Endogenous virus genomes become hypomethylated tissue--specifically during aging process of C57BL mice.
In an attempt to find out a cause for age-dependent derepression of endogenous viruses, extents of DNA methylation at the endogenous B- and C-type ecotropic viruses in brain, liver and spleen of C57BL/6NJc1 were examined at three ages, newborn, young adult and old. Both endogenous viruses showed a slight but significant tissue-specific either hypo- or hypermethylation during post-natal developmental phase in the three tissues. After maturation, however, no such change was detectable at most of the sites examined. The exceptions were C-type ecotropic virus in brain and B-type virus in spleen, where the age-dependent decreases of methylation were observed. The changes seemed to be continuations of preceding developmental hypomethylation. They indicated that the hypomethylation could be one of the causes for the age-dependent derepression of endogenous virus. It was further suggested that a mechanism to stop the developmental changes of DNA methylation at the maturation of individuals would be important in considering the reasons for the changes in senescent phase.
Ono
T
T
Radiation Biology Center, Kyoto University, Japan.
Shinya
K
K
Uehara
Y
Y
Okada
S
S
D000375:Aging; D000818:Animals; D001921:Brain / Q000382:microbiology; D004279:DNA, Viral / Q000378:metabolism*; D005260:Female; D008099:Liver / Q000382:microbiology; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics; D008745:Methylation; D051379:Mice; D008810:Mice, Inbred C57BL / Q000382:microbiology / Q000502:physiology*; D012190:Retroviridae / Q000235:genetics*; D013154:Spleen / Q000382:microbiology; D014775:Virus Activation / Q000235:genetics
D004279:DNA, Viral