Effect of Chronic Hyperoxic Exposure on Duroquinone Reduction in Adult Rat Lungs

NAD(P)H:quinone oxidoreductase 1 (NQO1) plays a dominant role in the reduction of the quinone compound 2,3,5,6-tetramethyl-1,4-benzoquinone (duroquinone, DQ) to durohydroquinone (DQH2) on passage through the rat lung. Exposure of adult rats to 85% O2 for ≥7 days stimulates adaptation to the otherwise lethal effects of \u3e95% O2. The objective of this study was to examine whether exposure of adult rats to hyperoxia affected lung NQO1 activity as measured by the rate of DQ reduction on passage through the lung. We measured DQH2 appearance in the venous effluent during DQ infusion at different concentrations into the pulmonary artery of isolated perfused lungs from rats exposed to room air or to 85% O2. We also evaluated the effect of hyperoxia on vascular transit time distribution and measured NQO1 activity and protein in lung homogenate. The results demonstrate that exposure to 85% O2 for 21 days increases lung capacity to reduce DQ to DQH2 and that NQO1 is the dominant DQ reductase in normoxic and hyperoxic lungs. Kinetic analysis revealed that 21-day hyperoxia exposure increased the maximum rate of pulmonary DQ reduction, Vmax, and the apparent Michaelis-Menten constant for DQ reduction, Kma. The increase in Vmax suggests a hyperoxia-induced increase in NQO1 activity of lung cells accessible to DQ from the vascular region, consistent qualitatively but not quantitatively with an increase in lung homogenate NQO1 activity in 21-day hyperoxic lungs. The increase in Kma could be accounted for by ∼40% increase in vascular transit time heterogeneity in 21-day hyperoxic lungs

Rare copy number variations in adults with tetralogy of Fallot implicate novel risk gene pathways.

Structural genetic changes, especially copy number variants (CNVs), represent a major source of genetic variation contributing to human disease. Tetralogy of Fallot (TOF) is the most common form of cyanotic congenital heart disease, but to date little is known about the role of CNVs in the etiology of TOF. Using high-resolution genome-wide microarrays and stringent calling methods, we investigated rare CNVs in a prospectively recruited cohort of 433 unrelated adults with TOF and/or pulmonary atresia at a single centre. We excluded those with recognized syndromes, including 22q11.2 deletion syndrome. We identified candidate genes for TOF based on converging evidence between rare CNVs that overlapped the same gene in unrelated individuals and from pathway analyses comparing rare CNVs in TOF cases to those in epidemiologic controls. Even after excluding the 53 (10.7%) subjects with 22q11.2 deletions, we found that adults with TOF had a greater burden of large rare genic CNVs compared to controls (8.82% vs. 4.33%, p = 0.0117). Six loci showed evidence for recurrence in TOF or related congenital heart disease, including typical 1q21.1 duplications in four (1.18%) of 340 Caucasian probands. The rare CNVs implicated novel candidate genes of interest for TOF, including PLXNA2, a gene involved in semaphorin signaling. Independent pathway analyses highlighted developmental processes as potential contributors to the pathogenesis of TOF. These results indicate that individually rare CNVs are collectively significant contributors to the genetic burden of TOF. Further, the data provide new evidence for dosage sensitive genes in PLXNA2-semaphorin signaling and related developmental processes in human cardiovascular development, consistent with previous animal models

Rare CNV burden in 340 unrelated adults with tetralogy of Fallot and/or pulmonary atresia.

a<p>Rare autosomal CNVs>10 kb and <6.5 Mb in size in individuals of European ancestry. Inclusion of three subjects with anomalies >6.5 Mb in a secondary analysis did not change the overall results (data not shown). Note that the above results also do not include 49 subjects of European ancestry with typical 1.5 to 3 Mb 22q11.2 deletions in the TOF group (all syndromic); see text for details on the results if these subjects had been included.</p>b<p>Fisher's exact test.</p

Rare large CNVs (>500 kb) in 43 of 433 unrelated adults with tetralogy of Fallot.

<p>Case, subjects from discovery sample (n = 433) with TOF; Locus, cytogenetic location of CNV; CNV start, hg18 (NCBI Build 36.1, March 2006); CNV size, in base pairs; CN, type of copy number aberration; Very rare, not found in 2,773 controls (•), see text for details; Confirmed, by qPCR and/or FISH (•) or not done (ND); Origin, <i>de novo</i> or inherited (where known); # of genes, number of known genes overlapped by a CNV as annotated in the Database of Genomic Variants (<a href="http://projects.tcag.ca/variation/" target="_blank">http://projects.tcag.ca/variation/</a>; September 2011); Candidate gene(s), selected based on reported cardiovascular system involvement; References derived from systematic searches of human (e.g., Online Mendelian Inheritance in Man; <a href="http://www.omim.org/" target="_blank">http://www.omim.org/</a>) and model organism (e.g., Mouse Genome Informatics; <a href="http://www.informatics.jax.org/" target="_blank">http://www.informatics.jax.org/</a>) databases presented in Table 4 in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002843#pgen.1002843.s001" target="_blank">Supporting Information S1</a>.</p>a<p><a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002843#pgen-1002843-g002" target="_blank">Figure 2</a> in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002843#pgen.1002843.s001" target="_blank">Supporting Information S1</a>.</p>b<p><a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002843#pgen-1002843-t003" target="_blank">Table 3</a>.</p>c<p>Neighbor of a top disease gene (GATA4, NKX2-5, TBX5), as identified in the pathway analysis (Table 11 in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002843#pgen.1002843.s001" target="_blank">Supporting Information S1</a>).</p>d<p>Non-European ancestry.</p>f<p>Previously reported by our group <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002843#pgen.1002843-Costain1" target="_blank">[21]</a>.</p>g<p>Figure 3 in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002843#pgen.1002843.s001" target="_blank">Supporting Information S1</a>.</p

Functional clusters of candidate genes for tetralogy of Fallot.

<p>Diagram of results of pathway analyses comparing rare CNVs in cases and controls. Five overlapping functional clusters involved 19 gene-sets; functional neighbors of three known candidate genes identified another cluster (circle size indicates relative number of cases involved).</p

Functional impact of global rare copy number variation in autism spectrum disorders.

International audienceThe autism spectrum disorders (ASDs) are a group of conditions characterized by impairments in reciprocal social interaction and communication, and the presence of restricted and repetitive behaviours. Individuals with an ASD vary greatly in cognitive development, which can range from above average to intellectual disability. Although ASDs are known to be highly heritable ( approximately 90%), the underlying genetic determinants are still largely unknown. Here we analysed the genome-wide characteristics of rare (<1% frequency) copy number variation in ASD using dense genotyping arrays. When comparing 996 ASD individuals of European ancestry to 1,287 matched controls, cases were found to carry a higher global burden of rare, genic copy number variants (CNVs) (1.19 fold, P = 0.012), especially so for loci previously implicated in either ASD and/or intellectual disability (1.69 fold, P = 3.4 x 10(-4)). Among the CNVs there were numerous de novo and inherited events, sometimes in combination in a given family, implicating many novel ASD genes such as SHANK2, SYNGAP1, DLGAP2 and the X-linked DDX53-PTCHD1 locus. We also discovered an enrichment of CNVs disrupting functional gene sets involved in cellular proliferation, projection and motility, and GTPase/Ras signalling. Our results reveal many new genetic and functional targets in ASD that may lead to final connected pathways