Heparin treatment increases 9-kb MAP2 mRNA 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 microtubules, this increased expression could be an attempt of the cells to rigidify their cytoskeleton to compensate for the reduced attachment. However, the MAP2 protein content was not increased after a 24-h heparin treatment. We discuss possible explanations for this observation and their implications on MAP2 metabolism.