here, we overview the current knowledge on translational signaling in ASD and highlight how correcting the activity of key pathways upstream of translation reverses distinct ASD-like phenotypes.
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Affiliation(s)
- Mehdi Hooshmandi
- Department of Anesthesia, Faculty of Dentistry, McGill University, Montreal, QC H3A 0G1, Canada
| | - Calvin Wong
- Department of Anesthesia, Faculty of Dentistry, McGill University, Montreal, QC H3A 0G1, Canada
| | - Arkady Khoutorsky
- Department of Anesthesia, Faculty of Dentistry, McGill University, Montreal, QC H3A 0G1, Canada.
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176
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Tang R, Yu Q. The significance of FMR1 CGG repeats in Chinese women with premature ovarian insufficiency and diminished ovarian reserve. Reprod Biol Endocrinol 2020; 18:82. [PMID: 32787884 PMCID: PMC7422563 DOI: 10.1186/s12958-020-00645-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 08/10/2020] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Previous studies have shown that there is an association between FMR1 CGG repeats and ovarian dysfunction. The aim of this study is to assess the association between the number of CGG repeats in FMR1 in Chinese patients with premature ovarian insufficiency (POI) and diminished ovarian reserve (DOR). METHODS This is a cross-sectional, case-control study, which enrolled 124 patients with POI, 57 patients with DOR and 111 normal menopausal controls. The demographic details along with other clinical data were recorded. The FMR1 CGG repeats were analyzed by polymerase chain reaction and microfluidic capillary electrophoresis. RESULTS We could detect two premutation carriers in the POI group (1.6%) and one in the control group (0.9%). No premutation carriers were identified in the DOR group. The frequency of FMR1 premutations was not different between POI or DOR and controls. The most common CGG repeat was 29 and 30, and the repeat length for allele 2 had a secondary peak around 36-39 repeats. The CGG repeats were divided into groups of five consecutive values, and the distribution of allele 1 in the POI group was different from that in the control group (P < 0.001). No statistically significant differences were found for allele 1 between DOR group vs. controls, and for allele 2 between three groups (P > 0.05). CONCLUSIONS The study shows that the frequency of FMR1 premutations is relatively low (1.6%) in Chinese women with POI. The distribution of allele 1 CGG repeat in patients with POI showed difference from that in healthy women.
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Affiliation(s)
- Ruiyi Tang
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, No 1 Shuaifuyuan, Wangfujing, Beijing, 100730, DongCheng District, China
| | - Qi Yu
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, No 1 Shuaifuyuan, Wangfujing, Beijing, 100730, DongCheng District, China.
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177
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Agote-Aran A, Schmucker S, Jerabkova K, Jmel Boyer I, Berto A, Pacini L, Ronchi P, Kleiss C, Guerard L, Schwab Y, Moine H, Mandel JL, Jacquemont S, Bagni C, Sumara I. Spatial control of nucleoporin condensation by fragile X-related proteins. EMBO J 2020; 39:e104467. [PMID: 32706158 PMCID: PMC7560220 DOI: 10.15252/embj.2020104467] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 06/16/2020] [Accepted: 06/22/2020] [Indexed: 01/14/2023] Open
Abstract
Nucleoporins (Nups) build highly organized nuclear pore complexes (NPCs) at the nuclear envelope (NE). Several Nups assemble into a sieve‐like hydrogel within the central channel of the NPCs. In the cytoplasm, the soluble Nups exist, but how their assembly is restricted to the NE is currently unknown. Here, we show that fragile X‐related protein 1 (FXR1) can interact with several Nups and facilitate their localization to the NE during interphase through a microtubule‐dependent mechanism. Downregulation of FXR1 or closely related orthologs FXR2 and fragile X mental retardation protein (FMRP) leads to the accumulation of cytoplasmic Nup condensates. Likewise, models of fragile X syndrome (FXS), characterized by a loss of FMRP, accumulate Nup granules. The Nup granule‐containing cells show defects in protein export, nuclear morphology and cell cycle progression. Our results reveal an unexpected role for the FXR protein family in the spatial regulation of nucleoporin condensation.
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Affiliation(s)
- Arantxa Agote-Aran
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique UMR 7104, Strasbourg, France.,Institut National de la Santé et de la Recherche Médicale U964, Strasbourg, France.,Université de Strasbourg, Strasbourg, France
| | - Stephane Schmucker
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique UMR 7104, Strasbourg, France.,Institut National de la Santé et de la Recherche Médicale U964, Strasbourg, France.,Université de Strasbourg, Strasbourg, France
| | - Katerina Jerabkova
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique UMR 7104, Strasbourg, France.,Institut National de la Santé et de la Recherche Médicale U964, Strasbourg, France.,Université de Strasbourg, Strasbourg, France
| | - Inès Jmel Boyer
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique UMR 7104, Strasbourg, France.,Institut National de la Santé et de la Recherche Médicale U964, Strasbourg, France.,Université de Strasbourg, Strasbourg, France
| | - Alessandro Berto
- Institut Jacques Monod, CNRS UMR7592-Université Paris Diderot, Sorbonne Paris Cité, Paris, France.,Ecole Doctorale SDSV, Université Paris Sud, Orsay, France
| | - Laura Pacini
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
| | - Paolo Ronchi
- European Molecular Biology Laboratory, Electron Microscopy Core Facility, Heidelberg, Germany
| | - Charlotte Kleiss
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique UMR 7104, Strasbourg, France.,Institut National de la Santé et de la Recherche Médicale U964, Strasbourg, France.,Université de Strasbourg, Strasbourg, France
| | - Laurent Guerard
- Imaging Core Facility, Biozentrum, University of Basel, Basel, Switzerland
| | - Yannick Schwab
- European Molecular Biology Laboratory, Electron Microscopy Core Facility, Heidelberg, Germany.,European Molecular Biology Laboratory, European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, Heidelberg, Germany
| | - Hervé Moine
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique UMR 7104, Strasbourg, France.,Institut National de la Santé et de la Recherche Médicale U964, Strasbourg, France.,Université de Strasbourg, Strasbourg, France
| | - Jean-Louis Mandel
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique UMR 7104, Strasbourg, France.,Institut National de la Santé et de la Recherche Médicale U964, Strasbourg, France.,Université de Strasbourg, Strasbourg, France
| | - Sebastien Jacquemont
- Service de Génétique Médicale, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Lausanne, Switzerland.,CHU Sainte-Justine Research Centre, University of Montreal, Montreal, QC, Canada
| | - Claudia Bagni
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy.,Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland
| | - Izabela Sumara
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique UMR 7104, Strasbourg, France.,Institut National de la Santé et de la Recherche Médicale U964, Strasbourg, France.,Université de Strasbourg, Strasbourg, France
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178
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Maurin T, Melancia F, Jarjat M, Castro L, Costa L, Delhaye S, Khayachi A, Castagnola S, Mota E, Di Giorgio A, Servadio M, Drozd M, Poupon G, Schiavi S, Sardone L, Azoulay S, Ciranna L, Martin S, Vincent P, Trezza V, Bardoni B. Involvement of Phosphodiesterase 2A Activity in the Pathophysiology of Fragile X Syndrome. Cereb Cortex 2020; 29:3241-3252. [PMID: 30137253 DOI: 10.1093/cercor/bhy192] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 07/12/2018] [Accepted: 07/20/2018] [Indexed: 12/26/2022] Open
Abstract
The fragile X mental retardation protein (FMRP) is an RNA-binding protein involved in translational regulation of mRNAs that play key roles in synaptic morphology and plasticity. The functional absence of FMRP causes the fragile X syndrome (FXS), the most common form of inherited intellectual disability and the most common monogenic cause of autism. No effective treatment is available for FXS. We recently identified the Phosphodiesterase 2A (Pde2a) mRNA as a prominent target of FMRP. PDE2A enzymatic activity is increased in the brain of Fmr1-KO mice, a recognized model of FXS, leading to decreased levels of cAMP and cGMP. Here, we pharmacologically inhibited PDE2A in Fmr1-KO mice and observed a rescue both of the maturity of dendritic spines and of the exaggerated hippocampal mGluR-dependent long-term depression. Remarkably, PDE2A blockade rescued the social and communicative deficits of both mouse and rat Fmr1-KO animals. Importantly, chronic inhibition of PDE2A in newborn Fmr1-KO mice followed by a washout interval, resulted in the rescue of the altered social behavior observed in adolescent mice. Altogether, these results reveal the key role of PDE2A in the physiopathology of FXS and suggest that its pharmacological inhibition represents a novel therapeutic approach for FXS.
