RNA synthesis by nuclei and chromatin isolated from adult and senescent Wistar rat liver.
Nuclei isolated from senescent (22-26 months) female Wistar rat liver show a decreased RNA synthesis compared to nuclei from adult (12 months) liver. Kinetic analyses demonstrate a decreased rate (25-42%) and maximal incorporation (41-54%) of labeled uridine triphosphate into both rRNA and mRNA in senescent nuclei. Chromatin-bound RNA polymerase activity is decreased by 36%, whereas free RNA polymerase activity, i.e., not bound to chromatin, is increased by 41% in senescent nuclei, but the total bound plus free activity is the same in senescent and adult nuclei. Isolated senescent chromatin shows reduced transcriptional capacity and requires a higher temperature to initiate melting. A decreased ability of chromatin to bind RNA polymerases appears to underlie the observed decreased RNA synthesis in senescent liver nuclei.
Park
G H
GH
Department of Physiology and Biophysics, University of Illinois, Urbana.
Buetow
D E
DE
D000375:Aging / Q000502:physiology*; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000502:physiology; D005260:Female; D008099:Liver / Q000502:physiology*; D012313:RNA / Q000096:biosynthesis*; D051381:Rats; D011919:Rats, Inbred Strains
D002843:Chromatin; D012313:RNA; D012321:DNA-Directed RNA Polymerases