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Wan L, Deng M, Zhang H. SR Splicing Factors Promote Cancer via Multiple Regulatory Mechanisms. Genes (Basel) 2022; 13:1659. [PMID: 36140826 PMCID: PMC9498594 DOI: 10.3390/genes13091659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/09/2022] [Accepted: 09/14/2022] [Indexed: 11/17/2022] Open
Abstract
Substantial emerging evidence supports that dysregulated RNA metabolism is associated with tumor initiation and development. Serine/Arginine-Rich proteins (SR) are a number of ultraconserved and structurally related proteins that contain a characteristic RS domain rich in arginine and serine residues. SR proteins perform a critical role in spliceosome assembling and conformational transformation, contributing to precise alternative RNA splicing. Moreover, SR proteins have been reported to participate in multiple other RNA-processing-related mechanisms than RNA splicing, such as genome stability, RNA export, and translation. The dysregulation of SR proteins has been reported to contribute to tumorigenesis through multiple mechanisms. Here we reviewed the different biological roles of SR proteins and strategies for functional rectification of SR proteins that may serve as potential therapeutic approaches for cancer.
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Affiliation(s)
- Ledong Wan
- Department of Pathology, Research Unit of Intelligence Classification of Tumor Pathology and Precision Therapy of Chinese Academy of Medical Sciences (2019RU042), Zhejiang University School of Medicine, Hangzhou 310058, China
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Min Deng
- Department of Pathology, First Peoples Hospital Fuyang, Hangzhou 311400, China
| | - Honghe Zhang
- Department of Pathology, Research Unit of Intelligence Classification of Tumor Pathology and Precision Therapy of Chinese Academy of Medical Sciences (2019RU042), Zhejiang University School of Medicine, Hangzhou 310058, China
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2
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Habiba U, Kuroshima T, Yanagawa-Matsuda A, Kitamura T, Chowdhury A, Jehung JP, Hossain E, Sano H, Kitagawa Y, Shindoh M, Higashino F. HuR translocation to the cytoplasm of cancer cells in actin-independent manner. Exp Cell Res 2018; 369:218-225. [PMID: 29807023 DOI: 10.1016/j.yexcr.2018.05.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 05/18/2018] [Accepted: 05/21/2018] [Indexed: 11/18/2022]
Abstract
Human antigen R (HuR) is a RNA-binding protein, which binds to the AU-rich element (ARE) in the 3'-untranslated region (3'-UTR) of certain mRNA and is involved in the export and stabilization of ARE-mRNA. HuR constitutively relocates to the cytoplasm in many cancer cells, however the mechanism of intracellular HuR trafficking is poorly understood. To address this question, we examined the functional role of the cytoskeleton in HuR relocalization. We tested the effect of actin depolymerizing macrolide latrunculin A or myosin II ATPase activity inhibitor blebbistatin for HuR relocalization induced by the vasoactive hormone Angiotensin II in cancer and control normal cells. Western blot and confocal imaging data revealed that both inhibitors attenuated the cytoplasmic HuR in normal cells but no such alteration was observed in cancer cells. Concomitant with changes in intracellular HuR localization, both inhibitors markedly decreased the accumulation and half-lives of HuR target ARE-mRNAs in normal cells, whereas no change was observed in cancer cells. Furthermore, co-immunoprecipitation experiments with HuR proteins revealed clear physical interaction with ß-actin only in normal cells. The current study is the first to verify that cancer cells can implicate a microfilament independent HuR transport. We hypothesized that when cytoskeleton structure is impaired, cancer cells can acquire an alternative HuR trafficking strategy.
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Affiliation(s)
- Umma Habiba
- Department of Oral Pathology and Biology, Hokkaido University Faculty of Dental Medicine and Graduate School of Dental Medicine, Sapporo, Japan
| | - Takeshi Kuroshima
- Department of Oral Diagnosis and Medicine, Hokkaido University Faculty of Dental Medicine and Graduate School of Dental Medicine, Sapporo, Japan
| | - Aya Yanagawa-Matsuda
- Department of Oral Pathology and Biology, Hokkaido University Faculty of Dental Medicine and Graduate School of Dental Medicine, Sapporo, Japan
| | - Tetsuya Kitamura
- Department of Oral Pathology and Biology, Hokkaido University Faculty of Dental Medicine and Graduate School of Dental Medicine, Sapporo, Japan
| | - Afma Chowdhury
- Department of Restorative Dentistry, Hokkaido University Faculty of Dental Medicine and Graduate School of Dental Medicine, Sapporo, Japan
| | - Jumond P Jehung
- Department of Restorative Dentistry, Hokkaido University Faculty of Dental Medicine and Graduate School of Dental Medicine, Sapporo, Japan
| | - Elora Hossain
- Department of Molecular Oncology, Hokkaido University Faculty of Dental Medicine and Graduate School of Biomedical Science and Engineering, 060-8586,North 13, West 7, Kita ku, Sapporo, Japan
| | - Hidehiko Sano
- Department of Restorative Dentistry, Hokkaido University Faculty of Dental Medicine and Graduate School of Dental Medicine, Sapporo, Japan
| | - Yoshimasa Kitagawa
- Department of Oral Diagnosis and Medicine, Hokkaido University Faculty of Dental Medicine and Graduate School of Dental Medicine, Sapporo, Japan
| | - Masanobu Shindoh
- Department of Oral Pathology and Biology, Hokkaido University Faculty of Dental Medicine and Graduate School of Dental Medicine, Sapporo, Japan
| | - Fumihiro Higashino
- Department of Oral Pathology and Biology, Hokkaido University Faculty of Dental Medicine and Graduate School of Dental Medicine, Sapporo, Japan; Department of Molecular Oncology, Hokkaido University Faculty of Dental Medicine and Graduate School of Biomedical Science and Engineering, 060-8586,North 13, West 7, Kita ku, Sapporo, Japan.
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3
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Rekosh D, Hammarskjold ML. Intron retention in viruses and cellular genes: Detention, border controls and passports. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 9:e1470. [PMID: 29508942 DOI: 10.1002/wrna.1470] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 01/04/2018] [Accepted: 01/24/2018] [Indexed: 02/06/2023]
Abstract
Intron retention (IR), where one or more introns remain in the RNA after splicing, was long thought to be rare in mammalian cells, albeit common in plants and some viruses. Largely due to the development of better methods for RNA analysis, it has now been recognized that IR is much more common than previously thought and that this mechanism is likely to play an important role in mammalian gene regulation. To date, most publications and reviews about IR have described the resulting mRNAs as "dead end" products, with no direct consequence for the proteome. However, there are also many reports of mRNAs with retained introns giving rise to alternative protein isoforms. Although this was originally revealed in viral systems, there are now numerous examples of bona fide cellular proteins that are translated from mRNAs with retained introns. These new isoforms have sometimes been shown to have important regulatory functions. In this review, we highlight recent developments in this area and the research on viruses that led the way to the realization of the many ways in which mRNAs with retained introns can be regulated. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Processing > Splicing Regulation/Alternative Splicing RNA Export and Localization > Nuclear Export/Import RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.
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Affiliation(s)
- David Rekosh
- The Myles H. Thaler Center for AIDS and Human Retrovirus Research and the Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia.,Department of Microbiology, University of Venda, Thohoyandou, South Africa
| | - Marie-Louise Hammarskjold
- The Myles H. Thaler Center for AIDS and Human Retrovirus Research and the Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia.,Department of Microbiology, University of Venda, Thohoyandou, South Africa
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4
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Li MW, Sletten AC, Lee J, Pyles KD, Matkovich SJ, Ory DS, Schaffer JE. Nuclear export factor 3 regulates localization of small nucleolar RNAs. J Biol Chem 2017; 292:20228-20239. [PMID: 29021253 DOI: 10.1074/jbc.m117.818146] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Revised: 10/05/2017] [Indexed: 01/04/2023] Open
Abstract
Small nucleolar RNAs (snoRNAs) guide chemical modifications of ribosomal and small nuclear RNAs, functions that are carried out in the nucleus. Although most snoRNAs reside in the nucleolus, a growing body of evidence indicates that snoRNAs are also present in the cytoplasm and that snoRNAs move between the nucleus and cytoplasm by a mechanism that is regulated by lipotoxic and oxidative stress. Here, in a genome-wide shRNA-based screen, we identified nuclear export factor 3 (NXF3) as a transporter that alters the nucleocytoplasmic distribution of box C/D snoRNAs from the ribosomal protein L13a (Rpl13a) locus. Using RNA-sequencing analysis, we show that NXF3 associates not only with Rpl13a snoRNAs, but also with a broad range of box C/D and box H/ACA snoRNAs. Under homeostatic conditions, gain- or loss-of-function of NXF3, but not related family member NXF1, decreases or increases cytosolic Rpl13a snoRNAs, respectively. Furthermore, treatment with the adenylyl cyclase activator forskolin diminishes cytosolic localization of the Rpl13a snoRNAs through a mechanism that is dependent on NXF3 but not NXF1. Our results provide evidence of a new role for NXF3 in regulating the distribution of snoRNAs between the nuclear and cytoplasmic compartments.
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Affiliation(s)
- Melissa W Li
- Diabetes Research Center, Department of Medicine, St. Louis, Missouri 63110
| | - Arthur C Sletten
- Diabetes Research Center, Department of Medicine, St. Louis, Missouri 63110
| | - Jiyeon Lee
- Diabetes Research Center, Department of Medicine, St. Louis, Missouri 63110
| | - Kelly D Pyles
- Diabetes Research Center, Department of Medicine, St. Louis, Missouri 63110
| | - Scot J Matkovich
- Center for Cardiovascular Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Daniel S Ory
- Diabetes Research Center, Department of Medicine, St. Louis, Missouri 63110
| | - Jean E Schaffer
- Diabetes Research Center, Department of Medicine, St. Louis, Missouri 63110.
