Defective complex I assembly due to C20orf7 mutations as a new cause of Leigh syndrome

Background: Leigh syndrome is an early onset, progressive, neurodegenerative disorder with developmental and motor skills regression. Characteristic magnetic resonance imaging abnormalities consist of focal bilateral lesions in the basal ganglia and/or the brainstem. The main cause is a deficiency in oxidative phosphorylation due to mutations in an mtDNA or nuclear oxidative phosphorylation gene. Methods and results: A consanguineous Moroccan family with Leigh syndrome comprise 11 children, three of which are affected. Marker analysis revealed a homozygous region of 11.5 Mb on chromosome 20, containing 111 genes. Eight possible mitochondrial candidate genes were sequenced. Patients were homozygous for an unclassified variant (p.P193L) in the cardiolipin synthase gene (CRLS1). As this variant was present in 20% of a Moroccan control population and enzyme activity was only reduced to 50%, this could not explain the rare clinical phenotype in our family. Patients were also homozygous for an amino acid substitution (p.L159F) in C20orf7, a new complex I assembly factor. Parents were heterozygous and unaffected sibs heterozygous or homozygous wild type. The mutation affects the predicted S-adenosylmethionine (SAM) dependent methyltransferase domain of C20orf7, possibly involved in methylation of NDUFB3 during the assembly process. Blue native gel electrophoresis showed an altered complex I assembly with only 30-40% of mature complex I present in patients and 70-90% in carriers. Conclusions: A new cause of Leigh syndrome can be a defect in early complex I assembly due to C20orf7 mutations

Коммутационные перенапряжения в сетях высокого напряжения

Исследование коммутационных перенапряжений в высоковольтных сетях. В работе проводилось моделирование коммутационных перенапряжений в двух расчётных программах. Был произведён подбор защитного оборудования.Research of surge overvoltages in high-voltage grids. The simulation of surge overvoltages in two computational programs was carried out. A selection of protective equipment was made

Sulfate Activation in Mitosomes Plays an Important Role in the Proliferation of Entamoeba histolytica

Mitochondrion-related organelles, mitosomes and hydrogenosomes, are found in a phylogenetically broad range of organisms. Their components and functions are highly diverse. We have previously shown that mitosomes of the anaerobic/microaerophilic intestinal protozoan parasite Entamoeba histolytica have uniquely evolved and compartmentalized a sulfate activation pathway. Although this confined metabolic pathway is the major function in E. histolytica mitosomes, their physiological role remains unknown. In this study, we examined the phenotypes of the parasites in which genes involved in the mitosome functions were suppressed by gene silencing, and showed that sulfate activation in mitosomes is important for sulfolipid synthesis and cell proliferation. We also demonstrated that both Cpn60 and unusual mitochondrial ADP/ATP transporter (mitochondria carrier family, MCF) are important for the mitosome functions. Immunoelectron microscopy demonstrated that the enzymes involved in sulfate activation, Cpn60, and mitochondrial carrier family were differentially distributed within the electron dense, double membrane-bounded organelles. The importance and topology of the components in E. histolytica mitosomes reinforce the notion that they are not “rudimentary” or “residual” mitochondria, but represent a uniquely evolved crucial organelle in E. histolytica

