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Ginevra Zanni - One of the best experts on this subject based on the ideXlab platform.
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Rho Kinase Inhibition Is Essential During In Vitro Neurogenesis and Promotes Phenotypic Rescue of Human Induced Pluripotent Stem Cell-Derived Neurons With Oligophrenin-1 Loss of Function
Stem cells translational medicine, 2016Co-Authors: Claudia Compagnucci, Enrico Bertini, Pierre Billuart, Pietro Chiurazzi, Sabina Barresi, Stefania Petrini, Giorgia Piccini, Paolo Alfieri, Ginevra ZanniAbstract:UNLABELLED : Rho-GTPases have relevant functions in various aspects of neuronal development, such as differentiation, migration, and synaptogenesis. Loss of function of the oligophrenin-1 gene (OPHN1) causes X-linked intellectual disability with cerebellar hypoplasia and leads to hyperactivation of the rho kinase (ROCK) pathway. ROCK mainly acts through phosphorylation of the myosin phosphatase targeting subunit 1, triggering actin-myosin contractility. We show that during in vitro neurogenesis, ROCK activity decreases from day 10 until terminal differentiation, whereas in OPHN1-deficient human induced pluripotent stem cells (h-iPSCs), the levels of ROCK are elevated throughout differentiation. ROCK inhibition favors neuronal-like appearance of h-iPSCs, in parallel with transcriptional upregulation of nuclear receptor NR4A1, which is known to induce neurite outgrowth. This study analyzed the morphological, biochemical, and functional features of OPHN1-deficient h-iPSCs and their rescue by treatment with the ROCK inhibitor fasudil, shedding light on the relevance of the ROCK pathway during neuronal differentiation and providing a neuronal model for human OPHN1 syndrome and its treatment. SIGNIFICANCE The analysis of the levels of rho kinase (ROCK) activity at different stages of in vitro neurogenesis of human induced pluripotent stem cells reveals that ROCK activity decreases progressively in parallel with the appearance of neuronal-like morphology and upregulation of nuclear receptor NR4A1. These results shed light on the role of the ROCK pathway during early stages of human neurogenesis and provide a neuronal stem cell-based model for the treatment of OPHN1 syndrome and other neurological disorders due to ROCK dysfunction.
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oligophrenin 1 OPHN1 a gene involved in x linked intellectual disability undergoes rna editing and alternative splicing during human brain development
PLOS ONE, 2014Co-Authors: Sabina Barresi, Ginevra Zanni, Enrico Bertini, Sara Tomaselli, Alekos Athanasiadis, Federica Galeano, Franco Locatelli, Angela GalloAbstract:Oligophrenin-1 (OPHN1) encodes for a Rho-GTPase-activating protein, important for dendritic morphogenesis and synaptic function. Mutations in this gene have been identified in patients with X-linked intellectual disability associated with cerebellar hypoplasia. ADAR enzymes are responsible for A-to-I RNA editing, an essential post-transcriptional RNA modification contributing to transcriptome and proteome diversification. Specifically, ADAR2 activity is essential for brain development and function. Herein, we show that the OPHN1 transcript undergoes post-transcriptional modifications such as A-to-I RNA editing and alternative splicing in human brain and other tissues. We found that OPHN1 editing is detectable already at the 18th week of gestation in human brain with a boost of editing at weeks 20 to 33, concomitantly with OPHN1 expression increase and the appearance of a novel OPHN1 splicing isoform. Our results demonstrate that multiple post-transcriptional events occur on OPHN1, a gene playing an important role in brain function and development.
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Oligophrenin-1 (OPHN1), a Gene Involved in X-Linked Intellectual Disability, Undergoes RNA Editing and Alternative Splicing during Human Brain Development
2014Co-Authors: Sabina Barresi, Ginevra Zanni, Enrico Bertini, Sara Tomaselli, Alekos Athanasiadis, Federica Galeano, Franco Locatelli, Angela GalloAbstract:Oligophrenin-1 (OPHN1) encodes for a Rho-GTPase-activating protein, important for dendritic morphogenesis and synaptic function. Mutations in this gene have been identified in patients with X-linked intellectual disability associated with cerebellar hypoplasia. ADAR enzymes are responsible for A-to-I RNA editing, an essential post-transcriptional RNA modification contributing to transcriptome and proteome diversification. Specifically, ADAR2 activity is essential for brain development and function. Herein, we show that the OPHN1 transcript undergoes post-transcriptional modifications such as A-to-I RNA editing and alternative splicing in human brain and other tissues. We found that OPHN1 editing is detectable already at the 18th week of gestation in human brain with a boost of editing at weeks 20 to 33, concomitantly with OPHN1 expression increase and the appearance of a novel OPHN1 splicing isoform. Our results demonstrate that multiple post
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Novel OPHN1 splicing isoforms.
