Beyond Genetics in Glioma Pathways: The Ever-Increasing Crosstalk between Epigenomic and Genomic Events

Figure 3

(a) 3D MRI. Normal glial cells CpG islands in the promoter regions of genes lack of methylation, which is a prerequisite for active gene transcription. Fully methylated CpG islands are found only in the promoters of silenced alleles for selected imprinted autosomal genes and silenced genes on the inactivated X-chromosomes of females. (b) 3D MRI showing a right frontal GBM, in which cells change their methylation pattern in a wide manner including deregulation of methylating DNA methyl-transferases 1, 3A, and 3B, global hypomethylation through demethylation in CpG islands of the promoters of a wide variety of genes as well as a severe hypermethylation locally affecting unmethylated regions. Densely methylated DNA is associated with deacetylated histones and compacted chromatin, which is refractory to gene transcription.