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Méndez-Albelo NM, Sandoval SO, Xu Z, Zhao X. An in-depth review of the function of RNA-binding protein FXR1 in neurodevelopment. Cell Tissue Res 2024:10.1007/s00441-024-03912-8. [PMID: 39155323 DOI: 10.1007/s00441-024-03912-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2024] [Accepted: 07/30/2024] [Indexed: 08/20/2024]
Abstract
FMR1 autosomal homolog 1 (FXR1) is an RNA-binding protein that belongs to the Fragile X-related protein (FXR) family. FXR1 is critical for development, as its loss of function is intolerant in humans and results in neonatal death in mice. Although FXR1 is expressed widely including the brain, functional studies on FXR1 have been mostly performed in cancer cells. Limited studies have demonstrated the importance of FXR1 in the brain. In this review, we will focus on the roles of FXR1 in brain development and pathogenesis of brain disorders. We will summarize the current knowledge in FXR1 in the context of neural biology, including structural features, isoform diversity and nomenclature, expression patterns, post-translational modifications, regulatory mechanisms, and molecular functions. Overall, FXR1 emerges as an important regulator of RNA metabolism in the brain, with strong implications in neurodevelopmental and psychiatric disorders.
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Affiliation(s)
- Natasha M Méndez-Albelo
- Waisman Center, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Molecular Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Soraya O Sandoval
- Waisman Center, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Zhiyan Xu
- Waisman Center, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Graduate Program in Cellular and Molecular Biology, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Xinyu Zhao
- Waisman Center, University of Wisconsin-Madison, Madison, WI, 53705, USA.
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA.
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2
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Nikonova E, Kao SY, Ravichandran K, Wittner A, Spletter ML. Conserved functions of RNA-binding proteins in muscle. Int J Biochem Cell Biol 2019; 110:29-49. [PMID: 30818081 DOI: 10.1016/j.biocel.2019.02.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 02/21/2019] [Accepted: 02/23/2019] [Indexed: 12/13/2022]
Abstract
Animals require different types of muscle for survival, for example for circulation, motility, reproduction and digestion. Much emphasis in the muscle field has been placed on understanding how transcriptional regulation generates diverse types of muscle during development. Recent work indicates that alternative splicing and RNA regulation are as critical to muscle development, and altered function of RNA-binding proteins causes muscle disease. Although hundreds of genes predicted to bind RNA are expressed in muscles, many fewer have been functionally characterized. We present a cross-species view summarizing what is known about RNA-binding protein function in muscle, from worms and flies to zebrafish, mice and humans. In particular, we focus on alternative splicing regulated by the CELF, MBNL and RBFOX families of proteins. We discuss the systemic nature of diseases associated with loss of RNA-binding proteins in muscle, focusing on mis-regulation of CELF and MBNL in myotonic dystrophy. These examples illustrate the conservation of RNA-binding protein function and the marked utility of genetic model systems in understanding mechanisms of RNA regulation.
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Affiliation(s)
- Elena Nikonova
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-University München, Großhaderner Str. 9, 82152, Martinsried-Planegg, Germany
| | - Shao-Yen Kao
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-University München, Großhaderner Str. 9, 82152, Martinsried-Planegg, Germany
| | - Keshika Ravichandran
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-University München, Großhaderner Str. 9, 82152, Martinsried-Planegg, Germany
| | - Anja Wittner
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-University München, Großhaderner Str. 9, 82152, Martinsried-Planegg, Germany
| | - Maria L Spletter
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-University München, Großhaderner Str. 9, 82152, Martinsried-Planegg, Germany; Center for Integrated Protein Science Munich (CIPSM) at the Department of Chemistry, Ludwig-Maximilians-Universität München, Munich, Germany.
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3
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Recessive mutations in muscle-specific isoforms of FXR1 cause congenital multi-minicore myopathy. Nat Commun 2019; 10:797. [PMID: 30770808 PMCID: PMC6377633 DOI: 10.1038/s41467-019-08548-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 01/18/2019] [Indexed: 02/06/2023] Open
Abstract
FXR1 is an alternatively spliced gene that encodes RNA binding proteins (FXR1P) involved in muscle development. In contrast to other tissues, cardiac and skeletal muscle express two FXR1P isoforms that incorporate an additional exon-15. We report that recessive mutations in this particular exon of FXR1 cause congenital multi-minicore myopathy in humans and mice. Additionally, we show that while Myf5-dependent depletion of all FXR1P isoforms is neonatal lethal, mice carrying mutations in exon-15 display non-lethal myopathies which vary in severity depending on the specific effect of each mutation on the protein.
