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Pan J, Zhou R, Yao LL, Zhang J, Zhang N, Cao QJ, Sun S, Li XD. Identification of a third myosin-5a-melanophilin interaction that mediates the association of myosin-5a with melanosomes. eLife 2024; 13:RP93662. [PMID: 38900147 PMCID: PMC11189624 DOI: 10.7554/elife.93662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2024] Open
Abstract
Transport and localization of melanosome at the periphery region of melanocyte are depended on myosin-5a (Myo5a), which associates with melanosome by interacting with its adaptor protein melanophilin (Mlph). Mlph contains four functional regions, including Rab27a-binding domain, Myo5a GTD-binding motif (GTBM), Myo5a exon F-binding domain (EFBD), and actin-binding domain (ABD). The association of Myo5a with Mlph is known to be mediated by two specific interactions: the interaction between the exon-F-encoded region of Myo5a and Mlph-EFBD and that between Myo5a-GTD and Mlph-GTBM. Here, we identify a third interaction between Myo5a and Mlph, that is, the interaction between the exon-G-encoded region of Myo5a and Mlph-ABD. The exon-G/ABD interaction is independent from the exon-F/EFBD interaction and is required for the association of Myo5a with melanosome. Moreover, we demonstrate that Mlph-ABD interacts with either the exon-G or actin filament, but cannot interact with both of them simultaneously. Based on above findings, we propose a new model for the Mlph-mediated Myo5a transportation of melanosomes.
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Affiliation(s)
- Jiabin Pan
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Rui Zhou
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Lin-Lin Yao
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijingChina
| | - Jie Zhang
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijingChina
| | - Ning Zhang
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijingChina
| | - Qing-Juan Cao
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijingChina
| | - Shaopeng Sun
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Xiang-dong Li
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
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2
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Carotti S, Zingariello M, Francesconi M, D'Andrea L, Latasa MU, Colyn L, Fernandez-Barrena MG, Flammia RS, Falchi M, Righi D, Pedini G, Pantano F, Bagni C, Perrone G, Rana RA, Avila MA, Morini S, Zalfa F. Fragile X mental retardation protein in intrahepatic cholangiocarcinoma: regulating the cancer cell behavior plasticity at the leading edge. Oncogene 2021; 40:4033-4049. [PMID: 34017076 PMCID: PMC8195741 DOI: 10.1038/s41388-021-01824-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 04/15/2021] [Accepted: 04/27/2021] [Indexed: 01/06/2023]
Abstract
Intrahepatic cholangiocarcinoma (iCCA) is a rare malignancy of the intrahepatic biliary tract with a very poor prognosis. Although some clinicopathological parameters can be prognostic factors for iCCA, the molecular prognostic markers and potential mechanisms of iCCA have not been well investigated. Here, we report that the Fragile X mental retardation protein (FMRP), a RNA binding protein functionally absent in patients with the Fragile X syndrome (FXS) and also involved in several types of cancers, is overexpressed in human iCCA and its expression is significantly increased in iCCA metastatic tissues. The silencing of FMRP in metastatic iCCA cell lines affects cell migration and invasion, suggesting a role of FMRP in iCCA progression. Moreover, we show evidence that FMRP is localized at the invasive front of human iCCA neoplastic nests and in pseudopodia and invadopodia protrusions of migrating and invading iCCA cancer cells. Here FMRP binds several mRNAs encoding key proteins involved in the formation and/or function of these protrusions. In particular, we find that FMRP binds to and regulates the expression of Cortactin, a critical regulator of invadopodia formation. Altogether, our findings suggest that FMRP could promote cell invasiveness modulating membrane plasticity and invadopodia formation at the leading edges of invading iCCA cells.
