Epigenetics

Structural insights into the binding mechanism of Clr4 methyltransferase to H3K9 methylated nucleosome

The establishment and maintenance of heterochromatin, a specific chromatin structure essential for genomic stability and regulation, rely on intricate interactions between chromatin-modifying enzymes and nucleosomal histone proteins. However, the precise trigger for these modifications remains unclear, thus highlighting the need for a deeper understanding of how methyltransferases facilitate histone methylation among others. Here, we investigate the molecular mechanisms underlying heterochromatin assembly by studying the interaction between the H3K9 methyltransferase Clr4 and H3K9-methylated nucleosomes. Using a combination of liquid-state nuclear magnetic resonance spectroscopy and cryo-electron microscopy, we elucidate the structural basis of Clr4 binding to H3K9-methylated nucleosomes. Our results reveal that Clr4 engages with nucleosomes through its chromodomain and disordered regions to promote de novo methylation. This study provides crucial insights into the molecular mechanisms governing heterochromatin formation by highlighting the significance of chromatin-modifying enzymes in genome regulation and disease pathology.

Current understanding of epigenetics role in melanoma treatment and resistance

Melanoma is the most aggressive form of skin cancer resulting from genetic mutations in melanocytes. Several factors have been considered to be involved in melanoma progression, including genetic alteration, processes of damaged DNA repair, and changes in mechanisms of cell growth and proliferation. Epigenetics is the other factor with a crucial role in melanoma development. Epigenetic changes have become novel targets for treating patients suffering from melanoma. These changes can alter the expression of microRNAs and their interaction with target genes, which involves cell growth, differentiation, or even death. Given these circumstances, we conducted the present review to discuss the melanoma risk factors and represent the current knowledge about the factors related to its etiopathogenesis. Moreover, various epigenetic pathways, which are involved in melanoma progression, treatment, and chemo-resistance, as well as employed epigenetic factors as a solution to the problems, will be discussed in detail.

The epitranscriptome of long noncoding RNAs in metabolic diseases

Long noncoding RNAs (lncRNAs) have abundant content and extensive functions that regulate the expression of genes at multiple levels. Recently, transcriptome-wide analysis confirmed that RNA can undergo various chemical modifications in response to stimulation by the environment that further determine the action mechanisms of RNAs and expand the diversity of the transcriptome. Modifications that occur in lncRNAs can affect their expression and the regulation of downstream molecules by changing the secondary structure, splicing, degradation or molecular stability of lncRNAs. During the development of metabolic diseases, reversible RNA modifications show a complex transcriptional landscape. Although a wide quantity and variety of lncRNA modifications have been identified, the knowledge regarding their underlying actions in alcohol use disorders (AUDs), osteoporosis, obesity, and cardiovascular disease (CVD) is still in its infancy. Herein, we will focus on the epitranscriptomic modifications that occur on lncRNAs and the crosstalk between them that affect metabolic diseases.