Calpain-PKC inter-relations in mouse hippocampus: A biochemical approach

In previous studies, we isolated and identified a mu-calpain/PKC alpha comp lex from rabbit skeletal muscle. Here, we have used specific purification p rocedures in order to study the interactions between mu-calpain and PKC in mouse hippocampus, a brain structure implicated in memory processes. We obs erved that mu-calpain and conventional PKCs (alpha, beta II and gamma) are co-eluted after anion exchange chromatography. In contrast to our previous results obtained on skeletal muscle, mu-calpain and PKC isoenzymes were dis sociated after gel filtration chromatography. Furthermore, mu-calpain induc ed the proteolytic conversion of PKC alpha, beta II,and gamma into PKM alph a, beta II, and gamma with a preferential hydrolysis of PKC gamma, a specif ic isoenzyme of the nervous system. Although the mu-calpain/PKC interaction s in the hippocampus are quite different from skeletal muscle, our results however, point out the functional importance of these inter-relations. More over, as PKC gamma has been involved in the biochemical events underlying l earning and memory, the preferential relationship between mu-calpain and PK C gamma promotes the importance of the role that mu-calpain could play in t he cellular mechanisms of memory formation.