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Disease Models & Mechanisms Jun 2024Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in MECP2, which encodes methyl-CpG-binding protein 2, a transcriptional regulator of many genes,...
Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in MECP2, which encodes methyl-CpG-binding protein 2, a transcriptional regulator of many genes, including brain-derived neurotrophic factor (BDNF). BDNF levels are lower in multiple brain regions of Mecp2-deficient mice, and experimentally increasing BDNF levels improve atypical phenotypes in Mecp2 mutant mice. Due to the low blood-brain barrier permeability of BDNF itself, we tested the effects of LM22A-4, a brain-penetrant, small-molecule ligand of the BDNF receptor TrkB (encoded by Ntrk2), on dendritic spine density and form in hippocampal pyramidal neurons and on behavioral phenotypes in female Mecp2 heterozygous (HET) mice. A 4-week systemic treatment of Mecp2 HET mice with LM22A-4 restored spine volume in MeCP2-expressing neurons to wild-type (WT) levels, whereas spine volume in MeCP2-lacking neurons remained comparable to that in neurons from female WT mice. Female Mecp2 HET mice engaged in aggressive behaviors more than WT mice, the levels of which were reduced to WT levels by the 4-week LM22A-4 treatment. These data provide additional support to the potential usefulness of novel therapies not only for RTT but also to other BDNF-related disorders.
Topics: Animals; Rett Syndrome; Dendritic Spines; Female; Phenotype; Receptor, trkB; Methyl-CpG-Binding Protein 2; Behavior, Animal; Ligands; Pyramidal Cells; Mice; Brain-Derived Neurotrophic Factor; Hippocampus; Heterozygote; Mice, Inbred C57BL; Disease Models, Animal; Benzamides
PubMed: 38785269
DOI: 10.1242/dmm.050612 -
Stem Cell Research Jun 2024Rett syndrome is characterized by severe global developmental impairments with autistic features and loss of purposeful hand skills. Here we show that human induced...
Rett syndrome is characterized by severe global developmental impairments with autistic features and loss of purposeful hand skills. Here we show that human induced pluripotent stem cell (hiPSC) lines derived from four Japanese female patients with Rett syndrome are generated from peripheral blood mononuclear cells using Sendai virus vectors. The generated hiPSC lines showed self-renewal and pluripotency and carried heterozygous frameshift, missense, or nonsense mutations in the MECP2 gene. Since the molecular pathogenesis caused by MECP2 dysfunction remains unclear, these cell resources are useful tools to establish disease models and develop new therapies for Rett syndrome.
Topics: Rett Syndrome; Humans; Induced Pluripotent Stem Cells; Methyl-CpG-Binding Protein 2; Female; Mutation; Cell Line; Cell Differentiation
PubMed: 38703668
DOI: 10.1016/j.scr.2024.103432 -
Annals of Medicine and Surgery (2012) May 2024
PubMed: 38694380
DOI: 10.1097/MS9.0000000000001896 -
Epilepsy & Behavior Reports 2024Contextual events are recognized to affect seizure-like behaviors, yet there is limited research on procedures assessing contextual control. This study aimed to examine...
Contextual events are recognized to affect seizure-like behaviors, yet there is limited research on procedures assessing contextual control. This study aimed to examine the utilization of a brief experimental precursor functional analysis within a clinical team assessment. Furthermore, the study explored if telehealth supervision could guide a parent administered replication of the functional analysis. The participants were a young female with Rett syndrome and a history of epilepsy as well as non-epileptic seizures and her mother. The functional analysis procedures consisted of the systematic alternations of contextual conditions that were hypothesized to either prevent or evoke seizure-like behaviors. The primary outcome measure was the occurrence of behavioral precursors that were identified to consequently signal subsequent seizure-like behaviors. In addition, procedure fidelity and interobserver agreement data were obtained alongside parent rating of the procedure's social validity. The clinical functional analysis clearly suggested that the seizure-like behaviors served the function of access to attention and preferred activities. A parent administered functional analysis replicated clinical functional analysis findings. The parent's fidelity to procedures was high and scores in social validity were excellent. The results show that functional analysis procedures could provide essential information in assessment of non-epileptic seizures. Strengths and limitations are discussed.
