title: The temporal relationships of synthesis and phosphorylation in stress proteins 70 and 90 in aged caloric restricted rats exposed to bleomycin.
abstract: A single intraperitoneal injection of the human therapeutic drug bleomycin (BL) was administered to three groups of male Fischer 344 rats at time 0, and the incorporation of [35S]methionine ("synthesis") and phosphorylation patterns of stress proteins (sps/hsps) from bone marrow cells were analyzed over time by two-dimensional electrophoresis and fluorography. Two groups of rats, young ad libitum (Y/AL--3 months) and old ad libitum (O/AL--28 months), had free access to rat chow, and a third group of old rats (O/CR--28 months) were maintained on a caloric restricted intake (60% of the AL diet). The administration of BL in Y/AL, O/AL and O/CR animals activated the 35S-labeling of sp 90 which reached a peak at 4 hours. Labeling of sp 90 was significantly greater in Y/AL compared to O/AL, and the incorporation pattern of O/CR was intermediate to Y/AL and O/AL animals. All labeling of sp 90 in each group had disappeared by 10 hours after BL administration. Stress protein 70x (inducible form) in these three animal groups displayed a similar pattern of 35S-incorporation, but the amount of labeling was less than that of sp 90. No labeling of sp 70x remained by 13 hours after BL administration. Phosphorylation ([32P] phosphate incorporation) of sp 90 reached a maximum level at 2 hours in all animals, and 32P-labeling in Y/AL was significantly increased over O/AL and O/CR with an intermediate level found in O/CR animals. The turnover rate (phosphorylation/dephosphorylation) of sp 90 induced by BL was significantly suppressed and temporarily extended in O/AL as compared with O/CR, which implied that CR not only increased incorporation of sp 90, but also enhanced a utilization of the phosphate pool very similar to that seen in Y/AL animals.
authors.affiliation: Department of Health and Human Services, Food and Drug Administration, Jefferson, AR 72079-9502.
authors.forename: J L
authors.initials: JL
authors.lastname: Pipkin
authors.forename: W G
authors.initials: WG
authors.lastname: Hinson
authors.forename: R J
authors.initials: RJ
authors.lastname: Feuers
authors.forename: L E
authors.initials: LE
authors.lastname: Lyn-Cook
authors.forename: E R
authors.initials: ER
authors.lastname: Burns
authors.forename: P H
authors.initials: PH
authors.lastname: Duffy
authors.forename: R
authors.initials: R
authors.lastname: Hart
authors.forename: D A
authors.initials: DA
authors.lastname: Casciano
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D001761:Bleomycin / Q000494:pharmacology*; D002149:Energy Intake; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D008297:Male; D008715:Methionine / Q000378:metabolism; D010756:Phosphoric Acids / Q000378:metabolism; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation; D051381:Rats; D011916:Rats, Inbred F344; D013462:Sulfur Radioisotopes; D013997:Time Factors
chemical_list: D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D010756:Phosphoric Acids; D010761:Phosphorus Radioisotopes; D013462:Sulfur Radioisotopes; D001761:Bleomycin; D008715:Methionine; C030242:phosphoric acid