eIF2B Mutations Cause Mitochondrial Malfunction in Oligodendrocytes

AbstractVanishing white matter (VWM) disease (OMIM#306896) is an autosomal recessive neurodegenerative leukodystrophy caused by hypomorphic mutations in any of the five genes encoding the subunits of eukaryotic translation initiation factor 2B (eIF2B). The disease is manifested by loss of cerebral white matter and progressive deterioration upon exposure to environmental and physiological stressors. “Foamy” oligodendrocytes (OLG), increased numbers of oligodendrocytes precursor cells (OPC), and immature defective astrocytes are major neuropathological denominators. Our recent work using Eif2b5R132H/R132H mice uncovered a fundamental link between eIF2B and mitochondrial function. A decrease in oxidative phosphorylation capacity was observed in mutant astrocytes and fibroblasts. While an adaptive increase in mitochondria abundance corrects the phenotype of mutant fibroblasts, it is not sufficient to compensate for the high-energy demand of astrocytes, explaining their involvement in the disease. To date, astrocytes are marked as central for the disease while eIF2B-mutant OLG are currently assumed to lack a cellular phenotype on their own. Here we show a reduced capacity of eIF2B-mutant OPC isolated from Eif2b5R132H/R132H mice to conduct oxidative respiration despite the adaptive increase in their mitochondrial abundance. We also show their impaired ability to efficiently complete critical differentiation steps towards mature OLG. The concept that defective differenti...
Source: NeuroMolecular Medicine - Category: Neurology Source Type: research

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ConclusionThe syndromic nature and selective vulnerability of white matter tracts in these disorders suggests there may be a shared mechanism of mitochondrial dysfunction to target for study. There is evidence that the clinical variability and white matter tract specificity of each mt-aaRS leukodystrophy depend on both canonical and non-canonical effects of the mutations on the process of mitochondrial translation. Furthermore, different sensitivities to the mt-aaRS mutations have been observed based on cell type. Most mutations result in at least partial retention of mt-aaRS enzyme function with varied effects on the mito...
Source: Journal of Neurodevelopmental Disorders - Category: Neurology Source Type: research
Authors: Ashrafi MR, Amanat M, Garshasbi M, Kameli R, Nilipour Y, Heidari M, Rezaei Z, Tavasoli AR Abstract Introduction: Leukodystrophies constitute heterogenous group of rare heritable disorders primarily affecting the white matter of central nervous system. These conditions are often under-appreciated among physicians. The first clinical manifestations of leukodystrophies are often nonspecific and can occur in different ages from neonatal to late adulthood periods. The diagnosis is, therefore, challenging in most cases.Area covered: Herein, the authors discuss different aspects of leukodystrophies. The authors used...
Source: Expert Review of Neurotherapeutics - Category: Neurology Tags: Expert Rev Neurother Source Type: research
Apoptosis-Inducing Factor Mitochondria-associated-1 gene (AIFM1) encodes a mitochondrial flavin adenine dinucleotide-dependent nicotinamide oxidoreductase, which has a biological role in oxidative phosphorylation (OXPHOS) and in apoptosis pathway [1]. AIFM1 mutations have been reported to be associated with various neurological diseases, including Cowchock syndrome (OMIM 310490) [2], X-linked recessive Charcot-Marie-Tooth disease-4 (CMTX4), X-linked deafness-5 (DFNX5; OMIM 300614) [3], and hypomyelinating leukodystrophy and spondylometaphyseal dysplasia (H-SMD) [4].
Source: Journal of the Neurological Sciences - Category: Neurology Authors: Tags: Letter to the Editor Source Type: research
We report that dCOA8 knockdown (KD) flies show locomotor defects, and other signs of neurological impairment, reduced COX enzymatic activity and reduced lifespan under oxidative stress conditions. Our data indicate that KD of dCOA8 in Drosophila phenocopies several features of the human disease, thus being a suitable model to characterize the molecular function/s of this protein in vivo and the pathogenic mechanisms associated with its defects.