2014Co-Authors: Sabina Barresi, Ginevra Zanni, Enrico Bertini, Sara Tomaselli, Alekos Athanasiadis, Federica Galeano, Franco Locatelli, Angela GalloAbstract:(A) Schematic representation of the OPHN1 pre-mRNA region (exons 8–11) undergoing alternative splicing events. (B) Partial sequence chromatograms of cDNAs (left side) with the corresponding schematic representations (right side) of the full length OPHN1 (upper sequence) and of the two novel OPHN1 alternative isoforms (middle and bottom sequences). (C) The putative protein sequence, derived from the skipping of exon 10 (isoform 9–11) carrying a novel COOH portion, is shown. (D) Protein domains of OPHN1 isoforms. The isoform 8–11 carries the BAR and the PH domains at a closer proximity compared to the full length, with possible consequences on protein conformation/activity. The isoform 9–11 carries only the BAR domain. As both the Rho-GTPase activity domain and the PR domains are lost in this isoform, the downstream signalling and the interaction with the actin cytoskeleton could be affected. This isoform displays a new COOH terminal portion of 33 amino acid (shown in blue in the cartoon), with still unknown functions and displaying no homology with known proteins (data not shown). BAR = Bin/Amphiphysin/Rvs, PH = Pleckstrin Homology, GAP = Rho-GTPase Activating Protein, PR = Proline Rich.
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Human OPHN1 gene and transcript organization.
2014Co-Authors: Sabina Barresi, Ginevra Zanni, Enrico Bertini, Sara Tomaselli, Alekos Athanasiadis, Federica Galeano, Franco Locatelli, Angela GalloAbstract:(A) Schematic representation of OPHN1 gene with exons represented as light grey rectangles and introns as black lines. Blue arrows indicate AluJo and AluSz within intron 9–10. (B) The predicted dsRNA secondary structure (by Zuker algorithm) formed by the AluJo and AluSz sequences. In detail a portion of the dsRNA structure with red rectangles indicating the edited adenosines. (C) OPHN1 pre-mRNA sequence of the intron 9–10, showing the AluJo and AluSz regions and the 33 adenosines that undergo editing in grey boxes.
Pierre Billuart - One of the best experts on this subject based on the ideXlab platform.
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ROCK/PKA inhibition rescues hippocampal hyperexcitability and GABAergic neuron alterations in Oligophrenin-1 Knock-out mouse model of X-linked intellectual disability
Journal of Neuroscience, 2020Co-Authors: Irene Busti, Pierre Billuart, Manuela Allegra, Cristina Spalletti, Chiara Panzi, Laura Restani, Matteo CaleoAbstract:Oligophrenin-1 (OPHN1) encodes a Rho GTPase activating protein whose mutations cause X-linked intellectual disability (XLID) in humans. Loss of function of OPHN1 leads to impairments in the maturation and function of excitatory and inhibitory synapses, causing deficits in synaptic structure, function and plasticity. Epilepsy is a frequent co-morbidity in patients with OPHN1-dependent XLID, but the cellular bases of hyperexcitability are poorly understood. Here we report that male mice knock-out (KO) for OPHN1 display hippocampal epileptiform alterations, which are associated with changes in parvalbumin-, somatostatin- and neuropeptide Y-positive interneurons. Since loss of function of OPHN1 is related to enhanced activity of Rho-associated protein kinase (ROCK) and protein kinase A (PKA), we attempted to rescue OPHN1-dependent pathological phenotypes by treatment with the ROCK/PKA inhibitor Fasudil. While acute administration of Fasudil had no impact on seizure activity, seven weeks of treatment in adulthood were able to correct electrographic, neuroanatomical and synaptic alterations of OPHN1 deficient mice. These data demonstrate that hyperexcitability and the associated changes in GABAergic markers can be rescued at the adult stage in OPHN1-dependent XLID through ROCK/PKA inhibition.Significance Statement: In this study we demonstrate enhanced seizure propensity and impairments in hippocampal GABAergic circuitry in OPHN1 mouse model of XLID. Importantly, the enhanced susceptibility to seizures, accompanied by an alteration of GABAergic markers were rescued by ROCK/PKA inhibitor Fasudil, a drug already tested on humans. Since seizures can significantly impact the quality of life of XLID patients, the present data suggest a potential therapeutic pathway to correct alterations in GABAergic networks and dampen pathological hyperexcitability in adults with XLID.
