Molecular Context-Dependent Effects Induced by Rett Syndrome-Associated Mutations in MeCP2

Methyl-CpG binding protein 2 (MeCP2) is a transcriptional regulator and a chromatin-binding protein involved in neuronal development and maturation. Loss-of-function mutations in MeCP2 result in Rett syndrome (RTT), a neurodevelopmental disorder that is the main cause of mental retardation in females. MeCP2 is an intrinsically disordered protein (IDP) constituted by six domains. Two domains are the main responsible elements for DNA binding (methyl-CpG binding domain, MBD) and recruitment of gene transcription/silencing machinery (transcription repressor domain, TRD). These two domains concentrate most of the RTT-associated mutations. R106W and R133C are associated with severe and mild RTT phenotype, respectively. We have performed a comprehensive characterization of the structural and functional impact of these substitutions at molecular level. Because we have previously shown that the MBD-flanking disordered domains (N-terminal domain, NTD, and intervening domain, ID) exert a considerable influence on the structural and functional features of the MBD (Claveria-Gimeno, R. et al. Sci Rep. 2017, 7, 41635), here we report the biophysical study of the influence of the protein scaffold on the structural and functional effect induced by these two RTT-associated mutations. These results represent an example of how a given mutation may show different effects (sometimes opposing effects) depending on the molecular context.

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Sphingolipid Metabolism Perturbations in Rett Syndrome

Metabolites ◽

10.3390/metabo9100221 ◽

2019 ◽

Vol 9 (10) ◽

pp. 221 ◽

Cited By ~ 1

Author(s):

Cappuccio ◽

Donti ◽

Pinelli ◽

Bernardo ◽

Bravaccio ◽

...

Keyword(s):

Rett Syndrome ◽

Metabolic Profiling ◽

Neurodevelopmental Disorder ◽

Sphingolipid Metabolism ◽

Tandem Mass ◽

Mecp2 Gene ◽

Loss Of Function ◽

Disease Pathogenesis ◽

Blood Samples ◽

Disease Biomarkers

Rett syndrome is a severe neurodevelopmental disorder affecting mostly females and is caused by loss-of-function mutations in the MECP2 gene that encoded the methyl-CpG-binding protein 2. The pathogenetic mechanisms of Rett syndrome are not completely understood and metabolic derangements are emerging as features of Rett syndrome. We performed a semi-quantitative tandem mass spectrometry-based analysis that measured over 900 metabolites on blood samples from 14 female subjects with Rett syndrome carrying MECP2 mutations. The metabolic profiling revealed alterations in lipids, mostly involved in sphingolipid metabolism, and sphinganine/sphingosine, that are known to have a neurotrophic role. Further investigations are required to understand the mechanisms underlying such perturbations and their significance in the disease pathogenesis. Nevertheless, these metabolites are attractive for studies on the disease pathogenesis and as potential disease biomarkers.

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SECIS-binding protein 2, a key player in selenoprotein synthesis, is an intrinsically disordered protein

Biochimie ◽

10.1016/j.biochi.2009.05.004 ◽

2009 ◽

Vol 91 (8) ◽

pp. 1003-1009 ◽

Cited By ~ 8

Author(s):

Vincent Oliéric ◽

Philippe Wolff ◽

Akiko Takeuchi ◽

Guillaume Bec ◽

Catherine Birck ◽

...

Keyword(s):

Binding Protein ◽

Intrinsically Disordered Protein ◽

Intrinsically Disordered ◽

Disordered Protein

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A selective 5-HT1a receptor agonist improves respiration in a mouse model of Rett syndrome

Journal of Applied Physiology ◽

10.1152/japplphysiol.00889.2013 ◽

2013 ◽

Vol 115 (11) ◽

pp. 1626-1633 ◽

Cited By ~ 25

Author(s):

Erica S. Levitt ◽

Barbara J. Hunnicutt ◽

Sharon J. Knopp ◽

John T. Williams ◽

John M. Bissonnette

Keyword(s):