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5
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Mamon LA, Ginanova VR, Kliver SF, Yakimova AO, Atsapkina AA, Golubkova EV. RNA-binding proteins of the NXF (nuclear export factor) family and their connection with the cytoskeleton. Cytoskeleton (Hoboken) 2017; 74:161-169. [PMID: 28296067 DOI: 10.1002/cm.21362] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 03/04/2017] [Accepted: 03/08/2017] [Indexed: 02/05/2023]
Abstract
The mutual relationship between mRNA and the cytoskeleton can be seen from two points of view. On the one hand, the cytoskeleton is necessary for mRNA trafficking and anchoring to subcellular domains. On the other hand, cytoskeletal growth and rearrangement require the translation of mRNAs that are connected to the cytoskeleton. β-actin mRNA localization may influence dynamic changes in the actin cytoskeleton. In the cytoplasm, long-lived mRNAs exist in the form of RNP (ribonucleoprotein) complexes, where they interact with RNA-binding proteins, including NXF (Nuclear eXport Factor). Dm NXF1 is an evolutionarily conserved protein in Drosophila melanogaster that has orthologs in different animals. The universal function of nxf1 genes is the nuclear export of different mRNAs in various organisms. In this mini-review, we briefly discuss the evidence demonstrating that Dm NXF1 fulfils not only universal but also specialized cytoplasmic functions. This protein is detected not only in the nucleus but also in the cytoplasm. It is a component of neuronal granules. Dm NXF1 marks nuclear division spindles during early embryogenesis and the dense body on one side of the elongated spermatid nuclei. The characteristic features of sbr mutants (sbr10 and sbr5 ) are impairment of chromosome segregation and spindle formation anomalies during female meiosis. sbr12 mutant sterile males with immobile spermatozoa exhibit disturbances in the axoneme, mitochondrial derivatives and cytokinesis. These data allow us to propose that the Dm NXF1 proteins transport certain mRNAs in neurites and interact with localized mRNAs that are necessary for dynamic changes of the cytoskeleton.
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Affiliation(s)
- L A Mamon
- Department of Genetics and Biotechnology, Faculty of Biology, St Petersburg State University Universitetskaya nab. 7-9, Saint-Petersburg, 199034, Russia
| | - V R Ginanova
- Department of Genetics and Biotechnology, Faculty of Biology, St Petersburg State University Universitetskaya nab. 7-9, Saint-Petersburg, 199034, Russia
| | - S F Kliver
- Department of Genetics and Biotechnology, Faculty of Biology, St Petersburg State University Universitetskaya nab. 7-9, Saint-Petersburg, 199034, Russia
| | - A O Yakimova
- Department of Genetics and Biotechnology, Faculty of Biology, St Petersburg State University Universitetskaya nab. 7-9, Saint-Petersburg, 199034, Russia
| | - A A Atsapkina
- Department of Genetics and Biotechnology, Faculty of Biology, St Petersburg State University Universitetskaya nab. 7-9, Saint-Petersburg, 199034, Russia
| | - E V Golubkova
- Department of Genetics and Biotechnology, Faculty of Biology, St Petersburg State University Universitetskaya nab. 7-9, Saint-Petersburg, 199034, Russia
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6
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Li Y, Bor YC, Fitzgerald MP, Lee KS, Rekosh D, Hammarskjold ML. An NXF1 mRNA with a retained intron is expressed in hippocampal and neocortical neurons and is translated into a protein that functions as an Nxf1 cofactor. Mol Biol Cell 2016; 27:3903-3912. [PMID: 27708137 PMCID: PMC5170612 DOI: 10.1091/mbc.e16-07-0515] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 09/14/2016] [Accepted: 09/26/2016] [Indexed: 12/22/2022] Open
Abstract
A small Nxf1 protein, expressed from an NXF1 mRNA with a retained intron is highly expressed in rodent hippocampal and neocortical neurons, colocalizes with Staufen2 proteins in neuronal RNA granules, is present in polysomes, and replaces Nxt1 as an Nxf1 cofactor in export and expression of mRNA with retained introns. The Nxf1 protein is a major nuclear export receptor for the transport of mRNA, and it also is essential for export of retroviral mRNAs with retained introns. In the latter case, it binds to RNA elements known as constitutive transport elements (CTEs) and functions in conjunction with a cofactor known as Nxt1. The NXF1 gene also regulates expression of its own intron-containing RNA through the use of a functional CTE within intron 10. mRNA containing this intron is exported to the cytoplasm, where it can be translated into the 356–amino acid short Nxf1(sNxf1) protein, despite the fact that it is a prime candidate for nonsense-mediated decay (NMD). Here we demonstrate that sNxf1 is highly expressed in nuclei and dendrites of hippocampal and neocortical neurons in rodent brain. Additionally, we show that sNxf1 localizes in RNA granules in neurites of differentiated N2a mouse neuroblastoma cells, where it shows partial colocalization with Staufen2 isoform SS, a protein known to play a role in dendritic mRNA trafficking. We also show that sNxf1 forms heterodimers in conjunction with the full-length Nxf1 and that sNxf1 can replace Nxt1 to enhance the expression of CTE-containing mRNA and promote its association with polyribosomes.
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Affiliation(s)
- Ying Li
- Myles H. Thaler Center for AIDS and Human Retrovirus Research and Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Yeou-Cherng Bor
- Myles H. Thaler Center for AIDS and Human Retrovirus Research and Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Mark P Fitzgerald
- Departments of Neuroscience and Neurosurgery, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Kevin S Lee
- Departments of Neuroscience and Neurosurgery, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - David Rekosh
- Myles H. Thaler Center for AIDS and Human Retrovirus Research and Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Marie-Louise Hammarskjold
- Myles H. Thaler Center for AIDS and Human Retrovirus Research and Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908
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7
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Yakimova AO, Pugacheva OM, Golubkova EV, Mamon LA. Cytoplasmic localization of SBR (Dm NXF1) protein and its zonal distribution in the ganglia of Drosophila melanogaster larvae. INVERTEBRATE NEUROSCIENCE 2016; 16:9. [DOI: 10.1007/s10158-016-0192-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2015] [Accepted: 06/24/2016] [Indexed: 10/21/2022]
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8
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Pilaz LJ, McMahon JJ, Miller EE, Lennox AL, Suzuki A, Salmon E, Silver DL. Prolonged Mitosis of Neural Progenitors Alters Cell Fate in the Developing Brain. Neuron 2016; 89:83-99. [PMID: 26748089 DOI: 10.1016/j.neuron.2015.12.007] [Citation(s) in RCA: 129] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 09/27/2015] [Accepted: 11/24/2015] [Indexed: 12/14/2022]
Abstract
Embryonic neocortical development depends on balanced production of progenitors and neurons. Genetic mutations disrupting progenitor mitosis frequently impair neurogenesis; however, the link between altered mitosis and cell fate remains poorly understood. Here we demonstrate that prolonged mitosis of radial glial progenitors directly alters neuronal fate specification and progeny viability. Live imaging of progenitors from a neurogenesis mutant, Magoh(+/-), reveals that mitotic delay significantly correlates with preferential production of neurons instead of progenitors, as well as apoptotic progeny. Independently, two pharmacological approaches reveal a causal relationship between mitotic delay and progeny fate. As mitotic duration increases, progenitors produce substantially more apoptotic progeny or neurons. We show that apoptosis, but not differentiation, is p53 dependent, demonstrating that these are distinct outcomes of mitotic delay. Together our findings reveal that prolonged mitosis is sufficient to alter fates of radial glia progeny and define a new paradigm to understand how mitosis perturbations underlie brain size disorders such as microcephaly.
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Affiliation(s)
- Louis-Jan Pilaz
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - John J McMahon
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Emily E Miller
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Ashley L Lennox
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Aussie Suzuki
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Edward Salmon
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Debra L Silver
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA; Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA; Duke Institute for Brain Sciences, Duke University Medical Center, Durham, NC 27710, USA.
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9
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Hu YC, Namekawa SH. Functional significance of the sex chromosomes during spermatogenesis. Reproduction 2016; 149:R265-77. [PMID: 25948089 DOI: 10.1530/rep-14-0613] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Mammalian sex chromosomes arose from an ordinary pair of autosomes. Over hundreds of millions of years, they have evolved into highly divergent X and Y chromosomes and have become increasingly specialized for male reproduction. Both sex chromosomes have acquired and amplified testis-specific genes, suggestive of roles in spermatogenesis. To understand how the sex chromosome genes participate in the regulation of spermatogenesis, we review genes, including single-copy, multi-copy, and ampliconic genes, whose spermatogenic functions have been demonstrated in mouse genetic studies. Sex chromosomes are subject to chromosome-wide transcriptional silencing in meiotic and postmeiotic stages of spermatogenesis. We also discuss particular sex-linked genes that escape postmeiotic silencing and their evolutionary implications. The unique gene contents and genomic structures of the sex chromosomes reflect their strategies to express genes at various stages of spermatogenesis and reveal the driving forces that shape their evolution.Free Chinese abstract: A Chinese translation of this abstract is freely available at http://www.reproduction-online.org/content/149/6/R265/suppl/DC1.Free Japanese abstract: A Japanese translation of this abstract is freely available at http://www.reproduction-online.org/content/149/6/R265/suppl/DC2.
