Characterization of the synthesis and accumulation of a 71-kilodalton protein induced in rat tissues after hyperthermia

Abstract

Tissues of rats subjected to brief hyperthermic shock were examined by two-dimensional gel electrophoresis for the synthesis and accumulation of a 71-kdalton stress-induced protein (P71). Tissues of 6-week-old rats, killed immediately or 30 min after hyperthermic shock, contained little or no P71. However, in all tissues tested, synthesis and accumulation of P71 was easily detected as early as 2.5 h after hyperthermic shock. The synthesis of P71 was markedly reduced by 1 and 2 days postshock, while the concentration of P71 in all tissues remained high up to 2 days postshock. After 4 days, P71 accumulation was not detected in brain and was reduced in other tissues; at 8 and 16 days after hyperthermic shock, P71 was still detectable but at ever diminishing amounts in heart, lung, liver, spleen, adrenals, and bladder. The subcellular distribution of P71 in brain and liver was determined 2.5 h and 1 and 2 days after hyperthermic shock. The soluble fractions of brain and liver had the greatest enrichment of P71 at each of these times. These results indicate that P71 is a soluble protein which may be present in at least some tissues of unstressed rats and that relatively high concentrations of P71 are found in most tissues after trauma. The increased synthesis of P71 is transient (persisting for less than 24 h after induction), suggesting that P71 is only slowly degraded in these tissues.