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Pharmacological rescue of adult hippocampal neurogenesis in a mouse model of X-linked intellectual disability
Neurobiology of disease, 2017Co-Authors: Manuela Allegra, Pierre Billuart, Cristina Spalletti, Beatrice Vignoli, Stefano Azzimondi, Irene Busti, Marco Canossa, Matteo CaleoAbstract:Oligophrenin-1 (OPHN1) is a Rho GTPase activating protein whose mutations cause X-linked intellectual disability (XLID). How loss of function of OPHN1 affects neuronal development is only partly understood. Here we have exploited adult hippocampal neurogenesis to dissect the steps of neuronal differentiation that are affected by OPHN1 deletion. We found that mice lacking OPHN1 display a reduction in the number of newborn neurons in the dentate gyrus. A significant fraction of the OPHN1-deficient newly generated neurons failed to extend an axon towards CA3, and showed an altered density of dendritic protrusions. Since OPHN1-deficient mice display overactivation of Rho-associated protein kinase (ROCK) and protein kinase A (PKA) signaling, we administered a clinically approved ROCK/PKA inhibitor (fasudil) to correct the neurogenesis defects. While administration of fasudil was not effective in rescuing axon formation, the same treatment completely restored spine density to control levels, and enhanced the long-term survival of adult-born neurons in mice lacking OPHN1. These results identify specific neurodevelopmental steps that are impacted by OPHN1 deletion, and indicate that they may be at least partially corrected by pharmacological treatment.
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Oligophrenin-1 regulates number, morphology and synaptic properties of adult-born inhibitory interneurons in the olfactory bulb.
Human molecular genetics, 2016Co-Authors: Nelly Redolfi, Pierre Billuart, Andrea Maset, Luisa Galla, Luca Murru, Eleonora Savoia, Ilaria Zamparo, Angela Gritti, Maria Passafaro, Claudia LodovichiAbstract:Among the X-linked genes associated with intellectual disability, Oligophrenin-1 (OPHN1) encodes for a Rho GTPase-activating protein, a key regulator of several developmental processes, such as dendrite and spine formation and synaptic activity. Inhibitory interneurons play a key role in the development and function of neuronal circuits. Whether a mutation of OPHN1 can affect morphology and synaptic properties of inhibitory interneurons remains poorly understood. To address these open questions, we studied in a well-established mouse model of X-linked intellectual disability, i.e. a line of mice carrying a null mutation of OPHN1, the development and function of adult generated inhibitory interneurons in the olfactory bulb. Combining quantitative morphological analysis and electrophysiological recordings we found that the adult generated inhibitory interneurons were dramatically reduced in number and exhibited a higher proportion of filopodia-like spines, with the consequences on their synaptic function, in OPHN1 ko mice. Furthermore, we found that olfactory behaviour was perturbed in OPHN1 ko mice. Chronic treatment with a Rho kinase inhibitor rescued most of the defects of the newly generated neurons. Altogether, our data indicated that OPHN1 plays a key role in regulating the number, morphology and function of adult-born inhibitory interneurons and contributed to identify potential therapeutic targets.
