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BACKGROUND AND AIMS: Type 1 long QT syndrome (LQT1) is caused by pathogenic variants in the KCNQ1-encoded Kv7.1 potassium channels, which pathologically prolong ventricular action potential duration (APD). Herein, the pathologic phenotype in transgenic LQT1 rabbits is rescued using a novel KCNQ1 suppression-replacement (SupRep) gene therapy. METHODS: KCNQ1-SupRep gene therapy was developed by combining into a single construct a KCNQ1 shRNA (suppression) and an shRNA-immune KCNQ1 cDNA (replacement), packaged into adeno-associated virus serotype 9, and delivered in vivo via an intra-aortic root injection (1E10 vg/kg). To ascertain the efficacy of SupRep, 12-lead electrocardiograms were assessed in adult LQT1 and wild-type (WT) rabbits and patch-clamp experiments were performed on isolated ventricular cardiomyocytes. RESULTS: KCNQ1-SupRep treatment of LQT1 rabbits resulted in significant shortening of the pathologically prolonged QT index (QTi) towards WT levels. Ventricular cardiomyocytes isolated from treated LQT1 rabbits demonstrated pronounced shortening of APD compared to LQT1 controls, leading to levels similar to WT (LQT1-UT vs. LQT1-SupRep, P < .0001, LQT1-SupRep vs. WT, P = ns). Under ß-adrenergic stimulation with isoproterenol, SupRep-treated rabbits demonstrated a WT-like physiological QTi and APD90 behaviour. CONCLUSIONS: This study provides the first animal-model, proof-of-concept gene therapy for correction of LQT1. In LQT1 rabbits, treatment with KCNQ1-SupRep gene therapy normalized the clinical QTi and cellular APD90 to near WT levels both at baseline and after isoproterenol. If similar QT/APD correction can be achieved with intravenous administration of KCNQ1-SupRep gene therapy in LQT1 rabbits, these encouraging data should compel continued development of this gene therapy for patients with LQT1.
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Histone deacetylases (HDACs) are enzymes pivotal for histone modification (i.e. acetylation marks removal), chromatin accessibility and gene expression regulation. Class I HDACs (including HDAC1, 2, 3, 8) are ubiquitously expressed and they often participate in multi-molecular protein complexes. To date, three neurodevelopmental disorders caused by mutations in genes encoding for HDACs (HDAC4, HDAC6 and HDAC8) and thus belonging to the group of chromatinopathies, have been described. We performed whole exome sequencing (WES) for a patient (#249) clinically diagnosed with the chromatinopathy Rubinstein-Taybi syndrome (RSTS) but negative for mutations in RSTS genes, identifying a de novo frameshift variant in HDAC2 gene. We then investigated its molecular effects in lymphoblastoid cell lines (LCLs) derived from the patient compared to LCLs from healthy donors (HD). As the variant was predicted to be likely pathogenetic and to affect the sequence of nuclear localization signal, we performed immunocytochemistry and lysates fractionation, observing a nuclear mis-localization of HDAC2 compared to HD LCLs. In addition, HDAC2 total protein abundance resulted altered in patient, and we found that newly identified variant in HDAC2 affects also acetylation levels, with significant difference in acetylation pattern among patient #249, HD and RSTS cells and in expression of a known molecular target. Remarkably, RNA-seq performed on #249, HD and RSTS cells shows differentially expressed genes (DEGs) common to #249 and RSTS. Interestingly, our reported patient was clinically diagnosed with RSTS, a chromatinopathy which known causative genes encode for enzymes antagonizing HDACs. These results support the role of HDAC2 as causative gene for chromatinopathies, strengthening the genotype-phenotype correlations in this relevant group of disorders.
