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. 2019 Apr 30;10:500. doi: 10.3389/fphys.2019.00500

Figure 2.

Figure 2

(A) DNA methylation and histone modifications are involved in epigenetic modulations of IL-6/JAK/STAT pathway members. They induce chromatin conformational transitions, altering accessibility of the transcriptional machinery (transcriptional active chromatin—blue arrow; transcriptional inactive chromatin – red arrow). DNA methylation is a process by which methyl groups are added to the cytosine of the DNA molecule and acts to repress gene transcription. Histone acetylation transfers acetyl groups to the histones and increases gene expression. Histone deacetylation removes acetyl groups from histones, allowing the histone to wrap more tightly the DNA and preventing transcription. Histone methylation adds methyl groups to the amino acids of the histones. Methylation of histones can either increase (i.e., H3K79, H3K4) or decrease (i.e. H3K9, H3K27) gene transcription. (B) Epigenetic modifications of IL-6/JAK/STAT pathway member genes that lead to gene repression (red) or gene activation (blue). (C) Epigenetic switches involving IL-6/JAK/STAT pathway members that lead to gene repression (red) or gene activation (blue) in tumorigenesis and development.