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DNA methylation is a major epigenetic modification involving the addition of a methyl group to the 5 position of cytosine by DNA methyltransferase to form 5-methylcytosine (5-mC). This epigenetic mark has the power to turn genes on or off and can be inherited through cell division. DNA methylation was the first epigenetic mark to be discovered and it plays an important role in normal human development, aging, tumorigenesis, and other genetic and epigenetic diseases. Similarly, DNA hydroxymethylation, caused by oxidation of 5-mC through the TET family of enzymes, was further discovered to be involved in controlling gene expression and is a key DNA demethylation process as part of the DNA methylation cycle.

RNA methylation is a reversible post-translational modification to RNA that epigenetically impacts numerous biological processes. It occurs in different RNAs including tRNA, rRNA, mRNA, tmRNA, snRNA, snoRNA, miRNA, and viral RNA. Different catalytic strategies are employed for RNA methylation by a variety of RNA-methyltransferases.

Chromatin structures are regulated by various mechanisms including histone modification and chromatin remodeling, which involve the binding of transcription factors. By using tools such as chromatin immunoprecipitation, it is possible to gain further insight into the dynamic interactions between transcription proteins and components of chromatin, and to ultimately understand their roles in cellular fu...

Histone methylation causes transcription repression or activation, depending on the target sites. Histone methyltransferases (HMTs) control or regulate DNA methylation through chromatin-dependent transcription repression or activation. Measurement of histone methyltrasferase activity and quantification of histone methylation patterns have become pivotal in studying epigenetic regulation of genes, as well as inhibitor discovery.

Histone acetylation and histone deacetylation involve the addition or removal of an acetyl group on lysine residues in the N-terminal tail and on the surface of the nucelosome core of histone proteins. Acetylated and deacetylated histones are considered epigenetic tags within chromatin by relaxing (euchromatin) or tightening (heterochromatin) chromatin structure, subsequently increasing or decreasing gene transcription levels.

Direct DNA damage or RNA damage can occur due to a number of factors including oxidative stress, cellular exposure to genotoxic agents, and exposure to cytotoxic agents. Oxidative stress has been shown to be one of the greatest factors in DNA & RNA damage, and increased levels have been closely correlated to harmful environmental factors such as ionizing radiation, industrial chemicals, air pollution, cigarette smoking, and cancer chemotherapy. Measurement of DNA/RNA damage...

Targeted gene knockdown using small interfering RNA (siRNA) or antisense oligonucleotides has been valuable technology in studying gene function. Gene knockdown leads to the reduction of messenger RNA and subsequently decreased protein expression. Alternatively, CRISPR/Cas9-based gene editing is also a versatile method to alter the genome. These gene editing and silencing methods give researchers valuable insight into biological processes and especially diseases.

Various histone modifications, such as histone citrullination and histone phosphorylation, have been shown to epigenetically impact gene expression through different mechanisms. Adjusting epigenetic marks and changing chromatin structure – known as chromatin remodeling – as a result of these histone modifications can influence gene regulation in many tissue types. Studying these histone modifications provides researchers with valuable insight into cellular processes such as apoptosis, cel...