Genomics and Applied Biology 2024, Vol.15, No.3, 153-161 http://bioscipublisher.com/index.php/gab 156 Figure 1 The epigenetic readers, writers and erasers (Adopted from Jin et al., 2021) Image caption: (a) Histone proteins wrap around DNA to form a nucleosome, which are then compacted to form chromatins and further into chromosomes. (b) A multiprotein complex (consisting METTL3, METTL14 and other subunits) methylates adenosine base at the nitrogen-6 position and forms m6A in the messenger RNA. The figure illustrates how histone acetylation and methylation affect chromatin structure and gene expression through the action of different enzymes. Histone acetyltransferases (HATs) add acetyl groups, opening the chromatin and promoting gene transcription, while histone deacetylases (HDACs) remove acetyl groups, closing the chromatin and inhibiting transcription. Additionally, methylated histones can either activate or repress gene expression depending on the modification site. The results reveal the dynamic regulation of DNA methylation and RNA modifications, highlighting the complexity and significance of epigenetic mechanisms in gene expression regulation, thus supporting the theoretical basis for epigenetic-targeted therapies (Adapted from Jin et al., 2021) 4.3 Impact of non-coding RNAs on gene expression Non-coding RNAs (ncRNAs), including microRNAs, piwi-interacting RNAs, and long non-coding RNAs, are crucial regulators of gene expression at the epigenetic level. These ncRNAs can modulate gene expression by guiding chromatin-modifying complexes to specific genomic loci, thereby influencing DNA methylation and histone modifications (Pathania et al., 2021). For example, ncRNAs can recruit DNA methyltransferases to target sites, leading to gene silencing, or they can interact with histone modifiers to alter chromatin structure and gene expression (Palicelli et al., 2021). The regulatory roles of ncRNAs are essential for various cellular processes, including development, differentiation, and response to environmental stimuli (Bure et al., 2022). 4.4 Crosstalk between epigenetic mechanisms The crosstalk between different epigenetic mechanisms, such as DNA methylation, histone modifications, and RNA modifications, adds an additional layer of complexity to gene regulation. For instance, N6-methyladenosine (m6A) RNA methylation has been shown to interact with histone and DNA modifications, influencing RNA stability and translation efficiency (Kan et al., 2021; Zhao et al., 2021). This intricate interplay ensures coordinated regulation of gene expression, allowing cells to respond dynamically to internal and external cues. Understanding these interactions is crucial for unraveling the complexities of epigenetic regulation and its impact on gene expression in Bt (Song et al., 2021).
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