Source: Frontiers in Physiology - Category: Physiology Source Type: research
Abstract Glutaric acidemia type I (GA I) is an inherited neurometabolic disease caused by deficient activity of the mitochondrial enzyme glutaryl-CoA dehydrogenase (GCDH), resulting in predominant accumulation of glutaric and 3-hydroxyglutaric acids derived from lysine (Lys), hydroxylysine, and tryptophan catabolism. GA I patients usually present progressive cortical leukodystrophy and frequently develop acute striatal degeneration during encephalopathic crises during the first three years of life. The pathophysiology of the neurodegeneration observed in GA I is still partly known, although the development of the ...
Source: International Journal of Developmental Neuroscience - Category: Neuroscience Authors: Tags: Int J Dev Neurosci Source Type: research
Neuropediatrics DOI: 10.1055/s-0039-1685529Leukodystrophies (LDs) predominantly affect the white matter of the central nervous system and its main component, the myelin. The majority of LDs manifests in infancy with progressive neurodegeneration. Main clinical signs are intellectual and motor function losses of already attained developmental skills. Classical LDs include lysosomal storage disorders like metachromatic leukodystrophy (MLD), peroxisomal disorders like X-linked adrenoleukodystrophy (X-ALD), disorders of mitochondrial dysfunction, and myelin protein defects like Pelizaeus-Merzbacher disease. So far, there are o...
Source: Neuropediatrics - Category: Neurology Authors: Tags: Review Article Source Type: research
In conclusion, we found a gradient of increasing blood pressure with higher levels of BMI. The fact that this gradient is present even in the fully adjusted analyses suggests that BMI may cause a direct effect on blood pressure, independent of other clinical risk factors. PRRX1 as a Possible Point of Control for Remyelination https://www.fightaging.org/archives/2018/12/prrx1-as-a-possible-point-of-control-for-remyelination/ Researchers here outline what is possibly a new point of intervention in the processes that maintain the myelin sheath that wraps nerves. This sheath is vital to the correct operatio...
Source: Fight Aging! - Category: Research Authors: Tags: Newsletters Source Type: blogs
Mitochondrial diseases are a clinically heterogeneous group of disorders caused by dysfunction of the mitochondrial respiratory chain. Some mitochondrial disorders affect a single organ, while many involve multiple systems such as skeletal muscle, brain, heart and liver, leading to diagnostic difficulties. Here we present three patients who were originally suspected to have a primary disease of skeletal muscle, leukodystrophy and brain malformation. Patients were recruited from three paediatric neurology clinics in Turkey: Izmir, Malatya and Diyarbakir.
Source: Neuromuscular Disorders - Category: Neurology Authors: Source Type: research
AbstractDementia represents one of the most diffuse disorders of our Era. Alzheimer ’s disease is the principle cause of dementia worldwide. Metabolic, infectious, autoimmune, inflammatory, and genetic dementias represent a not negligible number of disorders, with increasing numbers in younger subjects. Due to the heterogeneity of patients and disorders, the diagnosis of dementia is challenging. In the present article, we propose a practical diagnostic approach following the two-step investigation procedure. The first step includes basic blood tests and brain neuroimaging, performed on all patients. After this first-...
Source: Neurological Sciences - Category: Neurology Source Type: research
In this study, we used primary human fibroblasts from normal subjects and ALD patients to investigate whether VLCFA can induce endoplasmic reticulum stress. We show that saturated VLCFA (C26:0) induce endoplasmic reticulum stress in fibroblasts from ALD patients, but not in controls. Furthermore, there is a clear correlation between the chain-length of the fatty acid and the induction of endoplasmic reticulum stress. Exposure of ALD fibroblasts to C26:0, resulted in increased expression of additional endoplasmic reticulum stress markers (EDEM1, GADD34 and CHOP) and in lipoapoptosis. This new insight into the underlying mec...
Source: Biochimica et Biophysica Acta (BBA) Molecular Basis of Disease - Category: Molecular Biology Source Type: research
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