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Sequenciamento do Exoma , Histona Desacetilase 2 , Humanos , Histona Desacetilase 2/genética , Histona Desacetilase 2/metabolismo , Acetilação , Síndrome de Rubinstein-Taybi/genética , Síndrome de Rubinstein-Taybi/patologia , Cromatina/genética , Cromatina/metabolismo , Masculino , Feminino , Mutação , Mutação da Fase de Leitura , Linhagem CelularRESUMO
PRRT2 is a neuronal protein that controls neuronal excitability and network stability by modulating voltage-gated Na+ channel (Nav). PRRT2 pathogenic variants cause pleiotropic syndromes including epilepsy, paroxysmal kinesigenic dyskinesia and episodic ataxia attributable to loss-of-function pathogenetic mechanism. Based on the evidence that the transmembrane domain of PRRT2 interacts with Nav1.2/1.6, we focused on eight missense mutations located within the domain that show expression and membrane localization similar to the wild-type protein. Molecular dynamics simulations showed that the mutants do not alter the structural stability of the PRRT2 membrane domain and preserve its conformation. Using affinity assays, we found that the A320V and V286M mutants displayed respectively decreased and increased binding to Nav1.2. Accordingly, surface biotinylation showed an increased Nav1.2 surface exposure induced by the A320V mutant. Electrophysiological analysis confirmed the lack of modulation of Nav1.2 biophysical properties by the A320V mutant with a loss-of-function phenotype, while the V286M mutant displayed a gain-of-function with respect to wild-type PRRT2 with a more pronounced left-shift of the inactivation kinetics and delayed recovery from inactivation. The data confirm the key role played by the PRRT2-Nav interaction in the pathogenesis of the PRRT2-linked disorders and suggest an involvement of the A320 and V286 residues in the interaction site. Given the similar clinical phenotype caused by the two mutations, we speculate that circuit instability and paroxysmal manifestations may arise when PRRT2 function is outside the physiological range.
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Mutação de Sentido Incorreto , Canal de Sódio Disparado por Voltagem NAV1.2 , Canal de Sódio Disparado por Voltagem NAV1.2/genética , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Mutação/genéticaRESUMO
PURPOSE: The worldwide pandemic caused by SARS-CoV-2 virus posed many challenges to the scientific and medical communities, including the protection and management of fragile populations. People with epilepsy (PWE) are a heterogenous group of subjects, with different treatment regimens and severity of symptoms. During the National lockdown, in Italy many patients with chronic conditions lost their regular follow-up program. The aim of this study was to investigate the impact of COVID-19 on their health status, from the start of the pandemic (March 2020) to July 2021 and one year later. METHODS: We proposed an online questionnaire to subjects followed up at different epilepsy centers located in Milano, Monza & Lodi, three of Lombardy, Northern Italy, the most affected areas by the pandemic. Survey evaluated age, sex, characteristics of patients, type of epilepsy and therapies, COVID-19 diagnosis, vaccines, sleep quality, and anxiety status. RESULTS: Among 178 analyzed surveys, 37 individuals reported symptoms of COVID-19 in closed contacts, including 9 with molecular diagnosis and 16 PWE performing the nasopharyngeal swab with 3 positive cases. One year later, 35 individuals reported at least one symptom overlapping with those typical of COVID-19, 8 received COVID-19 diagnosis, among which 6 were positive for SARS-CoV-2 infection. According to the sleep quality scale assessment, most PWE (52.3%) had poor sleep quality. Assessing anxiety status, 32 (38.1%) had a pathological score. CONCLUSION: In this multicenter study, we observed that PWE do not appear to be at a higher risk of severe COVID-19. It will be fundamental monitoring this group to assess possible differences in long-COVID-19 and/or neuro-COVID-19 prevalence. On the other hand, our survey confirmed the impact of the pandemic on anxiety and quality of sleep in PWE. Thus, it is important to promptly recognize and treat psychological distress in PWE, because it could be a risk factor in seizure aggravation and quality-of-life deterioration. Telemedicine appears to be a useful tool to support patients with chronic diseases, such as epilepsy.
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COVID-19 , Epilepsia , COVID-19/complicações , COVID-19/epidemiologia , Teste para COVID-19 , Controle de Doenças Transmissíveis , Epilepsia/psicologia , Humanos , Pandemias , SARS-CoV-2 , Inquéritos e Questionários , Síndrome de COVID-19 Pós-AgudaRESUMO
Cornelia de Lange syndrome (CdLS), which is reported to affect â¼1 in 10 000 to 30 000 newborns, is a multisystem organ developmental disorder with relatively mild to severe effects. Among others, intellectual disability represents an important feature of this condition. CdLS can result from mutations in at least five genes: nipped-B-like protein, structural maintenance of chromosomes 1A, structural maintenance of chromosomes 3, RAD21 cohesin complex component and histone deacetylase 8 (HDAC8). It is believed that mutations in these genes cause CdLS by impairing the function of the cohesin complex (to which all the aforementioned genes contribute to the structure or function), disrupting gene regulation during critical stages of early development. Since intellectual disorder might result from alterations in neural development, in this work, we studied the role of Hdac8 gene in mouse neural stem cells (NSCs) and in vertebrate (Danio rerio) brain development by knockdown and chemical inhibition experiments. Underlying features of Hdac8 deficiency is an increased cell death in the developing neural tissues, either in mouse NSCs or in zebrafish embryos.
