Accumulation of Circulating Cell-Free CpG-Enriched Ribosomal DNA Fragments on the Background of High Endonuclease Activity of Blood Plasma in Schizophrenic Patients

Figure 5

The scheme illustrates the change in cfDNA characteristics during acute and chronic oxidative stress. (a) The onset of an acute process in the body. Oxidative stress induces cell death. DNA of the dead cells appears in the circulation. Ribosomal DNA is localized in the closed structure of the nucleolus and remains highly molecular. Therefore, the content of the rDNA in the composition of cfDNA is less than in the genome. (b) In response to an increase in the concentration of cfDNA, the endonuclease activity of the blood increases. AT-rich DNA fragments are fragmented to low-molecular weight fragments and are eliminated from the bloodstream. Total cfDNA is reduced, but rDNA content is elevated. (c) If the chronic process is exacerbated, then additional cfDNA fragments appear in the circulation. Ribosomal DNA content is elevated. (d) Sometimes the cells develop the DNA damage response. Since the cells do not die, the pool of cfDNA is not replenished.