The temporal relationships of synthesis and phosphorylation in stress proteins 70 and 90 in aged caloric restricted rats exposed to bleomycin

Autor: Pipkin, James, Hinson, W., Feuers, R., Lyn-Cook, L., Burns, E., Duffy, P., Hart, R., Casciano, D.
Zdroj: Aging: Clinical and Experimental Research; April 1994, Vol. 6 Issue: 2 p121-131, 11p
Abstrakt: 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 35Sincorporation, 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. (Aging Clin. Exp. Res. 6: 121- 131, 1994)
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