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Affiliation(s)
- Thomas Maurin
- Université Côte d'Azur, CNRS, IPMC, Valbonne, France.,CNRS LIA «Neogenex», Valbonne, France
| | | | - Marielle Jarjat
- Université Côte d'Azur, CNRS, IPMC, Valbonne, France.,CNRS LIA «Neogenex», Valbonne, France
| | - Liliana Castro
- Sorbonne Université, CNRS, Biological Adaptation and Ageing, Paris, France.,Labex BioPsy, Paris, France
| | - Lara Costa
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Sébastien Delhaye
- Université Côte d'Azur, CNRS, IPMC, Valbonne, France.,CNRS LIA «Neogenex», Valbonne, France
| | | | - Sara Castagnola
- Université Côte d'Azur, CNRS, IPMC, Valbonne, France.,CNRS LIA «Neogenex», Valbonne, France
| | - Elia Mota
- Sorbonne Université, CNRS, Biological Adaptation and Ageing, Paris, France.,Labex BioPsy, Paris, France
| | - Audrey Di Giorgio
- Université Côte d'Azur, CNRS, Institut de Chimie de Nice, Nice, France
| | | | - Malgorzata Drozd
- Université Côte d'Azur, CNRS, IPMC, Valbonne, France.,CNRS LIA «Neogenex», Valbonne, France
| | | | - Sara Schiavi
- Department of Sciences, Università RomaTre, Roma, Italy
| | - Lara Sardone
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Stéphane Azoulay
- Université Côte d'Azur, CNRS, Institut de Chimie de Nice, Nice, France
| | - Lucia Ciranna
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Stéphane Martin
- Université Côte d'Azur, INSERM, CNRS, IPMC, Valbonne, France
| | - Pierre Vincent
- Sorbonne Université, CNRS, Biological Adaptation and Ageing, Paris, France.,Labex BioPsy, Paris, France
| | | | - Barbara Bardoni
- CNRS LIA «Neogenex», Valbonne, France.,Université Côte d'Azur, INSERM, CNRS, IPMC, Valbonne, France
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179
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Westmark CJ, Maloney B, Alisch RS, Sokol DK, Lahiri DK. FMRP Regulates the Nuclear Export of Adam9 and Psen1 mRNAs: Secondary Analysis of an N 6-Methyladenosine Dataset. Sci Rep 2020; 10:10781. [PMID: 32612155 PMCID: PMC7329887 DOI: 10.1038/s41598-020-66394-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 05/19/2020] [Indexed: 01/19/2023] Open
Abstract
Fragile X mental retardation protein (FMRP) binds to and regulates the translation of amyloid-β protein precursor (App) mRNA, but the detailed mechanism remains to be determined. Differential methylation of App mRNA could underlie FMRP binding, message localization and translation efficiency. We sought to determine the role of FMRP and N6-methyladeonsine (m6A) on nuclear export of App mRNA. We utilized the m6A dataset by Hsu and colleagues to identify m6A sites in App mRNA and to determine if the abundance of message in the cytoplasm relative to the nucleus is altered in Fmr1 knockout mouse brain cortex. Given that processing of APP to Aβ and soluble APP alpha (sAPPα) contributes to disease phenotypes, we also investigated whether Fmr1KO associates with nuclear export of the mRNAs for APP protein processing enzymes, including β-site amyloid cleaving enzyme (Bace1), A disintegrin and metalloproteinases (Adams), and presenilins (Psen). Fmr1KO did not alter the nuclear/cytoplasmic abundance of App mRNA. Of 36 validated FMRP targets, 35 messages contained m6A peaks but only Agap2 mRNA was selectively enriched in Fmr1KO nucleus. The abundance of the APP processing enzymes Adam9 and Psen1 mRNA, which code for a minor alpha-secretase and gamma-secretase, respectively, were selectively enriched in wild type cytoplasm.
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Affiliation(s)
- Cara J Westmark
- Department of Neurology, University of Wisconsin-Madison, Madison, WI, USA.
| | - Bryan Maloney
- Department of Psychiatry, Indiana Alzheimer Disease Center, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Reid S Alisch
- Department of Neurological Surgery, University of Wisconsin-Madison, Madison, WI, USA
| | - Deborah K Sokol
- Department of Neurology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Debomoy K Lahiri
- Department of Psychiatry, Indiana Alzheimer Disease Center, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA. .,Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA.
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180
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Lai A, Valdez-Sinon AN, Bassell GJ. Regulation of RNA granules by FMRP and implications for neurological diseases. Traffic 2020; 21:454-462. [PMID: 32374065 PMCID: PMC7377269 DOI: 10.1111/tra.12733] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 04/29/2020] [Accepted: 04/29/2020] [Indexed: 12/14/2022]
Abstract
RNA granule formation, which can be regulated by RNA-binding proteins (RBPs) such as fragile X mental retardation protein (FMRP), acts as a mechanism to control both the repression and subcellular localization of translation. Dysregulated assembly of RNA granules has been implicated in multiple neurological disorders, such as amyotrophic lateral sclerosis. Thus, it is crucial to understand the cellular pathways impinging upon granule assembly or disassembly. The goal of this review is to summarize recent advances in our understanding of the role of the RBP, FMRP, in translational repression underlying RNA granule dynamics, mRNA transport and localized. We summarize the known mechanisms of translational regulation by FMRP, the role of FMRP in RNA transport granules, fragile X granules and stress granules. Focusing on the emerging link between FMRP and stress granules, we propose a model for how hyperassembly and hypoassembly of RNA granules may contribute to neurological diseases.
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Affiliation(s)
- Austin Lai
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - Gary J Bassell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, USA
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181
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Modeling Neurodevelopmental Deficits in Tuberous Sclerosis Complex with Stem Cell Derived Neural Precursors and Neurons. ADVANCES IN NEUROBIOLOGY 2020. [PMID: 32578142 DOI: 10.1007/978-3-030-45493-7_1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
Tuberous sclerosis complex (TSC) is a rare genetic disorder that is caused by mutations in TSC1 or TSC2. TSC is a multi-organ disorder characterized by development of non-malignant cellular overgrowths, called hamartomas, in different organs of the body. TSC is also characterized as a neurodevelopmental disorder presenting with epilepsy and autism, and formation of cortical malformations ("tubers"), subependymal giant cell astrocytomas (SEGAs), and subependymal nodules (SENs) in the patient's brain. In this chapter, we are going to give an overview of neural stem cell and neuronal development in TSC. In addition, we will also describe previously developed animal models of TSC that display seizures, autistic-like behaviors, and neuronal cell abnormalities in vivo, and we will compare them to disease phenotypes detected with human stem cell derived neuronal cells in vitro. We will describe the effects of TSC-mutations in different neural cell subtypes, and discuss the mitochondrial function, autophagy, and synaptic development and functional deficits in the neurons. Finally, we will review utilization of these human TSC-patient derived neuronal models for drug screening to develop new treatment options for the neurological phenotypes seen in TSC patients.
