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CGG-repeat dynamics and FMR1 gene silencing in fragile X syndrome stem cells and stem cell-derived neurons / Y. ZHOU in Molecular Autism, 7 (2016)
[article]
Titre : CGG-repeat dynamics and FMR1 gene silencing in fragile X syndrome stem cells and stem cell-derived neurons Type de document : Texte imprimé et/ou numérique Auteurs : Y. ZHOU, Auteur ; D. KUMARI, Auteur ; N. SCIASCIA, Auteur ; K. USDIN, Auteur Article en page(s) : 42p. Langues : Anglais (eng) Mots-clés : 5' Untranslated Regions Alleles Cell Differentiation Cell Line DNA Methylation Embryonic Stem Cells/metabolism/pathology Fragile X Mental Retardation Protein/genetics/metabolism Fragile X Syndrome/genetics/metabolism/pathology Gene Silencing Humans Induced Pluripotent Stem Cells/metabolism/pathology Male Neurons/metabolism/pathology Primary Cell Culture Time Factors Trinucleotide Repeat Expansion Fragile X syndrome Repeat contractions Repeat expansion mutation Repeat-mediated gene silencing Stem cells Index. décimale : PER Périodiques Résumé : BACKGROUND: Fragile X syndrome (FXS), a common cause of intellectual disability and autism, results from the expansion of a CGG-repeat tract in the 5' untranslated region of the FMR1 gene to >200 repeats. Such expanded alleles, known as full mutation (FM) alleles, are epigenetically silenced in differentiated cells thus resulting in the loss of FMRP, a protein important for learning and memory. The timing of repeat expansion and FMR1 gene silencing is controversial. METHODS: We monitored the repeat size and methylation status of FMR1 alleles with expanded CGG repeats in patient-derived induced pluripotent stem cells (iPSCs) and embryonic stem cells (ESCs) that were grown for extended period of time either as stem cells or differentiated into neurons. We used a PCR assay optimized for the amplification of large CGG repeats for sizing, and a quantitative methylation-specific PCR for the analysis of FMR1 promoter methylation. The FMR1 mRNA levels were analyzed by qRT-PCR. FMRP levels were determined by western blotting and immunofluorescence. Chromatin immunoprecipitation was used to study the association of repressive histone marks with the FMR1 gene in FXS ESCs. RESULTS: We show here that while FMR1 gene silencing can be seen in FXS embryonic stem cells (ESCs), some silenced alleles contract and when the repeat number drops below ~400, DNA methylation erodes, even when the repeat number remains >200. The resultant active alleles do not show the large step-wise expansions seen in stem cells from other repeat expansion diseases. Furthermore, there may be selection against large active alleles and these alleles do not expand further or become silenced on neuronal differentiation. CONCLUSIONS: Our data support the hypotheses that (i) large expansions occur prezygotically or in the very early embryo, (ii) large unmethylated alleles may be deleterious in stem cells, (iii) methylation can occur on alleles with >400 repeats very early in embryogenesis, and (iv) expansion and contraction may occur by different mechanisms. Our data also suggest that the threshold for stable methylation of FM alleles may be higher than previously thought. A higher threshold might explain why some carriers of FM alleles escape methylation. It may also provide a simple explanation for why silencing has not been observed in mouse models with >200 repeats. En ligne : http://dx.doi.org/10.1186/s13229-016-0105-9 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=329
in Molecular Autism > 7 (2016) . - 42p.[article] CGG-repeat dynamics and FMR1 gene silencing in fragile X syndrome stem cells and stem cell-derived neurons [Texte imprimé et/ou numérique] / Y. ZHOU, Auteur ; D. KUMARI, Auteur ; N. SCIASCIA, Auteur ; K. USDIN, Auteur . - 42p.
Langues : Anglais (eng)
in Molecular Autism > 7 (2016) . - 42p.