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Affiliation(s)
- Yueh-Chiang Hu
- Division of Developmental BiologyDivision of Reproductive SciencesCincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA
| | - Satoshi H Namekawa
- Division of Developmental BiologyDivision of Reproductive SciencesCincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA Division of Developmental BiologyDivision of Reproductive SciencesCincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA
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10
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Li H, Chen K, Wang Z, Li D, Lin J, Yu C, Yu F, Wang X, Huang L, Jiang C, Gu H, Fang J. Genetic analysis of the clonal stability of Chinese hamster ovary cells for recombinant protein production. MOLECULAR BIOSYSTEMS 2015; 12:102-9. [PMID: 26563441 DOI: 10.1039/c5mb00627a] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Chinese hamster ovary (CHO) cells are frequently used for the production of recombinant proteins for therapeutical applications. However, the recombinant protein expression level of CHO cells may reduce during long-term culture. The physiological changes related to the stability of expression were not well understood. In this study, we performed a series of genetic analysis on stable and unstable clonal derived populations. Transcriptome analysis revealed that a large number of differentially expressed genes (>100) were identified in the unstable population between early and late generations, while only a few differentially expressed genes were found in the stable population, suggesting that the gene expression change is related to the instability of recombinant protein production. On the other hand, no significant differences were found in promoter methylation or gene copy numbers in the unstable population. Taken together, our data help better understand the molecular mechanism underlying the stability of recombinant protein production in CHO cells.
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Affiliation(s)
- Hongwen Li
- School of Life Sciences and Technology, Tongji University, Shanghai, China.
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11
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Golubkova EV, Atsapkina AA, Mamon LA. The role of sbr/Dm nxf1 gene in syncytial development in Drosophila melanogaster. ACTA ACUST UNITED AC 2015. [DOI: 10.1134/s1990519x15040057] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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12
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Callaerts-Vegh Z, Ahmed T, Vermaercke B, Marynen P, Balschun D, Froyen G, D'Hooge R. Nxf7 deficiency impairs social exploration and spatio-cognitive abilities as well as hippocampal synaptic plasticity in mice. Front Behav Neurosci 2015. [PMID: 26217206 PMCID: PMC4498129 DOI: 10.3389/fnbeh.2015.00179] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Nuclear RNA export factors (NXF) are conserved in all metazoans and are deemed essential for shuttling RNA across the nuclear envelope and other post-transcriptional processes (such as mRNA metabolism, storage and stability). Disruption of human NXF5 has been implicated in intellectual and psychosocial disabilities. In the present report, we use recently described Nxf7 knockout (KO) mice as an experimental model to analyze in detail the behavioral consequences of clinical NXF5 deficiency. We examined male Nxf7 KO mice using an extended cognitive and behavioral test battery, and recorded extracellular field potentials in the hippocampal CA1 region. We observed various cognitive and behavioral changes including alterations in social exploration, impaired spatial learning and spatio-cognitive abilities. We also defined a new experimental paradigm to discriminate search strategies in Morris water maze and showed significant differences between Nxf7 KO and control animals. Furthermore, while we observed no difference in a nose poke suppression in an conditioned emotional response (CER) protocol, Nxf7 KO mice were impaired in discriminating between differentially reinforced cues in an auditory fear conditioning protocol. This distinct neurocognitive phenotype was accompanied by impaired hippocampal Long-term potentiation (LTP), while long-term depression (LTD) was not affected by Nxf7 deficiency. Our data demonstrate that disruption of murine Nxf7 leads to behavioral phenotypes that may relate to the intellectual and social deficits in patients with NXF5 deficiency.
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Affiliation(s)
| | - Tariq Ahmed
- Laboratory of Biological Psychology, University of Leuven, KU Leuven Leuven, Belgium
| | - Ben Vermaercke
- Laboratory of Biological Psychology, University of Leuven, KU Leuven Leuven, Belgium
| | - Peter Marynen
- Human Genome Laboratory, University of Leuven and VIB Center for the Biology of Disease Leuven, Belgium
| | - Detlef Balschun
- Laboratory of Biological Psychology, University of Leuven, KU Leuven Leuven, Belgium
| | - Guy Froyen
- Human Genome Laboratory, University of Leuven and VIB Center for the Biology of Disease Leuven, Belgium
| | - Rudi D'Hooge
- Laboratory of Biological Psychology, University of Leuven, KU Leuven Leuven, Belgium
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13
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Nuclear export of messenger RNA. Genes (Basel) 2015; 6:163-84. [PMID: 25836925 PMCID: PMC4488659 DOI: 10.3390/genes6020163] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 03/23/2015] [Accepted: 03/24/2015] [Indexed: 11/29/2022] Open
Abstract
Transport of messenger RNA (mRNA) from the nucleus to the cytoplasm is an essential step of eukaryotic gene expression. In the cell nucleus, a precursor mRNA undergoes a series of processing steps, including capping at the 5' ends, splicing and cleavage/polyadenylation at the 3' ends. During this process, the mRNA associates with a wide variety of proteins, forming a messenger ribonucleoprotein (mRNP) particle. Association with factors involved in nuclear export also occurs during transcription and processing, and thus nuclear export is fully integrated into mRNA maturation. The coupling between mRNA maturation and nuclear export is an important mechanism for providing only fully functional and competent mRNA to the cytoplasmic translational machinery, thereby ensuring accuracy and swiftness of gene expression. This review describes the molecular mechanism of nuclear mRNA export mediated by the principal transport factors, including Tap-p15 and the TREX complex.
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14
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Villarroel-Campos D, Gonzalez-Billault C. The MAP1B case: an old MAP that is new again. Dev Neurobiol 2014; 74:953-71. [PMID: 24700609 DOI: 10.1002/dneu.22178] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 03/27/2014] [Accepted: 03/31/2014] [Indexed: 12/24/2022]
Abstract
The functions of microtubule-associated protein 1B (MAP1B) have historically been linked to the development of the nervous system, based on its very early expression in neurons and glial cells. Moreover, mice in which MAP1B is genetically inactivated have been used extensively to show its role in axonal elongation, neuronal migration, and axonal guidance. In the last few years, it has become apparent that MAP1B has other cellular and molecular functions that are not related to its microtubule-stabilizing properties in the embryonic and adult brain. In this review, we present a systematic review of the canonical and novel functions of MAP1B and propose that, in addition to regulating the polymerization of microtubule and actin microfilaments, MAP1B also acts as a signaling protein involved in normal physiology and pathological conditions in the nervous system.
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Affiliation(s)
- David Villarroel-Campos
- Laboratory of Cell and Neuronal Dynamics (Cenedyn), Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile
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15
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Doller A, Schulz S, Pfeilschifter J, Eberhardt W. RNA-dependent association with myosin IIA promotes F-actin-guided trafficking of the ELAV-like protein HuR to polysomes. Nucleic Acids Res 2013; 41:9152-67. [PMID: 23921630 PMCID: PMC3799433 DOI: 10.1093/nar/gkt663] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The role of the mRNA-binding protein human antigen R (HuR) in stabilization and translation of AU-rich elements (ARE) containing mRNAs is well established. However, the trafficking of HuR and bound mRNA cargo, which comprises a fundamental requirement for the aforementioned HuR functions is only poorly understood. By administering different cytoskeletal inhibitors, we found that the protein kinase Cδ (PKCδ)-triggered accumulation of cytoplasmic HuR by Angiotensin II (AngII) is an actin-myosin driven process functionally relevant for stabilization of ARE-bearing mRNAs. Furthermore, we show that the AngII-induced recruitment of HuR and its bound mRNA from ribonucleoprotein particles to free and cytoskeleton bound polysomes strongly depended on an intact actomyosin cytoskeleton. In addition, HuR allocation to free and cytoskeletal bound polysomes is highly sensitive toward RNase and PPtase and structurally depends on serine 318 (S318) located within the C-terminal RNA recognition motif (RRM3). Conversely, the trafficking of the phosphomimetic HuRS318D, mimicking HuR phosphorylation at S318 by the PKCδ remained PPtase resistant. Co-immunoprecipitation experiments with truncated HuR proteins revealed that the stimulus-induced association of HuR with myosin IIA is strictly RNA dependent and mediated via the RRM3. Our data implicate a microfilament dependent transport of HuR, which is relevant for stimulus-induced targeting of ARE-bearing mRNAs from translational inactive ribonucleoprotein particles to polysomes.
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Affiliation(s)
- Anke Doller
- pharmazentrum frankfurt/ZAFES, Klinikum der Johann Wolfgang Goethe-Universität, D-60590 Frankfurt am Main, Germany
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Esposito T, Lea RA, Maher BH, Moses D, Cox HC, Magliocca S, Angius A, Nyholt DR, Titus T, Kay T, Gray NA, Rastaldi MP, Parnham A, Gianfrancesco F, Griffiths LR. Unique X-linked familial FSGS with co-segregating heart block disorder is associated with a mutation in the NXF5 gene. Hum Mol Genet 2013; 22:3654-66. [PMID: 23686279 DOI: 10.1093/hmg/ddt215] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is the consequence of a disease process that attacks the kidney's filtering system, causing serious scarring. More than half of FSGS patients develop chronic kidney failure within 10 years, ultimately requiring dialysis or renal transplantation. There are currently several genes known to cause the hereditary forms of FSGS (ACTN4, TRPC6, CD2AP, INF2, MYO1E and NPHS2). This study involves a large, unique, multigenerational Australian pedigree in which FSGS co-segregates with progressive heart block with apparent X-linked recessive inheritance. Through a classical combined approach of linkage and haplotype analysis, we identified a 21.19 cM interval implicated on the X chromosome. We then used a whole exome sequencing approach to identify two mutated genes, NXF5 and ALG13, which are located within this linkage interval. The two mutations NXF5-R113W and ALG13-T141L segregated perfectly with the disease phenotype in the pedigree and were not found in a large healthy control cohort. Analysis using bioinformatics tools predicted the R113W mutation in the NXF5 gene to be deleterious and cellular studies support a role in the stability and localization of the protein suggesting a causative role of this mutation in these co-morbid disorders. Further studies are now required to determine the functional consequence of these novel mutations to development of FSGS and heart block in this pedigree and to determine whether these mutations have implications for more common forms of these diseases in the general population.
