Severe dysfunction of respiratory chain and cholesterol metabolism in Atp7b−/− mice as a model for Wilson disease

AbstractWilson disease (WD) is caused by mutations of the WD gene ATP7B resulting in copper accumulation in different tissues. WD patients display hepatic and neurological disease with yet poorly understood pathomechanisms. Therefore, we studied age-dependent (3, 6, 47weeks) biochemical and bioenergetical changes in Atp7b−/− mice focusing on liver and brain. Mutant mice showed strongly elevated copper and iron levels. Age-dependently decreasing hepatic reduced glutathione levels along with increasing oxidized to reduced glutathione ratios in liver and brain of 47weeks old mice as well as elevated hepatic and cerebral superoxide dismutase activities in 3weeks old mutant mice highlighted oxidative stress in the investigated tissues. We could not find evidence that amino acid metabolism or beta-oxidation is impaired by deficiency of ATP7B. In contrast, sterol metabolism was severely dysregulated. In brains of 3week old mice cholesterol, 8-dehydrocholesterol, desmosterol, 7-dehydrocholesterol, and lathosterol were all highly increased. These changes reversed age-dependently resulting in reduced levels of all previously increased sterol metabolites in 47weeks old mice. A similar pattern of sterol metabolite changes was found in hepatic tissue, though less pronounced. Moreover, mitochondrial energy production was severely affected. Respiratory chain complex I activity was increased in liver and brain of mutant mice, whereas complex II, III, and IV activities were reduced. In addition, aconitase activity was diminished in brains of Atp7b−/− mice. Summarizing, our study reveals oxidative stress along with severe dysfunction of mitochondrial energy production and of sterol metabolism in Atp7b−/− mice shedding new light on the pathogenesis of WD

DHTKD1 Mutations Cause 2-Aminoadipic and 2-Oxoadipic Aciduria

Abnormalities in metabolite profiles are valuable indicators of underlying pathologic conditions at the molecular level. However, their interpretation relies on detailed knowledge of the pathways, enzymes, and genes involved. Identification and characterization of their physiological function are therefore crucial for our understanding of human disease: they can provide guidance for therapeutic intervention and help us to identify suitable biomarkers for monitoring associated disorders. We studied two individuals with 2-aminoadipic and 2-oxoadipic aciduria, a metabolic condition that is still unresolved at the molecular level. This disorder has been associated with varying neurological symptoms. Exome sequencing of a single affected individual revealed compound heterozygosity for an initiating methionine mutation (c.1A>G) and a missense mutation (c.2185G>A [p.Gly729Arg]) in DHTKD1. This gene codes for dehydrogenase E1 and transketolase domain-containing protein 1, which is part of a 2-oxoglutarate-dehydrogenase-complex-like protein. Sequence analysis of a second individual identified the same missense mutation together with a nonsense mutation (c.1228C>T [p.Arg410∗]) in DHTKD1. Increased levels of 2-oxoadipate in individual-derived fibroblasts normalized upon lentiviral expression of the wild-type DHTKD1 mRNA. Moreover, investigation of L-lysine metabolism showed an accumulation of deuterium-labeled 2-oxoadipate only in noncomplemented cells, demonstrating that DHTKD1 codes for the enzyme mediating the last unresolved step in the L-lysine-degradation pathway. All together, our results establish mutations in DHTKD1 as a cause of human 2-aminoadipic and 2-oxoadipic aciduria via impaired turnover of decarboxylation 2-oxoadipate to glutaryl-CoA

Population structure and distribution patterns of the sibling mosquito apecies Culex pipiens and Culex torrentium (Diptera: Culicidae) reveal different evolutionary paths

