HEPARIN TREATMENT INCREASES 9-KB MAP2 MESSENGER-RNA LEVELS IN NEURONAL CELL-CULTURES

When neuronal adhesion is reduced by heparin, cultured neurons detach from the substratum and form clusters connected by neuritic fascicles. 24 h after treatment, Northern blots analysis revealed an increase in the expression of the 9-kb MAP2 mRNA in the heparin-treated neuronal cultures. MAP2 being associated with the cross-bridges between microtu bules, this increased expression could be an attempt of the cells to r igidify their cytoskeleton to compensate for the reduced attachment. H owever, the MAP2 protein content was not increased after a 24-h hepari n treatment. We discuss possible explanations for this observation and their implications on MAP2 metabolism.