Rett Syndrome ◽

Binding Protein ◽

Glutamate Release ◽

Outward Current ◽

Cell Voltage ◽

Equilibrium Potential ◽

Maximal Effect ◽

Dependent Manner ◽

Male Mice ◽

Loss Of Function

Rett syndrome is a neurological disorder caused by loss of function mutations in the gene that encodes the DNA binding protein methyl-CpG-binding protein 2 (Mecp2). A prominent feature of the syndrome is disturbances in respiration characterized by frequent apnea and an irregular interbreath cycle. 8-Hydroxy-2-dipropylaminotetralin has been shown to positively modulate these disturbances (Abdala AP, Dutschmann M, Bissonnette JM, Paton JF, Proc Natl Acad Sci U S A 107: 18208–18213, 2010), but the mode of action is not understood. Here we show that the selective 5-HT1a biased agonist 3-chloro-4-fluorophenyl-(4-fluoro-4-{[(5-methylpyrimidin-2-ylmethyl)-amino]-methyl}-piperidin-1-yl)-methanone (F15599) decreases apnea and corrects irregularity in both heterozygous Mecp2-deficient female and in Mecp2 null male mice. In whole cell voltage-clamp recordings from dorsal raphe neurons, F15599 potently induced an outward current, which was blocked by barium, reversed at the potassium equilibrium potential, and was antagonized by the 5-HT1a antagonist WAY100135. This is consistent with somatodendritic 5-HT1a receptor-mediated activation of G protein-coupled inwardly rectifying potassium channels (GIRK). In contrast, F15599 did not activate 5-HT1b/d receptors that mediate inhibition of glutamate release from terminals in the nucleus accumbens by a presynaptic mechanism. Thus F15599 activated somatodendritic 5-HT1a autoreceptors, but not axonal 5-HT1b/d receptors. In unanesthetized Mecp2-deficient heterozygous female mice, F15599 reduced apnea in a dose-dependent manner with maximal effect of 74.5 ± 6.9% at 0.1 mg/kg and improved breath irrregularity. Similarly, in Mecp2 null male mice, apnea was reduced by 62 ± 6.6% at 0.25 mg/kg, and breathing became regular. The results indicate respiration is improved with a 5-HT1a agonist that activates GIRK channels without affecting neurotransmitter release.

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MeCP2: The Genetic Driver of Rett Syndrome Epigenetics

Frontiers in Genetics ◽

10.3389/fgene.2021.620859 ◽

2021 ◽

Vol 12 ◽

Author(s):

Katrina V. Good ◽

John B. Vincent ◽

Juan Ausió

Keyword(s):

Rett Syndrome ◽

Neuronal Development ◽

Neurodevelopmental Disorder ◽

Epigenetic Mark ◽

Initial Development ◽

Genetic Ablation ◽

Developmental Regression ◽

The Stability ◽

The Brain

Mutations in methyl CpG binding protein 2 (MeCP2) are the major cause of Rett syndrome (RTT), a rare neurodevelopmental disorder with a notable period of developmental regression following apparently normal initial development. Such MeCP2 alterations often result in changes to DNA binding and chromatin clustering ability, and in the stability of this protein. Among other functions, MeCP2 binds to methylated genomic DNA, which represents an important epigenetic mark with broad physiological implications, including neuronal development. In this review, we will summarize the genetic foundations behind RTT, and the variable degrees of protein stability exhibited by MeCP2 and its mutated versions. Also, past and emerging relationships that MeCP2 has with mRNA splicing, miRNA processing, and other non-coding RNAs (ncRNA) will be explored, and we suggest that these molecules could be missing links in understanding the epigenetic consequences incurred from genetic ablation of this important chromatin modifier. Importantly, although MeCP2 is highly expressed in the brain, where it has been most extensively studied, the role of this protein and its alterations in other tissues cannot be ignored and will also be discussed. Finally, the additional complexity to RTT pathology introduced by structural and functional implications of the two MeCP2 isoforms (MeCP2-E1 and MeCP2-E2) will be described. Epigenetic therapeutics are gaining clinical popularity, yet treatment for Rett syndrome is more complicated than would be anticipated for a purely epigenetic disorder, which should be taken into account in future clinical contexts.

