SPONTANEOUS MORPHOLOGICAL-CHANGES BY OVEREXPRESSION OF THE GROWTH-ASSOCIATED PROTEIN B-50 GAP-43 IN A PC12 CELL-LINE/

In order to study the direct effects of B-50 on neural cell morphology , rat B-50 cDNA was transfected into a PC12 cell line (PC-B2) exhibiti ng neurite outgrowth independent of the expression of endogenous B-50. The morphological changes were visualized by confocal scanning laser microscopy using fluorescence labelling for B-50 and for F-actin. The transfected cells exhibited filopodia and/or blebs on the plasma membr ane, containing most of the B-50 immunoreactivity. No spontaneous neur ite outgrowth was observed. Following NGF treatment transfected and no n-transfected PC-B2 cells extended F-actin positive filopodia and neur ites with a striking colocalisation of B-50 and F-actin. Our data show that the presence of B-50 can influence cell surface morphology indep endent of the presence of NGF. The colocalisation of B-50 and F-actin in the filopodial protrusions but not in the blebs might be indicative for a role of B-50 in actin polymerization and depolymerization.