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Rho Kinase Inhibition Is Essential During In Vitro Neurogenesis and Promotes Phenotypic Rescue of Human Induced Pluripotent Stem Cell-Derived Neurons With Oligophrenin-1 Loss of Function
Stem cells translational medicine, 2016Co-Authors: Claudia Compagnucci, Enrico Bertini, Pierre Billuart, Pietro Chiurazzi, Sabina Barresi, Stefania Petrini, Giorgia Piccini, Paolo Alfieri, Ginevra ZanniAbstract:UNLABELLED : Rho-GTPases have relevant functions in various aspects of neuronal development, such as differentiation, migration, and synaptogenesis. Loss of function of the oligophrenin-1 gene (OPHN1) causes X-linked intellectual disability with cerebellar hypoplasia and leads to hyperactivation of the rho kinase (ROCK) pathway. ROCK mainly acts through phosphorylation of the myosin phosphatase targeting subunit 1, triggering actin-myosin contractility. We show that during in vitro neurogenesis, ROCK activity decreases from day 10 until terminal differentiation, whereas in OPHN1-deficient human induced pluripotent stem cells (h-iPSCs), the levels of ROCK are elevated throughout differentiation. ROCK inhibition favors neuronal-like appearance of h-iPSCs, in parallel with transcriptional upregulation of nuclear receptor NR4A1, which is known to induce neurite outgrowth. This study analyzed the morphological, biochemical, and functional features of OPHN1-deficient h-iPSCs and their rescue by treatment with the ROCK inhibitor fasudil, shedding light on the relevance of the ROCK pathway during neuronal differentiation and providing a neuronal model for human OPHN1 syndrome and its treatment. SIGNIFICANCE The analysis of the levels of rho kinase (ROCK) activity at different stages of in vitro neurogenesis of human induced pluripotent stem cells reveals that ROCK activity decreases progressively in parallel with the appearance of neuronal-like morphology and upregulation of nuclear receptor NR4A1. These results shed light on the role of the ROCK pathway during early stages of human neurogenesis and provide a neuronal stem cell-based model for the treatment of OPHN1 syndrome and other neurological disorders due to ROCK dysfunction.
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Oligophrenin1 protects mice against myocardial ischemia and reperfusion injury by modulating inflammation and myocardial apoptosis.
Cellular signalling, 2016Co-Authors: Christina Niermann, Pierre Billuart, Simone Gorressen, Meike Klier, Nina Sarah Gowert, Malte Kelm, Marc W. Merx, Margitta ElversAbstract:Abstract The Rho family of small GTPases has been analyzed in cardiac physiology and pathophysiology including myocardial infarction (MI) in the last years. Contradictory results show either a protective or a declined effect of RhoA and the RhoA effector Rho-associated protein kinase (ROCK) in myocardial ischemia and reperfusion injury that is associated with cardiomyocyte survival and caspase-3 activation. Cardiac-specific deletion of Rac1 reduced ischemia reperfusion injury in diabetic hearts, whereas cardiomyocyte specific overexpression of active Rac1 predisposes the heart to increased myocardial injury with enhanced contractile dysfunction. GTPase-activating proteins (GAPs) control the activation of Rho proteins through stimulation of GTP hydrolysis. However, the impact of GAPs in myocardial ischemia and reperfusion injury remains elusive. Here we analyzed the role of oligophrenin1 (OPHN1), a RhoGAP with Bin/Amphiphysin/Rvs (BAR) domain known to regulate the activity of RhoA, Rac1 and Cdc42 in MI. The expression of OPHN1, RhoA and Rac1 is strongly upregulated 24 h after myocardial ischemia. Loss of OPHN1 induced enhanced activity of Rho effector molecules leading to elevated cardiomyocyte apoptosis and increased migration of inflammatory cells into the infarct border zone of OPHN1 deficient mice. Consequently, echocardiography 24 h after myocardial ischemia revealed declined left ventricle function in OPHN1 deficient mice. Our results indicate that OPHN1 mediated regulation of RhoA, Rac1 and Cdc42 is crucial for the preservation of cardiac function after myocardial injury.
Enrico Bertini - One of the best experts on this subject based on the ideXlab platform.