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Proteínas de Ciclo Celular/fisiologia , Proteínas Cromossômicas não Histona/fisiologia , Síndrome de Cornélia de Lange/genética , Histona Desacetilases/genética , Animais , Proteínas de Ciclo Celular/genética , Diferenciação Celular/genética , Diferenciação Celular/fisiologia , Proteínas Cromossômicas não Histona/genética , Síndrome de Cornélia de Lange/fisiopatologia , Regulação da Expressão Gênica/genética , Histona Desacetilases/metabolismo , Histona Desacetilases/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mutação/genética , Células-Tronco Neurais/fisiologia , Neurônios/fisiologia , Fenótipo , Proteínas Repressoras/genética , Peixe-Zebra , Proteínas de Peixe-Zebra , CoesinasRESUMO
Autophagy plays a crucial role in health and disease, regulating central cellular processes such as adaptive stress responses, differentiation, tissue development, and homeostasis. However, the role of autophagy in human physiology is poorly understood, highlighting a need for a model human organ system to assess the efficacy and safety of strategies to therapeutically modulate autophagy. As a complete, cyclically remodelled (mini-)organ, the organ culture of human scalp hair follicles (HFs), which, after massive growth (anagen), spontaneously enter into an apoptosis-driven organ involution (catagen) process, may provide such a model. Here, we reveal that in anagen, hair matrix keratinocytes (MKs) of organ-cultured HFs exhibit an active autophagic flux, as documented by evaluation of endogenous lipidated Light Chain 3B (LC3B) and sequestosome 1 (SQSTM1/p62) proteins and the ultrastructural visualization of autophagosomes at all stages of the autophagy process. This autophagic flux is altered during catagen, and genetic inhibition of autophagy promotes catagen development. Conversely, an anti-hair loss product markedly enhances intrafollicular autophagy, leading to anagen prolongation. Collectively, our data reveal a novel role of autophagy in human hair growth. Moreover, we show that organ-cultured scalp HFs are an excellent preclinical research model for exploring the role of autophagy in human tissue physiology and for evaluating the efficacy and tissue toxicity of candidate autophagy-modulatory agents in a living human (mini-)organ.
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Autofagia/fisiologia , Folículo Piloso/citologia , Técnicas de Cultura de Células , Linhagem Celular , Folículo Piloso/efeitos dos fármacos , Folículo Piloso/crescimento & desenvolvimento , Humanos , Queratinócitos/citologia , Técnicas de Cultura de ÓrgãosRESUMO
Monitoring the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) community-wide transmission with a suitable and effective sampling method would be of great support for public health response to the spreading due to asymptomatic subjects in the community.Here, we describe how using saliva samples for SARS-CoV-2 detection has allowed for a weekly surveillance of a small business company and the early detection of coronavirus disease 2019 cases.As on 23rd March, two cases were detected and investigated, and control measures were rapidly applied.
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COVID-19/prevenção & controle , Surtos de Doenças/prevenção & controle , SARS-CoV-2/isolamento & purificação , Saliva/virologia , Adulto , Idoso , COVID-19/diagnóstico , COVID-19/epidemiologia , Teste de Ácido Nucleico para COVID-19 , Busca de Comunicante , Monitoramento Epidemiológico , Feminino , Humanos , Itália/epidemiologia , Masculino , Pessoa de Meia-Idade , SARS-CoV-2/imunologiaRESUMO
The short-chain fatty acid butyrate, produced by the gut microbiota, acts as a potent histone deacetylase (HDAC) inhibitor. We assessed possible ameliorative effects of butyrate, relative to other HDAC inhibitors, in in vitro and in vivo models of Rubinstein-Taybi syndrome (RSTS), a severe neurodevelopmental disorder caused by variants in the genes encoding the histone acetyltransferases CBP and p300. In RSTS cell lines, butyrate led to the patient-specific rescue of acetylation defects at subtoxic concentrations. Remarkably, we observed that the commensal gut microbiota composition in a cohort of RSTS patients is significantly depleted in butyrate-producing bacteria compared to healthy siblings. We demonstrate that the effects of butyrate and the differences in microbiota composition are conserved in a Drosophila melanogaster mutant for CBP, enabling future dissection of the gut-host interactions in an in vivo RSTS model. This study sheds light on microbiota composition in a chromatinopathy, paving the way for novel therapeutic interventions.