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182
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Taha MS, Haghighi F, Stefanski A, Nakhaei-Rad S, Kazemein Jasemi NS, Al Kabbani MA, Görg B, Fujii M, Lang PA, Häussinger D, Piekorz RP, Stühler K, Ahmadian MR. Novel FMRP interaction networks linked to cellular stress. FEBS J 2020; 288:837-860. [PMID: 32525608 DOI: 10.1111/febs.15443] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 04/09/2020] [Accepted: 06/03/2020] [Indexed: 12/12/2022]
Abstract
Silencing of the fragile X mental retardation 1 (FMR1) gene and consequently lack of synthesis of FMR protein (FMRP) are associated with fragile X syndrome, which is one of the most prevalent inherited intellectual disabilities, with additional roles in increased viral infection, liver disease, and reduced cancer risk. FMRP plays critical roles in chromatin dynamics, RNA binding, mRNA transport, and mRNA translation. However, the underlying molecular mechanisms, including the (sub)cellular FMRP protein networks, remain elusive. Here, we employed affinity pull-down and quantitative LC-MS/MS analyses with FMRP. We identified known and novel candidate FMRP-binding proteins as well as protein complexes. FMRP interacted with 180 proteins, 28 of which interacted with its N terminus. Interaction with the C terminus of FMRP was observed for 102 proteins, and 48 proteins interacted with both termini. This FMRP interactome comprises known FMRP-binding proteins, including the ribosomal proteins FXR1P, NUFIP2, Caprin-1, and numerous novel FMRP candidate interacting proteins that localize to different subcellular compartments, including CARF, LARP1, LEO1, NOG2, G3BP1, NONO, NPM1, SKIP, SND1, SQSTM1, and TRIM28. Our data considerably expand the protein and RNA interaction networks of FMRP, which thereby suggest that, in addition to its known functions, FMRP participates in transcription, RNA metabolism, ribonucleoprotein stress granule formation, translation, DNA damage response, chromatin dynamics, cell cycle regulation, ribosome biogenesis, miRNA biogenesis, and mitochondrial organization. Thus, FMRP seems associated with multiple cellular processes both under normal and cell stress conditions in neuronal as well as non-neuronal cell types, as exemplified by its role in the formation of stress granules.
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Affiliation(s)
- Mohamed S Taha
- Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich Heine University, Düsseldorf, Germany.,Research on Children with Special Needs Department, Medical Research Branch, National Research Centre, Cairo, Egypt
| | - Fereshteh Haghighi
- Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich Heine University, Düsseldorf, Germany
| | - Anja Stefanski
- Molecular Proteomics Laboratory, Heinrich Heine-University, Düsseldorf, Germany
| | - Saeideh Nakhaei-Rad
- Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich Heine University, Düsseldorf, Germany
| | - Neda S Kazemein Jasemi
- Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich Heine University, Düsseldorf, Germany
| | - Mohamed Aghyad Al Kabbani
- Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich Heine University, Düsseldorf, Germany
| | - Boris Görg
- Clinic of Gastroenterology, Hepatology and Infectious Diseases, Medical Faculty of the Heinrich Heine-University, Düsseldorf, Germany
| | - Masahiro Fujii
- Division of Virology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Phillip A Lang
- Department of Molecular Medicine II, Medical Faculty, Heinrich Heine-University, Düsseldorf, Germany
| | - Dieter Häussinger
- Clinic of Gastroenterology, Hepatology and Infectious Diseases, Medical Faculty of the Heinrich Heine-University, Düsseldorf, Germany
| | - Roland P Piekorz
- Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich Heine University, Düsseldorf, Germany
| | - Kai Stühler
- Molecular Proteomics Laboratory, Heinrich Heine-University, Düsseldorf, Germany
| | - Mohammad R Ahmadian
- Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich Heine University, Düsseldorf, Germany
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183
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Schmidt KC, Loutaev I, Quezado Z, Sheeler C, Smith CB. Regional rates of brain protein synthesis are unaltered in dexmedetomidine sedated young men with fragile X syndrome: A L-[1- 11C]leucine PET study. Neurobiol Dis 2020; 143:104978. [PMID: 32569795 PMCID: PMC7425798 DOI: 10.1016/j.nbd.2020.104978] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/01/2020] [Accepted: 06/15/2020] [Indexed: 02/06/2023] Open
Abstract
Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability. Fragile X mental retardation protein (FMRP), a putative translation suppressor, is absent or significantly reduced in FXS. One prevailing hypothesis is that rates of protein synthesis are increased by the absence of this regulatory protein. In accord with this hypothesis, we have previously reported increased rates of cerebral protein synthesis (rCPS) in the Fmr1 knockout mouse model of FXS and others have reported similar effects in hippocampal slices. To address the hypothesis in human subjects, we applied the L[1-11C]leucine PET method to measure rCPS in adults with FXS and healthy controls. All subjects were males between the ages of 18 and 24 years and free of psychotropic medication. As most fragile X participants were not able to undergo the PET study awake, we used dexmedetomidine for sedation during the imaging studies. We found no differences between rCPS measured during dexmedetomidine-sedation and the awake state in ten healthy controls. In the comparison of rCPS in dexmedetomidine-sedated fragile X participants (n = 9) and healthy controls (n = 14) we found no statistically significant differences. Our results from in vivo measurements in human brain do not support the hypothesis that rCPS are elevated due to the absence of FMRP. This hypothesis is based on findings in animal models and in vitro measurements in human peripheral cells. The absence of a translation suppressor may produce a more complex response in pathways regulating translation than previously thought. We may need to revise our working hypotheses regarding FXS and our thinking about potential therapeutics.
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Affiliation(s)
- Kathleen C Schmidt
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, 10 Center Drive, Room 2D54, Bethesda, MD 20892-1298, United States of America
| | - Inna Loutaev
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, 10 Center Drive, Room 2D54, Bethesda, MD 20892-1298, United States of America
| | - Zenaide Quezado
- Department of Perioperative Medicine, Clinical Center, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892-1512, United States of America
| | - Carrie Sheeler
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, 10 Center Drive, Room 2D54, Bethesda, MD 20892-1298, United States of America
| | - Carolyn Beebe Smith
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, 10 Center Drive, Room 2D54, Bethesda, MD 20892-1298, United States of America.
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184
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Telias M. Pharmacological Treatments for Fragile X Syndrome Based on Synaptic Dysfunction. Curr Pharm Des 2020; 25:4394-4404. [PMID: 31682210 DOI: 10.2174/1381612825666191102165206] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 10/31/2019] [Indexed: 12/29/2022]
Abstract
BACKGROUND Fragile X syndrome (FXS) is the most common form of monogenic hereditary cognitive impairment, including intellectual disability, autism, hyperactivity, and epilepsy. METHODS This article reviews the literature pertaining to the role of synaptic dysfunction in FXS. RESULTS In FXS, synaptic dysfunction alters the excitation-inhibition ratio, dysregulating molecular and cellular processes underlying cognition, learning, memory, and social behavior. Decades of research have yielded important hypotheses that could explain, at least in part, the development of these neurological disorders in FXS patients. However, the main goal of translating lab research in animal models to pharmacological treatments in the clinic has been so far largely unsuccessful, leaving FXS a still incurable disease. CONCLUSION In this concise review, we summarize and analyze the main hypotheses proposed to explain synaptic dysregulation in FXS, by reviewing the scientific evidence that led to pharmaceutical clinical trials and their outcome.