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Affiliation(s)
- Teresa Esposito
- Institute of Genetics and Biophysics Adriano Buzzati-Traverso, National Research Council of Italy, Naples, Italy
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Vanmarsenille L, Verbeeck J, Belet S, Roebroek AJ, Van de Putte T, Nevelsteen J, Callaerts-Vegh Z, D’Hooge R, Marynen P, Froyen G. Generation and characterization of an Nxf7 knockout mouse to study NXF5 deficiency in a patient with intellectual disability. PLoS One 2013; 8:e64144. [PMID: 23675524 PMCID: PMC3652825 DOI: 10.1371/journal.pone.0064144] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 04/09/2013] [Indexed: 12/11/2022] Open
Abstract
Members of the Nuclear eXport Factor (NXF) family are involved in the export of mRNA from the nucleus to the cytoplasm, or hypothesized to play a role in transport of cytoplasmic mRNA. We previously reported on the loss of NXF5 in a male patient with a syndromic form of intellectual disability. To study the functional role of NXF5 we identified the mouse counterpart. Based on synteny, mouse Nxf2 is the ortholog of human NXF5. However, we provide several lines of evidence that mouse Nxf7 is the actual functional equivalent of NXF5. Both Nxf7 and NXF5 are predominantly expressed in the brain, show cytoplasmic localization, and present as granules in neuronal dendrites suggesting a role in cytoplasmic mRNA metabolism in neurons. Nxf7 was primarily detected in the pyramidal cells of the hippocampus and in layer V of the cortex. Similar to human NXF2, mouse Nxf2 is highly expressed in testis and shows a nuclear localization. Interestingly, these findings point to a different evolutionary path for both NXF genes in human and mouse. We thus generated and validated Nxf7 knockout mice, which were fertile and did not present any gross anatomical or morphological abnormalities. Expression profiling in the hippocampus and the cortex did not reveal significant changes between wild-type and Nxf7 knockout mice. However, impaired spatial memory was observed in these KO mice when evaluated in the Morris water maze test. In conclusion, our findings provide strong evidence that mouse Nxf7 is the functional counterpart of human NXF5, which might play a critical role in mRNA metabolism in the brain.
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Affiliation(s)
- Lieselot Vanmarsenille
- Human Genome Laboratory, VIB Center for the Biology of Disease, Leuven, Belgium
- Human Genome Laboratory, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Jelle Verbeeck
- Human Genome Laboratory, VIB Center for the Biology of Disease, Leuven, Belgium
- Human Genome Laboratory, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Stefanie Belet
- Human Genome Laboratory, VIB Center for the Biology of Disease, Leuven, Belgium
- Human Genome Laboratory, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Anton J. Roebroek
- Experimental Mouse Genetics, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Tom Van de Putte
- Laboratory of Molecular Biology (Celgen), Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Joke Nevelsteen
- Human Genome Laboratory, VIB Center for the Biology of Disease, Leuven, Belgium
- Human Genome Laboratory, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | | | - Rudi D’Hooge
- Laboratory of Biological Psychology, KU Leuven, Leuven, Belgium
- Leuven Institute for Neuroscience and Disease (LIND), KU Leuven, Leuven, Belgium
| | - Peter Marynen
- Human Genome Laboratory, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Guy Froyen
- Human Genome Laboratory, VIB Center for the Biology of Disease, Leuven, Belgium
- Human Genome Laboratory, Department of Human Genetics, KU Leuven, Leuven, Belgium
- * E-mail:
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18
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Mamon LA, Kliver SF, Golubkova EV. Evolutionarily conserved features of the retained intron in alternative transcripts of the <i>nxf1</i> (nuclear export factor) genes in different organisms. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/ojgen.2013.33018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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19
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Fuhrmann-Stroissnigg H, Noiges R, Descovich L, Fischer I, Albrecht DE, Nothias F, Froehner SC, Propst F. The light chains of microtubule-associated proteins MAP1A and MAP1B interact with α1-syntrophin in the central and peripheral nervous system. PLoS One 2012; 7:e49722. [PMID: 23152929 PMCID: PMC3496707 DOI: 10.1371/journal.pone.0049722] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 10/17/2012] [Indexed: 12/24/2022] Open
Abstract
Microtubule-associated proteins of the MAP1 family (MAP1A, MAP1B, and MAP1S) share, among other features, a highly conserved COOH-terminal domain approximately 125 amino acids in length. We conducted a yeast 2-hybrid screen to search for proteins interacting with this domain and identified α1-syntrophin, a member of a multigene family of adapter proteins involved in signal transduction. We further demonstrate that the interaction between the conserved COOH-terminal 125-amino acid domain (which is located in the light chains of MAP1A, MAP1B, and MAP1S) and α1-syntrophin is direct and occurs through the pleckstrin homology domain 2 (PH2) and the postsynaptic density protein 95/disk large/zonula occludens-1 protein homology domain (PDZ) of α1-syntrophin. We confirmed the interaction of MAP1B and α1-syntrophin by co-localization of the two proteins in transfected cells and by co-immunoprecipitation experiments from mouse brain. In addition, we show that MAP1B and α1-syntrophin partially co-localize in Schwann cells of the murine sciatic nerve during postnatal development and in the adult. However, intracellular localization of α1-syntrophin and other Schwann cell proteins such as ezrin and dystrophin-related protein 2 (DRP2) and the localization of the axonal node of Ranvier-associated protein Caspr1/paranodin were not affected in MAP1B null mice. Our findings add to a growing body of evidence that classical MAPs are likely to be involved in signal transduction not only by directly modulating microtubule function, but also through their interaction with signal transduction proteins.
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Affiliation(s)
- Heike Fuhrmann-Stroissnigg
- Max F. Perutz Laboratories, University of Vienna, Department of Biochemistry and Cell Biology, Vienna, Austria
| | - Rainer Noiges
- Max F. Perutz Laboratories, University of Vienna, Department of Biochemistry and Cell Biology, Vienna, Austria
| | - Luise Descovich
- Max F. Perutz Laboratories, University of Vienna, Department of Biochemistry and Cell Biology, Vienna, Austria
| | - Irmgard Fischer
- Max F. Perutz Laboratories, University of Vienna, Department of Biochemistry and Cell Biology, Vienna, Austria
| | - Douglas E. Albrecht
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Fatiha Nothias
- INSERM U952, CNRS UMR 7224, Université Pierre et Marie Curie (UPMC) - Paris-06, Paris, France
| | - Stanley C. Froehner
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Friedrich Propst
- Max F. Perutz Laboratories, University of Vienna, Department of Biochemistry and Cell Biology, Vienna, Austria
- * E-mail:
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20
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Probing Retroviral and Retrotransposon Genome Structures: The "SHAPE" of Things to Come. Mol Biol Int 2012; 2012:530754. [PMID: 22685659 PMCID: PMC3362945 DOI: 10.1155/2012/530754] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 03/13/2012] [Indexed: 11/28/2022] Open
Abstract
Understanding the nuances of RNA structure as they pertain to biological function remains a formidable challenge for retrovirus research and development of RNA-based therapeutics, an area of particular importance with respect to combating HIV infection. Although a variety of chemical and enzymatic RNA probing techniques have been successfully employed for more than 30 years, they primarily interrogate small (100–500 nt) RNAs that have been removed from their biological context, potentially eliminating long-range tertiary interactions (such as kissing loops and pseudoknots) that may play a critical regulatory role. Selective 2′ hydroxyl acylation analyzed by primer extension (SHAPE), pioneered recently by Merino and colleagues, represents a facile, user-friendly technology capable of interrogating RNA structure with a single reagent and, combined with automated capillary electrophoresis, can analyze an entire 10,000-nucleotide RNA genome in a matter of weeks. Despite these obvious advantages, SHAPE essentially provides a nucleotide “connectivity map,” conversion of which into a 3-D structure requires a variety of complementary approaches. This paper summarizes contributions from SHAPE towards our understanding of the structure of retroviral genomes, modifications to which technology that have been developed to address some of its limitations, and future challenges.
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21
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Fallini C, Bassell GJ, Rossoll W. Spinal muscular atrophy: the role of SMN in axonal mRNA regulation. Brain Res 2012; 1462:81-92. [PMID: 22330725 DOI: 10.1016/j.brainres.2012.01.044] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2011] [Accepted: 01/19/2012] [Indexed: 01/15/2023]
Abstract
Spinal muscular atrophy (SMA) is a neurodegenerative disease caused by homozygous mutations or deletions in the survival of motor neuron (SMN1) gene, encoding the ubiquitously expressed SMN protein. SMN associates with different proteins (Gemins 2-8, Unrip) to form a multimeric complex involved in the assembly of small nuclear ribonucleoprotein complexes (snRNPs). Since this activity is essential for the survival of all cell types, it still remains unclear why motor neurons are selectively vulnerable to low levels of SMN protein. Aside from its housekeeping role in the assembly of snRNPs, additional functions of SMN have been proposed. The well-documented localization of SMN in axonal transport granules and its interaction with numerous mRNA-binding proteins not involved in splicing regulation suggest a role in axonal RNA metabolism. This review will focus on the neuropathological and experimental evidence supporting a role for SMN in regulating the assembly, localization, or stability of axonal messenger ribonucleoprotein complexes (mRNPs). Furthermore, how defects in this non-canonical SMN function may contribute to the motor neuron pathology observed in SMA will be discussed. This article is part of a Special Issue entitled RNA-Binding Proteins.
