Glucocorticoids regulate the synthesis of HSP27 in rat brain slices.
Using mild heat shock of rat brain slices as a model for cellular insult, corticosteroid-mediated regulation of protein synthesis has been investigated. Following a single in vivo injection of rats with corticosterone or the Type II glucocorticoid receptor agonist, RU-28362, synthesis of a 28 kDa protein is elevated in cerebellar slices which are subsequently incubated in vitro at 39 degrees C for 3 h. Immunoblotting of proteins subsequent to separation by two-dimensional gel electrophoresis has identified this glucocorticoid-sensitive protein to be the small molecular weight heat-shock protein, HSP27. Synthesis of the major heat-shock proteins, HSP70 and HSP90, is not glucocorticoid-sensitive. When animals are sacrificed at either 4 h following an aldosterone injection or at 24 h following a corticosterone injection, the synthesis of HSP27 in cerebellar slices is decreased. Treatment of adrenalectomized rats with either corticosterone, RU-28362 or aldosterone produces increased synthesis of HSP27. With duration of heat shock, there is a transient increase in the synthesis of HSP27 after 2 h at 39 degrees C in slices from the cerebral cortex, with a more sustained synthesis of HSP27 in cerebellar slices. In hippocampal slices, HSP27 is rarely present. The upregulated synthesis of HSP27 in the cerebellum following an acute exposure to stress-like elevations in corticosterone titers may contribute to the relative resistance of this brain region to cellular insults.
Barr
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Department of Neurosciences, Medical College of Ohio, Toledo, OH, USA.
Dokas
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D000732:Androstanols / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism*; D003345:Corticosterone / Q000494:pharmacology*; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018869:Heat-Shock Response / Q000187:drug effects / Q000502:physiology; D008297:Male; D009363:Neoplasm Proteins / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D000732:Androstanols; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C486114:Hspb1 protein, rat; D009363:Neoplasm Proteins; C049154:11,17-dihydroxy-6-methyl-17-(1-propynyl)androsta-1,4,6-triene-3-one; D003345:Corticosterone