INDUCTION OF CL100 PROTEIN-TYROSINE-PHOSPHATASE FOLLOWING TRANSIENT FOREBRAIN ISCHEMIA IN THE RAT-BRAIN

Protein tyrosine phosphorylation is thought to play an important role in the regulation of neural function. To elucidate the role that prote in tyrosine phosphatases (PTPs) may play in the postischemic brain, PT Ps expressed in regions of the rat brain vulnerable to transient foreb rain ischemia were examined. With the reverse-transcriptase polymerase chain reaction using degenerate primers, three PTPs, STEP, PTP delta, and SH-PTP2, were identified. They were expressed in the hippocampus 12 h after transient ischemia for 20 min. During the reperfusion perio d, the mRNA levels of these PTPs were not different from those in sham -operated rats. In contrast, a fourfold increase in the mRNA level of CL100 (3CH134), a PTP that is inducible by oxidative stress, was detec ted by Northern blotting in the hippocampus and cerebral cortex 1 h af ter the onset of reperfusion. In situ hybridization histochemistry sho wed a slight increase in the level of CL100 mRNA in neuronal cells in the hippocampus and cortex of postischemic rats compared to control ra ts. These findings suggest that PTPs play a role in the normal functio n of the hippocampus and cerebral cortex and demonstrate that ischemia induced CL100 expression.