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Butiratos/metabolismo , Síndrome de Rubinstein-Taybi/metabolismo , Síndrome de Rubinstein-Taybi/microbiologia , Acetilação , Adolescente , Animais , Butiratos/farmacologia , Proteína de Ligação a CREB/metabolismo , Criança , Pré-Escolar , Estudos de Coortes , Modelos Animais de Doenças , Drosophila melanogaster/metabolismo , Proteína p300 Associada a E1A/metabolismo , Ácidos Graxos Voláteis/metabolismo , Ácidos Graxos Voláteis/fisiologia , Feminino , Microbioma Gastrointestinal/fisiologia , Histona Acetiltransferases/metabolismo , Inibidores de Histona Desacetilases/farmacologia , Humanos , Masculino , Mutação , Processamento de Proteína Pós-Traducional , Fatores de Transcrição de p300-CBP/metabolismoRESUMO
In recent years, many genes have been associated with chromatinopathies classified as "Cornelia de Lange Syndrome-like." It is known that the phenotype of these patients becomes less recognizable, overlapping to features characteristic of other syndromes caused by genetic variants affecting different regulators of chromatin structure and function. Therefore, Cornelia de Lange syndrome diagnosis might be arduous due to the seldom discordance between unexpected molecular diagnosis and clinical evaluation. Here, we review the molecular features of Cornelia de Lange syndrome, supporting the hypothesis that "CdLS-like syndromes" are part of a larger "rare disease family" sharing multiple clinical features and common disrupted molecular pathways.
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Proteínas de Ciclo Celular/genética , Cromatina/patologia , Proteínas Cromossômicas não Histona/genética , Síndrome de Cornélia de Lange/diagnóstico , Patologia Molecular , Cromatina/genética , Síndrome de Cornélia de Lange/genética , Síndrome de Cornélia de Lange/patologia , Estudos de Associação Genética , Humanos , Mutação/genética , Fenótipo , Transdução de Sinais/genética , CoesinasRESUMO
Disruption of the circadian clock is associated with a variety of human pathologies, including cancer. Rather than being a mere consequence of a global changes associated with the cancer cell transcriptome, the aberrant clock gene expression observed in many tumors may serve for cancer cell survival. This scenario suggests the provocative hypothesis that pharmacological modulation of clock-related proteins may be suitable as an effective anticancer strategy. In this review, we focus on the functions of the druggable circadian nuclear receptors, REV-ERBα and REV-ERBß, in cancer cell survival and describe the potential development of small molecule compounds that modulate REV-ERB activity as novel anticancer therapeutics. In addition, we debate the use of circadian rhythm-based synthetic lethal approaches to identify yet unexplored anticancer strategies.
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Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Relógios Circadianos/efeitos dos fármacos , Ritmo Circadiano/efeitos dos fármacos , Neoplasias/tratamento farmacológico , Animais , Relógios Circadianos/genética , Ritmo Circadiano/genética , Humanos , Neoplasias/genética , Receptores Citoplasmáticos e Nucleares/genética , Bibliotecas de Moléculas Pequenas/farmacologia , Bibliotecas de Moléculas Pequenas/uso terapêuticoRESUMO
BACKGROUND: Chromatinopathies are a heterogeneous group of genetic disorders caused by pathogenic variants in genes coding for chromatin state balance proteins. Remarkably, many of these syndromes present unbalanced postnatal growth, both under- and over-, although little has been described in the literature. Fetal growth measurements are common practice in pregnancy management and values within normal ranges indicate proper intrauterine growth progression; on the contrary, abnormalities in intrauterine fetal growth open the discussion of possible pathogenesis affecting growth even in the postnatal period. METHODS: Among the numerous chromatinopathies, we have selected six of the most documented in the literature offering evidence about two fetal overgrowth (Sotos and Weaver syndrome) and four fetal undergrowth syndromes (Bohring Opitz, Cornelia de Lange, Floating-Harbor, and Meier Gorlin syndrome), describing their molecular characteristics, maternal biochemical results and early pregnancy findings, prenatal ultrasound findings, and postnatal characteristics. RESULTS/CONCLUSION: To date, the scarce data in the literature on prenatal findings are few and inconclusive, even though these parameters may contribute to a more rapid and accurate diagnosis, calling for a better and more detailed description of pregnancy findings.
