16 research outputs found
Metabolomic Fingerprint of Mecp2-Deficient Mouse Cortex: Evidence for a Pronounced Multi-Facetted Metabolic Component in Rett Syndrome
No full textUsing unsupervised metabolomics, we defined the complex metabolic conditions in the cortex of a mouse model of Rett syndrome (RTT). RTT, which represents a cause of mental and cognitive disabilities in females, results in profound cognitive impairment with autistic features, motor disabilities, seizures, gastrointestinal problems, and cardiorespiratory irregularities. Typical RTT originates from mutations in the X-chromosomal methyl-CpG-binding-protein-2 (Mecp2) gene, which encodes a transcriptional modulator. It then causes a deregulation of several target genes and metabolic alterations in the nervous system and peripheral organs. We identified 101 significantly deregulated metabolites in the Mecp2-deficient cortex of adult male mice; 68 were increased and 33 were decreased compared to wildtypes. Pathway analysis identified 31 mostly upregulated metabolic pathways, in particular carbohydrate and amino acid metabolism, key metabolic mitochondrial/extramitochondrial pathways, and lipid metabolism. In contrast, neurotransmitter-signaling is dampened. This metabolic fingerprint of the Mecp2-deficient cortex of severely symptomatic mice provides further mechanistic insights into the complex RTT pathogenesis. The deregulated pathways that were identified—in particular the markedly affected amino acid and carbohydrate metabolism—confirm a complex and multifaceted metabolic component in RTT, which in turn signifies putative therapeutic targets. Furthermore, the deregulated key metabolites provide a choice of potential biomarkers for a more detailed rating of disease severity and disease progression
Mitochondrial Proteome Changes in Rett Syndrome
No full textRett syndrome (RTT) is a genetic neurodevelopmental disorder with mutations in the X-chromosomal MECP2 (methyl-CpG-binding protein 2) gene. Most patients are young girls. For 7-18 months after birth, they hardly present any symptoms; later they develop mental problems, a lack of communication, irregular sleep and breathing, motor dysfunction, hand stereotypies, and seizures. The complex pathology involves mitochondrial structure and function. Mecp2-/y hippocampal astrocytes show increased mitochondrial contents. Neurons and glia suffer from oxidative stress, a lack of ATP, and increased hypoxia vulnerability. This spectrum of changes demands comprehensive molecular studies of mitochondria to further define their pathogenic role in RTT. Therefore, we applied a comparative proteomic approach for the first time to study the entity of mitochondrial proteins in a mouse model of RTT. In the neocortex and hippocampus of symptomatic male mice, two-dimensional gel electrophoresis and subsequent mass-spectrometry identified various differentially expressed mitochondrial proteins, including components of respiratory chain complexes I and III and the ATP-synthase FoF1 complex. The NADH-ubiquinone oxidoreductase 75 kDa subunit, NADH dehydrogenase [ubiquinone] iron-sulfur protein 8, NADH dehydrogenase [ubiquinone] flavoprotein 2, cytochrome b-c1 complex subunit 1, and ATP synthase subunit d are upregulated either in the hippocampus alone or both the hippocampus and neocortex of Mecp2-/y mice. Furthermore, the regulatory mitochondrial proteins mitofusin-1, HSP60, and 14-3-3 protein theta are decreased in the Mecp2-/y neocortex. The expressional changes identified provide further details of the altered mitochondrial function and morphology in RTT. They emphasize brain-region-specific alterations of the mitochondrial proteome and support the notion of a metabolic component of this devastating disorder.Open-Access-Publikationsfonds 202
Intensified mitochondrial hydrogen peroxide release occurs in all brain regions, affects male as well as female Rett mice, and constitutes a life-long burden
No full textRetraction notice to “Intensified mitochondrial hydrogen peroxide release occurs in all brain regions, affects male as well as female Rett mice, and constitutes a life-long burden” [Arch. Biochem. Biophys. 696 (15 December 2020) 10866]
No full textNeuronal Redox-Imbalance in Rett Syndrome Affects Mitochondria as Well as Cytosol, and Is Accompanied by Intensified Mitochondrial O2 Consumption and ROS Release
No full textRett syndrome (RTT), an X chromosome-linked neurodevelopmental disorder affecting almost exclusively females, is associated with various mitochondrial alterations. Mitochondria are swollen, show altered respiratory rates, and their inner membrane is leaking protons. To advance the understanding of these disturbances and clarify their link to redox impairment and oxidative stress, we assessed mitochondrial respiration in defined brain regions and cardiac tissue of male wildtype (WT) and MeCP2-deficient (Mecp2-/y) mice. Also, we quantified for the first time neuronal redox-balance with subcellular resolution in cytosol and mitochondrial matrix. Quantitative roGFP1 redox imaging revealed more oxidized conditions in the cytosol of Mecp2-/y hippocampal neurons than in WT neurons. Furthermore, cytosol and mitochondria of Mecp2-/y neurons showed exaggerated redox-responses to hypoxia and cell-endogenous reactive oxygen species (ROS) formation. Biochemical analyzes exclude disease-related increases in mitochondrial mass in Mecp2-/y hippocampus and cortex. Protein levels of complex I core constituents were slightly lower in Mecp2-/y hippocampus and cortex than in WT; those of complex V were lower in Mecp2-/y cortex. Respiratory supercomplex-formation did not differ among genotypes. Yet, supplied with the complex II substrate succinate, mitochondria of Mecp2-/y cortex and hippocampus consumed more O2 than WT. Furthermore, mitochondria from Mecp2-/y hippocampus and cortex mediated an enhanced oxidative burden. In conclusion, we further advanced the molecular understanding of mitochondrial dysfunction in RTT. Intensified mitochondrial O2 consumption, increased mitochondrial ROS generation and disturbed redox balance in mitochondria and cytosol may represent a causal chain, which provokes dysregulated proteins, oxidative tissue damage, and contributes to neuronal network dysfunction in RTT
Comparative analysis of the mitochondrial proteome in a mouse model of Rett syndrome
No full textShota Rustaveli National Scientific Foundation of GeorgiaVolkswagen FoundationRett syndrome is a neural development disorder. The gene, for culprit protein, MeCP2 (methylated CpG binding protein) is located on chromosome X and the majority of patients are young girls. Rett syndrome patients do not suffer from neurodegenerative processes, instead, due to the neurons´ abnormal small size and denser packaging, the brain´s general volume is reduced and synapses as well as dendrite structure are weakened.
