Tissue-specific regulation of sirtuin and nicotinamide adenine dinucleotide biosynthetic pathways identified in C57Bl/6 mice in response to high-fat feeding

Funding: The Scottish Government's Rural and Environment Science and Analytical Services Division.Peer reviewedPostprin

The metabolome regulates the epigenetic landscape during naive-to-primed human embryonic stem cell transition.

For nearly a century developmental biologists have recognized that cells from embryos can differ in their potential to differentiate into distinct cell types. Recently, it has been recognized that embryonic stem cells derived from both mice and humans exhibit two stable yet epigenetically distinct states of pluripotency: naive and primed. We now show that nicotinamide N-methyltransferase (NNMT) and the metabolic state regulate pluripotency in human embryonic stem cells (hESCs).  Specifically, in naive hESCs, NNMT and its enzymatic product 1-methylnicotinamide are highly upregulated, and NNMT is required for low S-adenosyl methionine (SAM) levels and the H3K27me3 repressive state. NNMT consumes SAM in naive cells, making it unavailable for histone methylation that represses Wnt and activates the HIF pathway in primed hESCs. These data support the hypothesis that the metabolome regulates the epigenetic landscape of the earliest steps in human development

Nicotinamide N-methyltransferase catalyses the N-methylation of the endogenous ß-carboline norharman: evidence for a novel detoxification pathway

Nicotinamide N-methyltransferase (NNMT) is responsible for the N-methylation of nicotinamide to 1-methylnicotinamide. Our recent studies have demonstrated that NNMT regulates cellular processes fundamental to the correct functioning and survival of the cell. It has been proposed that NNMT may possess β-carboline (BC) N-methyltransferase activity, endogenously and exogenously produced pyridine-containing compounds which, when N-methylated, are potent inhibitors of Complex I and have been proposed to have a role in the pathogenesis of Parkinson's disease. We have investigated the ability of recombinant NNMT to N-methylate norharman (NH) to 2-N-methylnorharman (MeNH). In addition, we have investigated the toxicity of the BC NH, its precursor 1,2,3,4-tetrahydronorharman (THNH) and its N-methylated metabolite MeNH, using our in vitro SH-SY5Y NNMT expression model. Recombinant NNMT demonstrated NH 2N-methyltransferase activity, with a Km of 90 ± 20 µM, a kcat of 3 × 10(-4) ± 2 × 10(-5) s(-1) and a specificity constant (kcat/Km) of 3 ± 1 s(-1) M(-1) THNH was the least toxic of all three compounds investigated, whereas NH demonstrated the greatest, with no difference observed in terms of cell viability and cell death between NNMT-expressing and non-expressing cells. In NNMT-expressing cells, MeNH increased cell viability and cellular ATP concentration in a dose-dependent manner after 72 and 120 h incubation, an effect that was not observed after 24 h incubation or in non-NNNT-expressing cells at any time point. Taken together, these results suggest that NNMT may be a detoxification pathway for BCs such as NH

Use of molecular markers contribute to the identification of priority coconut accessions in the framework of the global strategy for conservation and use of coconut genetic resources

To assist germplasm management using molecular markers, we propose here a method to be used in conjunction with geographic and phenotypic information. It can be used to evaluate the number of accessions that need to be reproduced as safety duplication or triplication. Current knowledge of coconut diversity suggests that 60 Tall or "compact" accessions are sufficient. The additional surface needed to accommodate this safety collection is about 60ha. Most homozygous Dwarf cultivars could be preserved in small numbers. A complementary microsatellite analyses should involve - cultivars/populations already analyzed with insufficient numbers (318 individuals),- analyses in "unchartered areas" of the coconut genetic diversity. map (860 individuals in 10 years),- country-wide studies in Sri Lanka and in the Philippines (with possible extension to India and Indonesia — 200 individuals per country ). To make microsatellite data more available, we improved the user interface of TropGENE-db, introduced more data (554 individuals) and invited 4 countries to input data from about 500 individuals. Finally, we recommend that, once more powerful genotyping methods become available, a representative subset of 50 to 100 individuals analyzed with into analysis programmes. (Résumé d'auteur

Genetic and environmental influences on plasma homocysteine: results from a Danish twin study

  Udgivelsesdato: 2007-MayBACKGROUND: Increased plasma homocysteine has been linked to many clinical conditions including atherosclerosis and ischemic stroke. We assessed the genetic and environmental influences on homocysteine in adult twins and tested the influence of 3 candidate polymorphisms. METHODS: Homocysteine was analyzed in 1206 healthy twins, who were genotyped for 3 polymorphisms: MTHFR 677C>T, MTR 2756A>G, and NNMT (dbSNP: rs694539). To perform quantitative trait linkage analysis of the MTHFR locus, the genotyping was supplemented with 2 genetic markers localized on each site of the MTHFR locus. The twin data were analyzed using biometric structural equation models as well as a combined association and linkage analysis in 2 age cohorts. RESULTS: Age, sex, and MTHFR genotype have a significant impact on homocysteine concentrations, whereas the other genotypes were not associated with homocysteine concentrations. The variance in homocysteine could be solely ascribed to additive genetic and nonshared environmental factors, with an estimated additive genetic proportion of total variation at age 18-39 years of 0.63 (95% CI, 0.53-0.71) and at age 40-65 years of 0.27 (95% CI, 0.10-0.41). The impact of the MTHFR locus is estimated to explain 53% (95% CI, 0.07-0.67) of the total phenotypic variation in persons 18-39 years old and 24% (95% CI, 0.00-0.39) in persons 40-65 years old, i.e., almost all additive genetic variance. CONCLUSIONS: Homocysteine concentrations have a high heritability that decreases with age. The MTHFR gene locus is responsible for almost all the variation attributable to genetic factors, leaving very little influence of other genetic variations

