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 protein tyrosine phosphatases (PTPs) may play in the postischemic brain, PTPs expressed in regions of the rat brain vulnerable to transient forebrain 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 period, 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 detected by Northern blotting in the hippocampus and cerebral cortex 1 h after the onset of reperfusion. In situ hybridization histochemistry showed a slight increase in the level of CL100 mRNA in neuronal cells in the hippocampus and cortex of postischemic rats compared to control rats. These findings suggest that PTPs play a role in the normal function of the hippocampus and cerebral cortex and demonstrate that ischemia induced CL100 expression.