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Affiliation(s)
- Simone Carotti
- Research Unit of Microscopic and Ultrastructural Anatomy, Department of Medicine, Campus Bio-Medico University, Rome, Italy
- Predictive Molecular Diagnostic Unit, Department of Pathology, Campus Bio-Medico University Hospital, Rome, Italy
| | - Maria Zingariello
- Research Unit of Microscopic and Ultrastructural Anatomy, Department of Medicine, Campus Bio-Medico University, Rome, Italy
| | - Maria Francesconi
- Research Unit of Microscopic and Ultrastructural Anatomy, Department of Medicine, Campus Bio-Medico University, Rome, Italy
| | - Laura D'Andrea
- Research Unit of Microscopic and Ultrastructural Anatomy, Department of Medicine, Campus Bio-Medico University, Rome, Italy
| | - M Ujue Latasa
- Hepatology Program, Center for Applied Medical Research (CIMA), University of Navarra and IdiSNA, Pamplona, Spain
| | - Leticia Colyn
- Hepatology Program, Center for Applied Medical Research (CIMA), University of Navarra and IdiSNA, Pamplona, Spain
| | - Maite G Fernandez-Barrena
- Hepatology Program, Center for Applied Medical Research (CIMA), University of Navarra and IdiSNA, Pamplona, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid, Spain
| | - Rocco Simone Flammia
- Research Unit of Microscopic and Ultrastructural Anatomy, Department of Medicine, Campus Bio-Medico University, Rome, Italy
| | - Mario Falchi
- National AIDS Center, Istituto Superiore di Sanità, Rome, Italy
| | - Daniela Righi
- Predictive Molecular Diagnostic Unit, Department of Pathology, Campus Bio-Medico University Hospital, Rome, Italy
| | - Giorgia Pedini
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
| | - Francesco Pantano
- Medical Oncology Department, Campus Bio-Medico University, Rome, Italy
| | - Claudia Bagni
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Giuseppe Perrone
- Predictive Molecular Diagnostic Unit, Department of Pathology, Campus Bio-Medico University Hospital, Rome, Italy
- Research Unit of Pathology, Campus Bio-Medico University, Rome, Italy
| | - Rosa Alba Rana
- Medicine and Aging Science Department, University G. D'Annunzio, Chieti-Pescara, Italy
| | - Matias A Avila
- Hepatology Program, Center for Applied Medical Research (CIMA), University of Navarra and IdiSNA, Pamplona, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid, Spain
| | - Sergio Morini
- Research Unit of Microscopic and Ultrastructural Anatomy, Department of Medicine, Campus Bio-Medico University, Rome, Italy.
| | - Francesca Zalfa
- Research Unit of Microscopic and Ultrastructural Anatomy, Department of Medicine, Campus Bio-Medico University, Rome, Italy.
- Predictive Molecular Diagnostic Unit, Department of Pathology, Campus Bio-Medico University Hospital, Rome, Italy.
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3
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Lai A, Valdez-Sinon AN, Bassell GJ. Regulation of RNA granules by FMRP and implications for neurological diseases. Traffic 2020; 21:454-462. [PMID: 32374065 PMCID: PMC7377269 DOI: 10.1111/tra.12733] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 04/29/2020] [Accepted: 04/29/2020] [Indexed: 12/14/2022]
Abstract
RNA granule formation, which can be regulated by RNA-binding proteins (RBPs) such as fragile X mental retardation protein (FMRP), acts as a mechanism to control both the repression and subcellular localization of translation. Dysregulated assembly of RNA granules has been implicated in multiple neurological disorders, such as amyotrophic lateral sclerosis. Thus, it is crucial to understand the cellular pathways impinging upon granule assembly or disassembly. The goal of this review is to summarize recent advances in our understanding of the role of the RBP, FMRP, in translational repression underlying RNA granule dynamics, mRNA transport and localized. We summarize the known mechanisms of translational regulation by FMRP, the role of FMRP in RNA transport granules, fragile X granules and stress granules. Focusing on the emerging link between FMRP and stress granules, we propose a model for how hyperassembly and hypoassembly of RNA granules may contribute to neurological diseases.