Rett syndrome patient’s postnatal development appears normal during the first 6 to 16 month of life. After that, phenotype signs such as mental problems and lack of communication are observed, which are followed by a number of additional severe symptoms: irregular sleep and breathing, labored motor movements, frequent epileptic seizures, body weight loss, scoliosis, and stereotypic hand movements.
Post mortem tissue analyses of Rett syndrome patients show that mitochondrial ultra-structure is damaged and organelle functions are hindered. Cells suffer from higher concentrations of free radicals, oxidative stress, lack of ATP, and increased susceptibility to hypoxia. Mitochondrial changes were first discovered in muscle tissue. Damaged mitochondria contain vacuoles, small granular inclusions, distorted inner membranes, are leaky to protons, and general mitochondrial mass is increased. Mitochondrial impairments obviously lead to insufficient respiratory chain protein activity, cellular ATP deficits, and increased oxidative stress on the systemic level. Frequent apneas in Rett syndrome patients give rise to transient drops in blood oxygen levels, and cells with malfunctioning mitochondria were proposed to suffer from an oxidative burden.
Main goals of this thesis were (i) broad-range comparative proteomic analyses of mitochondria obtained from the brains of wild type and Mecp2 gene knockout mice, specifically focusing on neocortex and hippocampus and (ii) untargeted metabolomic studies of the neocortex on the same group of animals. So far such a research approach was not carried out on the brains of Mecp2 knockout Rett syndrome mouse models.
For the experiments, flash frozen brain tissues of 50 days old Mecp2-deficent and wild type variant male mice were used. The broad range proteomic study involved analyzing samples with two-dimensional electrophoresis and identifying peptide contents of differently expressed spots by mass spectrometry. The observed differences for some proteins were further confirmed by western blotting and specific antibodies. Findings show an upregulation of cytochrome b-c1 complex subunit 1 and prohibitin-1, as well as a downregulation of gamma-enolase and cAMP-dependent protein
xi
kinase catalytic subunit alpha in both, Mecp2-/y neocortex and hippocampus. The other series of mitochondrial proteome experiments involved an ad hoc approach and were aiming at mitochondrial fission and fusion regulatory proteins and mitochondrial oxidative phosphorylation chain components. Here it became apparent that mitochondrial dynamics regulation proteins were decreased in RTT mice, specifically mitofusin 1 was found at lower levels in cortical tissue and DRP-1 was expressed less in hippocampus.
For the rating of physiological aspects of Rett syndrome and wild type mice, general phenotypic parameters – such as body weight, size and blood parameters – were assessed. Also, brain mitochondria purification was performed on freshly extirpated brain tissues and biochemical assays were conducted on live and still functioning mitochondria to measure their reactive oxygen species accumulation by recording the emitted fluorescence signal of an oxidation sensitive dye in a spectrometer-based cuvette assay.
Untargeted metabolomic analysis required higher amounts of tissue material and was therefore limited to the cortices of Mecp2-deficent and wild type male mice. Flash frozen cortices were sent to a service provider, who performed the analyses and provided a large amount of valuable raw data for further in-depths bioinformatics analyses. Metabolomic data reveals 101 significantly altered metabolites in the MeCP2-deficient neocortex of adult male mice; 68 of them were increased whilst 33 were decreased compared to wild types. These differences cover more than 31 metabolic pathways, including pivotal aspects of cellular metabolism, such as pyruvate metabolism, glycolysis, citrate cycle and oxidative phosphorylation.
Data collected from different experiments show various molecular and metabolic abnormalities in the brains of Rett syndrome mice. The mitochondrial proteome of RTT mice clearly differs from wild type mice and this difference is also brain-region specific. Mitochondrial fusion/fission dynamics as well as their physiological performance seem negatively affected. Mecp2-knockout mice are suffering from increased oxidative stress, which in part might be due to poor mitochondrial function, and these alterations might have additional tolling influence on the already impaired conditions of metabolic and mitochondrial activities as well as key features of cellular metabolism.
