| Summary: | Serine proteases in the central nervous system modulate developmental and synaptic plasticity and are implicated in the pathophysiology of Alzheimer's disease. This thesis aims to characterise the spectrum of serine proteases expressed in the brain. Degenerate primers were designed from regions conserved among the major chymotrypsin clan of serine proteases; these were used for the polymerase chain reaction amplification of family members represented in cDNA form adult rat hippocampus. 10 different members of the family were uncovered. The most abundant products corresponded to tissue plasminogen activator (t-PA) and RNK-Met-1, a lymphocyte protease not previously reported in brain. Evidence is provided to suggest that the major t-PA substrate, plasminogen, is absent from brain, arguing that the target for t-PA in brain is unlikely to be plasminogen, Other enzymes represented include elastase IV, proteinase3, complement C2, Hageman factor, chymotrypsin B, chymotrypsin-like protein and two novel family members, BSP-1 (brain serine protease-1) and BSP-2. Full length sequences of BSP-1 and BSP-2 are reported and sequence motifs and homologies suggest they represent trypsin-like proteases. The expression patterns for each of the serine proteases amplified, as determined by Northern and in-situ hybridization analysis, are presented. BSP-2 is expressed in the hippocampus and the cerebral cortex whereas BSP-1 is confined in its expression to the CA fields of the hippocampus. A gene restricted in expression to the hippocampus has considerable potential for transgenic experimentation into the role of this brain region. Directing expression of suitably modified components of the synaptic signalling pathway within this brain region would allow the relationship between hippocampal synaptic plasticity and learning and memory events to be assessed. To investigate the feasibility of such an approach, the murine BSP-1 locus has been targeted with an IRES-lacZ reporter cassette. Preliminary results indicate reporter expression is active from the murine BSP-1 locus.
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