Over time, as mice age, the once silent LINE-1 prisoners are turned into RNA and the RNA is turned into DNA, which is reinserted into the genome at a different place. Besides creating genome instability and epigenomic noise that causes inflammation, LINE-1 DNA leaks from the nucleus into the cytoplasm, where it is recognized as a foreign invader. In response, the cells release even more immunostimulatory cytokines that cause inflammation throughout the body.