Bile Acids Specifically Increase Hepatitis C Virus RNA-Replication

<div><h3>Background</h3><p>Hepatitis C virus (HCV) patients with high serum levels of bile acids (BAs) respond poorly to IFN therapy. BAs have been shown to increase RNA-replication of genotype 1 but not genotype 2a replicons. Since BAs modulate lipid metabolism including lipoprotein secretion and as HCV depends on lipids and lipoproteins during RNA-replication, virus production and cell entry, BAs may affect multiple steps of the HCV life cycle. Therefore, we analyzed the influence of BAs on individual steps of virus replication.</p> <h3>Methods</h3><p>We measured replication of subgenomic genotype (GT) 1b and 2a RNAs as well as full-length GT2a genomes in the presence of BAs using quantitative RT-PCR and luciferase assays. Cell entry was determined using HCV pseudoparticles (HCVpp). Virus assembly and release were quantified using a core-specific ELISA. Replicon chimeras were employed to characterize genotype-specific modulation of HCV by BAs. Lunet CD81/GFP-NLS-MAVS cells were used to determine infection of Con1 particles.</p> <h3>Results</h3><p>BAs increased RNA-replication of GT1b replicons up to 10-fold but had no effect on subgenomic GT2a replicons both in Huh-7 and HuH6 cells. They did not increase viral RNA translation, virus assembly and release or cell entry. Lowering replication efficiency of GT2a replicons rendered them susceptible to stimulation by BAs. Moreover, replication of full length GT1b with or without replication enhancing mutations and GT2a genomes were also stimulated by BAs.</p> <h3>Conclusions</h3><p>Bile acids specifically enhance RNA-replication. This is not limited to GT1, but also holds true for GT2a full length genomes and subgenomic replicons with low replication capacity. The increase of HCV replication by BAs may influence the efficacy of antiviral treatment in vivo and may improve replication of primary HCV genomes in cell culture.</p> </div

Viral-mediated oncolysis is the most critical factor in the late-phase of the tumor regression process upon vaccinia virus infection

<p>Abstract</p> <p>Background</p> <p>In principle, the elimination of malignancies by oncolytic virotherapy could proceed by different mechanisms - e.g. tumor cell specific oncolysis, destruction of the tumor vasculature or an anti-tumoral immunological response. In this study, we analyzed the contribution of these factors to elucidate the responsible mechanism for regression of human breast tumor xenografts upon colonization with an attenuated vaccinia virus (VACV).</p> <p>Methods</p> <p>Breast tumor xenografts were analyzed 6 weeks post VACV infection (p.i.; regression phase) by immunohistochemistry and mouse-specific expression arrays. Viral-mediated oncolysis was determined by tumor growth analysis combined with microscopic studies of intratumoral virus distribution. The tumor vasculature was morphologically characterized by diameter and density measurements and vessel functionality was analyzed by lectin perfusion and extravasation studies. Immunological aspects of viral-mediated tumor regression were studied in either immune-deficient mouse strains (T-, B-, NK-cell-deficient) or upon cyclophosphamide-induced immunosuppression (MHCII⁺-cell depletion) in nude mice.</p> <p>Results</p> <p>Late stage VACV-infected breast tumors showed extensive necrosis, which was highly specific to cancer cells. The tumor vasculature in infected tumor areas remained functional and the endothelial cells were not infected. However, viral colonization triggers hyperpermeability and dilatation of the tumor vessels, which resembled the activated endothelium in wounded tissue. Moreover, we demonstrated an increased expression of genes involved in leukocyte-endothelial cell interaction in VACV-infected tumors, which orchestrate perivascular inflammatory cell infiltration. The immunohistochemical analysis of infected tumors displayed intense infiltration of MHCII-positive cells and colocalization of tumor vessels with MHCII⁺/CD31⁺vascular leukocytes. However, GI-101A tumor growth analysis upon VACV-infection in either immunosuppressed nude mice (MHCII⁺-cell depleted) or in immune-deficient mouse strains (T-, B-, NK-cell-deficient) revealed that neither MHCII-positive immune cells nor T-, B-, or NK cells contributed significantly to VACV-mediated tumor regression. In contrast, tumors of immunosuppressed mice showed enhanced viral spreading and tumor necrosis.</p> <p>Conclusions</p> <p>Taken together, these results indicate that VACV-mediated oncolysis is the primary mechanism of tumor shrinkage in the late regression phase. Neither the destruction of the tumor vasculature nor the massive VACV-mediated intratumoral inflammation was a prerequisite for tumor regression. We propose that approaches to enhance viral replication and spread within the tumor microenvironment should improve therapeutical outcome.</p