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Rho Kinase Inhibition Is Essential During In Vitro Neurogenesis and Promotes Phenotypic Rescue of Human Induced Pluripotent Stem Cell-Derived Neurons With Oligophrenin-1 Loss of Function
Stem cells translational medicine, 2016Co-Authors: Claudia Compagnucci, Enrico Bertini, Pierre Billuart, Pietro Chiurazzi, Sabina Barresi, Stefania Petrini, Giorgia Piccini, Paolo Alfieri, Ginevra ZanniAbstract:UNLABELLED : Rho-GTPases have relevant functions in various aspects of neuronal development, such as differentiation, migration, and synaptogenesis. Loss of function of the oligophrenin-1 gene (OPHN1) causes X-linked intellectual disability with cerebellar hypoplasia and leads to hyperactivation of the rho kinase (ROCK) pathway. ROCK mainly acts through phosphorylation of the myosin phosphatase targeting subunit 1, triggering actin-myosin contractility. We show that during in vitro neurogenesis, ROCK activity decreases from day 10 until terminal differentiation, whereas in OPHN1-deficient human induced pluripotent stem cells (h-iPSCs), the levels of ROCK are elevated throughout differentiation. ROCK inhibition favors neuronal-like appearance of h-iPSCs, in parallel with transcriptional upregulation of nuclear receptor NR4A1, which is known to induce neurite outgrowth. This study analyzed the morphological, biochemical, and functional features of OPHN1-deficient h-iPSCs and their rescue by treatment with the ROCK inhibitor fasudil, shedding light on the relevance of the ROCK pathway during neuronal differentiation and providing a neuronal model for human OPHN1 syndrome and its treatment. SIGNIFICANCE The analysis of the levels of rho kinase (ROCK) activity at different stages of in vitro neurogenesis of human induced pluripotent stem cells reveals that ROCK activity decreases progressively in parallel with the appearance of neuronal-like morphology and upregulation of nuclear receptor NR4A1. These results shed light on the role of the ROCK pathway during early stages of human neurogenesis and provide a neuronal stem cell-based model for the treatment of OPHN1 syndrome and other neurological disorders due to ROCK dysfunction.
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oligophrenin 1 OPHN1 a gene involved in x linked intellectual disability undergoes rna editing and alternative splicing during human brain development
PLOS ONE, 2014Co-Authors: Sabina Barresi, Ginevra Zanni, Enrico Bertini, Sara Tomaselli, Alekos Athanasiadis, Federica Galeano, Franco Locatelli, Angela GalloAbstract:Oligophrenin-1 (OPHN1) encodes for a Rho-GTPase-activating protein, important for dendritic morphogenesis and synaptic function. Mutations in this gene have been identified in patients with X-linked intellectual disability associated with cerebellar hypoplasia. ADAR enzymes are responsible for A-to-I RNA editing, an essential post-transcriptional RNA modification contributing to transcriptome and proteome diversification. Specifically, ADAR2 activity is essential for brain development and function. Herein, we show that the OPHN1 transcript undergoes post-transcriptional modifications such as A-to-I RNA editing and alternative splicing in human brain and other tissues. We found that OPHN1 editing is detectable already at the 18th week of gestation in human brain with a boost of editing at weeks 20 to 33, concomitantly with OPHN1 expression increase and the appearance of a novel OPHN1 splicing isoform. Our results demonstrate that multiple post-transcriptional events occur on OPHN1, a gene playing an important role in brain function and development.
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Oligophrenin-1 (OPHN1), a Gene Involved in X-Linked Intellectual Disability, Undergoes RNA Editing and Alternative Splicing during Human Brain Development
2014Co-Authors: Sabina Barresi, Ginevra Zanni, Enrico Bertini, Sara Tomaselli, Alekos Athanasiadis, Federica Galeano, Franco Locatelli, Angela GalloAbstract:Oligophrenin-1 (OPHN1) encodes for a Rho-GTPase-activating protein, important for dendritic morphogenesis and synaptic function. Mutations in this gene have been identified in patients with X-linked intellectual disability associated with cerebellar hypoplasia. ADAR enzymes are responsible for A-to-I RNA editing, an essential post-transcriptional RNA modification contributing to transcriptome and proteome diversification. Specifically, ADAR2 activity is essential for brain development and function. Herein, we show that the OPHN1 transcript undergoes post-transcriptional modifications such as A-to-I RNA editing and alternative splicing in human brain and other tissues. We found that OPHN1 editing is detectable already at the 18th week of gestation in human brain with a boost of editing at weeks 20 to 33, concomitantly with OPHN1 expression increase and the appearance of a novel OPHN1 splicing isoform. Our results demonstrate that multiple post
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Novel OPHN1 splicing isoforms.
