DNAmetylaatiolla

DNA methylation is a fundamental epigenetic mechanism that plays a crucial role in gene regulation and cellular function. It involves the addition of a methyl group to a DNA base, typically cytosine, most commonly occurring in the context of CpG dinucleotides. This modification does not alter the underlying DNA sequence but can significantly influence how genes are expressed.

In mammals, DNA methylation is primarily catalyzed by DNA methyltransferases (DNMTs), which include DNMT1, DNMT3A, and DNMT3B. DNMT1 is responsible for maintaining methylation patterns during DNA replication, ensuring that epigenetic information is passed down to daughter cells. DNMT3A and DNMT3B establish new methylation patterns during development and in response to environmental cues.

The impact of DNA methylation on gene expression is generally repressive. Methylated CpG sites are often found in gene promoter regions, where they can impede the binding of transcription factors and recruit proteins that promote a more condensed chromatin structure, thus silencing gene transcription. Conversely, unmethylated CpG islands in promoter regions are typically associated with active gene expression.

DNA methylation is involved in a wide range of biological processes, including embryonic development, genomic imprinting, X-chromosome inactivation, and the suppression of transposable elements. Aberrant DNA methylation patterns are also implicated in various diseases, most notably cancer, where it can lead to the silencing of tumor suppressor genes or the activation of oncogenes. Understanding DNA methylation is therefore critical for comprehending normal cellular function and disease pathogenesis.