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Affiliation(s)
- Claudia Fallini
- Department of Cell Biology, School of Medicine, Emory University School of Medicine, Atlanta 30322, USA
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22
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Gomi F, Uchida Y. MAP1B 1–126 interacts with tubulin isoforms and induces neurite outgrowth and neuronal death of cultured cortical neurons. Brain Res 2012; 1433:1-8. [DOI: 10.1016/j.brainres.2011.11.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Revised: 10/12/2011] [Accepted: 11/11/2011] [Indexed: 01/11/2023]
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23
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Kashikar ND, Zhang W, Massion PP, Gonzalez AL, Datta PK. Role of STRAP in regulating GSK3β function and Notch3 stabilization. Cell Cycle 2011; 10:1639-54. [PMID: 21502811 DOI: 10.4161/cc.10.10.15630] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Glycogen synthase kinase 3β (GSK3β) can regulate a broad range of cellular processes in a variety of cell types and tissues through its ability to phosphorylate its substrates in a cell- and time-specific manner. Although it is known that Axin and presenilin help to recruit β-catenin/Smad3 and tau protein to GSK3β, respectively, it is not clear how many of the other GSK3β substrates are recruited to it. Here, we have established the binding of GSK3β with a novel scaffold protein, STRAP, through its WD40 domains. In a new finding, we have observed that STRAP, GSK3β and Axin form a ternary complex together. We show for the first time that intracellular fragment of Notch3 (ICN3) binds with GSK3β through the ankyrin repeat domain. This binding between STRAP and GSK3β is reduced by small-molecule inhibitors of GSK3β. Further studies revealed that STRAP also binds ICN3 through the ankyrin repeat region, and this binding is enhanced in a proteasomal inhibition-dependent manner. In vivo ubiquitination studies indicate that STRAP reduces ubiquitination of ICN3, suggesting a role of STRAP in stabilizing ICN3. This is supported by the fact that STRAP and Notch3 are co-upregulated and co-localized in 59% of non-small cell lung cancers, as observed in an immunohistochemical staining of tissue microarrays. These results provide a potential mechanism by which STRAP regulates GSK3β function and Notch3 stabilization and further support the oncogenic functions of STRAP.
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The survival of motor neuron (SMN) protein interacts with the mRNA-binding protein HuD and regulates localization of poly(A) mRNA in primary motor neuron axons. J Neurosci 2011; 31:3914-25. [PMID: 21389246 DOI: 10.1523/jneurosci.3631-10.2011] [Citation(s) in RCA: 166] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Spinal muscular atrophy (SMA) results from reduced levels of the survival of motor neuron (SMN) protein, which has a well characterized function in spliceosomal small nuclear ribonucleoprotein assembly. Currently, it is not understood how deficiency of a housekeeping protein leads to the selective degeneration of spinal cord motor neurons. Numerous studies have shown that SMN is present in neuronal processes and has many interaction partners, including mRNA-binding proteins, suggesting a potential noncanonical role in axonal mRNA metabolism. In this study, we have established a novel technological approach using bimolecular fluorescence complementation (BiFC) and quantitative image analysis to characterize SMN-protein interactions in primary motor neurons. Consistent with biochemical studies on the SMN complex, BiFC analysis revealed that SMN dimerizes and interacts with Gemin2 in nuclear gems and axonal granules. In addition, using pull down assays, immunofluorescence, cell transfection, and BiFC, we characterized a novel interaction between SMN and the neuronal mRNA-binding protein HuD, which was dependent on the Tudor domain of SMN. A missense mutation in the SMN Tudor domain, which is known to cause SMA, impaired the interaction with HuD, but did not affect SMN axonal localization or self-association. Furthermore, time-lapse microscopy revealed SMN cotransport with HuD in live motor neurons. Importantly, SMN knockdown in primary motor neurons resulted in a specific reduction of both HuD protein and poly(A) mRNA levels in the axonal compartment. These findings reveal a noncanonical role for SMN whereby its interaction with mRNA-binding proteins may facilitate the localization of associated poly(A) mRNAs into axons.
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25
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Fujiwara Y, Kasashima K, Saito K, Fukuda M, Fukao A, Sasano Y, Inoue K, Fujiwara T, Sakamoto H. Microtubule association of a neuronal RNA-binding protein HuD through its binding to the light chain of MAP1B. Biochimie 2011; 93:817-22. [PMID: 21288476 DOI: 10.1016/j.biochi.2011.01.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 01/20/2011] [Indexed: 11/30/2022]
Abstract
RNA-binding proteins (RBPs) play a vital role in the post-transcriptional regulation of gene expression during neuronal differentiation and synaptic plasticity. One such RBP family, the neuronal Hu protein family, serves as an early marker of neuronal differentiation and targets several mRNAs containing adenine/uridine-rich elements. Recently, we reported that one of the neuronal Hu proteins, HuD stimulates cap-dependent translation through interactions with eIF4A and poly (A) tail. Nevertheless, little is known with respect to how neuronal Hu proteins contribute to the local translation of target mRNAs in neuronal differentiation. Here, we found that neuronal Hu proteins, but not the ubiquitously expressed HuR protein, directly interact with the light chain of microtubule-associated proteins MAP1B (LC1). We also show that HuD simultaneously binds both RNA and LC1 in vitro and that it tightly associates with microtubules in cells in an LC1-dependent manner, raising the possibility that HuD recruits target mRNAs to microtubules. These results uncover the neuronal binding partners for neuron-specific Hu proteins and suggest the involvement of Hu proteins in microtubule-mediated regulation of mRNA expression within neuronal processes.
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Affiliation(s)
- Yuki Fujiwara
- Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe 657-8501, Japan
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26
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Bier C, Knauer SK, Klapthor A, Schweitzer A, Rekik A, Krämer OH, Marschalek R, Stauber RH. Cell-based analysis of structure-function activity of threonine aspartase 1. J Biol Chem 2011; 286:3007-17. [PMID: 21084304 PMCID: PMC3024795 DOI: 10.1074/jbc.m110.161646] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 10/22/2010] [Indexed: 12/24/2022] Open
Abstract
Taspase1 is a threonine protease responsible for cleaving intracellular substrates. As such, (de)regulated Taspase1 function is expected not only to be vital for ordered development but may also be relevant for disease. However, the full repertoires of Taspase1 targets as well as the exact biochemical requirements for its efficient and substrate-specific cleavage are not yet resolved. Also, no cellular assays for this protease are currently available, hampering the exploitation of the (patho)biological relevance of Taspase1. Here, we developed highly efficient cell-based translocation biosensor assays to probe Taspase1 trans-cleavage in vivo. These modular sensors harbor variations of Taspase1 cleavage sites and localize to the cytoplasm. Expression of Taspase1 but not of inactive Taspase1 mutants or of unrelated proteases triggers proteolytic cleavage and nuclear accumulation of the biosensors. Employing our assay combined with scanning mutagenesis, we identified the sequence and spatial requirements for efficient Taspase1 processing in liquid and solid tumor cell lines. Collectively, our results defined an improved Taspase1 consensus recognition sequence, Q(3)(F/I/L/V)(2)D(1)↓G(1)'X(2)'D(3)'D(4)', allowing the first genome-wide bioinformatic identification of the human Taspase1 degradome. Among the 27 most likely Taspase1 targets are cytoplasmic but also nuclear proteins, such as the upstream stimulatory factor 2 (USF2) or the nuclear RNA export factors 2/5 (NXF2/5). Cleavage site recognition and proteolytic processing of selected targets were verified in the context of the biosensor and for the full-length proteins. We provide novel mechanistic insights into the function and bona fide targets of Taspase1 allowing for a focused investigation of the (patho)biological relevance of this type 2 asparaginase.
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Affiliation(s)
- Carolin Bier
- From the Molecular and Cellular Oncology/Mainzer Screening Center, University Hospital of Mainz, Langenbeckstrasse 1, 55101 Mainz
| | - Shirley K. Knauer
- the Institute for Molecular Biology, Centre for Medical Biotechnology, University Duisburg-Essen, Universitätsstrasse, 45117 Essen
| | - Alexander Klapthor
- From the Molecular and Cellular Oncology/Mainzer Screening Center, University Hospital of Mainz, Langenbeckstrasse 1, 55101 Mainz
| | - Andrea Schweitzer
- From the Molecular and Cellular Oncology/Mainzer Screening Center, University Hospital of Mainz, Langenbeckstrasse 1, 55101 Mainz
| | - Alexander Rekik
- From the Molecular and Cellular Oncology/Mainzer Screening Center, University Hospital of Mainz, Langenbeckstrasse 1, 55101 Mainz
| | - Oliver H. Krämer
- the Institute for Biochemistry and Biophysics/Centre for Molecular Biomedicine, Friedrich-Schiller-University Jena, Hans-Knöll-Strasse 2, 07745 Jena, and
| | - Rolf Marschalek
- the Institute for Pharmaceutical Biology/ZAFES, Goethe-University, Max-von Laue-Strasse 9, 60438 Frankfurt/Main, Germany
| | - Roland H. Stauber
- From the Molecular and Cellular Oncology/Mainzer Screening Center, University Hospital of Mainz, Langenbeckstrasse 1, 55101 Mainz
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Kaposi's sarcoma-associated herpesvirus ORF57 interacts with cellular RNA export cofactors RBM15 and OTT3 to promote expression of viral ORF59. J Virol 2010; 85:1528-40. [PMID: 21106733 DOI: 10.1128/jvi.01709-10] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) encodes ORF57, which promotes the accumulation of specific KSHV mRNA targets, including ORF59 mRNA. We report that the cellular export NXF1 cofactors RBM15 and OTT3 participate in ORF57-enhanced expression of KSHV ORF59. We also found that ectopic expression of RBM15 or OTT3 augments ORF59 production in the absence of ORF57. While RBM15 promotes the accumulation of ORF59 RNA predominantly in the nucleus compared to the levels in the cytoplasm, we found that ORF57 shifted the nucleocytoplasmic balance by increasing ORF59 RNA accumulation in the cytoplasm more than in the nucleus. By promoting the accumulation of cytoplasmic ORF59 RNA, ORF57 offsets the nuclear RNA accumulation mediated by RBM15 by preventing nuclear ORF59 RNA from hyperpolyadenylation. ORF57 interacts directly with the RBM15 C-terminal portion containing the SPOC domain to reduce RBM15 binding to ORF59 RNA. Although ORF57 homologs Epstein-Barr virus (EBV) EB2, herpes simplex virus (HSV) ICP27, varicella-zoster virus (VZV) IE4/ORF4, and cytomegalovirus (CMV) UL69 also interact with RBM15 and OTT3, EBV EB2, which also promotes ORF59 expression, does not function like KSHV ORF57 to efficiently prevent RBM15-mediated nuclear accumulation of ORF59 RNA and RBM15's association with polyadenylated RNAs. Collectively, our data provide novel insight elucidating a molecular mechanism by which ORF57 promotes the expression of viral intronless genes.