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Affiliation(s)
- Michael Telias
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, United States
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185
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Alzheimer's disease-related dysregulation of mRNA translation causes key pathological features with ageing. Transl Psychiatry 2020; 10:192. [PMID: 32546772 PMCID: PMC7297996 DOI: 10.1038/s41398-020-00882-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 05/04/2020] [Accepted: 05/07/2020] [Indexed: 11/20/2022] Open
Abstract
Alzheimer's disease (AD) is characterised by Aβ and tau pathology as well as synaptic degeneration, which correlates best with cognitive impairment. Previous work suggested that this pathological complexity may result from changes in mRNA translation. Here, we studied whether mRNA translation and its underlying signalling are altered in an early model of AD, and whether modelling this deficiency in mice causes pathological features with ageing. Using an unbiased screen, we show that exposure of primary neurons to nanomolar amounts of Aβ increases FMRP-regulated protein synthesis. This selective regulation of mRNA translation is dependent on a signalling cascade involving MAPK-interacting kinase 1 (Mnk1) and the eukaryotic initiation factor 4E (eIF4E), and ultimately results in reduction of CYFIP2, an FMRP-binding protein. Modelling this CYFIP2 reduction in mice, we find age-dependent Aβ accumulation in the thalamus, development of tau pathology in entorhinal cortex and hippocampus, as well as gliosis and synapse loss in the hippocampus, together with deficits in memory formation. Therefore, we conclude that early stages of AD involve increased translation of specific CYFIP2/FMRP-regulated transcripts. Since reducing endogenous CYFIP2 expression is sufficient to cause key features of AD with ageing in mice, we suggest that prolonged activation of this pathway is a primary step toward AD pathology, highlighting a novel direction for therapeutic targeting.
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186
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Goering R, Hudish LI, Guzman BB, Raj N, Bassell GJ, Russ HA, Dominguez D, Taliaferro JM. FMRP promotes RNA localization to neuronal projections through interactions between its RGG domain and G-quadruplex RNA sequences. eLife 2020; 9:e52621. [PMID: 32510328 PMCID: PMC7279889 DOI: 10.7554/elife.52621] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 05/15/2020] [Indexed: 12/15/2022] Open
Abstract
The sorting of RNA molecules to subcellular locations facilitates the activity of spatially restricted processes. We have analyzed subcellular transcriptomes of FMRP-null mouse neuronal cells to identify transcripts that depend on FMRP for efficient transport to neurites. We found that these transcripts contain an enrichment of G-quadruplex sequences in their 3' UTRs, suggesting that FMRP recognizes them to promote RNA localization. We observed similar results in neurons derived from Fragile X Syndrome patients. We identified the RGG domain of FMRP as important for binding G-quadruplexes and the transport of G-quadruplex-containing transcripts. Finally, we found that the translation and localization targets of FMRP were distinct and that an FMRP mutant that is unable to bind ribosomes still promoted localization of G-quadruplex-containing messages. This suggests that these two regulatory modes of FMRP may be functionally separated. These results provide a framework for the elucidation of similar mechanisms governed by other RNA-binding proteins.
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Affiliation(s)
- Raeann Goering
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical CampusBoulderUnited States
| | - Laura I Hudish
- Barbara Davis Center for Diabetes, University of Colorado Anschutz Medical CampusBoulderUnited States
| | - Bryan B Guzman
- Department of Pharmacology, University of North Carolina at Chapel HillChapel HillUnited States
| | - Nisha Raj
- Departments of Cell Biology and Neurology, Emory University School of MedicineAtlantaGeorgia
| | - Gary J Bassell
- Departments of Cell Biology and Neurology, Emory University School of MedicineAtlantaGeorgia
| | - Holger A Russ
- Barbara Davis Center for Diabetes, University of Colorado Anschutz Medical CampusBoulderUnited States
| | - Daniel Dominguez
- Department of Pharmacology, University of North Carolina at Chapel HillChapel HillUnited States
| | - J Matthew Taliaferro
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical CampusBoulderUnited States
- RNA Bioscience Initiative, University of Colorado Anschutz Medical CampusBoulderUnited States
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187
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Seabra CM, Aneichyk T, Erdin S, Tai DJC, De Esch CEF, Razaz P, An Y, Manavalan P, Ragavendran A, Stortchevoi A, Abad C, Young JI, Maciel P, Talkowski ME, Gusella JF. Transcriptional consequences of MBD5 disruption in mouse brain and CRISPR-derived neurons. Mol Autism 2020; 11:45. [PMID: 32503625 PMCID: PMC7275313 DOI: 10.1186/s13229-020-00354-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 05/25/2020] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND MBD5, encoding the methyl-CpG-binding domain 5 protein, has been proposed as a necessary and sufficient driver of the 2q23.1 microdeletion syndrome. De novo missense and protein-truncating variants from exome sequencing studies have directly implicated MBD5 in the etiology of autism spectrum disorder (ASD) and related neurodevelopmental disorders (NDDs). However, little is known concerning the specific function(s) of MBD5. METHODS To gain insight into the complex interactions associated with alteration of MBD5 in individuals with ASD and related NDDs, we explored the transcriptional landscape of MBD5 haploinsufficiency across multiple mouse brain regions of a heterozygous hypomorphic Mbd5+/GT mouse model, and compared these results to CRISPR-mediated mutations of MBD5 in human iPSC-derived neuronal models. RESULTS Gene expression analyses across three brain regions from Mbd5+/GT mice showed subtle transcriptional changes, with cortex displaying the most widespread changes following Mbd5 reduction, indicating context-dependent effects. Comparison with MBD5 reduction in human neuronal cells reinforced the context-dependence of gene expression changes due to MBD5 deficiency. Gene co-expression network analyses revealed gene clusters that were associated with reduced MBD5 expression and enriched for terms related to ciliary function. LIMITATIONS These analyses included a limited number of mouse brain regions and neuronal models, and the effects of the gene knockdown are subtle. As such, these results will not reflect the full extent of MBD5 disruption across human brain regions during early neurodevelopment in ASD, or capture the diverse spectrum of cell-type-specific changes associated with MBD5 alterations. CONCLUSIONS Our study points to modest and context-dependent transcriptional consequences of Mbd5 disruption in the brain. It also suggests a possible link between MBD5 and perturbations in ciliary function, which is an established pathogenic mechanism in developmental disorders and syndromes.
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Affiliation(s)
- Catarina M Seabra
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard Medical School, Boston, MA, USA.,GABBA Program - Institute of Biomedical Sciences Abel Salazar of the University of Porto, Porto, Portugal
| | - Tatsiana Aneichyk
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard Medical School, Boston, MA, USA.,Independent Data Lab UG, Munich, Germany
| | - Serkan Erdin
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard Medical School, Boston, MA, USA
| | - Derek J C Tai
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard Medical School, Boston, MA, USA.,Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Celine E F De Esch
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard Medical School, Boston, MA, USA.,Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Parisa Razaz
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard Medical School, Boston, MA, USA.,Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Yu An
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.,Human Phenome Institute, Fudan University, Shanghai, China
| | - Poornima Manavalan
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Ashok Ragavendran
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard Medical School, Boston, MA, USA.,Center for Computational Biology of Human Disease & Center for Computation and Visualization, Brown University, Providence, Rhode Island, USA
| | - Alexei Stortchevoi
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Clemer Abad
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami, Miami, FL, USA
| | - Juan I Young
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami, Miami, FL, USA
| | - Patricia Maciel
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga, Guimarães, Portugal
| | - Michael E Talkowski
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard Medical School, Boston, MA, USA.,Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - James F Gusella
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA. .,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard Medical School, Boston, MA, USA. .,Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA. .,Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA.
