Induction of Krox-20 expression after focal cerebral ischemia.

Krox-20 is one of the transcription factors of "zinc finger" family. The expression of Krox-20 was investigated in a rat focal cerebral ischemia model by Northern blot analysis and in situ hybridization. Northern blot analysis showed that ischemia for 30 min which caused little cortical infarction induced a 29-fold increase in Krox-20 mRNA signal exclusively in the ischemic cortex. Ischemia for 90 min which led to large cortical infarction induced Krox-20 mRNA not only in the ischemic cortex but also in the ipsilateral hippocampus. The induction of Krox-20 mRNA was rapid, transient and appeared to be controlled at the transcriptional level, as indicated by nuclear run-on assays. The regional induction of Krox-20 mRNA was further confirmed by in situ hybridization. These results suggest that the expression of transcription factor genes may play a role in the post-ischemic changes of the injured brain.