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Histidine-rich Ca2+-binding protein stimulates the transport cycle of SERCA through a conformation-dependent fuzzy complex

10.1101/2020.09.17.302869 ◽

2020 ◽

Author(s):

Temitope I. Ayeotan ◽

Line Cecilie Hansen ◽

Thomas Boesen ◽

Claus Olesen ◽

Jesper V. Møller ◽

...

Keyword(s):

Electrostatic Interactions ◽

Binding Protein ◽

Intrinsically Disordered Protein ◽

Bound State ◽

Disordered Proteins ◽

Dependent Manner ◽

Intrinsically Disordered ◽

Intracellular Ca ◽

P Type ◽

Rate Limiting

AbstractThe histidine-rich Ca2+-binding protein (HRC) stimulates the sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) to increase Ca2+-uptake into the lumen. HRC also binds the triadin scaffold in a Ca2+-dependent manner, and HRC tunes both the uptake and release of Ca2+ depending on the concentration in the intracellular Ca2+-stores. We investigated how HRC stimulates SERCA pumping using biochemical and biophysical assays, and show that HRC is an intrinsically disordered protein that binds directly to SERCA via electrostatic interactions. The affinity of the interaction depends on the conformation of SERCA, and HRC binds most tightly in the calcium-released E2P state. This state marks the end of the rate-limiting [Ca2]E1P to E2P transition of SERCA, and suggests that HRC stimulates SERCA by preferentially stabilizing the end point of this transition. HRC remains disordered in the bound state and thus binds in a dynamic, fuzzy complex. The binding of HRC to SERCA shows that fuzzy complexes formed by disordered proteins may be conformation-specific, and use this specificity to modulate the functional cycle of complex molecular machines such as a P-type ATPase.

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Cyclin-Dependent Kinase-Like 5 (CDKL5): Possible Cellular Signalling Targets and Involvement in CDKL5 Deficiency Disorder

Neural Plasticity ◽

10.1155/2020/6970190 ◽

2020 ◽

Vol 2020 ◽

pp. 1-14

Author(s):

Syouichi Katayama ◽

Noriyuki Sueyoshi ◽

Tetsuya Inazu ◽

Isamu Kameshita

Keyword(s):

Catalytic Activity ◽

Rett Syndrome ◽

Neurodevelopmental Disorder ◽

Cyclin Dependent Kinase ◽

Loss Of Function ◽

Neuronal Function ◽

Transcriptional Mapping ◽

Target Molecules ◽

New Treatment ◽

The Relationship

Cyclin-dependent kinase-like 5 (CDKL5, also known as STK9) is a serine/threonine protein kinase originally identified in 1998 during a transcriptional mapping project of the human X chromosome. Thereafter, a mutation in CDKL5 was reported in individuals with the atypical Rett syndrome, a neurodevelopmental disorder, suggesting that CDKL5 plays an important regulatory role in neuronal function. The disease associated with CDKL5 mutation has recently been recognised as CDKL5 deficiency disorder (CDD) and has been distinguished from the Rett syndrome owing to its symptomatic manifestation. Because CDKL5 mutations identified in patients with CDD cause enzymatic loss of function, CDKL5 catalytic activity is likely strongly associated with the disease. Consequently, the exploration of CDKL5 substrate characteristics and regulatory mechanisms of its catalytic activity are important for identifying therapeutic target molecules and developing new treatment. In this review, we summarise recent findings on the phosphorylation of CDKL5 substrates and the mechanisms of CDKL5 phosphorylation and dephosphorylation. We also discuss the relationship between changes in the phosphorylation signalling pathways and the Cdkl5 knockout mouse phenotype and consider future prospects for the treatment of mental and neurological disease associated with CDKL5 mutations.

