FIGURE 1.

Epigenetic modifications regulate gene expression and contribute to the pathogenesis of chronic rhinosinusitis (CRS) with or without nasal polyps. (1) Methyl group (CH3) on cytosines inactivates gene transcription, which is catalyzed by DNA methyltransferase (DNMT); in contrast, the DNA demethylation contributes to gene expression. (2) When acetyl groups (COCH3) bind to histone tails via histone acetyltransferase (HAT), the gene is expressed. Conversely, the removal of the acetyl groups by histone deacetylase (HDAC) turns off the gene expression. (3) circRNA and lncRNA can regulate the 3′-UTR of mRNA through the sponging effect of miRNA, then control the gene expression.