epigenetic

Epigenetics is the study of heritable changes in gene function that do not involve changes to the DNA sequence. Epigenetic information is stored in chemical marks and chromatin structure that regulate when and where genes are expressed, and can respond to developmental cues and environmental factors.

The main mechanisms include DNA methylation, histone modifications, chromatin remodeling, and non-coding RNAs. DNA methylation at CpG sites often represses transcription. Histone acetylation and methylation influence chromatin accessibility. Chromatin remodelers reposition nucleosomes, and non-coding RNAs can recruit modifying enzymes or regulate transcription.

Epigenetic regulation guides development and cellular differentiation, enabling stem cells to form diverse tissues. Imprinting results in parent-of-origin–specific expression, and X-chromosome inactivation balances gene dosage in female mammals.

Epigenetic marks are heritable through cell division and can create cellular memory. Some marks may be transmitted across generations in certain organisms, a phenomenon called transgenerational epigenetic inheritance, though the prevalence and significance of this phenomenon remain under study.

Research using sequencing and chromatin assays—such as bisulfite sequencing, ChIP-seq, ATAC-seq, and Hi-C—maps epigenetic landscapes in health and disease. Aberrant epigenetic patterns are common in cancer and contribute to dysregulated gene expression; epigenetic therapies aim to reverse such marks.

Environmental influences, including nutrition, stress, and toxins, can modify epigenetic states, illustrating the genome’s plasticity. The field continues to investigate causality, tissue specificity, and interactions between genetic and epigenetic factors.