hypermetülation

Hypermethylation is a type of epigenetic modification that involves the addition of methyl groups to DNA, typically to cytosine bases within CpG dinucleotides. This process is catalyzed by DNA methyltransferases and is a common mechanism by which genes are silenced in eukaryotic organisms. Hypermethylation can occur in various contexts, including gene regulation, genomic imprinting, and DNA repair.

In gene regulation, hypermethylation of CpG islands, which are regions rich in CpG dinucleotides, often leads to the silencing of gene expression. This is because the methylated DNA is less accessible to transcription factors and RNA polymerase, preventing the initiation of transcription. Hypermethylation is particularly relevant in cancer, where it can contribute to the silencing of tumor suppressor genes and the activation of oncogenes.

Genomic imprinting is another context where hypermethylation plays a role. In this process, certain genes are expressed in a parent-of-origin-specific manner, and hypermethylation can contribute to the silencing of the paternally inherited allele in imprinted genes.

Hypermethylation can also occur in response to DNA damage, as part of the DNA repair process. In this context, hypermethylation can help to stabilize the DNA and prevent further damage.

The study of hypermethylation has important implications for understanding normal development, disease, and the potential for therapeutic interventions. For example, understanding the role of hypermethylation in cancer has led to the development of drugs that can reverse DNA methylation patterns and restore gene expression. Additionally, the study of hypermethylation in genomic imprinting has provided insights into the mechanisms underlying certain genetic disorders.