Project description:Comparison of gene expression profiles induced by the mycotoxin, aflatoxin B1 (AFB1), in primary human hepatocytes and HepaRG cells. Initial mechanisms involved in the complex multistep process leading to malignant transformation by chemicals remain largely unknown. We have analysed changes in gene expression profiles in primary human hepatocytes and differentiated human hepatoma HepaRG cells after a 24 h treatment with 0.05 or 0.25µM aflatoxin B1 (AFB1), a potent genotoxic hepatocarcinogen.
Project description:Aflatoxins are toxic and carcinogenic secondary metabolites produced by the fungi Aspergillus flavus and A. parasiticus. In order to better understand the molecular mechanisms that regulate aflatoxin production, the biosynthesis of the toxin in A. flavus and A. parasticus grown in yeast extract sucrose media supplemented with 50 mM tryptophan (Trp) were examined. A. flavus grown in the presence of 50 mM tryptophan was found to have significantly reduced aflatoxin B1 and B2 biosynthesis, while A. parasiticus cultures had significantly increased B1 and G1 biosynthesis. Microarray analysis of RNA extracted from fungi grown under these conditions revealed seventy seven genes that are expressed significantly different between A. flavus and A. parasiticus, including the aflatoxin biosynthetic genes aflD (nor-1), aflE (norA), and aflO (omtB). It is clear that the regulatory mechanisms of aflatoxin biosynthesis in response to Trp in A. flavus and A. parasiticus are different. These candidate genes may serve as regulatory factors of aflatoxin biosynthesis. Keywords: Aflatoxin, Aspergillus, flavus, Amnio Acids, Tryptophan
Project description:The evaluation of the toxicity of Aflatoxin B1 using yeast gene expressions. Two yeast strains; parental BY4743 and PTC1 mutant, were used for this study. SDS was used to raise the penetration of the yeast cell membrane. Two conditions are compared with three replicates each. Both strains were grown in 0.01% SDS containing YPD media or 0.01% SDS, 25 ppm ABF1 containing YPD media. Publication can be found at http://www.cbi.or.jp/cbi/CBIj/vol9/9_94-E.pdf.
Project description:Identification of protein changes and pathways involved in combined effects of aflatoxin B1 and ochratoxin A and the preventive effect of dietary by-product antioxidants administration against these mycotoxins damage.
Project description:Comparison of gene expression profiles induced by the mycotoxin, aflatoxin B1 (AFB1), in primary human hepatocytes and HepaRG cells. Initial mechanisms involved in the complex multistep process leading to malignant transformation by chemicals remain largely unknown. We have analysed changes in gene expression profiles in primary human hepatocytes and differentiated human hepatoma HepaRG cells after a 24 h treatment with 0.05 or 0.25µM aflatoxin B1 (AFB1), a potent genotoxic hepatocarcinogen. Three independent biological replicates of HepaRG cell cultures and two pools of three primary human hepatocyte cultures each, were investigated. Cells were treated with 0.05 or 0.25µM AFB1 for 24 h.
Project description:Aflatoxin B1 (AFB1) is amongst the mycotoxins commonly affecting human and animal health, raising global food safety and control concerns. The mechanisms underlying AFB1 toxicity are poorly understood. Moreover, antidotes against AFB1 are lacking. Genome-wide CRISPR/Cas9 knockout screening in porcine kidney cells identified the transcription factor BTB and CNC homolog 1 (BACH1) as a gene required for AFB1 toxicity. The inhibition of BACH1 expression in porcine kidney cells and human hepatoma cells resulted in increased resistance to AFB1. BACH1 depletion attenuates AFB1-induced oxidative damage via the upregulation of antioxidant genes.
Project description:The molecular mechanisms underlying aflatoxin production have been well-studied in strains of the fungus Aspergillus flavus (A. flavus) under artificial conditions. However, aflatoxin biosynthesis has rarely been studied in natural isolates of A. flavus strains. In the present study, tandem mass tag (TMT) labeling and high-performance liquid chromatography (HPLC) coupled with tandem-mass spectrometry analysiswere used for proteomic quantification in natural isolates of high- and low-aflatoxin-yield A. flavus strains.
Project description:Autophagy is a catabolic membrane trafficking process involved in degradation of cellular constituents through lysosomes, which maintains cell and tissue homeostasis. While much attention has been focused on autophagic turnover of cytoplasmic materials, little is known regarding the role of autophagy in degrading nuclear components. Here we report that autophagy machinery mediates degradation of nuclear lamina in mammalian cells, a process we term laminophagy. The autophagy protein LC3 is present in the nucleus and directly interacts with the nuclear lamina protein Lamin B1, and associates with lamin-associated domains (LADs) on chromatin. This interaction does not downregulate Lamin B1 during starvation, but mediates nuclear lamina degradation upon tumorigenic insults, such as by oncogenic Ras. Laminophagy is achieved by nucleus-to-cytosol transport that delivers Lamin B1 to lysosome for degradation. Inhibiting autophagy or LC3-Lamin B1 interaction prevents oncogenic Ras-induced Lamin B1 loss and delays oncogene-induced cell cycle arrest. Our study unveils a role of autophagy in degrading nuclear materials, and suggests laminophagy as a guarding mechanism protecting cells from tumorigenesis.