Table 1.

Epigenetic regulations of gene expression by histones. Summary of the type of modifications that histones undergo to regulate gene expression by repressing or enhancing gene transcription, thereby silencing and activating them, respectively.

Molecules Regulate Gene Expression	Types of Modification	Examples	Outcomes
Histones	Methylation [30]		Histone methylation commonly silences the gene by repressing transcription, involving factors such as H3K27me3 [26].
	Acetylation [31,32]		Histone acetylation activates genes by enhancing the transcription, involving factors such as H3K4ac [31].
	Phosphorylation [33,34]		Histone phosphorylation helps in chromatin remodeling and repairs the damaged DNA, such as H3T6 phosphorylation [35].