Epigenetics

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nEpigenetics is a regulatory mechanism of human gene that affects the differentiation of a cell and human development. All cells in the body are genomic identical but they differentiate differently to ensure normal functioning of body components such as skin, neurons and enzymes. Nonetheless, the normal cell differentiation is influenced by various external factors such as diet, exercise, environmental exposure, aging and illnesses such as cancer. These factors have both positive and negative effects in the gene function epigenetically (Shukla, & Meeran, 2014, p.2). The video Epigenetics shows how modification of the DNA or other protein related to DNA influences the activity of the genes. For instance, proteins such as histones can take place in modification mechanisms such as phosphorylation, methylation and acetylation. Enzymes such as “writers” add modifications to histones while “eraser” enzymes remove the modifications. Moreover, proteins known as “readers” are able to identify the particular modifications patterns by combing them and adding more proteins to control the activity of the gene (Shukla, & Meeran, 2014, p3). Various modification patterns happen between different organs and cells of the body or after a reaction to physiological stimuli. According to Shukla, & Meeran, (2014), the changes in the modification patterns cause multiple diseases. Most notably, epigenetics has enabled the discovery of modern medicines.

nEpigenetics Mechanism

nA specific cell encodes their epigenetic information via DNA modification or via histones – protein that helps the DNA to coil around. The mechanism of epigenetic controls the micro RNA. The DNA strands wraps around the histones creating a unit known as nucleosome that folds in great loops forming chromatin. Through epigenetic process, the processes can be broken into various categories (Shukla, & Meeran, 2014, p.4). The first process is the methylation of DNA while the second is histones modification.in DNA modification, the DNA strands are inactivated through combining methyl groups that can disrupt the transcriptional enzyme binding. In addition, it can indicate to increase enzymes that change the associated histones. Methyltransferase is an enzyme in the cell that can bind to unique dinucleotide and assign a methyl groups to the cytosine. In other words, methylated DNA is silent DNA.

nHistones are the spherical structures that have N-terminal tails that have covalently bonded creating methylation, ubiqutanation, phosphorylation and acetylation. In histone modification, the changes influence the how chromatin will be closely packed. The histone modification forms euchromatin that is loosely packed and the heterochromatin, which is tightly packed (Shukla, & Meeran, 2014, p.2). Shukla, & Meeran, (2014) argues that through histone modification the DNA becomes more active and more accessible. However, the histones are not identical but some are more pervasive while others have a tighter packing. The types of histones used determine the DNA actions. The epigenetic mechanism affects the reproductive health of the human beings (Shukla, & Meeran, 2014, p.5). Through genomic imprinting, genes are expressed through DNA methylation of the paternal or maternal allele.

nThere are usually two copies of alleles in each gene from either parent. Nevertheless, imprinted genes, the working copy is from either a father or mother. For instance, in paternally imprinted an allele such as H19 is expressed from the allele of the mother at the expense of the fathers allele (Shukla, & Meeran, 2014, p.8). Genomic imprinting helps in the gametogenesis because it encompasses the transposable elements methylation. In this regard, it maintains the genome integrity (Shukla, & Meeran, 2014, p.10). Nonetheless, the imprint genes fail to methylate well and can cause severe genetic diseases such as cancer.

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nShukla, S., & Meeran, S. M. (2014). Epigenetics of cancer stem cells: Pathways and therapeutics. Biochimica et Biophysica Acta (BBA)-General Subjects.

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