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Jin X, Zhai B, Fang T, Guo X, Xu L. FXR1 is elevated in colorectal cancer and acts as an oncogene. Tumour Biol 2015; 37:2683-90. [DOI: 10.1007/s13277-015-4068-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 09/13/2015] [Indexed: 01/28/2023] Open
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Smith R, Rathod RJ, Rajkumar S, Kennedy D. Nervous translation, do you get the message? A review of mRNPs, mRNA-protein interactions and translational control within cells of the nervous system. Cell Mol Life Sci 2014; 71:3917-37. [PMID: 24952431 PMCID: PMC11113408 DOI: 10.1007/s00018-014-1660-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 05/22/2014] [Accepted: 05/30/2014] [Indexed: 01/01/2023]
Abstract
In neurons, translation of a message RNA can occur metres away from its transcriptional origin and in normal cells this is orchestrated with perfection. The life of an mRNA will see it pass through multiple steps of processing in the nucleus and the cytoplasm before it reaches its final destination. Processing of mRNA is determined by a myriad of RNA-binding proteins in multi-protein complexes called messenger ribonucleoproteins; however, incorrect processing and delivery of mRNA can cause several human neurological disorders. This review takes us through the life of mRNA from the nucleus to its point of translation in the cytoplasm. The review looks at the various cis and trans factors that act on the mRNA and discusses their roles in different cells of the nervous system and human disorders.
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Affiliation(s)
- Ross Smith
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, 4072, Australia,
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6
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Li Y, Zhao X. Concise review: Fragile X proteins in stem cell maintenance and differentiation. Stem Cells 2014; 32:1724-33. [PMID: 24648324 PMCID: PMC4255947 DOI: 10.1002/stem.1698] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Revised: 02/18/2014] [Accepted: 03/01/2014] [Indexed: 12/15/2022]
Abstract
Fragile X syndrome (FXS), the most common genetic form of autism spectrum disorder, is caused by deficiency of the fragile X mental retardation protein (FMRP). Despite extensive research and scientific progress, understanding how FMRP regulates brain development and function remains a major challenge. FMRP is a neuronal RNA-binding protein that binds about a third of messenger RNAs in the brain and controls their translation, stability, and cellular localization. The absence of FMRP results in increased protein synthesis, leading to enhanced signaling in a number of intracellular pathways, including the mTOR, mGLuR5, ERK, Gsk3β, PI3K, and insulin pathways. Until recently, FXS was largely considered a deficit of mature neurons; however, a number of new studies have shown that FMRP may also play important roles in stem cells, among them neural stem cells, germline stem cells, and pluripotent stem cells. In this review, we will cover these newly discovered functions of FMRP, as well as the other two fragile X-related proteins, in stem cells. We will also discuss the literature on the use of stem cells, particularly neural stem cells and induced pluripotent stem cells, as model systems for studying the functions of FMRP in neuronal development.
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Affiliation(s)
- Yue Li
- Waisman Center and Department of Neuroscience, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
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7
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Ma Y, Wang C, Li B, Qin L, Su J, Yang M, He S. Bcl-2-associated transcription factor 1 interacts with fragile X-related protein 1. Acta Biochim Biophys Sin (Shanghai) 2014; 46:119-27. [PMID: 24389646 PMCID: PMC7109863 DOI: 10.1093/abbs/gmt134] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The absence of fragile X mental retardation protein (FMRP) causes fragile X syndrome (FXS), which is the leading cause of hereditary mental retardation. Fragile X-related protein 1 (FXR1P), which plays an important role in normal muscle development, is one of the two autosomal paralogs of FMRP. To understand the functions of FXR1P, we screened FXR1P-interacting proteins by using a yeast two-hybrid system. The fragile X-related gene 1 (FXR1) was fused to pGBKT7 and then used as the bait to screen the human fetal brain cDNA library. The screening results revealed 10 FXR1P-interacting proteins including Bcl-2-associated transcription factor 1 (BTF). The interaction between FXR1P and BTF was confirmed by using both β-galactosidase assay and growth test in selective media. Co-immunoprecipitation assay in mammalian cells was also carried out to confirm the FXR1P/BTF interaction. Moreover, we confirmed that BTF co-localized with FXR1P in the cytoplasm around the nucleus in rat vascular smooth muscle cells by using confocal fluorescence microscopy. These results provide clues to elucidate the relationship between FXR1P and FXS.