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Cromatina , Humanos , Feminino , Gravidez , Cromatina/metabolismo , Desenvolvimento Fetal/genética , Diagnóstico Pré-Natal/métodos , Ultrassonografia Pré-Natal/métodosRESUMO
BACKGROUND: Sarcopenia, the age-associated decline in skeletal muscle mass and strength, has long been considered a disease of muscle only, but accumulating evidence suggests that sarcopenia could originate from the neural components controlling muscles. To identify early molecular changes in nerves that may drive sarcopenia initiation, we performed a longitudinal transcriptomic analysis of the sciatic nerve, which governs lower limb muscles, in aging mice. METHODS: Sciatic nerve and gastrocnemius muscle were obtained from female C57BL/6JN mice aged 5, 18, 21 and 24 months old (n = 6 per age group). Sciatic nerve RNA was extracted and underwent RNA sequencing (RNA-seq). Differentially expressed genes (DEGs) were validated using quantitative reverse transcription PCR (qRT-PCR). Functional enrichment analysis of clusters of genes associated with patterns of gene expression across age groups (adjusted P-value < 0.05, likelihood ratio test [LRT]) was performed. Pathological skeletal muscle aging was confirmed between 21 and 24 months by a combination of molecular and pathological biomarkers. Myofiber denervation was confirmed with qRT-PCR of Chrnd, Chrng, Myog, Runx1 and Gadd45É in gastrocnemius muscle. Changes in muscle mass, cross-sectional myofiber size and percentage of fibres with centralized nuclei were analysed in a separate cohort of mice from the same colony (n = 4-6 per age group). RESULTS: We detected 51 significant DEGs in sciatic nerve of 18-month-old mice compared with 5-month-old mice (absolute value of fold change > 2; false discovery rate [FDR] < 0.05). Up-regulated DEGs included Dbp (log2 fold change [LFC] = 2.63, FDR < 0.001) and Lmod2 (LFC = 7.52, FDR = 0.001). Down-regulated DEGs included Cdh6 (LFC = -21.38, FDR < 0.001) and Gbp1 (LFC = -21.78, FDR < 0.001). We validated RNA-seq findings with qRT-PCR of various up- and down-regulated genes including Dbp and Cdh6. Up-regulated genes (FDR < 0.1) were associated with the AMP-activated protein kinase signalling pathway (FDR = 0.02) and circadian rhythm (FDR = 0.02), whereas down-regulated DEGs were associated with biosynthesis and metabolic pathways (FDR < 0.05). We identified seven significant clusters of genes (FDR < 0.05, LRT) with similar expression patterns across groups. Functional enrichment analysis of these clusters revealed biological processes that may be implicated in age-related changes in skeletal muscles and/or sarcopenia initiation including extracellular matrix organization and an immune response (FDR < 0.05). CONCLUSIONS: Gene expression changes in mouse peripheral nerve were detected prior to disturbances in myofiber innervation and sarcopenia onset. These early molecular changes we report shed a new light on biological processes that may be implicated in sarcopenia initiation and pathogenesis. Future studies are warranted to confirm the disease modifying and/or biomarker potential of the key changes we report here.