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28
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Atsapkina AA, Golubkova EV, Kasatkina VV, Avanesyan EO, Ivankova NA, Mamon LA. Peculiarities of spermatogenesis in Drosophila melanogaster: Role of main transport receptor of mRNA (Dm NXF1). ACTA ACUST UNITED AC 2010. [DOI: 10.1134/s1990519x10050044] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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29
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Legiewicz M, Zolotukhin AS, Pilkington GR, Purzycka KJ, Mitchell M, Uranishi H, Bear J, Pavlakis GN, Le Grice SFJ, Felber BK. The RNA transport element of the murine musD retrotransposon requires long-range intramolecular interactions for function. J Biol Chem 2010; 285:42097-104. [PMID: 20978285 DOI: 10.1074/jbc.m110.182840] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Retrovirus replication requires specialized transport mechanisms to export genomic mRNA from the nucleus to the cytoplasm of the infected cell. This regulation is mediated by a combination of viral and/or cellular factors that interact with cis-acting RNA export elements linking the viral RNA to the cellular CRM1 or NXF1 nuclear export pathways. Endogenous type D murine LTR retrotransposons (musD) were reported to contain an RNA export element located upstream of the 3'-LTR. Although functionally equivalent, the musD export element, termed the musD transport element, is distinct from the other retroviral RNA export elements, such as the constitutive transport element of simian/Mason-Pfizer monkey retroviruses and the RNA transport element found in rodent intracisternal A-particle LTR retrotransposons. We demonstrate here that the minimal RNA transport element (musD transport element) of musD comprises multiple secondary structure elements that presumably serve as recognition signals for the cellular export machinery. We identified two classes of tertiary interactions, namely kissing loops and a pseudoknot. This work constitutes the first example of an RNA transport element requiring such structural motifs to mediate nuclear export.
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Affiliation(s)
- Michal Legiewicz
- RT Biochemistry Section, NCI-Frederick, National Institutes of Health, Frederick, Maryland 21702-1201, USA
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30
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Ivankova N, Tretyakova I, Lyozin GT, Avanesyan E, Zolotukhin A, Zatsepina OG, Evgen'ev MB, Mamon LA. Alternative transcripts expressed by small bristles, the Drosophila melanogaster nxf1 gene. Gene 2010; 458:11-9. [DOI: 10.1016/j.gene.2010.02.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 02/16/2010] [Accepted: 02/25/2010] [Indexed: 11/30/2022]
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Zolotukhin AS, Uranishi H, Lindtner S, Bear J, Pavlakis GN, Felber BK. Nuclear export factor RBM15 facilitates the access of DBP5 to mRNA. Nucleic Acids Res 2010; 37:7151-62. [PMID: 19786495 PMCID: PMC2790900 DOI: 10.1093/nar/gkp782] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The conserved mRNA export receptor NXF1 (Mex67 in yeast) assembles with messenger ribonucleoproteins (mRNP) in the nucleus and guides them through the nuclear pore complex into the cytoplasm. The DEAD family RNA helicase Dbp5 is essential for nuclear export of mRNA and is thought to dissociate Mex67 from mRNP upon translocation, thereby generating directional passage. However, the molecular mechanism by which Dbp5 recognizes Mex67-containing mRNP is not clear. Here we report that the human NXF1-binding protein RBM15 binds specifically to human DBP5 and facilitates its direct contact with mRNA in vivo. We found that RBM15 is targeted to the nuclear envelope, where it colocalizes extensively with DBP5 and NXF1. Gene silencing of RBM15 leads to cytoplasmic depletion and nuclear accumulation of general mRNA as well as individual endogenous transcripts, indicating that RBM15 is required for efficient mRNA export. We propose a model in which RBM15 acts locally at the nuclear pore complex, by facilitating the recognition of NXF1–mRNP complexes by DBP5 during translocation, thereby contributing to efficient mRNA export.
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Affiliation(s)
- Andrei S Zolotukhin
- Human Retrovirus Pathogenesis Section, National Cancer Institute-Frederick, Frederick, MD 21702-1201, USA
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32
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Ding D, Dave KR, Bhattacharya SK. On Message Ribonucleic Acids Targeting to Mitochondria. BIOCHEMISTRY INSIGHTS 2009. [DOI: 10.4137/bci.s3745] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Mitochondria are subcellular organelles that provide energy for a variety of basic cellular processes in eukaryotic cells. Mitochondria maintain their own genomes and many of their endosymbiont genes are encoded by nuclear genomes. The crosstalk between the mitochondrial and nuclear genomes ensures mitochondrial biogenesis, dynamics and maintenance. Mitochondrial proteins are partly encoded by nucleus and synthesized in the cytosol and partly in the mitochondria coded by mitochondrial genome. The efficiency of transport systems that transport nuclear encoded gene products such as proteins and mRNAs to the mitochondrial vicinity to allow for their translation and/or import are recently receiving wide attention. There is currently no concrete evidence that nuclear encoded mRNA is transported into the mitochondria, however, they can be transported onto the mitochondrial surface and translated at the surface of mitochondria utilizing cytosolic machinery. In this review we present an overview of the recent advances in the mRNA transport, with emphasis on the transport of nuclear-encoded mitochondrial protein mRNA into the mitochondria.
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Affiliation(s)
- Di Ding
- Department of Biochemistry and Molecular Biology, University of Miami, Miami, FL, USA
- Bascom Palmer Eye Institute, University of Miami, Miami, FL, USA
| | - Kunjan R. Dave
- Department of Neurology, University of Miami, Miami, FL, USA
| | - Sanjoy K. Bhattacharya
- Department of Biochemistry and Molecular Biology, University of Miami, Miami, FL, USA
- Department of Neurology, University of Miami, Miami, FL, USA
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Abstract
Infertility is a worldwide reproductive health problem, affecting men and women about equally. Mouse genetic studies demonstrate that more than 200 genes specifically or predominantly regulate fertility. However, few genetic causes of infertility in humans have been identified. Here, we focus on the regulation of male fertility by X-linked, germ cell-specific genes. Previous genomic studies reveal that the mammalian X chromosome is enriched for genes expressed in early spermatogenesis. Recent genetic studies in mice show that X-linked, germ cell-specific genes, such as A-kinase anchor protein 4 (Akap4), nuclear RNA export factor 2 (Nxf2), TBP-associated factor 7l (Taf7l), and testis-expressed gene 11 (Tex11), indeed play important roles in the regulation of male fertility. Moreover, we find that the Taf7l Tex11 double-mutant males exhibit much more severe defects in meiosis than either single mutant, suggesting that these 2 X-linked genes regulate male meiosis synergistically. The X-linked, germ cell-specific genes are particularly attractive in the study of male infertility in humans. Because males are hemizygous for X-linked genes, loss-of-function mutations in the single-copy X-linked genes, unlike in autosomal genes, would not be masked by a normal allele. The genetic studies of X-linked, germ cell-specific genes in mice have laid a foundation for mutational analysis of their human orthologues in infertile men.
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Affiliation(s)
- Ke Zheng
- Department of Animal Biology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104, USA
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34
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Dm nxf1/sbr gene affects the formation of meiotic spindle in female Drosophila melanogaster. Chromosome Res 2009; 17:833-45. [PMID: 19779841 DOI: 10.1007/s10577-009-9046-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Revised: 06/08/2009] [Accepted: 06/08/2009] [Indexed: 10/20/2022]
Abstract
The small bristles (sbr) gene of Drosophila melanogaster belongs to the family of nuclear export factor (NXF) genes that participate in mRNA nuclear export. During meiosis, females of Drosophila melanogaster that carry various combinations of mutant alleles of the Dm nxf1/sbr gene exhibit disruption of the division spindle and misalignment of chromosomes at the metaphase plate. Meiosis of sbr ( 5 ) /+ females is characterized by the formation of tripolar spindles during the first cell division. According to the sequencing results, the sbr ( 5 ) (l(1)K4) lethal allele is a deletion of 492 nucleotides. In SBR(5) protein, 57 of the 146 amino acids that have been lost by deletion belong to the NTF2-like domain.