Mots-clés : 5' Untranslated Regions Alleles Cell Differentiation Cell Line DNA Methylation Embryonic Stem Cells/metabolism/pathology Fragile X Mental Retardation Protein/genetics/metabolism Fragile X Syndrome/genetics/metabolism/pathology Gene Silencing Humans Induced Pluripotent Stem Cells/metabolism/pathology Male Neurons/metabolism/pathology Primary Cell Culture Time Factors Trinucleotide Repeat Expansion Fragile X syndrome Repeat contractions Repeat expansion mutation Repeat-mediated gene silencing Stem cells Index. décimale : PER Périodiques Résumé : BACKGROUND: Fragile X syndrome (FXS), a common cause of intellectual disability and autism, results from the expansion of a CGG-repeat tract in the 5' untranslated region of the FMR1 gene to >200 repeats. Such expanded alleles, known as full mutation (FM) alleles, are epigenetically silenced in differentiated cells thus resulting in the loss of FMRP, a protein important for learning and memory. The timing of repeat expansion and FMR1 gene silencing is controversial. METHODS: We monitored the repeat size and methylation status of FMR1 alleles with expanded CGG repeats in patient-derived induced pluripotent stem cells (iPSCs) and embryonic stem cells (ESCs) that were grown for extended period of time either as stem cells or differentiated into neurons. We used a PCR assay optimized for the amplification of large CGG repeats for sizing, and a quantitative methylation-specific PCR for the analysis of FMR1 promoter methylation. The FMR1 mRNA levels were analyzed by qRT-PCR. FMRP levels were determined by western blotting and immunofluorescence. Chromatin immunoprecipitation was used to study the association of repressive histone marks with the FMR1 gene in FXS ESCs. RESULTS: We show here that while FMR1 gene silencing can be seen in FXS embryonic stem cells (ESCs), some silenced alleles contract and when the repeat number drops below ~400, DNA methylation erodes, even when the repeat number remains >200. The resultant active alleles do not show the large step-wise expansions seen in stem cells from other repeat expansion diseases. Furthermore, there may be selection against large active alleles and these alleles do not expand further or become silenced on neuronal differentiation. CONCLUSIONS: Our data support the hypotheses that (i) large expansions occur prezygotically or in the very early embryo, (ii) large unmethylated alleles may be deleterious in stem cells, (iii) methylation can occur on alleles with >400 repeats very early in embryogenesis, and (iv) expansion and contraction may occur by different mechanisms. Our data also suggest that the threshold for stable methylation of FM alleles may be higher than previously thought. A higher threshold might explain why some carriers of FM alleles escape methylation. It may also provide a simple explanation for why silencing has not been observed in mouse models with >200 repeats. En ligne : http://dx.doi.org/10.1186/s13229-016-0105-9 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=329 Deletion of Fmr1 in parvalbumin-expressing neurons results in dysregulated translation and selective behavioral deficits associated with fragile X syndrome / Magdalena KALINOWSKA in Molecular Autism, 13 (2022)
[article]
Titre : Deletion of Fmr1 in parvalbumin-expressing neurons results in dysregulated translation and selective behavioral deficits associated with fragile X syndrome Type de document : Texte imprimé et/ou numérique Auteurs : Magdalena KALINOWSKA, Auteur ; Mathijs B. VAN DER LEI, Auteur ; Michael KITIASHVILI, Auteur ; Maggie MAMCARZ, Auteur ; Mauricio M. OLIVEIRA, Auteur ; Francesco LONGO, Auteur ; Eric KLANN, Auteur Article en page(s) : 29 p. Langues : Anglais (eng) Mots-clés : Animals Autism Spectrum Disorder/metabolism Disease Models, Animal Fragile X Mental Retardation Protein/genetics/metabolism Fragile X Syndrome/genetics/metabolism/pathology Mice Mice, Knockout Neurons/metabolism/pathology Parvalbumins/metabolism RNA, Messenger/metabolism Somatostatin/metabolism Autism Behavior Fmrp Fragile X syndrome Inhibitory neurons Protein synthesis Index. décimale : PER Périodiques Résumé : BACKGROUND: Fragile X syndrome (FXS), the most common genetic cause of autism spectrum disorder and intellectual disability, is caused by the lack of fragile X mental retardation protein (FMRP) expression. FMRP is an mRNA binding protein with functions in mRNA transport, localization, and translational control. In Fmr1 knockout mice, dysregulated translation has been linked to pathophysiology, including abnormal synaptic function and dendritic morphology, and autistic-like behavioral phenotypes. The role of FMRP in morphology and function of excitatory neurons has been well studied in mice lacking Fmr1, but the impact of Fmr1 deletion on inhibitory neurons remains less characterized. Moreover, the contribution of FMRP in different cell types to FXS pathophysiology is not well defined. We sought to characterize whether FMRP loss in parvalbumin or somatostatin-expressing neurons results in FXS-like deficits in mice. METHODS: We used Cre-lox recombinase technology to generate two lines of