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Fenômenos Biológicos , Sarcopenia , Feminino , Camundongos , Animais , Sarcopenia/etiologia , Transcriptoma , Estudos Transversais , Camundongos Endogâmicos C57BL , Músculo Esquelético/patologia , Nervo Isquiático/metabolismo , Nervo Isquiático/patologia , Receptores Colinérgicos/genética , Receptores Colinérgicos/metabolismoRESUMO
Background: Saliva molecular tests have shown a similar sensitivity and specificity compared to nasopharyngeal test for SARS-CoV-2 diagnosis in both symptomatic and asymptomatic individuals. The SARS-CoV-2 pandemic affected Lombardy prisons, generating the need for extensive contact tracing activities and for detecting asymptomatic carriers. The availability of a less invasive test in a setting that hosts a high-risk and often hard-to-reach population, suggests its possible use in prisons. Methods: The study was carried out on a population of new incomers in Milan San Vittore pre-trial prison. All the new incomers were submitted to quarantine and to saliva test and nasopharyngeal swab (NPS) for SARS-CoV-2 detection at the entry and at the end of quarantine before their admission in community (Protocol 1-February 2nd to March 5th, 2021). Starting from March 8th to July 30th, 2021, the screening protocol was adjusted to avoid biases in sample collection (Protocol II), and saliva testing was performed at entrance. Results: 12/1,120 enrolled subjects were excluded from the study. Among the 1,080 processed samples, 1 tested positive, 5 weakly positive, 1,069 negative, 3 were invalid, and 2 samples tested positive for the viral gene N2 only, with Ct value above 38. During Protocol I, 6/156 coupled saliva/NPS tests were discordant due to food ingestion prior saliva collection, prompting us to establishing Protocol II. Conclusions: Saliva molecular testing is feasible in prison setting, being less invasive and easier to use, and reliable. Acceptability was very high even in a complex context as that of newly incarcerated persons.
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COVID-19 , Teste para COVID-19 , Estudos de Viabilidade , Humanos , Prisões , SARS-CoV-2 , SalivaRESUMO
Chromatinopathies are defined as genetic disorders caused by mutations in genes coding for protein involved in the chromatin state balance. So far 82 human conditions have been described belonging to this group of congenital disorders, sharing some molecular features and clinical signs. For almost all of these conditions, no specific treatment is available. For better understanding the molecular cascade caused by chromatin imbalance and for envisaging possible therapeutic strategies it is fundamental to combine clinical and basic research studies. To this end, animal modelling systems represent an invaluable tool to study chromatinopathies. In this review, we focused on available data in the literature of animal models mimicking the human genetic conditions. Importantly, affected organs and abnormalities are shared in the different animal models and most of these abnormalities are reported as clinical manifestation, underlying the parallelism between clinics and translational research.
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KMT2A (Lysine methyltransferase 2A) is a member of the epigenetic machinery, encoding a lysine methyltransferase responsible for the transcriptional activation through lysine 4 of histone 3 (H3K4) methylation. KMT2A has a crucial role in gene expression, thus it is associated to pathological conditions when found mutated. KMT2A germinal mutations are associated to Wiedemann-Steiner syndrome and also in patients with initial clinical diagnosis of several other chromatinopathies (i.e., Coffin-Siris syndromes, Kabuki syndrome, Cornelia De Lange syndrome, Rubinstein-Taybi syndrome), sharing an overlapping phenotype. On the other hand, KMT2A somatic mutations have been reported in several tumors, mainly blood malignancies. Due to its evolutionary conservation, the role of KMT2A in embryonic development, hematopoiesis and neurodevelopment has been explored in different animal models, and in recent decades, epigenetic treatments for disorders linked to KMT2A dysfunction have been extensively investigated. To note, pharmaceutical compounds acting on tumors characterized by KMT2A mutations have been formulated, and even nutritional interventions for chromatinopathies have become the object of study due to the role of microbiota in epigenetic regulation.
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Anormalidades Múltiplas , Deficiência Intelectual , Anormalidades Múltiplas/diagnóstico , Anormalidades Múltiplas/genética , Animais , Epigênese Genética , Humanos , Deficiência Intelectual/genética , Lisina , FenótipoRESUMO
Prenatal exposure to valproate (VPA), an antiepileptic drug, has been associated with fetal valproate spectrum disorders (FVSD), a clinical condition including congenital malformations, developmental delay, intellectual disability as well as autism spectrum disorder, together with a distinctive facial appearance. VPA is a known inhibitor of histone deacetylase which regulates the chromatin state. Interestingly, perturbations of this epigenetic balance are associated with chromatinopathies, a heterogeneous group of Mendelian disorders arising from mutations in components of the epigenetic machinery. Patients affected from these disorders display a plethora of clinical signs, mainly neurological deficits and intellectual disability, together with distinctive craniofacial dysmorphisms. Remarkably, critically examining the phenotype of FVSD and chromatinopathies, they shared several overlapping features that can be observed despite the different etiologies of these disorders, suggesting the possible existence of a common perturbed mechanism(s) during embryonic development.
