Fig. 2

Mechanisms of epigenetics. The epigenetic modifications cause alterations in gene expression without directly altering the DNA sequence. In general, DNA methylation causes a segment of DNA to associate more closely with a histone complex. This prevents transcription factors from binding to a DNA sequence, such as a promoter, resulting in reduced expression of a specific gene. In contrast, histone acetylation weakens the interaction between the histone complex and DNA, allowing transcription factors to bind to the promoter and increase gene expression. Non-coding RNAs also play a crucial role in the regulation of gene expression