EXPRESSION OF MESSENGER-RNA SPECIES ENCODING HEAT-SHOCK PROTEIN-90 (HSP90) IN CONTROL AND HYPERTHERMIC RABBIT BRAIN

Northern blot and in situ hybridization were employed to investigate r egional and cell type differences in the expression of hsp90 mRNA spec ies in control and hyperthermic rabbit brain. Riboprobes specific to h sp90 alpha and beta mRNA species were utilized in timecourse Northern blot studies on cerebral hemispheres and the cerebellum, Following hyp erthermia, levels of hsp90 alpha and beta mRNA were elevated in both b rain regions; however, the magnitude of induction was more robust in t he cerebellum than in cerebral hemispheres, The pattern of expression of hsp90 genes in rabbit brain was analyzed by in situ hybridization, These studies revealed that hsp90 genes are preferentially expressed i n neuronal cell populations in the unstressed mammalian brain, The dis tribution of hsp90 alpha and beta mRNA was similar, though the signal for the latter was stronger, Following hyperthermia, changes were not detected in the pattern of hsp90 beta mRNA expression in the hippocamp us, In the cerebellum, a rapid induction of hsp90 beta mRNA was appare nt in the neuron-enriched granule cell layer, followed by a delayed ac cumulation in Purkinje neurons, Unlike hsp70, induction of hsp90 was n ot detected in glial cells of hyperthermic rabbit brain, The localizat ion of hsp90 to neurons suggests that this heat shock protein plays an important role in neuronal function. (C) 1996 Wiley-Liss, Inc.