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35
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Kashikar ND, Reiner J, Datta A, Datta PK. Serine threonine receptor-associated protein (STRAP) plays a role in the maintenance of mesenchymal morphology. Cell Signal 2009; 22:138-49. [PMID: 19781628 DOI: 10.1016/j.cellsig.2009.09.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Accepted: 09/14/2009] [Indexed: 12/20/2022]
Abstract
The stromal tissue, made of extracellular matrix and mesenchymal cells, is vital for the functional design of all complex tissues. Fibroblasts are key components of stromal tissue and play a crucial role during organ development, wound repair, angiogenesis and fibrosis. We have previously reported the identification of a novel WD-domain protein, STRAP(1) that inhibits transforming growth factor-beta (TGF-beta) signaling and enhances tumorigenicity via TGF-beta-dependent and TGF-beta-independent mechanisms. Here, we report, for the first time, that deletion of STRAP from Mouse Embryonic Fibroblasts (MEFs) results in a loss of mesenchymal morphology. These cells lose their spindle shape and exhibit features of an epithelial morphology. Gene expression profiling has confirmed that deletion of STRAP affects expression of sets of genes important for diverse functions including cell-cell adhesion and cell polarization, and upregulates E-cadherin expression leading to the formation of adherens junctions, subsequent localization of beta-catenin to the cell membrane and downregulation of the mesenchymal markers like LEF1 (lymphoid enhancer-binding factor 1). Upregulation of WT1 (Wilms tumor homolog 1) in STRAP null MEFs plays a role in E-cadherin induction. Finally, stable expression of STRAP in these cells results in a loss of WT1 and E-cadherin expressions, and a reversal from epithelial to the mesenchymal morphology. Thus, these results provide a novel TGF-beta-independent function of STRAP and describe a mechanism for the role of STRAP in the maintenance of mesenchymal morphology.
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Affiliation(s)
- Nilesh D Kashikar
- Department of Surgery and Cancer Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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36
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Uranishi H, Zolotukhin AS, Lindtner S, Warming S, Zhang GM, Bear J, Copeland NG, Jenkins NA, Pavlakis GN, Felber BK. The RNA-binding motif protein 15B (RBM15B/OTT3) acts as cofactor of the nuclear export receptor NXF1. J Biol Chem 2009; 284:26106-16. [PMID: 19586903 PMCID: PMC2758010 DOI: 10.1074/jbc.m109.040113] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The human SPEN family proteins SHARP, RBM15/OTT1, and RBM15B/OTT3 share the structural domain architecture but show distinct functional properties. Here, we examined the function of OTT3 and compared it with its paralogues RBM15 and SHARP. We found that OTT3, like RBM15, has post-transcriptional regulatory activity, whereas SHARP does not, supporting a divergent role of RBM15 and OTT3. OTT3 shares with RBM15 the association with the splicing factor compartment and the nuclear envelope as well as the binding to mRNA export factors NXF1 and Aly/REF. Mutational analysis revealed direct interaction of OTT3 and RBM15 with NXF1 via their C-terminal regions. Biochemical and subcellular localization studies showed that OTT3 and RBM15 also interact with each other in vivo, further supporting a shared function. Genetic knockdown of RBM15 in mouse is embryonically lethal, indicating that OTT3 cannot compensate for the RBM15 loss, which supports the notion that these proteins, in addition to sharing similar activities, likely have distinct biological roles.
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Affiliation(s)
- Hiroaki Uranishi
- Human Retrovirus Section, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland 21702-1201, USA
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37
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Pan J, Eckardt S, Leu NA, Buffone MG, Zhou J, Gerton GL, McLaughlin KJ, Wang PJ. Inactivation of Nxf2 causes defects in male meiosis and age-dependent depletion of spermatogonia. Dev Biol 2009; 330:167-74. [PMID: 19345203 PMCID: PMC2702087 DOI: 10.1016/j.ydbio.2009.03.022] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Revised: 03/25/2009] [Accepted: 03/25/2009] [Indexed: 11/19/2022]
Abstract
In eukaryotes, mRNA is actively transported from nucleus to cytoplasm by a family of nuclear RNA export factors (NXF). While yeast harbors only one such factor (Mex67p), higher eukaryotes encode multiple NXFs. In mouse, four Nxf genes have been identified: Nxf1, Nxf2, Nxf3, and Nxf7. To date, the function of mouse Nxf genes has not been studied by targeted gene deletion in vivo. Here we report the generation of Nxf2 null mutant mice by homologous recombination in embryonic stem cells. Nxf2-deficient male mice exhibit fertility defects that differ between mouse strains. One third of Nxf2-deficient males on a mixed (C57BL/6x129) genetic background exhibit meiotic arrest and thus are sterile, whereas the remaining males are fertile. Disruption of Nxf2 in inbred (C57BL/6J) males impairs spermatogenesis, resulting in male subfertility, but causes no meiotic arrest. Testis weight and sperm output in C57BL/6J Nxf2(-/Y) mice are sharply reduced. Mutant epididymal sperm exhibit diminished motility. Importantly, proliferation of spermatogonia in Nxf2(-/Y) mice is significantly decreased. As a result, inactivation of Nxf2 causes depletion of germ cells in a substantial fraction of seminiferous tubules in aged mice. These studies demonstrate that Nxf2 plays a dual function in spermatogenesis: regulation of meiosis and maintenance of spermatogonial stem cells.
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Affiliation(s)
- Jieyan Pan
- Department of Animal Biology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104, USA
| | - Sigrid Eckardt
- Center for Animal Transgenesis and Germ Cell Research, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348, USA
| | - N. Adrian Leu
- Center for Animal Transgenesis and Germ Cell Research, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348, USA
| | - Mariano G. Buffone
- Center for Research on Reproduction and Women's Health, Department of Obstetrics and Gynecology, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104, USA
| | - Jian Zhou
- Department of Animal Biology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104, USA
| | - George L Gerton
- Center for Research on Reproduction and Women's Health, Department of Obstetrics and Gynecology, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104, USA
| | - K. John McLaughlin
- Center for Animal Transgenesis and Germ Cell Research, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348, USA
| | - Peijing Jeremy Wang
- Department of Animal Biology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104, USA
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38
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Morris GE. The Cajal body. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:2108-15. [PMID: 18755223 DOI: 10.1016/j.bbamcr.2008.07.016] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 07/21/2008] [Accepted: 07/23/2008] [Indexed: 12/30/2022]
Abstract
The Cajal body, originally identified over 100 years ago as a nucleolar accessory body in neurons, has come to be identified with nucleoplasmic structures, often quite tiny, that contain coiled threads of the marker protein, coilin. The interaction of coilin with other proteins appears to increase the efficiency of several nuclear processes by concentrating their components in the Cajal body. The best-known of these processes is the modification and assembly of U snRNPs, some of which eventually form the RNA splicing machinery, or spliceosome. Over the last 10 years, research into the function of Cajal bodies has been greatly stimulated by the discovery that SMN, the protein deficient in the inherited neuromuscular disease, spinal muscular atrophy, is a Cajal body component and has an essential role in the assembly of spliceosomal U snRNPs in the cytoplasm and their delivery to the Cajal body in the nucleus.
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Affiliation(s)
- Glenn E Morris
- Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, OSWESTRY, SY10 7AG, UK.
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39
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Piazzon N, Rage F, Schlotter F, Moine H, Branlant C, Massenet S. In vitro and in cellulo evidences for association of the survival of motor neuron complex with the fragile X mental retardation protein. J Biol Chem 2007; 283:5598-610. [PMID: 18093976 DOI: 10.1074/jbc.m707304200] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Spinal muscular atrophy (SMA) is caused by reduced levels of the survival of motor neuron (SMN) protein. Although the SMN complex is essential for assembly of spliceosomal U small nuclear RNPs, it is still not understood why reduced levels of the SMN protein specifically cause motor neuron degeneration. SMN was recently proposed to have specific functions in mRNA transport and translation regulation in neuronal processes. The defective protein in Fragile X mental retardation syndrome (FMRP) also plays a role in transport of mRNPs and in their translation. Therefore, we examined possible relationships of SMN with FMRP. We observed granules containing both transiently expressed red fluorescent protein(RFP)-tagged SMN and green fluorescent protein(GFP)-tagged FMRP in cell bodies and processes of rat primary neurons of hypothalamus in culture. By immunoprecipitation experiments, we detected an association of FMRP with the SMN complex in human neuroblastoma SH-SY5Y cells and in murine motor neuron MN-1 cells. Then, by in vitro experiments, we demonstrated that the SMN protein is essential for this association. We showed that the COOH-terminal region of FMRP, as well as the conserved YG box and the region encoded by exon 7 of SMN, are required for the interaction. Our findings suggest a link between the SMN complex and FMRP in neuronal cells.
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Affiliation(s)
- Nathalie Piazzon
- Laboratoire de Maturation des ARN et Enzymologie Moléculaire, UMR 7567 CNRS-UHP Nancy I, Faculté des Sciences, BP 239, 54506 Vandoeuvre-les-Nancy Cedex
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40
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Katahira J, Miki T, Takano K, Maruhashi M, Uchikawa M, Tachibana T, Yoneda Y. Nuclear RNA export factor 7 is localized in processing bodies and neuronal RNA granules through interactions with shuttling hnRNPs. Nucleic Acids Res 2007; 36:616-28. [PMID: 18063567 PMCID: PMC2241847 DOI: 10.1093/nar/gkm556] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The nuclear RNA export factor (NXF) family proteins have been implicated in various aspects of post-transcriptional gene expression. This study shows that mouse NXF7 exhibits heterologous localization, i.e. NXF7 associates with translating ribosomes, stress granules (SGs) and processing bodies (P-bodies), the latter two of which are believed to be cytoplasmic sites of storage, degradation and/or sorting of mRNAs. By yeast two-hybrid screening, a series of heterogeneous nuclear ribonucleoproteins (hnRNPs) were identified as possible binding partners for NXF7. Among them, hnRNP A3, which is believed to be involved in translational control and/or cytoplasmic localization of certain mRNAs, formed a stable complex with NXF7 in vitro. Although hnRNP A3 was not associated with translating ribosomes, it was co-localized with NXF7 in P-bodies. After exposing to oxidative stress, NXF7 trans-localized to SGs, whereas hnRNP A3 did not. In differentiated neuroblastoma Neuro2a cells, NXF7 was co-localized with hnRNP A3 in cell body and neurites. The amino terminal half of NXF7, which was required for stable complex formation with hnRNP A3, coincided with the region required for localization in both P-bodies and neuronal RNA granules. These findings suggest that NXF7 plays a role in sorting, transport and/or storage of mRNAs through interactions with hnRNP A3.