conditional knockout mice lacking FMRP in either parvalbumin or somatostatin-expressing cells and carried out a battery of behavioral tests to assess motor function, anxiety, repetitive, stereotypic, social behaviors, and learning and memory. In addition, we used fluorescent non-canonical amino acid tagging along with immunostaining to determine whether de novo protein synthesis is dysregulated in parvalbumin or somatostatin-expressing neurons. RESULTS: De novo protein synthesis was elevated in hippocampal parvalbumin and somatostatin-expressing inhibitory neurons in Fmr1 knockout mice. Cell type-specific deletion of Fmr1 in parvalbumin-expressing neurons resulted in anxiety-like behavior, impaired social behavior, and dysregulated de novo protein synthesis. In contrast, deletion of Fmr1 in somatostatin-expressing neurons did not result in behavioral abnormalities and did not significantly impact de novo protein synthesis. This is the first report of how loss of FMRP in two specific subtypes of inhibitory neurons is associated with distinct FXS-like abnormalities. LIMITATIONS: The mouse models we generated are limited by whole body knockout of FMRP in parvalbumin or somatostatin-expressing cells and further studies are needed to establish a causal relationship between cellular deficits and FXS-like behaviors. CONCLUSIONS: Our findings indicate a cell type-specific role for FMRP in parvalbumin-expressing neurons in regulating distinct behavioral features associated with FXS. En ligne : http://dx.doi.org/10.1186/s13229-022-00509-2 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=491
in Molecular Autism > 13 (2022) . - 29 p.[article] Deletion of Fmr1 in parvalbumin-expressing neurons results in dysregulated translation and selective behavioral deficits associated with fragile X syndrome [Texte imprimé et/ou numérique] / Magdalena KALINOWSKA, Auteur ; Mathijs B. VAN DER LEI, Auteur ; Michael KITIASHVILI, Auteur ; Maggie MAMCARZ, Auteur ; Mauricio M. OLIVEIRA, Auteur ; Francesco LONGO, Auteur ; Eric KLANN, Auteur . - 29 p.
Langues : Anglais (eng)
in Molecular Autism > 13 (2022) . - 29 p.
Mots-clés : Animals Autism Spectrum Disorder/metabolism Disease Models, Animal Fragile X Mental Retardation Protein/genetics/metabolism Fragile X Syndrome/genetics/metabolism/pathology Mice Mice, Knockout Neurons/metabolism/pathology Parvalbumins/metabolism RNA, Messenger/metabolism Somatostatin/metabolism Autism Behavior Fmrp Fragile X syndrome Inhibitory neurons Protein synthesis Index. décimale : PER Périodiques Résumé : BACKGROUND: Fragile X syndrome (FXS), the most common genetic cause of autism spectrum disorder and intellectual disability, is caused by the lack of fragile X mental retardation protein (FMRP) expression. FMRP is an mRNA binding protein with functions in mRNA transport, localization, and translational control. In Fmr1 knockout mice, dysregulated translation has been linked to pathophysiology, including abnormal synaptic function and dendritic morphology, and autistic-like behavioral phenotypes. The role of FMRP in morphology and function of excitatory neurons has been well studied in mice lacking Fmr1, but the impact of Fmr1 deletion on inhibitory neurons remains less characterized. Moreover, the contribution of FMRP in different cell types to FXS pathophysiology is not well defined. We sought to characterize whether FMRP loss in parvalbumin or somatostatin-expressing neurons results in FXS-like deficits in mice. METHODS: We used Cre-lox recombinase technology to generate two lines of conditional knockout mice lacking FMRP in either parvalbumin or somatostatin-expressing cells and carried out a battery of behavioral tests to assess motor function, anxiety, repetitive, stereotypic, social behaviors, and learning and memory. In addition, we used fluorescent non-canonical amino acid tagging along with immunostaining to determine whether de novo protein synthesis is dysregulated in parvalbumin or somatostatin-expressing neurons. RESULTS: De novo protein synthesis was elevated in hippocampal parvalbumin and somatostatin-expressing inhibitory neurons in Fmr1 knockout mice. Cell type-specific deletion of Fmr1 in parvalbumin-expressing neurons resulted in anxiety-like behavior, impaired social behavior, and dysregulated de novo protein synthesis. In contrast, deletion of Fmr1 in somatostatin-expressing neurons did not result in behavioral abnormalities and did not significantly impact de novo protein synthesis. This is the first report of how loss of FMRP in two specific subtypes of inhibitory neurons is associated with distinct FXS-like abnormalities. LIMITATIONS: The mouse models we generated are limited by whole body knockout of FMRP in parvalbumin or somatostatin-expressing cells and further studies are needed to establish a causal relationship between cellular deficits and FXS-like behaviors. CONCLUSIONS: Our findings indicate a cell type-specific role for FMRP in parvalbumin-expressing neurons in regulating distinct behavioral features associated with FXS. En ligne : http://dx.doi.org/10.1186/s13229-022-00509-2 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=491