Fig. 1
From: A review of epigenetic changes in asthma: methylation and acetylation
a When acetyl groups (COCH3) bind to histone tails via histone acetyltransferase (HAT), the DNA strand around nucleosomes loosens and, as a result, the gene will be expressed. Conversely, the removal of the acetyl groups by histone deacetylase (HDAC) turns off the gene transcription. b While the presence of methyl group (CH3) on cytosines inactivates the transcription of a gene, which is catalyzed by DNA methyltransferase (Dnmt), the DNA demethylation contributes to the gene expression