Alteration of Epigenetic Factors in Human Fibroblasts with Aryl Hydrocarbon Receptor (AHR) Activation

Background and Aim: Epigenetic, alters the gene expression that occursby making certain chemical changes on the DNA packing proteins(histones) and the DNA itself. These changes play a major role in creatingvast differences in gene expression, differentiation of somatic cells,and stem cells properties. Knowing the signaling pathways leading tothese changes greatly helps to recognize the mechanism of the effect of epigenetic changes in AHR activated fibroblastic cells.Methods: Human fibroblast cell cultured in DMEM/Ham s F-12, FetalBovine Serum (FBS) 10%, 2 mmol/L L-glutamine and 100 U/mL penicillin/streptomycin media and transfer to 5% Co2 incubator with temperature37°C. Cells were treated either with TCDD (2,3,7,8-tetrachlorodibenzo-P-dioxin) or DMSO. RNA extraction and RNA labeling using Cy3 andcRNA proliferation were performed with Agilent Technologies protocol.Then, using the Microarray system, the transcriptome of the cell groupswas investigated. The results were compared using GEO2R software andthe upregulation/downregulation of the selected genes was evaluated.Finally, using Reactome software, signaling pathways leading toepigenetic changes were evaluated.Results: AHR transcription factor activation in human fibroblast cells byTCDD, leads to activation of several pathways involving in epigeneticchanges. Studies conducted by Reactome software show that PolycombRepressive Complex 2 (PRC2) is used in chromatin and lysine 27methylates histone H3 and uses DNA methyltransferase. TET1,2,3oxidizes 5-methylcytosine to 5-carboxyl cytosine with oxidationand splits 5 Formyl cytosine and 5-carboxylic cytosine splits. DNAis demethylated and DNA methylation is performed by DNMT3A,DNMT3B, and DNMT3L. Positive epigenetic regulation of rRNAexpression is also accomplished by the B-WICH complex and histoneacetyltransferase, ERCC6 (CSB) and EHMT2 (G9a). Negative regulationof epigenetic expression of rRNA is also mediated by SIRT1 and NoRCsignaling.Conclusion: Inducing epigenetic alterations in somatic cells causeschanges in the transcriptomic level. Activating certain transcriptionfactors leads such epigenetic alterations. By activating AHR transcriptionfactor, large gene expression changes occur, many of which are due toepigenetic changes that the cell goes through the transcription of thetotipotency factors and with demethylation, acetylation, and otherepigenetic alterations increase the likelihood of stem cell transplantation.

Keywords:

Epigenetic factors , Aryl hydrocarbon receptor , Transcription factors , Human fibroblast cell