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Affiliation(s)
- Yun Ma
- Department of Biochemistry and Biology, South China University, Hengyang 421001, China
| | - Changbo Wang
- Department of Biochemistry and Biology, South China University, Hengyang 421001, China
| | - Binyuan Li
- Department of Biochemistry and Biology, South China University, Hengyang 421001, China
| | - Lingxue Qin
- Department of Biochemistry and Biology, South China University, Hengyang 421001, China
| | - Jiao Su
- Department of Biochemistry and Biology, South China University, Hengyang 421001, China
| | - Manjun Yang
- Department of Biochemistry and Biology, South China University, Hengyang 421001, China
| | - Shuya He
- Department of Biochemistry and Biology, South China University, Hengyang 421001, China
- Correspondence address. Tel: +86-13807348502; E-mail:
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8
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Bagni C, Oostra BA. Fragile X syndrome: From protein function to therapy. Am J Med Genet A 2013; 161A:2809-21. [PMID: 24115651 DOI: 10.1002/ajmg.a.36241] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 08/28/2013] [Indexed: 12/23/2022]
Abstract
Fragile X syndrome (FXS) is the leading monogenic cause of intellectual disability and autism. The FMR1 gene contains a CGG repeat present in the 5'-untranslated region which can be unstable upon transmission to the next generation. The repeat is up to 55 CGGs long in the normal population. In patients with fragile X syndrome (FXS), a repeat length exceeding 200 CGGs generally leads to methylation of the repeat and the promoter region, which is accompanied by silencing of the FMR1 gene. The disease is a result of lack of expression of the fragile X mental retardation protein leading to severe symptoms, including intellectual disability, hyperactivity, and autistic-like behavior. The FMR1 protein (FMRP) has a number of functions. The translational dysregulation of a subset of mRNAs targeted by FMRP is probably the major contribution to FXS. FMRP is also involved in mRNA transport to synapses where protein synthesis occurs. For some FMRP-bound mRNAs, FMRP is a direct modulator of mRNA stability either by sustaining or preventing mRNA decay. Increased knowledge about the role of FMRP has led to the identification of potential treatments for fragile X syndrome that were often tested first in the different animal models. This review gives an overview about the present knowledge of the function of FMRP and the therapeutic strategies in mouse and man.
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Affiliation(s)
- Claudia Bagni
- VIB Center for the Biology of Disease, Catholic University of Leuven, Leuven, Belgium; Department of Biomedicine and Prevention, University of Rome, Tor Vergata, Italy
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Blech-Hermoni Y, Ladd AN. RNA binding proteins in the regulation of heart development. Int J Biochem Cell Biol 2013; 45:2467-78. [PMID: 23973289 DOI: 10.1016/j.biocel.2013.08.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 08/09/2013] [Accepted: 08/13/2013] [Indexed: 11/28/2022]
Abstract
In vivo, RNA molecules are constantly accompanied by RNA binding proteins (RBPs), which are intimately involved in every step of RNA biology, including transcription, editing, splicing, transport and localization, stability, and translation. RBPs therefore have opportunities to shape gene expression at multiple levels. This capacity is particularly important during development, when dynamic chemical and physical changes give rise to complex organs and tissues. This review discusses RBPs in the context of heart development. Since the targets and functions of most RBPs--in the heart and at large--are not fully understood, this review focuses on the expression and roles of RBPs that have been implicated in specific stages of heart development or developmental pathology. RBPs are involved in nearly every stage of cardiogenesis, including the formation, morphogenesis, and maturation of the heart. A fuller understanding of the roles and substrates of these proteins could ultimately provide attractive targets for the design of therapies for congenital heart defects, cardiovascular disease, or cardiac tissue repair.
