MOTIVATION Recently, more stringent criteria for CpG islands have been introduced to exclude Alu repeats, thereby enabling a higher proportion of CpG islands associating with genes to be identified. Using these new criteria, several types of associations between CpG islands and genes were investigated to further establish the importance of CpG islands as gene markers. RESULTS The CpG islands ...

Mammalian CpG islands are key epigenomic elements that were first characterized experimentally as genomic fractions with low levels of DNA methylation. Currently, CpG islands are defined based on their genomic sequences alone. Here, we develop evolutionary models to show that several distinct evolutionary processes generate and maintain CpG islands. One central evolutionary regime resulting in ...

The primary target for DNA methylation in mammalian genomes is cytosine in the dinucleotide CpG. High densities of CpG dinucleotides are found in CpG islands, but paradoxically CpG islands are normally in a non-methylated state. Here, we speculate why CpG islands are immune to methylation and why they are so rich in guanine and cytosine relative to the surrounding DNA. We propose that CpG islan...

BACKGROUND Majority of CpG dinucleotides in mammalian genomes tend to undergo DNA methylation, but most CpG islands are resistant to such epigenetic modification. Understanding about mechanisms that may lead to the methylation resistance of CpG islands is still very poor. METHODOLOGY/PRINCIPAL FINDINGS Using the genome-scale in vivo DNA methylation data from human brain, we investigated the f...

alteration in methylation pattern of promoters is associated with tumorigenic events,(1, 2) and differentiation control,(3, 4) in several types of cells in humans.specific hypermethylation in promoter region of some genes exist in different types of neoplastic cells.(5) dna methylation indicates to the addition of a methyl moiety to the cytosine in a cpg dinucleotide. cpg dinucleotides tend to ...