Induction of mitochondrial heat shock protein 60 and 10 mRNAs following transient focal cerebral ischemia in the rat

Heat shock proteins (HSPs) 60 and 10 are stress-inducible mitochondrial mat rix proteins that form a chaperonin complex that is important for mitochond rial protein folding and function. The effect of cerebral ischemia on mitoc hondrial HSPs is unclear. The topographical and chronological patterns of H SP60 and HSP10 messenger ribonucleic acid (mRNA) expression and induction w ere investigated in the rat focal cerebral ischemia model. Focal cerebral i schemia was produced by transient middle cerebral artery occlusion for 30 o r 90 min. Expression of mRNAs was analyzed using reverse transcription-poly merase chain reaction (RT-PCR) and in situ hybridization. RT-PCR analysis s howed that both HSP60 and HSP10 mRNA levels increased significantly in the ischemic cortex from 4 to 24 h of reperfusion after 30 min of occlusion. Ln situ hybridization analysis demonstrated significant induction of both mRN As in the whole ischemic cortex after 30 min of occlusion and in the dorsom edial border (penumbra) of the ischemic cortex and ipsilateral hippocampus after 90 min of occlusion. Expression patterns and the timing of the induct ion of both HSP60 and HSP10 mRNAs were identical throughout the experiments . Simultaneous induction of the mRNAs for the mitochondrial chaperonins, HS P60 and HSP10, in various regions in focal cerebral ischemia demonstrates t hat mitochondrial stress conditions persist concomitantly with cytosolic st ress conditions in focal cerebral ischemia. (C) 2001 Elsevier Science B.V. All rights reserved.