2014Co-Authors: Sabina Barresi, Ginevra Zanni, Enrico Bertini, Sara Tomaselli, Alekos Athanasiadis, Federica Galeano, Franco Locatelli, Angela GalloAbstract:(A) Schematic representation of the OPHN1 pre-mRNA region (exons 8–11) undergoing alternative splicing events. (B) Partial sequence chromatograms of cDNAs (left side) with the corresponding schematic representations (right side) of the full length OPHN1 (upper sequence) and of the two novel OPHN1 alternative isoforms (middle and bottom sequences). (C) The putative protein sequence, derived from the skipping of exon 10 (isoform 9–11) carrying a novel COOH portion, is shown. (D) Protein domains of OPHN1 isoforms. The isoform 8–11 carries the BAR and the PH domains at a closer proximity compared to the full length, with possible consequences on protein conformation/activity. The isoform 9–11 carries only the BAR domain. As both the Rho-GTPase activity domain and the PR domains are lost in this isoform, the downstream signalling and the interaction with the actin cytoskeleton could be affected. This isoform displays a new COOH terminal portion of 33 amino acid (shown in blue in the cartoon), with still unknown functions and displaying no homology with known proteins (data not shown). BAR = Bin/Amphiphysin/Rvs, PH = Pleckstrin Homology, GAP = Rho-GTPase Activating Protein, PR = Proline Rich.
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Human OPHN1 gene and transcript organization.
2014Co-Authors: Sabina Barresi, Ginevra Zanni, Enrico Bertini, Sara Tomaselli, Alekos Athanasiadis, Federica Galeano, Franco Locatelli, Angela GalloAbstract:(A) Schematic representation of OPHN1 gene with exons represented as light grey rectangles and introns as black lines. Blue arrows indicate AluJo and AluSz within intron 9–10. (B) The predicted dsRNA secondary structure (by Zuker algorithm) formed by the AluJo and AluSz sequences. In detail a portion of the dsRNA structure with red rectangles indicating the edited adenosines. (C) OPHN1 pre-mRNA sequence of the intron 9–10, showing the AluJo and AluSz regions and the 33 adenosines that undergo editing in grey boxes.
Angela Gallo - One of the best experts on this subject based on the ideXlab platform.
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oligophrenin 1 OPHN1 a gene involved in x linked intellectual disability undergoes rna editing and alternative splicing during human brain development
PLOS ONE, 2014Co-Authors: Sabina Barresi, Ginevra Zanni, Enrico Bertini, Sara Tomaselli, Alekos Athanasiadis, Federica Galeano, Franco Locatelli, Angela GalloAbstract:Oligophrenin-1 (OPHN1) encodes for a Rho-GTPase-activating protein, important for dendritic morphogenesis and synaptic function. Mutations in this gene have been identified in patients with X-linked intellectual disability associated with cerebellar hypoplasia. ADAR enzymes are responsible for A-to-I RNA editing, an essential post-transcriptional RNA modification contributing to transcriptome and proteome diversification. Specifically, ADAR2 activity is essential for brain development and function. Herein, we show that the OPHN1 transcript undergoes post-transcriptional modifications such as A-to-I RNA editing and alternative splicing in human brain and other tissues. We found that OPHN1 editing is detectable already at the 18th week of gestation in human brain with a boost of editing at weeks 20 to 33, concomitantly with OPHN1 expression increase and the appearance of a novel OPHN1 splicing isoform. Our results demonstrate that multiple post-transcriptional events occur on OPHN1, a gene playing an important role in brain function and development.
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Oligophrenin-1 (OPHN1), a Gene Involved in X-Linked Intellectual Disability, Undergoes RNA Editing and Alternative Splicing during Human Brain Development
2014Co-Authors: Sabina Barresi, Ginevra Zanni, Enrico Bertini, Sara Tomaselli, Alekos Athanasiadis, Federica Galeano, Franco Locatelli, Angela GalloAbstract:Oligophrenin-1 (OPHN1) encodes for a Rho-GTPase-activating protein, important for dendritic morphogenesis and synaptic function. Mutations in this gene have been identified in patients with X-linked intellectual disability associated with cerebellar hypoplasia. ADAR enzymes are responsible for A-to-I RNA editing, an essential post-transcriptional RNA modification contributing to transcriptome and proteome diversification. Specifically, ADAR2 activity is essential for brain development and function. Herein, we show that the OPHN1 transcript undergoes post-transcriptional modifications such as A-to-I RNA editing and alternative splicing in human brain and other tissues. We found that OPHN1 editing is detectable already at the 18th week of gestation in human brain with a boost of editing at weeks 20 to 33, concomitantly with OPHN1 expression increase and the appearance of a novel OPHN1 splicing isoform. Our results demonstrate that multiple post
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Novel OPHN1 splicing isoforms.