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188
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Das Sharma S, Metz JB, Li H, Hobson BD, Hornstein N, Sulzer D, Tang G, Sims PA. Widespread Alterations in Translation Elongation in the Brain of Juvenile Fmr1 Knockout Mice. Cell Rep 2020; 26:3313-3322.e5. [PMID: 30893603 DOI: 10.1016/j.celrep.2019.02.086] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 08/27/2018] [Accepted: 02/21/2019] [Indexed: 12/18/2022] Open
Abstract
FMRP (fragile X mental retardation protein) is a polysome-associated RNA-binding protein encoded by Fmr1 that is lost in fragile X syndrome. Increasing evidence suggests that FMRP regulates both translation initiation and elongation, but the gene specificity of these effects is unclear. To elucidate the impact of Fmr1 loss on translation, we utilize ribosome profiling for genome-wide measurements of ribosomal occupancy and positioning in the cortex of 24-day-old Fmr1 knockout mice. We find a remarkably coherent reduction in ribosome footprint abundance per mRNA for previously identified, high-affinity mRNA binding partners of FMRP and an increase for terminal oligopyrimidine (TOP) motif-containing genes canonically controlled by mammalian target of rapamycin-eIF4E-binding protein-eIF4E binding protein-eukaryotic initiation factor 4E (mTOR-4E-BP-eIF4E) signaling. Amino acid motif- and gene-level analyses both show a widespread reduction of translational pausing in Fmr1 knockout mice. Our findings are consistent with a model of FMRP-mediated regulation of both translation initiation through eIF4E and elongation that is disrupted in fragile X syndrome.
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Affiliation(s)
- Sohani Das Sharma
- Department of Systems Biology, Columbia University Medical Center, New York, NY 10032, USA
| | - Jordan B Metz
- Department of Systems Biology, Columbia University Medical Center, New York, NY 10032, USA; Medical Scientist Training Program, Columbia University Medical Center, New York, NY 10032, USA
| | - Hongyu Li
- Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA
| | - Benjamin D Hobson
- Department of Systems Biology, Columbia University Medical Center, New York, NY 10032, USA; Medical Scientist Training Program, Columbia University Medical Center, New York, NY 10032, USA
| | - Nicholas Hornstein
- Department of Systems Biology, Columbia University Medical Center, New York, NY 10032, USA; Medical Scientist Training Program, Columbia University Medical Center, New York, NY 10032, USA
| | - David Sulzer
- Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA; Department of Psychiatry, Columbia University Medical Center, New York, NY 10032, USA; Department of Pharmacology, Columbia University Medical Center, New York, NY 10032, USA; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Guomei Tang
- Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA
| | - Peter A Sims
- Department of Systems Biology, Columbia University Medical Center, New York, NY 10032, USA; Department of Biochemistry & Molecular Biophysics, Columbia University Medical Center, New York, NY 10032, USA; Sulzberger Columbia Genome Center, Columbia University Medical Center, New York, NY 10032, USA.
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189
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Athar YM, Joseph S. RNA-Binding Specificity of the Human Fragile X Mental Retardation Protein. J Mol Biol 2020; 432:3851-3868. [PMID: 32343993 DOI: 10.1016/j.jmb.2020.04.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 04/16/2020] [Accepted: 04/22/2020] [Indexed: 10/24/2022]
Abstract
Fragile X syndrome is the most common form of inherited intellectual disability and is caused by a deficiency of the fragile X mental retardation protein (FMRP) in neurons. FMRP regulates the translation of numerous mRNAs within dendritic synapses, but how FMRP recognizes these target mRNAs remains unknown. FMRP has KH0, KH1, KH2, and RGG domains, which are thought to bind to specific RNA recognition elements (RREs). Several studies used high-throughput methods to identify various RREs in mRNAs that FMRP may bind to in vivo. However, there is little overlap in the mRNA targets identified by each study, suggesting that the RNA-binding specificity of FMRP is still unknown. To determine the specificity of FMRP for the RREs, we performed quantitative in vitroRNA binding studies with various constructs of human FMRP. Unexpectedly, our studies show that the KH domains do not bind to the previously identified RREs. To further investigate the RNA-binding specificity of FMRP, we developed a new method called Motif Identification by Analysis of Simple sequences (MIDAS) to identify single-stranded RNA sequences bound by KH domains. We find that the FMRP KH0, KH1, and KH2 domains bind weakly to the single-stranded RNA sequences suggesting that they may have evolved to bind more complex RNA structures. Additionally, we find that the RGG motif of human FMRP binds with a high affinity to an RNAG-quadruplex structure that lacks single-stranded loops, double-stranded stems, or junctions.
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Affiliation(s)
- Youssi M Athar
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA92093-0314, USA
| | - Simpson Joseph
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA92093-0314, USA.
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190
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Griffiths KK, Wang A, Wang L, Tracey M, Kleiner G, Quinzii CM, Sun L, Yang G, Perez-Zoghbi JF, Licznerski P, Yang M, Jonas EA, Levy RJ. Inefficient thermogenic mitochondrial respiration due to futile proton leak in a mouse model of fragile X syndrome. FASEB J 2020; 34:7404-7426. [PMID: 32307754 DOI: 10.1096/fj.202000283rr] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 03/13/2020] [Accepted: 03/16/2020] [Indexed: 12/20/2022]
Abstract
Fragile X syndrome (FXS) is the leading known inherited intellectual disability and the most common genetic cause of autism. The full mutation results in transcriptional silencing of the Fmr1 gene and loss of fragile X mental retardation protein (FMRP) expression. Defects in neuroenergetic capacity are known to cause a variety of neurodevelopmental disorders. Thus, we explored the integrity of forebrain mitochondria in Fmr1 knockout mice during the peak of synaptogenesis. We found inefficient thermogenic respiration due to futile proton leak in Fmr1 KO mitochondria caused by coenzyme Q (CoQ) deficiency and an open cyclosporine-sensitive channel. Repletion of mitochondrial CoQ within the Fmr1 KO forebrain closed the channel, blocked the pathological proton leak, restored rates of protein synthesis during synaptogenesis, and normalized the key phenotypic features later in life. The findings demonstrate that FMRP deficiency results in inefficient oxidative phosphorylation during the neurodevelopment and suggest that dysfunctional mitochondria may contribute to the FXS phenotype.