PubMed: 38681818
DOI: 10.1016/j.ebr.2024.100666 -
Biomolecules Apr 2024Rett Syndrome (RTT) is a progressive X-linked neurodevelopmental disorder with no cure. RTT patients show disease-associated symptoms within 18 months of age that...
Rett Syndrome (RTT) is a progressive X-linked neurodevelopmental disorder with no cure. RTT patients show disease-associated symptoms within 18 months of age that include developmental regression, progressive loss of useful hand movements, and breathing difficulties, along with neurological impairments, seizures, tremor, and mental disability. Rett Syndrome is also associated with metabolic abnormalities, and the anti-diabetic drug metformin is suggested to be a potential drug of choice with low or no side-effects. Previously, we showed that exposure of metformin in a human brain cell line induces transcripts, the dominant isoform of the gene in the brain, mutations in which causes RTT. Here, we report the molecular impact of metformin in mice. Protein analysis of specific brain regions in the male and female mice by immunoblotting indicated that metformin induces MeCP2 in the hippocampus, in a sex-dependent manner. Additional experiments confirm that the regulatory role of metformin on the MeCP2 target "BDNF" is brain region-dependent and sex-specific. Measurement of the ribosomal protein S6 (in both phosphorylated and unphosphorylated forms) confirms the sex-dependent role of metformin in the liver. Our results can help foster a better understanding of the molecular impact of metformin in different brain regions of male and female adult mice, while providing some insight towards its potential in therapeutic strategies for the treatment of Rett Syndrome.
Topics: Animals; Female; Male; Mice; Brain; Brain-Derived Neurotrophic Factor; Hippocampus; Metformin; Methyl-CpG-Binding Protein 2; Mice, Inbred C57BL; Phosphorylation; Rett Syndrome; Ribosomal Protein S6; Sex Characteristics; Sex Factors
PubMed: 38672521
DOI: 10.3390/biom14040505 -
Molecular and Cellular Neurosciences Jun 2024Astrocytes are in constant communication with neurons during the establishment and maturation of functional networks in the developing brain. Astrocytes release...
Astrocytes are in constant communication with neurons during the establishment and maturation of functional networks in the developing brain. Astrocytes release extracellular vesicles (EVs) containing microRNA (miRNA) cargo that regulates transcript stability in recipient cells. Astrocyte released factors are thought to be involved in neurodevelopmental disorders. Healthy astrocytes partially rescue Rett Syndrome (RTT) neuron function. EVs isolated from stem cell progeny also correct aspects of RTT. EVs cross the blood-brain barrier (BBB) and their cargo is found in peripheral blood which may allow non-invasive detection of EV cargo as biomarkers produced by healthy astrocytes. Here we characterize miRNA cargo and sequence motifs in healthy human astrocyte derived EVs (ADEVs). First, human induced Pluripotent Stem Cells (iPSC) were differentiated into Neural Progenitor Cells (NPCs) and subsequently into astrocytes using a rapid differentiation protocol. iPSC derived astrocytes expressed specific markers, displayed intracellular calcium transients and secreted ADEVs. miRNAs were identified by RNA-Seq on astrocytes and ADEVs and target gene pathway analysis detected brain and immune related terms. The miRNA profile was consistent with astrocyte identity, and included approximately 80 miRNAs found in astrocytes that were relatively depleted in ADEVs suggestive of passive loading. About 120 miRNAs were relatively enriched in ADEVs and motif analysis discovered binding sites for RNA binding proteins FUS, SRSF7 and CELF5. miR-483-5p was the most significantly enriched in ADEVs. This miRNA regulates MECP2 expression in neurons and has been found differentially expressed in blood samples from RTT patients. Our results identify potential miRNA biomarkers selectively sorted into ADEVs and implicate RNA binding protein sequence dependent mechanisms for miRNA cargo loading.