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Affiliation(s)
- Yotam Blech-Hermoni
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; Program in Cell Biology, Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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10
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Huot ME, Bisson N, Moss T, Khandjian EW. Manipulating the Fragile X Mental Retardation Proteins in the Frog. Results Probl Cell Differ 2012; 54:165-79. [DOI: 10.1007/978-3-642-21649-7_9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
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Whitman SA, Cover C, Yu L, Nelson DL, Zarnescu DC, Gregorio CC. Desmoplakin and talin2 are novel mRNA targets of fragile X-related protein-1 in cardiac muscle. Circ Res 2011; 109:262-71. [PMID: 21659647 DOI: 10.1161/circresaha.111.244244] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
RATIONALE The proper function of cardiac muscle requires the precise assembly and interactions of numerous cytoskeletal and regulatory proteins into specialized structures that orchestrate contraction and force transmission. Evidence suggests that posttranscriptional regulation is critical for muscle function, but the mechanisms involved remain understudied. OBJECTIVE To investigate the molecular mechanisms and targets of the muscle-specific fragile X mental retardation, autosomal homolog 1 (FXR1), an RNA binding protein whose loss leads to perinatal lethality in mice and cardiomyopathy in zebrafish. METHODS AND RESULTS Using RNA immunoprecipitation approaches we found that desmoplakin and talin2 mRNAs associate with FXR1 in a complex. In vitro assays indicate that FXR1 binds these mRNA targets directly and represses their translation. Fxr1 KO hearts exhibit an up-regulation of desmoplakin and talin2 proteins, which is accompanied by severe disruption of desmosome as well as costamere architecture and composition in the heart, as determined by electron microscopy and deconvolution immunofluorescence analysis. CONCLUSIONS Our findings reveal the first direct mRNA targets of FXR1 in striated muscle and support translational repression as a novel mechanism for regulating heart muscle development and function, in particular the assembly of specialized cytoskeletal structures.
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Affiliation(s)
- Samantha A Whitman
- Department of Cellular and Molecular Medicine, University of Arizona, 1656 East Mabel, Tucson, AZ 85724, USA
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12
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Khera TK, Dick AD, Nicholson LB. Mechanisms of TNFα regulation in uveitis: Focus on RNA-binding proteins. Prog Retin Eye Res 2010; 29:610-21. [DOI: 10.1016/j.preteyeres.2010.08.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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13
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A Functional Requirement for PAK1 Binding to the KH(2) Domain of the Fragile X Protein-Related FXR1. Mol Cell 2010; 38:236-49. [DOI: 10.1016/j.molcel.2010.04.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Revised: 12/21/2009] [Accepted: 02/21/2010] [Indexed: 01/14/2023]
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Van't Padje S, Chaudhry B, Severijnen LA, van der Linde HC, Mientjes EJ, Oostra BA, Willemsen R. Reduction in fragile X related 1 protein causes cardiomyopathy and muscular dystrophy in zebrafish. ACTA ACUST UNITED AC 2009; 212:2564-70. [PMID: 19648401 DOI: 10.1242/jeb.032532] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Lack of the FMR1 gene product causes fragile X syndrome, the commonest inherited cause of mental impairment. We know little of the roles that fragile X related (FXR) gene family members (FMR1, FXR2 and FXR1) play during embryonic development. Although all are expressed in the brain and testis, FXR1 is the principal member found in striated and cardiac muscle. The Fxr1 knockout mice display a striated muscle phenotype but it is not known why they die shortly after birth; however, a cardiac cause is possible. The zebrafish is an ideal model to investigate the role of fxr1 during development of the heart. We have carried out morpholino knockdown of fxr1 and have demonstrated abnormalities of striated muscle development and abnormal development of the zebrafish heart, including failure of looping and snapping of the atrium from its venous pole. In addition, we have measured cardiac function using high-speed video microscopy and demonstrated a significant reduction in cardiac function. This cardiac phenotype has not been previously described and suggests that fxr1 is essential for normal cardiac form and function.
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Affiliation(s)
- Sandra Van't Padje
- CBG-Department of Clinical Genetics, Erasmus MC, 3015 CE Rotterdam, The Netherlands
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15
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Tucker B, Richards RI, Lardelli M. Contribution of mGluR and Fmr1 functional pathways to neurite morphogenesis, craniofacial development and fragile X syndrome. Hum Mol Genet 2006; 15:3446-58. [PMID: 17065172 DOI: 10.1093/hmg/ddl422] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Fragile X Syndrome is a leading heritable cause of mental retardation that results from the loss of FMR1 gene function. Studies in mouse and Drosophila model organisms have been critical in understanding many aspects of the loss of function of the FMR1 gene in the human syndrome. Here, we establish that the zebrafish is a useful model organism for the study of the human fragile X syndrome and can be used to examine phenotypes that are difficult or inaccessible to observation in other model organisms. Using morpholino knockdown of the fmr1 gene, we observed abnormal axonal branching of Rohon-Beard and trigeminal ganglion neurons and guidance and defasciculation defects in the lateral longitudinal fasciculus. We demonstrate that this axonal branching defect can be rescued by treatment with MPEP [2-methyl-6-(phenylethynyl) pyridine]. This is consistent with an interaction between mGluR signalling and fmr1 function in neurite morphogenesis. We also describe novel findings of abnormalities in the abundance of trigeminal ganglion neurons and of craniofacial abnormalities apparently due to dysmorphic cartilage formation. These abnormalities may be related to a role for fmr1 in neural crest cell specification and possibly in migration.
