TRANSCRIPTS ENCODING A NEURAL MEMBRANE CD26 PEPTIDASE-LIKE PROTEIN ARE STIMULATED BY SYNAPTIC ACTIVITY

We isolated a cDNA clone, named BSPL, that encodes a brain-specific di peptidyl peptidase-like protein with 30% identity and 50% similarity t o CD26, a lymphocyte membrane antigen involved in T-cell activation. B SPL lacks, however, the catalytic residue responsible for peptidase ac tivity. The expression of BSPL is widespread throughout the CNS but re stricted to neurons under normal conditions. Twenty-four hours after i njection of kainic acid into the hippocampus, a dramatic increase in t he concentration of BSPL mRNA was detected by in situ hybridization in the CA3 region of the injected hemisphere as compared with the contra lateral hemisphere or sham-injected animals. An increase in the steady -state level of BSPL mRNA concentration was also found following tetan ic stimulation of the perforant path to produce LTP in granule cells o f the dentate gyrus. Hybridization signals could be detected in dendri tic processes of pyramidal neurons and in some glial cells upon either type of stimulation. These data suggest that BSPL may be involved in synaptic plasticity.