2014Co-Authors: Sabina Barresi, Ginevra Zanni, Enrico Bertini, Sara Tomaselli, Alekos Athanasiadis, Federica Galeano, Franco Locatelli, Angela GalloAbstract:(A) Schematic representation of the OPHN1 pre-mRNA region (exons 8–11) undergoing alternative splicing events. (B) Partial sequence chromatograms of cDNAs (left side) with the corresponding schematic representations (right side) of the full length OPHN1 (upper sequence) and of the two novel OPHN1 alternative isoforms (middle and bottom sequences). (C) The putative protein sequence, derived from the skipping of exon 10 (isoform 9–11) carrying a novel COOH portion, is shown. (D) Protein domains of OPHN1 isoforms. The isoform 8–11 carries the BAR and the PH domains at a closer proximity compared to the full length, with possible consequences on protein conformation/activity. The isoform 9–11 carries only the BAR domain. As both the Rho-GTPase activity domain and the PR domains are lost in this isoform, the downstream signalling and the interaction with the actin cytoskeleton could be affected. This isoform displays a new COOH terminal portion of 33 amino acid (shown in blue in the cartoon), with still unknown functions and displaying no homology with known proteins (data not shown). BAR = Bin/Amphiphysin/Rvs, PH = Pleckstrin Homology, GAP = Rho-GTPase Activating Protein, PR = Proline Rich.
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Human OPHN1 gene and transcript organization.
2014Co-Authors: Sabina Barresi, Ginevra Zanni, Enrico Bertini, Sara Tomaselli, Alekos Athanasiadis, Federica Galeano, Franco Locatelli, Angela GalloAbstract:(A) Schematic representation of OPHN1 gene with exons represented as light grey rectangles and introns as black lines. Blue arrows indicate AluJo and AluSz within intron 9–10. (B) The predicted dsRNA secondary structure (by Zuker algorithm) formed by the AluJo and AluSz sequences. In detail a portion of the dsRNA structure with red rectangles indicating the edited adenosines. (C) OPHN1 pre-mRNA sequence of the intron 9–10, showing the AluJo and AluSz regions and the 33 adenosines that undergo editing in grey boxes.
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OPHN1 RNA editing levels in human tissues.
2014Co-Authors: Sabina Barresi, Ginevra Zanni, Enrico Bertini, Sara Tomaselli, Alekos Athanasiadis, Federica Galeano, Franco Locatelli, Angela GalloAbstract:RNA editing levels of the AluJo sequence in OPHN1 pre-mRNA (sites 1–14) in human adult brain, spinal cord, skin, kidney and thyroid tissues. All the editing percentages are expressed as mean ± s.e.m. (n = 3).
John G. R. Jefferys - One of the best experts on this subject based on the ideXlab platform.
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Reduced Gamma Oscillations in a Mouse Model of Intellectual Disability: A Role for Impaired Repetitive Neurotransmission?
PloS one, 2014Co-Authors: Andrew D. Powell, Pierre-philippe Saintot, Kalbinder K. Gill, Ashtami Bharathan, Gareth Morris, Premysl Jiruska, S. Caroline Buck, John G. R. JefferysAbstract:Intellectual disability affects 2–3% of the population; mutations of the X-chromosome are a major cause of moderate to severe cases. The link between the molecular consequences of the mutation and impaired cognitive function remains unclear. Loss of function mutations of oligophrenin-1 (OPHN1) disrupt Rho-GTPase signalling. Here we demonstrate abnormal neurotransmission at CA3 synapses in hippocampal slices from OPHN1-/y mice, resulting from a substantial decrease in the readily releasable pool of vesicles. As a result, synaptic transmission fails at high frequencies required for oscillations associated with cognitive functions. Both spontaneous and KA-induced gamma oscillations were reduced in OPHN1-/y hippocampal slices. Spontaneous oscillations were rapidly rescued by inhibition of the downstream signalling pathway of oligophrenin-1. These findings suggest that the intellectual disability due to mutations of oligophrenin-1 results from a synaptopathy and consequent network malfunction, providing a plausible mechanism for the learning disabilities. Furthermore, they raise the prospect of drug treatments for affected individuals.
