CpG islands are regions with an high frequency of CpG (Cytosine-phosphate-Guanine) sites. The usual formal definition is that of a region with at least 200 bp, a GC percentage greater than 50% and an observed to expected ratio grater than 60%. In colorectal cancer, these regions have been found drastically methylated with respect to the normal mucosa tissues surrounding the tumor (Illingworth et al. 2010). This brought to speculate a role in the cancer onset. My question is: are there any other kind of dinucleotide rich regions that represent important cases of study in literature?If yes, can you suggest me some papers and references?Than you
Illingworth RS, Gruenewald-Schneider U, Webb S, Kerr AR, James KD, Turner DJ, Smith C, Harrison DJ, Andrews R, Bird AP (2010). "Orphan CpG islands identify numerous conserved promoters in the mammalian genome". PLOS Genet. 6 (9): e1001134. doi:10.1371/journal.pgen.1001134. PMC 2944787. PMID 20885785.
In some types of cancers like breast cancer, APOBEC3 cytidine deaminases can become upregulated and enhance mutagenesis. As shown in this mutational signature from cancer tissue data the enzymes prefer TC motifs. Source: https://cancer.sanger.ac.uk/cosmic/signatures/SBS/index.tt