Globale Expressionsprofile Pneumokokken-infizierter Bronchialepithelzellen - Einfluss der miRNA-3135b und des Nicotinamidstoffwechselweges auf die bakterielle Replikation

Streptococcus pneumoniae (S. pneumoniae), auch als Pneumococcus bezeichnet, ist ein grampositives Bakterium, welches gewöhnlich als Kommensale asymptomatisch den humanen Nasopharynx besiedelt, jedoch auch schwere Erkrankungen bis hin zur Sepsis oder Meningitis auslösen kann. Pneumokokken sind Hauptverursacher der Pneumonie beim Menschen und fordern jährlich mehrere Millionen Opfer weltweit. Weiterhin können Koinfektionen mit Influenza A Viren die Erkrankung verschlimmern. Die Epithelzellen des humanen Respirationstraktes bilden die erste Verteidigungsbarriere gegen die Infektion. Es sind jedoch viele Aspekte der Interaktion zwischen Epithelzellen und S. pneumoniae noch nicht umfassend geklärt. Um diese Interaktion detailliert zu analysieren, wurde ein Expressionsprofil aus mRNAs, Proteinen und miRNAs von infizierten Bronchialepithelzellen erstellt. Zusätzlich wurde ein Koinfektionsmodell in humanem ex vivo Lungengewebe zu Vergleichszwecken untersucht. Signalweg‐Analysen der infizierten Epithelzellen ergaben eine verstärkte Regulation des Zellzyklus zum späten Zeitpunkt der Infektion (16 h). Eine Vernetzung der Daten mit dem miRNA‐Profil offenbarte wenige, bereits bekannte Verknüpfungen. Dennoch konnten mit Hilfe der miRNA‐Untersuchungen behandlungsabhängige Expressionsmuster detektierten werden, welche S. pneumoniae‐spezifische miRNAs, wie die induzierte miRNA‐3135b, aufzeigten. Bei dieser hypothetischen miRNA könnte es sich tatsächlich um ein t‐RNA‐deriviertes Fragment (tRF) handeln. Eine Überexpression der miRNA‐3135b resultierte in einer signifikanten Reduktion der Pneumokokken‐Last, was auf einen Abwehrmechanismus der Epithelzellen hindeutet. Zudem zeigte die RNA‐Sequenzierung nach miRNA‐3135b‐Überexpression verschiedene putative Ziel‐mRNAs, deren Funktionen bisher nur eingeschränkt bekannt sind. Des Weiteren weisen funktionelle Analysen der mRNAs und Proteine auf eine Regulation des Nicotinamidmetabolismus hin. Die in den Epithelzellen durchgeführte Depletion von NAMPT, dem Schlüsselenzym dieses Stoffwechselweges, führte zu einer verminderten Replikation von S. pneumoniae. Weiterhin bewirkte die Zugabe von Nicotinamid‐Mononukleotid (NMN) eine gesteigerte Replikationsrate der Bakterien. Dies deutet auf NMN als wichtige Nährstoffquelle von Pneumokokken hin. Die Daten dieser Arbeit erweitern die Kenntnisse zur Interaktion von humanen Epithelzellen und Pneumokokken und könnten zur Identifizierung alternativer und neuer Therapiestrategien genutzt werden

Genome sequence and genetic linkage analysis of Shiitake mushroom _Lentinula edodes_

_Lentinula edodes_ (Shiitake/Xianggu) is an important cultivated mushroom. Understanding the genomics and functional genomics of _L. edodes_ allows us to improve its cultivation and quality. Genome sequence is a key to develop molecular genetic markers for breeding and genetic manipulation. We sequenced the genome of _L. edodes_ monokaryon L54A using Roche 454 and ABI SOLiD genome sequencing. Sequencing reads of about 1400Mb were de novo assembled into a 40.2 Mb genome sequence. We compiled the genome sequence into a searchable database with which we have been annotating the genes and analyzing the metabolic pathways. In addition, we have been using many molecular techniques to analyze genes differentially expressed during development. Gene ortholog groups of _L. edodes_ genome sequence compared across genomes of several fungi including mushrooms identified gene families unique to mushroom-forming fungi. We used a mapping population of haploid basidiospores of dikaryon L54 for genetic linkage analysis. High-quality variations such as single nucleotide polymorphisms, insertions, and deletions of the mapping population formed a high-density genetic linkage map. We compared the linkage map to the _L. edodes_ L54A genome sequence and located selected quantitative trait loci. The Shiitake community will benefit from these resources for genetic studies and breeding.
&#xa