page_title: CpG island hypermethylation
section_title: Structure
hierarchical_section_title: CpG island hypermethylation / Structure
caption_attribution_description: English: In a normal cell, the CpG island is hypomethylated, as can be seen from the unfilled stubs, but the genome, in general, is methylated, as can be seen from the filled in stubs. In contrast, in the cancer cell, the CpG island is more likely to be methylated, and the rest of the genome is hypomethylated. There is a swap of where DNA methylation is found between a normal cell and a cancer cell.
context_page_description: CpG island hypermethylation is an epigenetic control aberration that is important for gene inactivation in cancer cells. Hypermethylation of CpG islands has been described in almost every type of tumor. Many important cellular pathways, such as DNA repair, cell cycle, apoptosis, cell adherence, are inactivated by this epigenetic lesion. Hypermethylation is linked to methyl-binding proteins, DNA methyltransferases and histone deacetylase, but the degree to which this process selectively silences tumor suppressor genes remains a vibrant field of study. The list for hypermethylated genes is growing and functional and genetic studies are being performed to determine which hypermethylation events are relevant for tumorigenesis. Basic as well as translational research will be needed to understand the mechanisms and roles of CpG island hypermethylation in cancer.
context_section_description: In a normal cell, the CpG island is hypomethylated, and the rest of the genome is methylated. It is evident that the hypomethylation of the CpG island in normal cells provides no additional steric hindrance to future binding. The majority of CpG pairs in mammals are chemically modified by the covalent attachment of a methyl group to the C5 position of the cytosine ring. This modification is distributed throughout the genome and represses transcription. A CpG island is a Cytosine and Guanine linked by a phosphate in a repeated sequence. These are genetic hotspots as they are sites for active methylation. The expression of a gene is tissue specific, which leads to variation in tissue function. Methylation of a gene prevents expression of a gene in a particular way.
  The reason for methylation to be almost exclusive to CpG dinucleotides is the symmetry of the dinucleotide. This allows for preservation during cell division and is a hallmark for epigenetic modifications.
caption: In a normal cell, the CpG island is hypomethylated, as can be seen from the unfilled stubs, but the genome, in general, is methylated, as can be seen from the filled in stubs. In contrast, in the cancer cell, the CpG island is more likely to be methylated, and the rest of the genome is hypomethylated. There is a swap of where DNA methylation is found between a normal cell and a cancer cell.
exif: {}