Topics: Humans; Extracellular Vesicles; Induced Pluripotent Stem Cells; MicroRNAs; Astrocytes; Neurons; Cell Differentiation; Cells, Cultured; Neural Stem Cells
PubMed: 38663691
DOI: 10.1016/j.mcn.2024.103933 -
BioRxiv : the Preprint Server For... Apr 2024Rett syndrome (RTT) is a neurodevelopmental disorder that is caused by loss-of-function mutations in the ( ) gene. RTT patients experience a myriad of debilitating...
Rett syndrome (RTT) is a neurodevelopmental disorder that is caused by loss-of-function mutations in the ( ) gene. RTT patients experience a myriad of debilitating symptoms, which include respiratory phenotypes that are often associated with lethality. Our previous work established that expression of the M muscarinic acetylcholine receptor (mAchR) is decreased in RTT autopsy samples, and that potentiation of the M receptor improves apneas in a mouse model of RTT; however, the population of neurons driving this rescue is unclear. Loss of Mecp2 correlates with excessive neuronal activity in cardiorespiratory nuclei. Since M is found on cholinergic interneurons, we hypothesized that M -potentiating compounds decrease apnea frequency by tempering brainstem hyperactivity. To test this, and mice were screened for apneas before and after administration of the M positive allosteric modulator (PAM) VU0453595 (VU595). Brains from the same mice were then imaged for c-Fos, ChAT, and Syto16 using whole-brain light-sheet microscopy to establish genotype and drug-dependent activation patterns that could be correlated with VU595's efficacy on apneas. The vehicle-treated brain exhibited broad hyperactivity when coupled with the phenotypic prescreen, which was significantly decreased by administration of VU595, particularly in regions known to modulate the activity of respiratory nuclei (i.e. hippocampus and striatum). Further, the extent of apnea rescue in each mouse showed a significant positive correlation with c-Fos expression in non-cholinergic neurons in the striatum, thalamus, dentate gyrus, and within the cholinergic neurons of the brainstem. These results indicate that mice are prone to hyperactivity in brain regions that regulate respiration, which can be normalized through M potentiation.
PubMed: 38659804
DOI: 10.1101/2024.04.15.586099 -
Advanced Science (Weinheim,... Jun 2024The CRISPR-Cas9 technology has the potential to revolutionize the treatment of various diseases, including Rett syndrome, by enabling the correction of genes or...
The CRISPR-Cas9 technology has the potential to revolutionize the treatment of various diseases, including Rett syndrome, by enabling the correction of genes or mutations in human patient cells. However, several challenges need to be addressed before its widespread clinical application. These challenges include the low delivery efficiencies to target cells, the actual efficiency of the genome-editing process, and the precision with which the CRISPR-Cas system operates. Herein, the study presents a Magnetic Nanoparticle-Assisted Genome Editing (MAGE) platform, which significantly improves the transfection efficiency, biocompatibility, and genome-editing accuracy of CRISPR-Cas9 technology. To demonstrate the feasibility of the developed technology, MAGE is applied to correct the mutated MeCP2 gene in induced pluripotent stem cell-derived neural progenitor cells (iPSC-NPCs) from a Rett syndrome patient. By combining magnetofection and magnetic-activated cell sorting, MAGE achieves higher multi-plasmid delivery (99.3%) and repairing efficiencies (42.95%) with significantly shorter incubation times than conventional transfection agents without size limitations on plasmids. The repaired iPSC-NPCs showed similar characteristics as wild-type neurons when they differentiated into neurons, further validating MAGE and its potential for future clinical applications. In short, the developed nanobio-combined CRISPR-Cas9 technology offers the potential for various clinical applications, particularly in stem cell therapies targeting different genetic diseases.