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Affiliation(s)
- Austin Lai
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - Gary J Bassell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, USA
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4
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Suardi GAM, Haddad LA. FMRP ribonucleoprotein complexes and RNA homeostasis. ADVANCES IN GENETICS 2020; 105:95-136. [PMID: 32560791 DOI: 10.1016/bs.adgen.2020.01.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The Fragile Mental Retardation 1 gene (FMR1), at Xq27.3, encodes the fragile mental retardation protein (FMRP), and displays in its 5'-untranslated region a series of polymorphic CGG triplet repeats that may undergo dynamic mutation. Fragile X syndrome (FXS) is the leading cause of inherited intellectual disability among men, and is most frequently due to FMR1 full mutation and consequent transcription repression. FMR1 premutations may associate with at least two other clinical conditions, named fragile X-associated primary ovarian insufficiency (FXPOI) and tremor and ataxia syndrome (FXTAS). While FXPOI and FXTAS appear to be mediated by FMR1 mRNA accumulation, relative reduction of FMRP, and triplet repeat translation, FXS is due to the lack of the RNA-binding protein FMRP. Besides its function as mRNA translation repressor in neuronal and stem/progenitor cells, RNA editing roles have been assigned to FMRP. In this review, we provide a brief description of FMR1 transcribed microsatellite and associated clinical disorders, and discuss FMRP molecular roles in ribonucleoprotein complex assembly and trafficking, as well as aspects of RNA homeostasis affected in FXS cells.
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Affiliation(s)
- Gabriela Aparecida Marcondes Suardi
- Human Genome and Stem Cell Research Center, Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Luciana Amaral Haddad
- Human Genome and Stem Cell Research Center, Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.
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5
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Bercier V, Rosello M, Del Bene F, Revenu C. Zebrafish as a Model for the Study of Live in vivo Processive Transport in Neurons. Front Cell Dev Biol 2019; 7:17. [PMID: 30838208 PMCID: PMC6389722 DOI: 10.3389/fcell.2019.00017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 02/01/2019] [Indexed: 12/13/2022] Open
Abstract
Motor proteins are responsible for transport of vesicles and organelles within the cell cytoplasm. They interact with the actin cytoskeleton and with microtubules to ensure communication and supply throughout the cell. Much work has been done in vitro and in silico to unravel the key players, including the dynein motor complex, the kinesin and myosin superfamilies, and their interacting regulatory complexes, but there is a clear need for in vivo data as recent evidence suggests previous models might not recapitulate physiological conditions. The zebrafish embryo provides an excellent system to study these processes in intact animals due to the ease of genetic manipulation and the optical transparency allowing live imaging. We present here the advantages of the zebrafish embryo as a system to study live in vivo processive transport in neurons and provide technical recommendations for successful analysis.
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Affiliation(s)
- Valérie Bercier
- Institut Curie, PSL Research University, Inserm U934, CNRS UMR3215, Paris, France.,Laboratory of Neurobiology, Center for Brain and Disease Research, Research Group Experimental Neurology, Department of Neurosciences, VIB-KU Leuven, Leuven, Belgium
| | - Marion Rosello
- Institut Curie, PSL Research University, Inserm U934, CNRS UMR3215, Paris, France
| | - Filippo Del Bene
- Institut Curie, PSL Research University, Inserm U934, CNRS UMR3215, Paris, France
| | - Céline Revenu
- Institut Curie, PSL Research University, Inserm U934, CNRS UMR3215, Paris, France
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6
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Abstract
The delivery of intracellular material within cells is crucial for maintaining normal function. Myosins transport a wide variety of cargo, ranging from vesicles to ribonuclear protein particles (RNPs), in plants, fungi, and metazoa. The properties of a given myosin transporter are adapted to move on different actin filament tracks, either on the disordered actin networks at the cell cortex or along highly organized actin bundles to distribute their cargo in a localized manner or move it across long distances in the cell. Transport is controlled by selective recruitment of the myosin to its cargo that also plays a role in activation of the motor.
