Investigation of human promoter CpG content and methylation profiles at different conservation levels

Demiralay, Burak
Methylation of CpG islands located at the promoter regions is a mechanism which controls gene silencing and expression. Hyper or hypo methylation of these sites on promoter sequences have been associated with many diseases, like cancer. Even though promoter CpG islands and their methylation profiles are important regulators of gene expression, the exact mechanism of gene silencing through methylation is not known. Here, we have investigated the status of promoter CpG methylation under various evolutionary pressures by calculating the differences in promoter CpG content and methylation profiles at different pass points. In order to determine the list of genes under each category we have analyzed and compared the orthologs among 58 genomes available through ENSEMBL. The total number of CpG dinucleotides at the promoter regions of all groups of genes have been calculated and compared. Additionally, we have compared the experimentally determined methylation profiles of these CpG's between human blood cells and fibroblast cells. While the promoter CpG content changed through common to newer genes, the number of the CpG units methylated found to be consistent. Here, we present the functional level analysis of common gene lists at different pass points and report the differences of the promoter CpG content and the methylation profiles among these groups with distinct evolutionary conservation status. We have also observed the conservation status of individual methylated CpG units on the low and high methylated genes. Our analysis revealed that the surrounding methylation content had a positive effect on the conservation of individual CpG’s.