Topics: Rett Syndrome; CRISPR-Cas Systems; Gene Editing; Humans; Induced Pluripotent Stem Cells; Magnetite Nanoparticles; Methyl-CpG-Binding Protein 2; Genetic Therapy
PubMed: 38647391
DOI: 10.1002/advs.202306432 -
Frontiers in Public Health 2024The main aim of the present study was to examine whether the use of a low-tech tool, called click4all, inserted into cognitive and motor training can increase social... (Observational Study)
Observational Study Randomized Controlled Trial
INTRODUCTION
The main aim of the present study was to examine whether the use of a low-tech tool, called click4all, inserted into cognitive and motor training can increase social interaction of patients with Rett Syndrome (RTT) with classmates in a school setting.
METHODS
Twenty-seven participants with RTT were randomly assigned to two groups: the experimental group received treatment with click4all, and the control group received traditional treatment without click4all. Parameters were measured before treatment (T1), 6 months after treatment (T2), 6 months after the second treatment phase (T3) and at the end of the third treatment phase (T4).
RESULTS
The results demonstrated an increase in levels of social interaction among classmates and patients with RTT in the experimental group, over time, compared to the control group, 95% CI [5.20-15.30]. Classmates also showed a higher level of knowledge related to participants of the experimental group, and this increased over time, 95% CI [24.98-63.52]. The level of knowledge related to the control group was stable over time and lower than the experimental group.
DISCUSSION
This study demonstrated that the use of a low-tech tool can increase social interactions of patients with RTT in a school setting. This is important, as patients with RTT are often restricted in an isolation condition.
Topics: Humans; Rett Syndrome; Female; Social Interaction; Child; Adolescent; Male; Schools
PubMed: 38645452
DOI: 10.3389/fpubh.2024.1353099 -
Frontiers in Genetics 2024Rett syndrome (RTT, MIM #312750) is a rare genetic disorder that leads to developmental regression and severe disability and is caused by pathogenic variants in the...
Rett syndrome (RTT, MIM #312750) is a rare genetic disorder that leads to developmental regression and severe disability and is caused by pathogenic variants in the gene. The diagnosis of RTT is based on clinical features and, depending on resources and access, on molecular confirmation. There is scarce information on molecular diagnosis from patients in Latin America, mostly due to limited availability and coverage of genomic testing. This pilot study aimed to implement genomic testing and characterize clinical and molecular findings in a group of Chilean patients with a clinical diagnosis of RTT. Twenty-eight patients with suspected RTT underwent characterization of phenotypic manifestations and molecular testing using Clinical Exome Solution CES_V2 by SOPHiA Genetics. Data was analyzed using the commercial bioinformatics platform, SOPHiA DDM. A virtual panel of 34 genes, including and other genes that are in the differential diagnosis of RTT, was used to prioritize initial analyses, followed by evaluation of the complete exome sequence data. Twelve patients (42.8% of participants) had variants in , of which 11 (39.2%) were interpreted as pathogenic/likely pathogenic (P/LP), thus confirming the diagnosis of RTT in them. Eight additional patients (28.5%) harbored ten variants in nine other genes. Four of these variants were interpreted as P/LP (14.2%) ( and ) resulting in alternative neurodevelopmental diagnoses, and six were considered of uncertain significance. No evident candidate variant was found for eight patients. This study allowed to reach a diagnosis in half of the participants. The diagnosis of RTT was confirmed in over a third of them, while others were found to have alternative neurodevelopmental disorders. Further evaluation is needed to identify the cause in those with negative or uncertain results. This information is useful for the patients, families, and clinicians to guide clinical management, even more so since the development of novel therapies for RTT. We also show the feasibility of implementing a step-wide approach to genomic testing in a setting with limited resources.
PubMed: 38566815
DOI: 10.3389/fgene.2024.1278198