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Affiliation(s)
- Margaret A Titus
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota 55455
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7
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Zalfa F, Panasiti V, Carotti S, Zingariello M, Perrone G, Sancillo L, Pacini L, Luciani F, Roberti V, D'Amico S, Coppola R, Abate SO, Rana RA, De Luca A, Fiers M, Melocchi V, Bianchi F, Farace MG, Achsel T, Marine JC, Morini S, Bagni C. The fragile X mental retardation protein regulates tumor invasiveness-related pathways in melanoma cells. Cell Death Dis 2017; 8:e3169. [PMID: 29144507 PMCID: PMC5775405 DOI: 10.1038/cddis.2017.521] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 08/24/2017] [Accepted: 08/25/2017] [Indexed: 02/06/2023]
Abstract
The fragile X mental retardation protein (FMRP) is lacking or mutated in patients with the fragile X syndrome (FXS), the most frequent form of inherited intellectual disability. FMRP affects metastasis formation in a mouse model for breast cancer. Here we show that FMRP is overexpressed in human melanoma with high Breslow thickness and high Clark level. Furthermore, meta-analysis of the TCGA melanoma data revealed that high levels of FMRP expression correlate significantly with metastatic tumor tissues, risk of relapsing and disease-free survival. Reduction of FMRP in metastatic melanoma cell lines impinges on cell migration, invasion and adhesion. Next-generation sequencing in human melanoma cells revealed that FMRP regulates a large number of mRNAs involved in relevant processes of melanoma progression. Our findings suggest an association between FMRP levels and the invasive phenotype in melanoma and might open new avenues towards the discovery of novel therapeutic targets.
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Affiliation(s)
- Francesca Zalfa
- Department of Medicine, Campus Bio-Medico University, via Alvaro del Portillo 21, 00128 Rome, Italy
| | - Vincenzo Panasiti
- Department of Medicine, Campus Bio-Medico University, via Alvaro del Portillo 21, 00128 Rome, Italy
| | - Simone Carotti
- Department of Medicine, Campus Bio-Medico University, via Alvaro del Portillo 21, 00128 Rome, Italy
| | - Maria Zingariello
- Department of Medicine, Campus Bio-Medico University, via Alvaro del Portillo 21, 00128 Rome, Italy
| | - Giuseppe Perrone
- Department of Medicine, Campus Bio-Medico University, via Alvaro del Portillo 21, 00128 Rome, Italy
| | - Laura Sancillo
- Department of Medicine and Science of Aging, University of Chieti 'G d'Annunzio', via dei Vestini 31, 66100 Chieti-Pescara, Italy
| | - Laura Pacini
- Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', via Montpellier 1, 00133 Rome, Italy
| | - Flavie Luciani
- VIB/Center for the Biology of Disease, KU Leuven, O&N 4, Herestraat 49 Box 602, 3000, Leuven, Belgium.,Center for Human Genetics, Leuven Institute for Neuroscience and Disease, KU Leuven, O&N 4, Herestraat 49 Box 602, Leuven, 3000, Belgium
| | - Vincenzo Roberti
- Department of Dermatology, University of Rome 'La Sapienza', viale dell'Università 1, 00185 Rome, Italy
| | - Silvia D'Amico
- Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', via Montpellier 1, 00133 Rome, Italy
| | - Rosa Coppola
- Department of Medicine, Campus Bio-Medico University, via Alvaro del Portillo 21, 00128 Rome, Italy
| | - Simona Osella Abate
- Department of Medical Science and Human Oncology, Section of Dermato-Oncology, University of Turin, via Verdi 8, 10124 Turin, Italy
| | - Rosa Alba Rana
- Department of Medicine and Science of Aging, University of Chieti 'G d'Annunzio', via dei Vestini 31, 66100 Chieti-Pescara, Italy
| | - Anastasia De Luca
- Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', via Montpellier 1, 00133 Rome, Italy
