Regulation of endogenous murine leukemia virus-related nuclear and cytoplasmic RNA complexity in C57BL/6J mice of increasing age.
The nucleotide sequence complexity of murine leukemia virus *MuLV)-related RNA has been measured by RNA-complementary DNA hybridization analysis in nuclear and cytoplasmic RNA isolated from liver and brain of low-leukemia-strain C57BL/6J mice of different ages. In these two tissues, an approximate 1.5- to 2-fold increase in the complexity of steadystate nuclear MuLV-related RNA sequences was observed as a function of age. Maximum complexity was observed with nuclear RNA extracts from old mice and corresponded to roughly 70 to 75% of the total MuLV genome. In contrast to the age-related increase in complexity of nuclear MuLV genome was detected in liver and brain steady-state cytoplasmic RNA, irrespective of animal age. These data suggest that control mechanisms regulating the transcription and/or stabilization of nuclear RNA transcripts of endogenous mouse MuLV-related genomes become less stringent with animal age even in low-tumor mouse strains. The data also support the existence of independent posttranscriptional mechanisms which prevent accumulation of these MuLV-related transcripts in steady-state cytoplasmic RNA and which do not seem to be as subject to the relaxation of stringency as a function of age.
D000375:Aging; D000818:Animals; D001921:Brain / Q000502:physiology; D002467:Cell Nucleus / Q000502:physiology; D003593:Cytoplasm / Q000502:physiology; D009052:Leukemia Virus, Murine / Q000235:genetics*; D008099:Liver / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL / Q000235:genetics*; D009694:Nucleic Acid Precursors / Q000235:genetics; D012332:RNA, Heterogeneous Nuclear / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D014158:Transcription, Genetic
D009694:Nucleic Acid Precursors; D012332:RNA, Heterogeneous Nuclear; D012333:RNA, Messenger