Role of ALKBH1 in the Core Transcriptional Network of Embryonic Stem Cells

Background/Aims: ALKBH1, an AlkB homologue in the 2-oxoglutarate and Fe2+ dependent hydroxylase family, is a histone dioxygenase that removes methyl groups from histone H2A. Studies of transgenic mice lacking Alkbh1 reveal that most Alkbh1-/- embryos die during embryonic development. Embryonic stem cells (ESCs) derived from these mice have prolonged expression of pluripotency markers and delayed induction of genes involved in neural differentiation, indicating that ALKBH1 is involved in regulation of pluripotency and differentiation. The aim of this study was to further investigate the role ALKBH1 in early development. Methods: Double-filter methods for nitrocellulose-filter binding, dot blot, enzyme-linked immunosorbent assay (ELISA), immonocytochemistry, cell culture and differentiation of mouse ESCs, Co-IP and miRNA analysis. Results: We found that SOX2 and NANOG bind the ALKBH1 promoter, and we identified protein-protein interactions between ALKBH1 and these core transcription factors of the pluripotency network. Furthermore, lack of ALKBH1 affected the expression of developmentally important miRNAs, which are involved in the regulation of NANOG, SOX2 and neural differentiation. Conclusion: Our results suggest that ALKBH1 interacts with the core transcriptional pluripotency network of ESCs and is involved in regulation of pluripotency and differentiation

Spontaneous mutagenesis in Csbm/mOgg1−/− mice is attenuated by dietary resveratrol

Oxidative DNA modifications such as 7,8-dihydro-8-oxoguanine (8-oxoG) are generated endogenously in apparently all living cells. The defect of the repair of 8-oxoG in Csb(m/m)Ogg1(-)(/)(-) mice results in elevated basal levels of these lesions and increased frequencies of spontaneous mutations, which initiate tumorigenesis in the liver if cell proliferation is stimulated. Here, we describe that the phytoalexin resveratrol, applied either for 7 days per gavage (100 mg/kg body wt) or for 3-9 months in the diet (0.04% ad libitum), reduces the endogenous oxidative DNA base damage in the livers of the Csb(m/m)Ogg1(-)(/)(-) mice by 20-30% (P < 0.01). A small but consistent effect is also observed in the wild-type animals. The spontaneous mutation frequencies determined in the lacI gene of BigBlue(R) Csb(m/m)Ogg1(-)(/)(-) mice are concomitantly reduced by resveratrol to similar extents. Mechanistically, the protection is caused by an induction of the antioxidant defense system since (i) hepatocytes isolated from all resveratrol-treated animals were less susceptible to the generation of single-strand breaks and to cell killing by H(2)O(2), (ii) messenger RNA levels of superoxide dismutases 1 and 2 (SOD1 and SOD2) heme oxygenase-1 and glutathione peroxidase were significantly upregulated after the short-term treatment and (iii) mutations primarily ascribed to the oxidative base modification 8-oxoG (G:C to T:A transversions) were more strongly suppressed than G:C to A:T transitions ascribed to spontaneous deamination. The results thus demonstrate that spontaneous somatic mutation rates resulting from endogenous oxidative DNA damage can be reduced by application of an exogenous agent

Increased nuclear DNA damage precedes mitochondrial dysfunction in peripheral blood mononuclear cells from Huntington's disease patients

Huntington’s disease (HD) is a progressive neurodegenerative disorder primarily afecting the basal ganglia and is caused by expanded CAG repeats in the huntingtin gene. Except for CAG sizing, mitochondrial and nuclear DNA (mtDNA and nDNA) parameters have not yet proven to be representative biomarkers for disease and future therapy. Here, we identifed a general suppression of genes associated with aerobic metabolism in peripheral blood mononuclear cells (PBMCs) from HD patients compared to controls. In HD, the complex II subunit SDHB was lowered although not sufciently to afect complex II activity. Nevertheless, we found decreased level of factors associated with mitochondrial biogenesis and an associated dampening of the mitochondrial DNA damage frequency in HD, implying an early defect in mitochondrial activity. In contrast to mtDNA, nDNA from HD patients was four-fold more modifed than controls and demonstrated that nDNA integrity is severely reduced in HD. Interestingly, the level of nDNA damage correlated inversely with the total functional capacity (TFC) score; an established functional score of HD. Our data show that PBMCs are a promising source to monitor HD progression and highlights nDNA damage and diverging mitochondrial and nuclear genome responses representing early cellular impairments in HD

Kinetics of endogenous mouse FEN1 in base excision repair

International audienc

Human telomerase is directly regulated by non-telomeric TRF2-G-quadruplex interaction

Human telomerase reverse transcriptase (hTERT) remains suppressed in most normal somatic cells. Resulting erosion of telomeres leads eventually to replicative senescence. Reactivation of hTERT maintains telomeres and triggers progression of >90% of cancers. However, any direct causal link between telomeres and telomerase regulation remains unclear. Here, we show that the telomere-repeat-binding-factor 2 (TRF2) binds hTERT promoter G-quadruplexes and recruits the polycomb-repressor EZH2/PRC2 complex. This is causal for H3K27 trimethylation at the hTERT promoter and represses hTERT in cancer as well as normal cells. Two highly recurrent hTERT promoter mutations found in many cancers, including ∼83% glioblastoma multiforme, that are known to destabilize hTERT promoter G-quadruplexes, showed loss of TRF2 binding in patient-derived primary glioblastoma multiforme cells. Ligand-induced G-quadruplex stabilization restored TRF2 binding, H3K27-trimethylation, and hTERT re-suppression. These results uncover a mechanism of hTERT regulation through a telomeric factor, implicating telomere-telomerase molecular links important in neoplastic transformation, aging, and regenerative therapy

Importation of roughage to Norway - Implications for plant and animal health, zoonoses, and biodiversity. Opinion of the scientific committee of the Norwegian Scientific Committee for Food and Enviroment

publishedVersio

Importation of roughage to Norway - Implications for plant and animal health, zoonoses, and biodiversity. Opinion of the scientific committee of the Norwegian Scientific Committee for Food and Enviroment

Source at https://vkm.no/risikovurderinger/allevurderinger/konsekvenseravaimporteregrovfor.4.372fcd091727089bb664ab15.html.Det er stor usikkerhet om import av grovfôr til Norge kan føre med seg planteskadegjørere, invaderende planter og smittestoff som kan forårsake sykdom hos dyr og mennesker