| | - Mark Fiers
- VIB/Center for the Biology of Disease, KU Leuven, O&N 4, Herestraat 49 Box 602, 3000, Leuven, Belgium.,Center for Human Genetics, Leuven Institute for Neuroscience and Disease, KU Leuven, O&N 4, Herestraat 49 Box 602, Leuven, 3000, Belgium
| | - Valentina Melocchi
- ISBREMIT, Institute for Stem-cell Biology, Regenerative Medicine and Innovative Therapies, IRCCS Casa Sollievo della Sofferenza, viale Padre Pio 7, 71013 San Giovanni Rotondo (FG), Italy
| | - Fabrizio Bianchi
- ISBREMIT, Institute for Stem-cell Biology, Regenerative Medicine and Innovative Therapies, IRCCS Casa Sollievo della Sofferenza, viale Padre Pio 7, 71013 San Giovanni Rotondo (FG), Italy
| | - Maria Giulia Farace
- Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', via Montpellier 1, 00133 Rome, Italy
| | - Tilmann Achsel
- VIB/Center for the Biology of Disease, KU Leuven, O&N 4, Herestraat 49 Box 602, 3000, Leuven, Belgium.,Center for Human Genetics, Leuven Institute for Neuroscience and Disease, KU Leuven, O&N 4, Herestraat 49 Box 602, Leuven, 3000, Belgium
| | - Jean-Christophe Marine
- VIB/Center for the Biology of Disease, KU Leuven, O&N 4, Herestraat 49 Box 602, 3000, Leuven, Belgium.,Center for Human Genetics, Leuven Institute for Neuroscience and Disease, KU Leuven, O&N 4, Herestraat 49 Box 602, Leuven, 3000, Belgium
| | - Sergio Morini
- Department of Medicine, Campus Bio-Medico University, via Alvaro del Portillo 21, 00128 Rome, Italy
| | - Claudia Bagni
- Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', via Montpellier 1, 00133 Rome, Italy.,VIB/Center for the Biology of Disease, KU Leuven, O&N 4, Herestraat 49 Box 602, 3000, Leuven, Belgium.,Center for Human Genetics, Leuven Institute for Neuroscience and Disease, KU Leuven, O&N 4, Herestraat 49 Box 602, Leuven, 3000, Belgium.,Department of Fundamental Neuroscience, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
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8
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Extracellular matrix stiffness and cell contractility control RNA localization to promote cell migration. Nat Commun 2017; 8:896. [PMID: 29026081 PMCID: PMC5638855 DOI: 10.1038/s41467-017-00884-y] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 08/02/2017] [Indexed: 01/13/2023] Open
Abstract
Numerous RNAs are enriched within cellular protrusions, but the underlying mechanisms are largely unknown. We had shown that the APC (adenomatous polyposis coli) protein controls localization of some RNAs at protrusions. Here, using protrusion-isolation schemes and RNA-Seq, we find that RNAs localized in protrusions of migrating fibroblasts can be distinguished in two groups, which are differentially enriched in distinct types of protrusions, and are additionally differentially dependent on APC. APC-dependent RNAs become enriched in high-contractility protrusions and, accordingly, their localization is promoted by increasing stiffness of the extracellular matrix. Dissecting the underlying mechanism, we show that actomyosin contractility activates a RhoA-mDia1 signaling pathway that leads to formation of a detyrosinated-microtubule network, which in turn is required for localization of APC-dependent RNAs. Importantly, a competition-based approach to specifically mislocalize APC-dependent RNAs suggests that localization of the APC-dependent RNA subgroup is functionally important for cell migration.Adenomatous polyposis coli (APC) regulates the localization of some mRNAs at cellular protrusions but the underlying mechanisms and functional roles are not known. Here the authors show that APC-dependent RNAs are enriched in contractile protrusions, via detyrosinated microtubules, and enhance cell migration.