All these results shed further light onto the mitochondrial and the metabolic alterations that appear as part of the pathogenesis of Rett syndrome in MeCP2 deficient brain tissue. Accordingly, these aspects should be taken into account when therapeutic approaches in RTT are developed and/or when further treatment concepts are formulated.2023-10-1
From Emporia to 'Diaspora'? The Samians in the Western Mediterranean (7th-5th centuries BC)
No full textThe paper examines a set of experiences related to the presence of Samians both in eastern and in western parts of the archaic Mediterranean and explores the idea that a special model of their attendance abroad could be traced. Based on various examples from the sixth to the first quarter of the fifth centuries, the Author argues that this peculiar feature might be singled out within the wider framework of occurrences in Western Mediterranean of Greek people from Ionia, a scenario in which emporie and “diaspora” seem to have been the two main forms
Neuronal Redox-Imbalance in Rett Syndrome Affects Mitochondria as Well as Cytosol, and Is Accompanied by Intensified Mitochondrial O2 Consumption and ROS Release
No full textRett syndrome (RTT), an X chromosome-linked neurodevelopmental disorder affecting almost exclusively females, is associated with various mitochondrial alterations. Mitochondria are swollen, show altered respiratory rates, and their inner membrane is leaking protons. To advance the understanding of these disturbances and clarify their link to redox impairment and oxidative stress, we assessed mitochondrial respiration in defined brain regions and cardiac tissue of male wildtype (WT) and MeCP2-deficient (Mecp2-/y) mice. Also, we quantified for the first time neuronal redox-balance with subcellular resolution in cytosol and mitochondrial matrix. Quantitative roGFP1 redox imaging revealed more oxidized conditions in the cytosol of Mecp2-/y hippocampal neurons than in WT neurons. Furthermore, cytosol and mitochondria of Mecp2-/y neurons showed exaggerated redox-responses to hypoxia and cell-endogenous reactive oxygen species (ROS) formation. Biochemical analyzes exclude disease-related increases in mitochondrial mass in Mecp2-/y hippocampus and cortex. Protein levels of complex I core constituents were slightly lower in Mecp2-/y hippocampus and cortex than in WT; those of complex V were lower in Mecp2-/y cortex. Respiratory supercomplex-formation did not differ among genotypes. Yet, supplied with the complex II substrate succinate, mitochondria of Mecp2-/y cortex and hippocampus consumed more O2 than WT. Furthermore, mitochondria from Mecp2-/y hippocampus and cortex mediated an enhanced oxidative burden. In conclusion, we further advanced the molecular understanding of mitochondrial dysfunction in RTT. Intensified mitochondrial O2 consumption, increased mitochondrial ROS generation and disturbed redox balance in mitochondria and cytosol may represent a causal chain, which provokes dysregulated proteins, oxidative tissue damage, and contributes to neuronal network dysfunction in RTT
Author Correction: The bears from Dmanisi and the first dispersal of early Homo out of Africa
No full textAn amendment to this paper has been published and can be accessed via a link at the top of the paper
Biallelic ELOVL1 Variants Are Linked to Hypomyelinating Leukodystrophy, Movement Disorder, and Ichthyosis
No full textAbstract Background Very long chain fatty acids (VLCFAs) are an integral component of myelin and the epidermal water barrier. Variants in genes encoding enzymes responsible for catalyzing the first and rate limiting step in the production of VLCFAs, elongation of VLCFAs (ELOVLs), underlie a novel group of metabolic disorders. Objectives The goal was to describe the clinical phenotype and disturbance in VLCFA metabolism associated with variants in the ELOV1 gene. Methods The following methods were employed: Exome sequencing, clinical phenotyping, magnetic resonance imaging (MRI), metabolomics, liquid chromatography–tandem mass spectrometry, fatty acid elongation assay. Results We, here, describe seven patients with autosomal recessive variants in ELOVL1 . Common clinical features included ichthyosis (5/7), developmental delay (7/7), progressive spasticity (7/7), nystagmus (5/6), and a complex movement disorder characterized by pronounced head tremor (7/7), myoclonus (6/7), and dysarthria (6/6). Brain MRI revealed non‐progressive hypomyelination (6/6) and hypoplasia of the corpus callosum (5/6). Plasma VLCFA analysis in one patient showed reduced concentrations of C24:0 and C26:0. Biochemical analysis of fibroblasts from this patient revealed elongation defects in VLCFA synthesis and dysregulation of other ELOVL enzymes. Conclusions We show that biallelic variants in ELOVL1 are associated with a unique and recognizable phenotype of hypomyelinating leukodystrophy, ichthyosis, and a complex movement disorder including progressive spasticity, head tremor, and myoclonus. Biochemical analyses confirmed a defect in VLCFA synthesis. Variants in genes encoding enzymes involved in the elongation of VLCFAs are a novel group of metabolic disorders with overlapping symptoms. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society
