Cerebellar Heat Shock Protein 25 is not Changed by Hyperthermic Induction

Heat shock proteins has molecular chaperone functions in protein biogenesis as well as cytoprotective functions against deleterious environmental stresses. Heat shock proteins (HSP) are classified according to their molecular weight into four general families: HSP110 (110 kDa), HSP90 (84-90 kDa), HSP70 (68-78 kDa) and small heat shock proteins (20-30 kDa). Among these families, mouse HSP25 is expressed in many motor and sensory neurons of the brain stem and spinal cord. However, very little is known about the function of this low molecular weighted heat shock protein in the central nervous system. Recently, it has clearly demonstrated that HSP25 is constitutively expressed in the adult mouse cerebellum by parasagittal bands of Purkinje cells in three distinct regions, the central zone (lobule Ⅵ-Ⅶ) an nodular zone (lobule Ⅸ-Ⅹ), and paraflocculus. Using by immunohistochemistry and western blotting, we investigated the HSP70 and HSP25 expressions after hyperthermic induction and to compared the distribution of HSP70 and HSP25-immunoreactive neruons. In the present study, we observed a little difference between anti-HSP25 and anti-HSP70 immunoreactivity in the cerebellum. Anti-HSP70 immunoreactivity in Purkinje cells showed the time course-varient characteristics in all lobules of cerebellum and cranial nerve Ⅶ motor nuclei and its tract in the brain stem. Moreover, anti-HSP25 immunoreactivity in the brain stem gradually increased by post-heat shock acquisition times. However, cerebellar HSP25 expression was not changed by hyperthermic induction. Immunoblot analysis of protein lysates from controls and hyperthermic mice brains showed a pattern of induction complementary to the immunohistochemical data pattern of expression of HSP70 and HSP25 after hyperthermic induction. This finding means that, in contrast to the expression of HSP25 in brainstem, cerebellar HSP25 expression does not induced by hyperthermic induction.