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9
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El Fatimy R, Davidovic L, Tremblay S, Jaglin X, Dury A, Robert C, De Koninck P, Khandjian EW. Tracking the Fragile X Mental Retardation Protein in a Highly Ordered Neuronal RiboNucleoParticles Population: A Link between Stalled Polyribosomes and RNA Granules. PLoS Genet 2016; 12:e1006192. [PMID: 27462983 PMCID: PMC4963131 DOI: 10.1371/journal.pgen.1006192] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 06/22/2016] [Indexed: 11/30/2022] Open
Abstract
Local translation at the synapse plays key roles in neuron development and activity-dependent synaptic plasticity. mRNAs are translocated from the neuronal soma to the distant synapses as compacted ribonucleoparticles referred to as RNA granules. These contain many RNA-binding proteins, including the Fragile X Mental Retardation Protein (FMRP), the absence of which results in Fragile X Syndrome, the most common inherited form of intellectual disability and the leading genetic cause of autism. Using FMRP as a tracer, we purified a specific population of RNA granules from mouse brain homogenates. Protein composition analyses revealed a strong relationship between polyribosomes and RNA granules. However, the latter have distinct architectural and structural properties, since they are detected as close compact structures as observed by electron microscopy, and converging evidence point to the possibility that these structures emerge from stalled polyribosomes. Time-lapse video microscopy indicated that single granules merge to form cargoes that are transported from the soma to distal locations. Transcriptomic analyses showed that a subset of mRNAs involved in cytoskeleton remodelling and neural development is selectively enriched in RNA granules. One third of the putative mRNA targets described for FMRP appear to be transported in granules and FMRP is more abundant in granules than in polyribosomes. This observation supports a primary role for FMRP in granules biology. Our findings open new avenues for the study of RNA granule dysfunctions in animal models of nervous system disorders, such as Fragile X syndrome. Fragile X syndrome is the most common form of inherited mental retardation affecting approximately 1 female out of 7000 and 1 male out of 4000 worldwide. The syndrome is due to the silencing of a single gene, the Fragile Mental Retardation 1 (FMR1), that codes for the Fragile X mental retardation protein (FMRP). This protein is highly expressed in brain and controls local protein synthesis essential for neuronal development and maturation as well as the formation of neural circuits. Several studies suggest a role for FMRP in the regulation of mRNA transport along axons and dendrites to distant synaptic locations in structures called RNA granules. Here we report the isolation of a particular subpopulation of these structures and the analysis of their architecture and composition in terms of RNA and protein. Also, using time-lapse video microscopy, we monitored granule transport and fusion throughout neuronal processes. These findings open new avenues for the study of RNA transport dysfunctions in animal models of nervous system disorders.
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Affiliation(s)
- Rachid El Fatimy
- Institut universitaire en santé mentale de Québec, Quebec, Canada
- Département de Psychiatrie et de Neurosciences, Faculté de Médecine, Université Laval, Québec, Quebec, Canada
| | - Laetitia Davidovic
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, Université de Nice-Sophia Antipolis, F-06560 Valbonne, France
| | - Sandra Tremblay
- Institut universitaire en santé mentale de Québec, Quebec, Canada
| | - Xavier Jaglin
- Neuroscience Institute, Department of Neuroscience and Physiology, New York University, New York, New York, United States of America
| | - Alain Dury
- Institut universitaire en santé mentale de Québec, Quebec, Canada
- Département de Psychiatrie et de Neurosciences, Faculté de Médecine, Université Laval, Québec, Quebec, Canada
| | - Claude Robert
- Centre de recherche en biologie de la reproduction, Département des sciences animales, Faculté des sciences de l’agriculture et de l’alimentation, Université Laval, Québec, Quebec, Canada
| | - Paul De Koninck
- Institut universitaire en santé mentale de Québec, Quebec, Canada
- Département de Biochimie, Microbiologie et Bio-Informatique, Université Laval, Québec, Quebec, Canada
| | - Edouard W. Khandjian
- Institut universitaire en santé mentale de Québec, Quebec, Canada
- Département de Psychiatrie et de Neurosciences, Faculté de Médecine, Université Laval, Québec, Quebec, Canada
- * E-mail:
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10
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Abstract
Fluorescence microscopy is employed to identify Kinesin-1 cargos. Recently, the heavy chain of Kinesin-1 (KIF5B) was shown to transport the nuclear transcription factor c-MYC for proteosomal degradation in the cytoplasm. The method described here involves the study of a motorless KIF5B mutant for fluorescence microscopy. The wild-type and motorless KIF5B proteins are tagged with the fluorescent protein tdTomato. The wild-type tdTomato-KIF5B appears homogenously in the cytoplasm, while the motorless tdTomato-KIF5B mutant forms aggregates in the cytoplasm. Aggregation of the motorless KIF5B mutant induces aggregation of its cargo c-MYC in the cytoplasm. Hence, this method provides a visual means to identify the cargos of Kinesin-1. A similar strategy can be utilized to identify cargos of other motor proteins.
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Affiliation(s)
- Clement M Lee
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai;
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11
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Czaplinski K. Understanding mRNA trafficking: Are we there yet? Semin Cell Dev Biol 2014; 32:63-70. [DOI: 10.1016/j.semcdb.2014.04.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 04/17/2014] [Indexed: 10/25/2022]
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