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Mutations in PRoline Rich Transmembrane protein 2 (PRRT2) cause pleiotropic syndromes including benign infantile epilepsy, paroxysmal kinesigenic dyskinesia, episodic ataxia, that share the paroxysmal character of the clinical manifestations. PRRT2 is a neuronal protein that plays multiple roles in the regulation of neuronal development, excitability, and neurotransmitter release. To better understand the physiopathology of these clinical phenotypes, we investigated PRRT2 interactome in mouse brain by a pulldown-based proteomic approach and identified α1 and α3 Na+/K+ ATPase (NKA) pumps as major PRRT2-binding proteins. We confirmed PRRT2 and NKA interaction by biochemical approaches and showed their colocalization at neuronal plasma membrane. The acute or constitutive inactivation of PRRT2 had a functional impact on NKA. While PRRT2-deficiency did not modify NKA expression and surface exposure, it caused an increased clustering of α3-NKA on the plasma membrane. Electrophysiological recordings showed that PRRT2-deficiency in primary neurons impaired NKA function during neuronal stimulation without affecting pump activity under resting conditions. Both phenotypes were fully normalized by re-expression of PRRT2 in PRRT2-deficient neurons. In addition, the NKA-dependent afterhyperpolarization that follows high-frequency firing was also reduced in PRRT2-silenced neurons. Taken together, these results demonstrate that PRRT2 is a physiological modulator of NKA function and suggest that an impaired NKA activity contributes to the hyperexcitability phenotype caused by PRRT2 deficiency.
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Adenosina Trifosfatases/metabolismo , Proteínas de Membrana/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismo , Proteômica/métodos , Humanos , Transmissão SinápticaRESUMO
Cornelia de Lange Syndrome (CdLS) is a rare developmental disorder affecting a multitude of organs including the central nervous system, inducing a variable neurodevelopmental delay. CdLS malformations derive from the deregulation of developmental pathways, inclusive of the canonical WNT pathway. We have evaluated MRI anomalies and behavioral and neurological clinical manifestations in CdLS patients. Importantly, we observed in our cohort a significant association between behavioral disturbance and structural abnormalities in brain structures of hindbrain embryonic origin. Considering the cumulative evidence on the cohesin-WNT-hindbrain shaping cascade, we have explored possible ameliorative effects of chemical activation of the canonical WNT pathway with lithium chloride in different models: (I) Drosophila melanogaster CdLS model showing a significant rescue of mushroom bodies morphology in the adult flies; (II) mouse neural stem cells restoring physiological levels in proliferation rate and differentiation capabilities toward the neuronal lineage; (III) lymphoblastoid cell lines from CdLS patients and healthy donors restoring cellular proliferation rate and inducing the expression of CyclinD1. This work supports a role for WNT-pathway regulation of CdLS brain and behavioral abnormalities and a consistent phenotype rescue by lithium in experimental models.
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BACKGROUND: Neural tube defects (NTDs) result from failure of neural tube closure during embryogenesis. These severe birth defects of the central nervous system include anencephaly and spina bifida, and affect 0.5-2 per 1,000 pregnancies worldwide in humans. It has been demonstrated that acetylation plays a pivotal role during neural tube closure, as animal models for defective histone acetyltransferase proteins display NTDs. Acetylation represents an important component of the complex network of posttranslational regulatory interactions, suggesting a possible fundamental role during primary neurulation events. This study aimed to assess protein acetylation contribution to early patterning of the central nervous system both in human and murine specimens. METHODS: We used both human and mouse (Cited2 -/- ) samples to analyze the dynamic acetylation of proteins during embryo development through immunohistochemistry, western blot analysis and quantitative polymerase chain reaction. RESULTS: We report the dynamic profile of histone and protein acetylation status during neural tube closure. We also report a rescue effect in an animal model by chemical p53 inhibition. CONCLUSIONS: Our data suggest that the p53-acetylation equilibrium may play a role in primary neurulation in mammals.