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Affiliation(s)
- Keren K Griffiths
- Department of Anesthesiology, Columbia University Medical Center, New York, NY, USA
| | - Aili Wang
- Department of Anesthesiology, Columbia University Medical Center, New York, NY, USA
| | - Lifei Wang
- Department of Anesthesiology, Columbia University Medical Center, New York, NY, USA
| | - Matthew Tracey
- Department of Anesthesiology, Columbia University Medical Center, New York, NY, USA
| | - Giulio Kleiner
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Catarina M Quinzii
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Linlin Sun
- Department of Anesthesiology, Columbia University Medical Center, New York, NY, USA
| | - Guang Yang
- Department of Anesthesiology, Columbia University Medical Center, New York, NY, USA
| | - Jose F Perez-Zoghbi
- Department of Anesthesiology, Columbia University Medical Center, New York, NY, USA
| | - Pawel Licznerski
- Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Mu Yang
- Institute of Genomic Medicine and Psychiatry, Columbia University Medical Center, New York, NY, USA
| | - Elizabeth A Jonas
- Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Richard J Levy
- Department of Anesthesiology, Columbia University Medical Center, New York, NY, USA
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191
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Shah S, Molinaro G, Liu B, Wang R, Huber KM, Richter JD. FMRP Control of Ribosome Translocation Promotes Chromatin Modifications and Alternative Splicing of Neuronal Genes Linked to Autism. Cell Rep 2020; 30:4459-4472.e6. [PMID: 32234480 PMCID: PMC7179797 DOI: 10.1016/j.celrep.2020.02.076] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 12/24/2019] [Accepted: 02/19/2020] [Indexed: 12/13/2022] Open
Abstract
Silencing of FMR1 and loss of its gene product, FMRP, results in fragile X syndrome (FXS). FMRP binds brain mRNAs and inhibits polypeptide elongation. Using ribosome profiling of the hippocampus, we find that ribosome footprint levels in Fmr1-deficient tissue mostly reflect changes in RNA abundance. Profiling over a time course of ribosome runoff in wild-type tissue reveals a wide range of ribosome translocation rates; on many mRNAs, the ribosomes are stalled. Sucrose gradient ultracentrifugation of hippocampal slices after ribosome runoff reveals that FMRP co-sediments with stalled ribosomes, and its loss results in decline of ribosome stalling on specific mRNAs. One such mRNA encodes SETD2, a lysine methyltransferase that catalyzes H3K36me3. Chromatin immunoprecipitation sequencing (ChIP-seq) demonstrates that loss of FMRP alters the deployment of this histone mark. H3K36me3 is associated with alternative pre-RNA processing, which we find occurs in an FMRP-dependent manner on transcripts linked to neural function and autism spectrum disorders.
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Affiliation(s)
- Sneha Shah
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Gemma Molinaro
- Department of Neuroscience, University of Texas Southwestern Medical School, Dallas, TX 75390, USA
| | - Botao Liu
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Ruijia Wang
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Kimberly M Huber
- Department of Neuroscience, University of Texas Southwestern Medical School, Dallas, TX 75390, USA.
| | - Joel D Richter
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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192
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Li M, Shin J, Risgaard RD, Parries MJ, Wang J, Chasman D, Liu S, Roy S, Bhattacharyya A, Zhao X. Identification of FMR1-regulated molecular networks in human neurodevelopment. Genome Res 2020; 30:361-374. [PMID: 32179589 PMCID: PMC7111522 DOI: 10.1101/gr.251405.119] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Accepted: 02/21/2020] [Indexed: 12/17/2022]
Abstract
RNA-binding proteins (RNA-BPs) play critical roles in development and disease to regulate gene expression. However, genome-wide identification of their targets in primary human cells has been challenging. Here, we applied a modified CLIP-seq strategy to identify genome-wide targets of the FMRP translational regulator 1 (FMR1), a brain-enriched RNA-BP, whose deficiency leads to Fragile X Syndrome (FXS), the most prevalent inherited intellectual disability. We identified FMR1 targets in human dorsal and ventral forebrain neural progenitors and excitatory and inhibitory neurons differentiated from human pluripotent stem cells. In parallel, we measured the transcriptomes of the same four cell types upon FMR1 gene deletion. We discovered that FMR1 preferentially binds long transcripts in human neural cells. FMR1 targets include genes unique to human neural cells and associated with clinical phenotypes of FXS and autism. Integrative network analysis using graph diffusion and multitask clustering of FMR1 CLIP-seq and transcriptional targets reveals critical pathways regulated by FMR1 in human neural development. Our results demonstrate that FMR1 regulates a common set of targets among different neural cell types but also operates in a cell type-specific manner targeting distinct sets of genes in human excitatory and inhibitory neural progenitors and neurons. By defining molecular subnetworks and validating specific high-priority genes, we identify novel components of the FMR1 regulation program. Our results provide new insights into gene regulation by a critical neuronal RNA-BP in human neurodevelopment.
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Affiliation(s)
- Meng Li
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA.,Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
| | - Junha Shin
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
| | - Ryan D Risgaard
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA.,Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
| | - Molly J Parries
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA.,Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
| | - Jianyi Wang
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA.,Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
| | - Deborah Chasman
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
| | - Shuang Liu
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
| | - Sushmita Roy
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA.,Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
| | - Anita Bhattacharyya
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA.,Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
| | - Xinyu Zhao
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA.,Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
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193
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Friedman-Gohas M, Elizur SE, Dratviman-Storobinsky O, Aizer A, Haas J, Raanani H, Orvieto R, Cohen Y. FMRpolyG accumulates in FMR1 premutation granulosa cells. J Ovarian Res 2020; 13:22. [PMID: 32101156 PMCID: PMC7045455 DOI: 10.1186/s13048-020-00623-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 02/10/2020] [Indexed: 12/18/2022] Open
Abstract
Background Fragile X premutation (Amplification of CGG number 55–200) is associated with increased risk for fragile X-Associated Premature Ovarian Insufficiency (FXPOI) in females and fragile X-associated tremor/ataxia syndrome (FXTAS) predominantly in males. Recently, it has been shown that CGG repeats trigger repeat associated non-AUG initiated translation (RAN) of a cryptic polyglycine-containing protein, FMRpolyG. This protein accumulates in ubiquitin-positive inclusions in neuronal brain cells of FXTAS patients and may lead to protein-mediated neurodegeneration. FMRpolyG inclusions were also found in ovary stromal cells of a FXPOI patient. The role of FMRpolyG expression has not been thoroughly examined in folliculogenesis related cells. The main goal of this study is to evaluate whether FMRpolyG accumulates in mural granulosa cells of FMR1 premutation carriers. Following FMRpolyG detection, we aim to examine premutation transfected COV434 as a suitable model used to identify RAN translation functions in FXPOI pathogenesis. Results FMRpolyG and ubiquitin immunostained mural granulosa cells from six FMR1 premutation carriers demonstrated FMRpolyG aggregates. However, co-localization of FMRpolyG and ubiquitin appeared to vary within the FMR1 premutation carriers’ group as three exhibited partial ubiquitin and FMRpolyG double staining and three premutation carriers demonstrated FMRpolyG single staining. None of the granulosa cells from the five control women expressed FMRpolyG. Additionally, human ovarian granulosa tumor, COV434, were transfected with two plasmids; both expressing 99CGG repeats but only one enables FMRpolyG expression. Like in granulosa cells from FMR1 premutation carriers, FMRpolyG aggregates were found only in COV434 transfected with expended CGG repeats and the ability to express FMRpolyG. Conclusions Corresponding with previous studies in FXTAS, we demonstrated accumulation of FMRpolyG in mural granulosa cells of FMR1 premutation carriers. We also suggest that following further investigation, the premutation transfected COV434 might be an appropriate model for RAN translation studies. Detecting FMRpolyG accumulation in folliculogenesis related cells supports previous observations and imply a possible common protein-mediated toxic mechanism for both FXPOI and FXTAS.
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Affiliation(s)
- M Friedman-Gohas
- Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel
| | - S E Elizur
- Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel.,IVF Unit, Chaim Sheba Medical Centre, Tel-Hashomer, 52621, Ramat-Gan, Israel
| | - O Dratviman-Storobinsky
- Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel.,IVF Unit, Chaim Sheba Medical Centre, Tel-Hashomer, 52621, Ramat-Gan, Israel
| | - A Aizer
- Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel.,IVF Unit, Chaim Sheba Medical Centre, Tel-Hashomer, 52621, Ramat-Gan, Israel
| | - J Haas
- Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel.,IVF Unit, Chaim Sheba Medical Centre, Tel-Hashomer, 52621, Ramat-Gan, Israel
| | - H Raanani
- Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel.,IVF Unit, Chaim Sheba Medical Centre, Tel-Hashomer, 52621, Ramat-Gan, Israel
| | - R Orvieto
- Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel.,IVF Unit, Chaim Sheba Medical Centre, Tel-Hashomer, 52621, Ramat-Gan, Israel
| | - Y Cohen
- Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel. .,IVF Unit, Chaim Sheba Medical Centre, Tel-Hashomer, 52621, Ramat-Gan, Israel.
