Genotoxicity and Epigenetic Regulations Modified by NPs
According to the tiny size of NPs, they are likely to enter the nucleus of cells and to interact with the chromosomes resulting in abnormal protein production and the anonymous aftermath. The mechanisms of how NPs cause geno- toxicity are not yet clarified in depth. Meanwhile, a nomenclature has been suggested for the classes of genotoxicity. Primary genotoxicity happens when NPs enter the cells and impart their genotoxicity effect, while secondary genotoxicity is actually caused by the chemical production of oxidant agents due to the activation of body cells like phagocytes following inflammation or ulcerations (Gonzalez & Kirsch-Volders, 2016). The two types of genotoxicity can be either indirect or direct. Regarding the first case, the cellular objective is the DNA, whereas the second case is not related to that. Studies have been carried out to obtain information about DNA hypermethy- lation and the following expression of genes, especially for the DNA methyl- transferases (DNMTs) (Dai, Tang, Li, Zhao, & Xiao, 2015; Pirela et al., 2016; Xiao, Wang, & Han, 2016). However, epigenetics has suggested that hypomethylation can induce both overexpression of genes plus their instability. Therefore, it is necessary to connect the epigenetic and genetic fields to have a better understanding of the chemical reactions of NPs inducing toxicity (Gonzalez & Kirsch-Volders, 2016).
Epigenetics is a field of genetic refers to the study of cellular and physiological phenotypic characteristic differences emanating from the environment, which turns the genes on and off and thus altering the gene expression (Corujo, Mas, Malinverni, Di Croce, & Buschbeck, 2016; Moore, 2015). Currently, the epigenetics procedures are not investigated in depth and the role of these processes in health and appearance of diseases should be analyzed accurately (Jaenisch & Bird, 2003). Here, some of the influences of NPs on genetic structures are explored. Also, Fig. 10.10 elucidates the basic factors regulating the epigenetic phenomena.