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OPHN1−/y slices show reduced postsynaptic potentials.
2014Co-Authors: Andrew D. Powell, Pierre-philippe Saintot, Kalbinder K. Gill, Ashtami Bharathan, Caroline S. Buck, Gareth Morris, Premysl Jiruska, John G. R. JefferysAbstract:(a) Representative traces of postsynaptic potentials from OPHN1+/y (black traces) and OPHN1−/y (grey traces) slices. (b) Stimulus response curve of postsynaptic potentials recorded from the s. radiatum of CA3. PSP slopes were significantly smaller in OPHN1−/y (n = 5) than in OPHN1+/y slices (n = 12; p = 0.011, ANOVA). Representative traces of spontaneous EPSCs in OPHN1+/y (c) and OPHN1−/y (d). Representative individual spontaneous EPSCs are shown in the right panel. Cumulative frequency plots show that the interevent intervals (e), but not amplitude (f) of EPSCs are altered in OPHN1−/y neurons compared to OPHN1+/y neurons. (inset) Mean frequency and amplitude of spontaneous EPSCs.
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Smaller gamma oscillations in OPHN1−/y slices.
2014Co-Authors: Andrew D. Powell, Pierre-philippe Saintot, Kalbinder K. Gill, Ashtami Bharathan, Caroline S. Buck, Gareth Morris, Premysl Jiruska, John G. R. JefferysAbstract:(a) Application of 50 nM KA induced neuronal synchrony in the gamma frequency range; the power of these oscillations increased over time (e). (b) Spectrogram illustrating the development of the dominant frequency of gamma oscillations in OPHN1+/y (left panel) and OPHN1−/y (right panel) slices. (c) Power spectra for OPHN1+/y (left panel) and OPHN1−/y (right panel) slices at t = 60 minutes. (d) The peak frequency did not differ significantly between OPHN1+/y (•) and OPHN1−/y (○) slices. (e) Summated power of gamma oscillations was reduced in OPHN1−/y slices.
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Gamma oscillation synchrony and coherence unchanged in OPHN1−/y slices.
2014Co-Authors: Andrew D. Powell, Pierre-philippe Saintot, Kalbinder K. Gill, Ashtami Bharathan, Caroline S. Buck, Gareth Morris, Premysl Jiruska, John G. R. JefferysAbstract:(a) Average gamma waveforms for OPHN1+/y (black trace) and OPHN1−/y (grey trace) slices revealed a reduced amplitude without alteration in gamma waveform kinetics (b; grey trace, normalised OPHN1−/y). The reduced gamma power in OPHN1−/y slices was not associated with an altered spatial distribution; (c) waveform averages phase-zeroed at the peak of the oscillation recorded from CA3c (black trace), CA3b (dotted trace), CA3a (short dashed trace) and CA1 (long dashed trace) in an OPHN1+/y slice. (d) Cross-correlation (left panel) and phase lead (right panel) for CA regions with CA3c as the reference, data are expressed as mean±s.e.m. No differences were observed between OPHN1+/y (filled symbols) and OPHN1−/y (open symbols) slices.
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Inhibitory transmission is reduced in CA3 synapses.
2014Co-Authors: Andrew D. Powell, Pierre-philippe Saintot, Kalbinder K. Gill, Ashtami Bharathan, Caroline S. Buck, Gareth Morris, Premysl Jiruska, John G. R. JefferysAbstract:(a) Evoked IPSCs were smaller in OPHN1−/y (grey trace) than OPHN1+/y (black trace) neurons. Normalisation (right panel) of the OPHN1−/y evoked IPSC (grey trace) revealed that the kinetics of the eIPSCs were unaltered by genotype. (b) Mean evoked IPSC amplitude for an 18 V stimulus applied to mossy fibre pathway. (c) Spontaneous IPSCs were less frequent in OPHN1−/y (grey trace) than OPHN1+/y (black trace) neurons. Cumulative frequency plots (e) showed that spontaneous events in OPHN1−/y neurons shifted to longer inter-event intervals (IEI, grey line), which resulted in a lower frequency of spontaneous IPSCs (f). (d) The amplitude of spontaneous IPSCs was unaltered. (p:*