Effects of 2(3)-tert-butyl-4-hydroxyanisole administration on the activities of several hepatic microsomal and cytoplasmic enzymes in mice.

Administration of 2(3)-tert-butyl-4-hydroxyanisole (BHA) (0.75%) caused a marked increase in the activities of several hepatic enzymes in CD-1 mice. This was associated with increased liver weights and total protein contents, especially of the microsomal and cytosol fractions. While the specific content of cytochrome P-450 was decreased slightly in microsomes, the specific content of cytochrome b₅ and the specific activities of cytochrome c reductases (NADPH- or NADH-dependent) were increased (2-fold). In spite of a slight decrease in the specific activities of aminopyrine demethylase and of benzo(a)pyrene hydroxylase, both aniline hydroxylase and UDP-glucronyltransferase activities were increased (2.7- and 4.6-fold respectively). The specific activity of a microsomal membrane marker enzyme, glucose-6-phosphatase, was decreased slightly (?25 per cent). In the cytosol fraction, the specific activities of glucose-6-phosphate dehydrogenase and of UDP-glucose dehydrogenase were increased (3.8- and 6.1-fold respectively). Differences were noted in the time cources of increase and decrease in these enzyme activities after initiation and discontinuation of BHA treatment.     

Toxicity of methylmercury chloride in rats III. Long-term toxicity study

Four groups, each of 25 male and 25 female weanling rats, were given dietary levels of 0, 0.1, 0.5 and 2.5 ppm MeHgCl for 2 years. Observations were made on behaviour, growth, food intake, haematology, serum enzymes, urinalysis, microsomal liver enzymes, organ weights and histology with special reference to the nervous system, hitochemistry of the kidneys and cerebellum and on tissue Hg concentrations.Significant findings included a slight growth reduction in females at 2.5 ppm, increased relative kidney weight at 2.5 ppm and histochemical changes in kidney enzymes at 2.5 ppm. No effect was seen on the nature or incidence of pathological lesions or tumours at any level.From the results obtained in the short-term, reproduction and long-term studies, the no-toxic effect level for rats appears to be between 0.1 and 0.5 ppm MeHgCl in the diet.Exposure of the Dutch population does not appear to present a health hazard at the moment because the mean intake of total Hg is still far below the intake deemed to be safe.     

Effects of disulfiram on mixed function oxidase system and trace element concentration in the liver of rats

Disulfiram (DSF), an inhibitor of chemically induced carcinogenesis, and its metabolite diethyldithiocarbamate (DDTC) have been investigated for their influence on trace element distribution and on certain enzymes of the drug metabolizing system in the livers of phenobarbital (PB) treated rats. Both substances diminished the PB induced enzyme response in liver microsomes, DDTC being more effective (?85%) than DSF (?60%). The copper, cobalt and zinc content of the livers of DSF treated animals were increased by factors of 6, 3 and 1.5 respectively as compared to controls, while DDTC treatment had no influence on liver trace element content. A correlation between enzyme inhibition and enhanced trace element uptake of the liver after DSF administration could not be observed. The change of trace element transport into the liver during DSF treatment is discussed.     

LSD1 knockdown confers protection against osteoclast formation by reducing histone 3 lysine 9 monomethylation and dimethylation in ITGB3 promoter

ITGB3, an osteoclast marker, is involved in osteoclast formation. Nevertheless, its related mechanism remains poorly characterized. Herein, this study examines the mechanisms affecting osteoclast formation with the involvement of ITGB3. Osteoclast formation was induced with macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor-kappa B ligand (RANKL), followed by measurement of the mRNA and protein expression of ITGB3 and LSD1. After gain- and loss-of-function assays, cell viability and the expression of osteoclast marker genes (NFATc1, ACP5, and CTSK) were assessed, and osteoclast formation was evaluated with TRAP staining. ChIP assays were used to examine histone 3 lysine 9 (H3K9) monomethylation (H3K9me1) and H3K9 dimethylation (H3K9me2) modifications and LSD1 protein enrichment in the ITGB3 promoter. During osteoclast formation, ITGB3 and LSD1 were gradually augmented. Knockdown of LSD1 or ITGB3 curbed cell viability, the expression of osteoclast marker genes, and osteoclast formation. Moreover, overexpression of ITGB3 nullified the suppressive impact of LSD1 knockdown on osteoclast formation. Mechanistically, LSD1 promoted ITGB3 expression by reducing H3K9 levels in the ITGB3 promoter. LSD1 enhanced ITGB3 expression by decreasing H3K9me1 and H3K9me2 levels in ITGB3 promoter to boost osteoclast formation.     

组蛋白去甲基酶JMJD1A/KDM3A在小鼠骨骼肌细胞中介导活性氧诱导的E2F1表达

骨骼肌细胞中的活性氧水平增高引起细胞凋亡是衰老性肌肉萎缩的重要机制之一。我们前期研究发现,转录因子E2F1激活促凋亡基因PERP转录从而介导活性氧诱导的骨骼肌细胞凋亡。本文研究在小鼠骨骼肌细胞凋亡过程中E2F1表达上调的表观表观遗传机制。方法：利用H2O2处理C2C12细胞,利用干扰RNA和瞬时转染相关因子。最终用实时定量PCR（real-time quantitative PCR, RT-qPCR）与免疫印记检测E2F1基因表达水平,染色质免疫沉淀（chromatin immunoprecipitation, ChIP）检测蛋白质与DNA的结合。结果：小鼠骨骼肌细胞凋亡过程中E2F1表达水平被活性氧上调,同时伴随E2F1基因启动子上H3K9甲基化水平的下降。进一步研究发现,活性氧促进H3K9去甲基酶JMJD1A/KDM3A结合到E2F1启动子上促进E2F1转录。相反,使用干扰RNA敲减KDM3A显著减弱活性氧引起的E2F1表达上调。KDM3A干扰同时降低了E2F1启动子上乙酰化H3与H3K4甲基化水平并恢复了H3K9甲基化水平。结论：综上所述,我们的结果提示KDM3A通过改变组蛋白修饰参与活性氧诱导的E2F1转录激活。