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Synaptic vesicle dynamic changes in a model of fragile X

BACKGROUND: Fragile X syndrome (FXS) is a single-gene disorder that is the most common heritable cause of intellectual disability and the most frequent monogenic cause of autism spectrum disorders (ASD). FXS is caused by an expansion of trinucleotide repeats in the promoter region of the fragile X m...

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Autores principales: Broek, Jantine A. C., Lin, Zhanmin, de Gruiter, H. Martijn, van ‘t Spijker, Heleen, Haasdijk, Elize D., Cox, David, Ozcan, Sureyya, van Cappellen, Gert W. A., Houtsmuller, Adriaan B., Willemsen, Rob, de Zeeuw, Chris I., Bahn, Sabine
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4772588/
https://www.ncbi.nlm.nih.gov/pubmed/26933487
http://dx.doi.org/10.1186/s13229-016-0080-1
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author Broek, Jantine A. C.
Lin, Zhanmin
de Gruiter, H. Martijn
van ‘t Spijker, Heleen
Haasdijk, Elize D.
Cox, David
Ozcan, Sureyya
van Cappellen, Gert W. A.
Houtsmuller, Adriaan B.
Willemsen, Rob
de Zeeuw, Chris I.
Bahn, Sabine
author_facet Broek, Jantine A. C.
Lin, Zhanmin
de Gruiter, H. Martijn
van ‘t Spijker, Heleen
Haasdijk, Elize D.
Cox, David
Ozcan, Sureyya
van Cappellen, Gert W. A.
Houtsmuller, Adriaan B.
Willemsen, Rob
de Zeeuw, Chris I.
Bahn, Sabine
author_sort Broek, Jantine A. C.
collection PubMed
description BACKGROUND: Fragile X syndrome (FXS) is a single-gene disorder that is the most common heritable cause of intellectual disability and the most frequent monogenic cause of autism spectrum disorders (ASD). FXS is caused by an expansion of trinucleotide repeats in the promoter region of the fragile X mental retardation gene (Fmr1). This leads to a lack of fragile X mental retardation protein (FMRP), which regulates translation of a wide range of messenger RNAs (mRNAs). The extent of expression level alterations of synaptic proteins affected by FMRP loss and their consequences on synaptic dynamics in FXS has not been fully investigated. METHODS: Here, we used an Fmr1 knockout (KO) mouse model to investigate the molecular mechanisms underlying FXS by monitoring protein expression changes using shotgun label-free liquid-chromatography mass spectrometry (LC-MS(E)) in brain tissue and synaptosome fractions. FXS-associated candidate proteins were validated using selected reaction monitoring (SRM) in synaptosome fractions for targeted protein quantification. Furthermore, functional alterations in synaptic release and dynamics were evaluated using live-cell imaging, and interpretation of synaptic dynamics differences was investigated using electron microscopy. RESULTS: Key findings relate to altered levels of proteins involved in GABA-signalling, especially in the cerebellum. Further exploration using microscopy studies found reduced synaptic vesicle unloading of hippocampal neurons and increased vesicle unloading in cerebellar neurons, which suggests a general decrease of synaptic transmission. CONCLUSIONS: Our findings suggest that FMRP is a regulator of synaptic vesicle dynamics, which supports the role of FMRP in presynaptic functions. Taken together, these studies provide novel insights into the molecular changes associated with FXS. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13229-016-0080-1) contains supplementary material, which is available to authorized users.
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spelling pubmed-47725882016-03-02 Synaptic vesicle dynamic changes in a model of fragile X Broek, Jantine A. C. Lin, Zhanmin de Gruiter, H. Martijn van ‘t Spijker, Heleen Haasdijk, Elize D. Cox, David Ozcan, Sureyya van Cappellen, Gert W. A. Houtsmuller, Adriaan B. Willemsen, Rob de Zeeuw, Chris I. Bahn, Sabine Mol Autism Research BACKGROUND: Fragile X syndrome (FXS) is a single-gene disorder that is the most common heritable cause of intellectual disability and the most frequent monogenic cause of autism spectrum disorders (ASD). FXS is caused by an expansion of trinucleotide repeats in the promoter region of the fragile X mental retardation gene (Fmr1). This leads to a lack of fragile X mental retardation protein (FMRP), which regulates translation of a wide range of messenger RNAs (mRNAs). The extent of expression level alterations of synaptic proteins affected by FMRP loss and their consequences on synaptic dynamics in FXS has not been fully investigated. METHODS: Here, we used an Fmr1 knockout (KO) mouse model to investigate the molecular mechanisms underlying FXS by monitoring protein expression changes using shotgun label-free liquid-chromatography mass spectrometry (LC-MS(E)) in brain tissue and synaptosome fractions. FXS-associated candidate proteins were validated using selected reaction monitoring (SRM) in synaptosome fractions for targeted protein quantification. Furthermore, functional alterations in synaptic release and dynamics were evaluated using live-cell imaging, and interpretation of synaptic dynamics differences was investigated using electron microscopy. RESULTS: Key findings relate to altered levels of proteins involved in GABA-signalling, especially in the cerebellum. Further exploration using microscopy studies found reduced synaptic vesicle unloading of hippocampal neurons and increased vesicle unloading in cerebellar neurons, which suggests a general decrease of synaptic transmission. CONCLUSIONS: Our findings suggest that FMRP is a regulator of synaptic vesicle dynamics, which supports the role of FMRP in presynaptic functions. Taken together, these studies provide novel insights into the molecular changes associated with FXS. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13229-016-0080-1) contains supplementary material, which is available to authorized users. BioMed Central 2016-03-01 /pmc/articles/PMC4772588/ /pubmed/26933487 http://dx.doi.org/10.1186/s13229-016-0080-1 Text en © Broek et al. 2016 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research
Broek, Jantine A. C.
Lin, Zhanmin
de Gruiter, H. Martijn
van ‘t Spijker, Heleen
Haasdijk, Elize D.
Cox, David
Ozcan, Sureyya
van Cappellen, Gert W. A.
Houtsmuller, Adriaan B.
Willemsen, Rob
de Zeeuw, Chris I.
Bahn, Sabine
Synaptic vesicle dynamic changes in a model of fragile X
title Synaptic vesicle dynamic changes in a model of fragile X
title_full Synaptic vesicle dynamic changes in a model of fragile X
title_fullStr Synaptic vesicle dynamic changes in a model of fragile X
title_full_unstemmed Synaptic vesicle dynamic changes in a model of fragile X
title_short Synaptic vesicle dynamic changes in a model of fragile X
title_sort synaptic vesicle dynamic changes in a model of fragile x
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4772588/
https://www.ncbi.nlm.nih.gov/pubmed/26933487
http://dx.doi.org/10.1186/s13229-016-0080-1
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