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194
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Bacchelli E, Cameli C, Viggiano M, Igliozzi R, Mancini A, Tancredi R, Battaglia A, Maestrini E. An integrated analysis of rare CNV and exome variation in Autism Spectrum Disorder using the Infinium PsychArray. Sci Rep 2020; 10:3198. [PMID: 32081867 PMCID: PMC7035424 DOI: 10.1038/s41598-020-59922-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 01/19/2020] [Indexed: 01/11/2023] Open
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental condition with a complex and heterogeneous genetic etiology. While a proportion of ASD risk is attributable to common variants, rare copy-number variants (CNVs) and protein-disrupting single-nucleotide variants (SNVs) have been shown to significantly contribute to ASD etiology. We analyzed a homogeneous cohort of 127 ASD Italian families genotyped with the Illumina PsychArray, to perform an integrated analysis of CNVs and SNVs and to assess their contribution to ASD risk. We observed a higher burden of rare CNVs, especially deletions, in ASD individuals versus unaffected controls. Furthermore, we identified a significant enrichment of rare CNVs intersecting ASD candidate genes reported in the SFARI database. Family-based analysis of rare SNVs genotyped by the PsychArray also indicated an increased transmission of rare SNV variants from heterozygous parents to probands, supporting a multigenic model of ASD risk with significant contributions of both variant types. Moreover, our study reinforced the evidence for a significant role of VPS13B, WWOX, CNTNAP2, RBFOX1, MACROD2, APBA2, PARK2, GPHN, and RNF113A genes in ASD susceptibility. Finally, we showed that the PsychArray, besides providing useful genotyping data in psychiatric disorders, is a valuable and cost-efficient tool for genic CNV detection, down to 10 kb.
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Affiliation(s)
- Elena Bacchelli
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy.
| | - Cinzia Cameli
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Marta Viggiano
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Roberta Igliozzi
- IRCCS Stella Maris Foundation, Viale del Tirreno 331, 56128, Calambrone, Pisa, Italy
| | - Alice Mancini
- IRCCS Stella Maris Foundation, Viale del Tirreno 331, 56128, Calambrone, Pisa, Italy
| | - Raffaella Tancredi
- IRCCS Stella Maris Foundation, Viale del Tirreno 331, 56128, Calambrone, Pisa, Italy
| | - Agatino Battaglia
- IRCCS Stella Maris Foundation, Viale del Tirreno 331, 56128, Calambrone, Pisa, Italy
| | - Elena Maestrini
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy.
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195
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Suardi GAM, Haddad LA. FMRP ribonucleoprotein complexes and RNA homeostasis. ADVANCES IN GENETICS 2020; 105:95-136. [PMID: 32560791 DOI: 10.1016/bs.adgen.2020.01.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The Fragile Mental Retardation 1 gene (FMR1), at Xq27.3, encodes the fragile mental retardation protein (FMRP), and displays in its 5'-untranslated region a series of polymorphic CGG triplet repeats that may undergo dynamic mutation. Fragile X syndrome (FXS) is the leading cause of inherited intellectual disability among men, and is most frequently due to FMR1 full mutation and consequent transcription repression. FMR1 premutations may associate with at least two other clinical conditions, named fragile X-associated primary ovarian insufficiency (FXPOI) and tremor and ataxia syndrome (FXTAS). While FXPOI and FXTAS appear to be mediated by FMR1 mRNA accumulation, relative reduction of FMRP, and triplet repeat translation, FXS is due to the lack of the RNA-binding protein FMRP. Besides its function as mRNA translation repressor in neuronal and stem/progenitor cells, RNA editing roles have been assigned to FMRP. In this review, we provide a brief description of FMR1 transcribed microsatellite and associated clinical disorders, and discuss FMRP molecular roles in ribonucleoprotein complex assembly and trafficking, as well as aspects of RNA homeostasis affected in FXS cells.
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Affiliation(s)
- Gabriela Aparecida Marcondes Suardi
- Human Genome and Stem Cell Research Center, Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Luciana Amaral Haddad
- Human Genome and Stem Cell Research Center, Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.
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196
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Kenny PJ, Kim M, Skariah G, Nielsen J, Lannom MC, Ceman S. The FMRP-MOV10 complex: a translational regulatory switch modulated by G-Quadruplexes. Nucleic Acids Res 2020; 48:862-878. [PMID: 31740951 PMCID: PMC7145700 DOI: 10.1093/nar/gkz1092] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 10/30/2019] [Accepted: 11/04/2019] [Indexed: 01/19/2023] Open
Abstract
The Fragile X Mental Retardation Protein (FMRP) is an RNA binding protein that regulates translation and is required for normal cognition. FMRP upregulates and downregulates the activity of microRNA (miRNA)-mediated silencing in the 3' UTR of a subset of mRNAs through its interaction with RNA helicase Moloney leukemia virus 10 (MOV10). This bi-functional role is modulated through RNA secondary structures known as G-Quadruplexes. We elucidated the mechanism of FMRP's role in suppressing Argonaute (AGO) family members' association with mRNAs by mapping the interacting domains of FMRP, MOV10 and AGO and then showed that the RGG box of FMRP protects a subset of co-bound mRNAs from AGO association. The N-terminus of MOV10 is required for this protection: its over-expression leads to increased levels of the endogenous proteins encoded by this co-bound subset of mRNAs. The N-terminus of MOV10 also leads to increased RGG box-dependent binding to the SC1 RNA G-Quadruplex and is required for outgrowth of neurites. Lastly, we showed that FMRP has a global role in miRNA-mediated translational regulation by recruiting AGO2 to a large subset of RNAs in mouse brain.
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Affiliation(s)
- Phillip J Kenny
- Cell and Developmental Biology, University of Illinois-Urbana Champaign, Urbana, IL 61801, USA
| | - Miri Kim
- Neuroscience Program, University of Illinois-Urbana Champaign, Urbana, IL 61801, USA
| | - Geena Skariah
- Neuroscience Program, University of Illinois-Urbana Champaign, Urbana, IL 61801, USA
| | - Joshua Nielsen
- Integrative Biology, University of Illinois-Urbana Champaign, Urbana, IL 61801, USA
| | - Monica C Lannom
- Cell and Developmental Biology, University of Illinois-Urbana Champaign, Urbana, IL 61801, USA
| | - Stephanie Ceman
- Cell and Developmental Biology, University of Illinois-Urbana Champaign, Urbana, IL 61801, USA
- Neuroscience Program, University of Illinois-Urbana Champaign, Urbana, IL 61801, USA
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197
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Cataloguing and Selection of mRNAs Localized to Dendrites in Neurons and Regulated by RNA-Binding Proteins in RNA Granules. Biomolecules 2020; 10:biom10020167. [PMID: 31978946 PMCID: PMC7072219 DOI: 10.3390/biom10020167] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/18/2020] [Accepted: 01/20/2020] [Indexed: 12/15/2022] Open
Abstract
Spatiotemporal translational regulation plays a key role in determining cell fate and function. Specifically, in neurons, local translation in dendrites is essential for synaptic plasticity and long-term memory formation. To achieve local translation, RNA-binding proteins in RNA granules regulate target mRNA stability, localization, and translation. To date, mRNAs localized to dendrites have been identified by comprehensive analyses. In addition, mRNAs associated with and regulated by RNA-binding proteins have been identified using various methods in many studies. However, the results obtained from these numerous studies have not been compiled together. In this review, we have catalogued mRNAs that are localized to dendrites and are associated with and regulated by the RNA-binding proteins fragile X mental retardation protein (FMRP), RNA granule protein 105 (RNG105, also known as Caprin1), Ras-GAP SH3 domain binding protein (G3BP), cytoplasmic polyadenylation element binding protein 1 (CPEB1), and staufen double-stranded RNA binding proteins 1 and 2 (Stau1 and Stau2) in RNA granules. This review provides comprehensive information on dendritic mRNAs, the neuronal functions of mRNA-encoded proteins, the association of dendritic mRNAs with RNA-binding proteins in RNA granules, and the effects of RNA-binding proteins on mRNA regulation. These findings provide insights into the mechanistic basis of protein-synthesis-dependent synaptic plasticity and memory formation and contribute to future efforts to understand the physiological implications of local regulation of dendritic mRNAs in neurons.