Nowadays a number of endemic mosquito species are known to possess vector abilities for various diseases, as e.g. the sibling species Culex pipiens and Culex torrentium. Due to their morphological similarity, ecology, distribution and vector abilities, knowledge about these species' population structure is essential. Culicidae from 25 different sampling sites were collected from March till October 2012. All analyses were performed with aligned cox1 sequences with a total length of 658 bp. Population structure as well as distribution patterns of both species were analysed using molecular methods and different statistical tests like distance based redundancy analysis (dbDRA), analysis of molecular variances (AMOVA) or McDonald & Kreitman test and Tajima's D. Within both species, we could show a genetic variability among the cox1 fragment. The construction of haplotype networks revealed one dominating haplotype for Cx. pipiens, widely distributed within Germany and a more homogeneous pattern for Cx. torrentium. The low genetic differences within Cx. pipiens could be a result of an infection with Wolbachia which can induce a sweep through populations by passively taking the also maternally inherited mtDNA through the population, thereby reducing the mitochondrial diversity as an outcome of reproductive incompatibility. Pairwise population genetic differentiation (FST) ranged significantly from moderate to very great between populations of Cx. pipiens and Cx. torrentium. Analyses of molecular variances revealed for both species that the main genetic variability exists within the populations (Cx. pipiens [88.38%]; Cx. torrentium [66.54%]). Based on a distance based redundancy analysis geographical origin explained a small but significant part of the species' genetic variation. Overall, the results confirm that Cx. pipiens and Cx. torrentium underlie different factors regarding their mitochondrial differentiation, which could be a result of endosymbiosis, dispersal between nearly located populations or human introduction

Population Structure and Distribution Patterns of the Sibling Mosquito Species <i>Culex pipiens</i> and <i>Culex torrentium</i> (Diptera: Culicidae) Reveal Different Evolutionary Paths

<div><p>Nowadays a number of endemic mosquito species are known to possess vector abilities for various diseases, as e.g. the sibling species <i>Culex pipiens</i> and <i>Culex torrentium</i>. Due to their morphological similarity, ecology, distribution and vector abilities, knowledge about these species' population structure is essential. Culicidae from 25 different sampling sites were collected from March till October 2012. All analyses were performed with aligned cox1 sequences with a total length of 658 bp. Population structure as well as distribution patterns of both species were analysed using molecular methods and different statistical tests like distance based redundancy analysis (dbDRA), analysis of molecular variances (AMOVA) or McDonald & Kreitman test and Tajima's D. Within both species, we could show a genetic variability among the cox1 fragment. The construction of haplotype networks revealed one dominating haplotype for <i>Cx. pipiens</i>, widely distributed within Germany and a more homogeneous pattern for <i>Cx. torrentium</i>. The low genetic differences within <i>Cx. pipiens</i> could be a result of an infection with <i>Wolbachia</i> which can induce a sweep through populations by passively taking the also maternally inherited mtDNA through the population, thereby reducing the mitochondrial diversity as an outcome of reproductive incompatibility. Pairwise population genetic differentiation (F_ST) ranged significantly from moderate to very great between populations of <i>Cx. pipiens</i> and <i>Cx. torrentium</i>. Analyses of molecular variances revealed for both species that the main genetic variability exists within the populations (<i>Cx. pipiens</i> [88.38%]; <i>Cx. torrentium</i> [66.54%]). Based on a distance based redundancy analysis geographical origin explained a small but significant part of the species' genetic variation. Overall, the results confirm that <i>Cx. pipiens</i> and <i>Cx. torrentium</i> underlie different factors regarding their mitochondrial differentiation, which could be a result of endosymbiosis, dispersal between nearly located populations or human introduction.</p></div

Sampling localities of <i>Culex pipiens</i> across Germany with significant different population pairwise F_ST values.

<p>Significant different pairwise F_ST values between populations are indicated using different line colors. Significant F_ST values were grouped into the four following categories: very great population differentiation (red lines), great population differentiation (yellow lines), moderate population differentiation (green lines) and low population differentiation (purple lines) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0102158#pone.0102158-Balloux1" target="_blank">[67]</a>. Pictured are all sampling points listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0102158#pone-0102158-t004" target="_blank">Table 4</a> with a summary of their haplotypes. Map was created with ArcMap 10.1.</p

Sampling localities of <i>Culex torrentium</i> across Germany with significant different population pairwise F_ST values.

<p>Significant F_ST values were grouped into the four following categories: very great population differentiation (red lines), great population differentiation (yellow lines), moderate population differentiation (green lines) and low population differentiation (purple lines) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0102158#pone.0102158-Balloux1" target="_blank">[67]</a>. Pictured are all sampling points listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0102158#pone-0102158-t005" target="_blank">Table 5</a> with a summary of their haplotypes. There were no significant moderate or low F_ST values. Map was created with ArcMap 10.1.</p

AMOVA group structure of <i>Culex pipiens</i> and <i>Culex torrentium</i>.

<p>Group structures are based on pairwise F_ST's of <i>Culex pipiens</i> and <i>Culex torrentium</i>.</p