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Affiliation(s)
- Jun Katahira
- Biomolecular Networks Laboratories, Biomolecular Dynamics Laboratory, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Japan.
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41
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Froyen G, Van Esch H, Bauters M, Hollanders K, Frints SGM, Vermeesch JR, Devriendt K, Fryns JP, Marynen P. Detection of genomic copy number changes in patients with idiopathic mental retardation by high-resolution X-array-CGH: important role for increased gene dosage of XLMR genes. Hum Mutat 2007; 28:1034-42. [PMID: 17546640 DOI: 10.1002/humu.20564] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A tiling X-chromosome-specific genomic array with a theoretical resolution of 80 kb was developed to screen patients with idiopathic mental retardation (MR) for submicroscopic copy number differences. Four patients with aberrations previously detected at lower resolution were first analyzed. This facilitated delineation of the location and extent of the aberration at high resolution and subsequently, more precise genotype-phenotype analyses. A cohort of 108 patients was screened, 57 of which were suspected of X-linked mental retardation (XLMR), 26 were probands of brother pairs, and 25 were sporadic cases. A total of 15 copy number changes in 14 patients (13%) were detected, which included two deletions and 13 duplications ranging from 0.1 to 2.7 Mb. The aberrations are associated with the phenotype in five patients (4.6%), based on the following criteria: de novo aberration; involvement of a known or candidate X-linked nonsyndromic(syndromic) MR (MRX(S)) gene; segregation with the disease in the family; absence in control individuals; and skewed X-inactivation in carrier females. These include deletions that contain the MRX(S) genes CDKL5, OPHN1, and CASK, and duplications harboring CDKL5, NXF5, MECP2, and GDI1. In addition, seven imbalances were apparent novel polymorphic regions because they do not fulfill the proposed criteria. Taken together, our data strongly suggest that not only deletions but also duplications on the X chromosome contribute to the phenotype more often than expected, supporting the increased gene dosage mechanism for deregulation of normal cognitive development.
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Affiliation(s)
- Guy Froyen
- Human Genome Laboratory, Department for Molecular and Developmental Genetics, VIB, Leuven, Belgium.
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42
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Takano K, Miki T, Katahira J, Yoneda Y. NXF2 is involved in cytoplasmic mRNA dynamics through interactions with motor proteins. Nucleic Acids Res 2007; 35:2513-21. [PMID: 17403691 PMCID: PMC1885657 DOI: 10.1093/nar/gkm125] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Tap/NXF1, the founding member of the evolutionarily conserved NXF (Nuclear RNA export Factor) family of proteins, is required for the nuclear export of bulk poly(A)+ RNAs. In mice, three additional NXF family genes (NXF2, NXF3, NXF7) have been identified and characterized to date. Cumulative data suggest that NXF family members play roles, not only in nuclear mRNA export, but also in various aspects of post-transcriptional mRNA metabolism. In order to better understand the functional role of NXF2, we searched for its binding partners by yeast two-hybrid screening and identified several cytoplasmic motor proteins, including KIF17. The interaction of NXF2 with KIF17, which was confirmed by GST pull-down and co-immunoprecipitation assays, is mediated by the N-terminal domain of NXF2, which is required for the punctate localization patterns in dendrites of primary neurons. We also found that the NXF2-containing dendritic granules, which were co-localized with KIF17, mRNA and Staufen1, a known component of neuronal mRNA granules, moved bidirectionally along dendrites in a microtubule-dependent manner. These results suggest that NXF2, a nucleo-cytoplasmic mRNA transporter, plays additional roles in the cytoplasmic localization of mRNAs through interactions with cytoplasmic motor proteins.
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Affiliation(s)
- Keizo Takano
- Department of Cell Biology and Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan and Laboratories for Biomolecular Networks, Department of Frontier Biosciences, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Takashi Miki
- Department of Cell Biology and Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan and Laboratories for Biomolecular Networks, Department of Frontier Biosciences, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Jun Katahira
- Department of Cell Biology and Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan and Laboratories for Biomolecular Networks, Department of Frontier Biosciences, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
- *To whom correspondence should be addressed +81-6-6879-4606+81-6-6879-4609
| | - Yoshihiro Yoneda
- Department of Cell Biology and Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan and Laboratories for Biomolecular Networks, Department of Frontier Biosciences, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
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43
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Lerch-Gaggl AF, Sun K, Duncan SA. Light chain 1 of microtubule-associated protein 1B can negatively regulate the action of Pes1. J Biol Chem 2007; 282:11308-16. [PMID: 17308336 DOI: 10.1074/jbc.m610977200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pes1 was first identified as the locus affected in the zebrafish mutant pescadillo, which exhibits severe defects in gut and liver development. It has since been demonstrated that loss of Pes1 expression in mammals and yeast affects ribosome biogenesis, resulting in a block in cell proliferation. Pes1 contains a BRCA1 C-terminal domain, a structural motif that has been shown to facilitate protein-protein interactions, suggesting that Pes1 has binding partners. We used a yeast two-hybrid screen to identify putative interacting proteins. We found that light chain 1 of the microtubule-associated protein 1B (Mtap1b-LC1) could partner with Pes1, and deletion analyses revealed a specific interaction of Mtap1b-LC1 with the Pes1 BRCA1 C-terminal domain. We confirmed the integrity of the interaction between Pes1 and Mtap1b-LC1 by co-immunoprecipitation experiments. Protein localization studies in NIH3T3 cells revealed that exogenously expressed Pes1 was typically restricted to nuclei and nucleoli. However, exogenous Pes1 was found predominantly in the cytoplasm in cells that were forced to express Mtap1b-LC1. We also observed that the expression of endogenous Pes1 protein was significantly reduced or undetectable in nuclei when Mtap1b-LC1 was overexpressed, implying that a dynamic interaction exists between the two proteins and that Mtap1b-LC1 has the potential to negatively impact Pes1 function. Finally, we demonstrated that, as is the case when Pes1 expression is depleted by shRNA, overexpression of Mtap1b-LC1 resulted in diminished proliferation of NIH3T3 cells, suggesting that Mtap1b-LC1 has the potential to repress cell proliferation by modulating the nucleolar levels of Pes1.
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Affiliation(s)
- Alexandra F Lerch-Gaggl
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, 53226, USA
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44
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Felber BK, Zolotukhin AS, Pavlakis GN. Posttranscriptional Control of HIV‐1 and Other Retroviruses and Its Practical Applications. ADVANCES IN PHARMACOLOGY 2007; 55:161-97. [PMID: 17586315 DOI: 10.1016/s1054-3589(07)55005-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Barbara K Felber
- Human Retrovirus Pathogenesis Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD 21702, USA
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45
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Riederer BM. Microtubule-associated protein 1B, a growth-associated and phosphorylated scaffold protein. Brain Res Bull 2006; 71:541-58. [PMID: 17292797 DOI: 10.1016/j.brainresbull.2006.11.012] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Accepted: 11/28/2006] [Indexed: 11/25/2022]
Abstract
Microtubule-associated protein 1B, MAP1B, is one of the major growth associated and cytoskeletal proteins in neuronal and glial cells. It is present as a full length protein or may be fragmented into a heavy chain and a light chain. It is essential to stabilize microtubules during the elongation of dendrites and neurites and is involved in the dynamics of morphological structures such as microtubules, microfilaments and growth cones. MAP1B function is modulated by phosphorylation and influences microtubule stability, microfilaments and growth cone motility. Considering its large size, several interactions with a variety of other proteins have been reported and there is increasing evidence that MAP1B plays a crucial role in the stability of the cytoskeleton and may have other cellular functions. Here we review molecular and functional aspects of this protein, evoke its role as a scaffold protein and have a look at several pathologies where the protein may be involved.
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Affiliation(s)
- Beat M Riederer
- Département de Biologie Cellulaire et de Morphologi), Université de Lausanne, 9 rue du Bugnon, CH-1005 Lausanne, Switzerland.
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46
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Lindtner S, Zolotukhin AS, Uranishi H, Bear J, Kulkarni V, Smulevitch S, Samiotaki M, Panayotou G, Felber BK, Pavlakis GN. RNA-binding Motif Protein 15 Binds to the RNA Transport Element RTE and Provides a Direct Link to the NXF1 Export Pathway. J Biol Chem 2006; 281:36915-28. [PMID: 17001072 DOI: 10.1074/jbc.m608745200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Retroviruses/retroelements provide tools enabling the identification and dissection of basic steps for post-transcriptional regulation of cellular mRNAs. The RNA transport element (RTE) identified in mouse retrotransposons is functionally equivalent to constitutive transport element of Type D retroviruses, yet does not bind directly to the mRNA export receptor NXF1. Here, we report that the RNA-binding motif protein 15 (RBM15) recognizes RTE directly and specifically in vitro and stimulates export and expression of RTE-containing reporter mRNAs in vivo. Tethering of RBM15 to a reporter mRNA showed that RBM15 acts by promoting mRNA export from the nucleus. We also found that RBM15 binds to NXF1 and the two proteins cooperate in stimulating RTE-mediated mRNA export and expression. Thus, RBM15 is a novel mRNA export factor and is part of the NXF1 pathway. We propose that RTE evolved as a high affinity RBM15 ligand to provide a splicing-independent link to NXF1, thereby ensuring efficient nuclear export and expression of retrotransposon transcripts.
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