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198
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Thelen MP, Kye MJ. The Role of RNA Binding Proteins for Local mRNA Translation: Implications in Neurological Disorders. Front Mol Biosci 2020; 6:161. [PMID: 32010708 PMCID: PMC6974540 DOI: 10.3389/fmolb.2019.00161] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 12/20/2019] [Indexed: 12/11/2022] Open
Abstract
As neurons are one of the most highly polarized cells in our body, they require sophisticated cellular mechanisms to maintain protein homeostasis in their subcellular compartments such as axons and dendrites. When neuronal protein homeostasis is disturbed due to genetic mutations or deletions, this often results in degeneration of neurons leading to devastating outcome such as spinal muscular atrophy (SMA), amyotrophic lateral sclerosis (ALS), and fragile X syndrome (FXS). Ribonucleoprotein (RNP) complexes are macromolecular complexes composed of RNA binding proteins (RBPs) and their target RNAs. RBPs contain RNA binding domains and bind to RNA molecules via specific sequence motifs. RNP complexes have various functions in gene expression including messenger RNA (mRNA) trafficking, RNA processing and silencing. In neurons, RBPs deliver specific sets of mRNAs to subcellular compartments such as axons and dendrites to be locally translated. Mutations or deletions in genes coding for RNPs have been reported as causes for neurological disorders such as SMA, ALS, and FXS. As RBPs determine axonal or dendritic mRNA repertoires as well as proteomes by trafficking selective mRNAs and regulating local protein synthesis, they play a crucial role for neuronal function. In this review, we summarize the role of well-known RBPs, SMN, TDP-43, FUS, and FMRP, and review their function for local protein synthesis in neurons. Furthermore, we discuss their pathological contribution to the neurological disorders.
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Affiliation(s)
| | - Min Jeong Kye
- Institute of Human Genetics, University of Cologne, Cologne, Germany
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199
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Fu XG, Yan AZ, Xu YJ, Liao J, Guo XY, Zhang D, Yang WJ, Zheng DZ, Lan FH. Splicing of exon 9a in FMR1 transcripts results in a truncated FMRP with altered subcellular distribution. Gene 2020; 731:144359. [PMID: 31935509 DOI: 10.1016/j.gene.2020.144359] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 01/07/2020] [Accepted: 01/08/2020] [Indexed: 12/13/2022]
Abstract
FMRP is an RNA-binding protein, loss of which causes fragile X syndrome (FXS). FMRP has several isoforms resulted from alternative splicing (AS) of fragile X mental retardation 1 (FMR1) gene, but their biological functions are still poorly understood. In the analysis of alternatively spliced FMR1 transcripts in the blood cells from a patient with FXS-like phenotypes (normal CGG repeats and no mutation in coding sequence of FMR1), we identified three novel FMR1 transcripts that include a previously unidentified microexon (46 bp), terming the exon 9a. This microexon exists widely in unaffected individuals, inclusion of which introduces an in-frame termination codon. To address whether these exon 9a-containing transcripts could produce protein by evading nonsense-mediated decay (NMD), Western blot was used to analysis blood cell lysate from unaffected individuals and a 34 kDa protein that consistent in size with the molecular weight of the predicted truncated protein produced from mRNA with this microexon was found. Meanwhile, treatment of peripheral blood mononuclear cells with an inhibitor of NMD (Cycloheximide) did not result in significant increase in exon 9a-containing transcripts. Using confocal immunofluorescence, we found the truncated protein displayed both nuclear and cytoplasmic localization in HEK293T and HeLa cells due to lacking C-terminal domains including KH2, NES, and RGG, while the full-length FMRP protein mainly localized in the cytoplasm. Therefore, we hypothesize that the inclusion of this microexon to generate exon 9a-containing transcripts may regulate the normal functionality of FMRP, and the dysregulation of normal FMRP due to increased exon 9a-containing alternatively spliced transcripts in that patient may be associated with the manifestation of FXS phenotype.
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Affiliation(s)
- Xian-Guo Fu
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China
| | - Ai-Zhen Yan
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China
| | - Yong-Jun Xu
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China
| | - Juan Liao
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China
| | - Xiao-Yan Guo
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China
| | - Duo Zhang
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China
| | - Wen-Jing Yang
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China
| | - De-Zhu Zheng
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China
| | - Feng-Hua Lan
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China.
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200
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Mailick MR, Hong J, DaWalt LS, Greenberg JS, Movaghar A, Baker MW, Rathouz PJ, Brilliant MH. FMR1 Low Zone CGG Repeats: Phenotypic Associations in the Context of Parenting Stress. Front Pediatr 2020; 8:223. [PMID: 32478017 PMCID: PMC7240007 DOI: 10.3389/fped.2020.00223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 04/14/2020] [Indexed: 11/28/2022] Open
Abstract
The FMR1 gene on the X chromosome has varying numbers of CGG repeats. The modal number is 30, and expansion to >200 results in fragile X syndrome, but the copy number extends down to 6. Past research suggests that individuals whose CGGs are in the "low zone" (LZ; defined here as ≤ 25 CGGs) may be more environmentally-reactive than those with normal range repeats (26-40 CGGs)-a gene x environment interaction. Using a population-based DNA biobank, in our primary analysis we compared 96 mothers with LZ CGG repeats on both alleles to 280 mothers who had CGG repeats in the normal range. Secondarily, we conducted parallel analyses on fathers. We investigated how parents in these two CGG repeat categories differentially responded to stress, defined as parenting a child with disabilities. Significant gene x environment interactions indicated that LZ mothers who had children with disabilities had greater limitations (in executive functioning, depression, anxiety, daily health symptoms, and balance) than LZ mothers whose children did not have disabilities. In contrast, mothers with normal-range CGG repeats did not differ based on stress exposure. For fathers, a similar pattern was evident for one phenotype only (hand tremors). Although on average LZ CGGs are not associated with compromised functioning, the average masks differential response to the environment.
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Affiliation(s)
- Marsha R Mailick
- Waisman Center, University of Wisconsin-Madison, Madison, WI, United States
| | - Jinkuk Hong
- Waisman Center, University of Wisconsin-Madison, Madison, WI, United States
| | - Leann Smith DaWalt
- Waisman Center, University of Wisconsin-Madison, Madison, WI, United States
| | - Jan S Greenberg
- Waisman Center, University of Wisconsin-Madison, Madison, WI, United States
| | - Arezoo Movaghar
- Waisman Center, University of Wisconsin-Madison, Madison, WI, United States
| | - Mei Wang Baker
- Wisconsin State Laboratory of Hygiene, Madison, WI, United States
| | - Paul J Rathouz
- Dell Medical School at the University of Texas at Austin, Austin, TX, United States
| | - Murray H Brilliant
- Waisman Center, University of Wisconsin-Madison, Madison, WI, United States.,Marshfield Clinic Research Institute, Marshfield, WI, United States
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