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Persistent Unresolved Inflammation in the Mecp2-308 Female Mutated Mouse Model of Rett Syndrome

Mediators of Inflammation ◽

10.1155/2017/9467819 ◽

2017 ◽

Vol 2017 ◽

pp. 1-9 ◽

Cited By ~ 11

Author(s):

Alessio Cortelazzo ◽

Claudio De Felice ◽

Bianca De Filippis ◽

Laura Ricceri ◽

Giovanni Laviola ◽

...

Keyword(s):

Mouse Model ◽

Rett Syndrome ◽

Binding Protein ◽

Neurodevelopmental Disorder ◽

Unknown Origin ◽

Apolipoprotein A1 ◽

Inflammatory Status ◽

Truncating Mutation ◽

Alpha 1 Antitrypsin ◽

First Time

Rett syndrome (RTT) is a rare neurodevelopmental disorder usually caused by mutations in the X-linked gene methyl-CpG-binding protein 2 (MECP2). Several Mecp2 mutant mouse lines have been developed recapitulating part of the clinical features. In particular, Mecp2-308 female heterozygous mice, bearing a truncating mutation, are a validated model of the disease. While recent data suggest a role for inflammation in RTT, little information on the inflammatory status in murine models of the disease is available. Here, we investigated the inflammatory status by proteomic 2-DE/MALDI-ToF/ToF analyses in symptomatic Mecp2-308 female mice. Ten differentially expressed proteins were evidenced in the Mecp2-308 mutated plasma proteome. In particular, 5 positive acute-phase response (APR) proteins increased (i.e., kininogen-1, alpha-fetoprotein, mannose-binding protein C, alpha-1-antitrypsin, and alpha-2-macroglobulin), and 3 negative APR reactants were decreased (i.e., serotransferrin, albumin, and apolipoprotein A1). CD5 antigen-like and vitamin D-binding protein, two proteins strictly related to inflammation, were also changed. These results indicate for the first time a persistent unresolved inflammation of unknown origin in the Mecp2-308 mouse model.

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Rescue of Methyl-CpG Binding Protein 2 Dysfunction-induced Defects in Newborn Neurons by Pentobarbital

Neurotherapeutics ◽

10.1007/s13311-015-0343-0 ◽

2015 ◽

Vol 12 (2) ◽

pp. 477-490 ◽

Cited By ~ 12

Author(s):

Dongliang Ma ◽

Su-In Yoon ◽

Chih-Hao Yang ◽

Guillaume Marcy ◽

Na Zhao ◽

...

Keyword(s):

Rett Syndrome ◽

Hippocampal Neurons ◽

Granule Cells ◽

Binding Protein ◽

Neurodevelopmental Disorder ◽

Network Activity ◽

Aminobutyric Acid ◽

Structural Defects

Abstract Rett syndrome is a neurodevelopmental disorder that usually arises from mutations or deletions in methyl-CpG binding protein 2 (MeCP2), a transcriptional regulator that affects neuronal development and maturation without causing cell loss. Here, we show that silencing of MeCP2 decreased neurite arborization and synaptogenesis in cultured hippocampal neurons from rat fetal brains. These structural defects were associated with alterations in synaptic transmission and neural network activity. Similar retardation of dendritic growth was also observed in MeCP2-deficient newborn granule cells in the dentate gyrus of adult mouse brains in vivo, demonstrating direct and cell-autonomous effects on individual neurons. These defects, caused by MeCP2 deficiency, were reversed by treatment with the US Food and Drug Administration-approved drug, pentobarbital, in vitro and in vivo, possibly caused by modulation of γ-aminobutyric acid signaling. The results indicate that drugs modulating γ-aminobutyric acid signaling are potential therapeutics for Rett syndrome.