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Affiliation(s)
- Ben Tucker
- ARC Special Research Center for the Molecular Genetics of Development and Discipline of Genetics, School of Molecular and Biomedical Science, The University of Adelaide, South Australia, Australia.
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Huot ME, Bisson N, Davidovic L, Mazroui R, Labelle Y, Moss T, Khandjian EW. The RNA-binding protein fragile X-related 1 regulates somite formation in Xenopus laevis. Mol Biol Cell 2005; 16:4350-61. [PMID: 16000371 PMCID: PMC1196343 DOI: 10.1091/mbc.e05-04-0304] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Fragile X-related 1 protein (FXR1P) is a member of a small family of RNA-binding proteins that includes the Fragile X mental retardation 1 protein (FMR1P) and the Fragile X-related 2 protein (FXR2P). These proteins are thought to transport mRNA and to control their translation. While FMR1P is highly expressed in neurons, substantial levels of FXR1P are found in striated muscles and heart, which are devoid of FMRP and FXR2P. However, little is known about the functions of FXR1P. We have isolated cDNAs for Xenopus Fxr1 and found that two specific splice variants are conserved in evolution. Knockdown of xFxr1p in Xenopus had highly muscle-specific effects, normal MyoD expression being disrupted, somitic myotomal cell rotation and segmentation being inhibited, and dermatome formation being abnormal. Consistent with the absence of the long muscle-specific xFxr1p isoform during early somite formation, these effects could be rescued by both the long and short mRNA variants. Microarray analyses showed that xFxr1p depletion affected the expression of 129 known genes of which 50% were implicated in muscle and nervous system formation. These studies shed significant new light on Fxr1p function(s).
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Affiliation(s)
- Marc-Etienne Huot
- Unité de recherche en génétique humaine et moléculaire, CHUQ-St-François d'Assise, Québec, Québec G1L 3L5, Canada
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17
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van 't Padje S, Engels B, Blonden L, Severijnen LA, Verheijen F, Oostra BA, Willemsen R. Characterisation of Fmrp in zebrafish: evolutionary dynamics of the fmr1 gene. Dev Genes Evol 2005; 215:198-206. [PMID: 15818485 DOI: 10.1007/s00427-005-0466-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2004] [Accepted: 12/21/2004] [Indexed: 10/25/2022]
Abstract
Fragile X syndrome is the most common inherited form of mental retardation. It is caused by the lack of the Fragile X Mental Retardation Protein (FMRP), which is encoded by the FMR1 gene. Although Fmr1 knockout mice display some characteristics also found in fragile X patients, it is a complex animal model to study brain abnormalities, especially during early embryonic development. Interestingly, the ortholog of the FMR1 gene has been identified not only in mouse, but also in zebrafish (Danio rerio). In this study, an amino acid sequence comparison of FMRP orthologs was performed to determine the similar regions of FMRP between several species, including human, mouse, frog, fruitfly and zebrafish. Further characterisation of Fmrp has been performed in both adults and embryos of zebrafish using immunohistochemistry and western blotting with specific antibodies raised against zebrafish Fmrp. We have demonstrated a strong Fmrp expression in neurons of the brain and only a very weak expression in the testis. In brain tissue, a different distribution of the isoforms of Fmrp, compared to human and mouse brain tissue, was shown using western blot analysis. Due to the high similarity between zebrafish Fmrp and human FMRP and their similar expression pattern, the zebrafish has great potential as a complementary animal model to study the pathogenesis of the fragile X syndrome, especially during embryonic development.
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Affiliation(s)
- Sandra van 't Padje
- Department of Clinical Genetics, Erasmus MC, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands
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