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Immune Dysfunction in Rett Syndrome Patients Revealed by High Levels of Serum Anti-N(Glc) IgM Antibody Fraction

Journal of Immunology Research ◽

10.1155/2014/260973 ◽

2014 ◽

Vol 2014 ◽

pp. 1-6 ◽

Cited By ~ 10

Author(s):

Anna Maria Papini ◽

Francesca Nuti ◽

Feliciana Real-Fernandez ◽

Giada Rossi ◽

Caterina Tiberi ◽

...

Keyword(s):

Immune System ◽

Rett Syndrome ◽

Pervasive Developmental Disorders ◽

Developmental Disorders ◽

Neurodevelopmental Disorder ◽

Loss Of Function ◽

Gene Encoding ◽

Antibody Recognition ◽

Forkhead Box ◽

Significant Difference

Rett syndrome (RTT), a neurodevelopmental disorder affecting exclusively (99%) female infants, is associated with loss-of-function mutations in the gene encoding methyl-CpG binding protein 2 (MECP2) and, more rarely, cyclin-dependent kinase-like 5 (CDKL5) and forkhead box protein G1 (FOXG1). In this study, we aimed to evaluate the function of the immune system by measuring serum immunoglobulins (IgG and IgM) in RTT patients (n=53) and, by comparison, in age-matched children affected by non-RTT pervasive developmental disorders (non-RTT PDD) (n=82) and healthy age-matched controls (n=29). To determine immunoglobulins we used both a conventional agglutination assay and a novel ELISA based on antibody recognition by a surrogate antigen probe, CSF114(Glc), a syntheticN-glucosylated peptide. Both assays provided evidence for an increase in IgM titer, but not in IgG, in RTT patients relative to both healthy controls and non-RTT PDD patients. The significant difference in IgM titers between RTT patients and healthy subjects in the CSF114(Glc) assay (P=0.001) suggests that this procedure specifically detects a fraction of IgM antibodies likely to be relevant for the RTT disease. These findings offer a new insight into the mechanism underlying the Rett disease as they unveil the possible involvement of the immune system in this pathology.

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Subclinical Inflammatory Status in Rett Syndrome

Mediators of Inflammation ◽

10.1155/2014/480980 ◽

2014 ◽

Vol 2014 ◽

pp. 1-13 ◽

Cited By ~ 40

Author(s):

Alessio Cortelazzo ◽

Claudio De Felice ◽

Roberto Guerranti ◽

Cinzia Signorini ◽

Silvia Leoncini ◽

...

Keyword(s):

Gene Mutation ◽

Rett Syndrome ◽

De Novo ◽

Clinical Chemistry ◽

Neurodevelopmental Disorder ◽

Loss Of Function ◽

Gene Encoding ◽

Protein Levels ◽

Large Deletions ◽

Inflammatory Status

Inflammation has been advocated as a possible common central mechanism for developmental cognitive impairment. Rett syndrome (RTT) is a devastating neurodevelopmental disorder, mainly caused byde novoloss-of-function mutations in the gene encoding MeCP2. Here, we investigated plasma acute phase response (APR) in stage II (i.e., “pseudo-autistic”) RTT patients by routine haematology/clinical chemistry and proteomic 2-DE/MALDI-TOF analyses as a function of four majorMECP2gene mutation types (R306C, T158M, R168X, and large deletions). Elevated erythrocyte sedimentation rate values (median 33.0 mm/h versus 8.0 mm/h,P<0.0001) were detectable in RTT, whereas C-reactive protein levels were unchanged (P=0.63). The 2-DE analysis identified significant changes for a total of 17 proteins, the majority of which were categorized as APR proteins, either positive (n=6spots) or negative (n=9spots), and to a lesser extent as proteins involved in the immune system (n=2spots), with some proteins having overlapping functions on metabolism (n=7spots). The number of protein changes was proportional to the severity of the mutation. Our findings reveal for the first time the presence of a subclinical chronic inflammatory status related to the “pseudo-autistic” phase of RTT, which is related to the severity carried by theMECP2gene mutation.

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