F3 NEURONAL ADHESION MOLECULE CONTROLS OUTGROWTH AND FASCICULATION OFCEREBELLAR GRANULE CELL NEURITES - A CELL-TYPE-SPECIFIC EFFECT MEDIATED BY THE IG-LIKE DOMAINS

F3 is a glycane phosphatidylinositol-anchored neuronal adhesion glycop rotein which consists of immunoglobulin (Ig) domains and fibronectin t ype III repeats. Here we showed that total F3 or F3-Ig domains when pr esented as membrane components of CHO transfected cells influenced gro wth cone morphology, strongly inhibited outgrowth, and induced fascicu lation of cerebellar granule cell axons. An F3-Ig-Fc chimera induced n eurite fasciculation from cerebellar neuron aggregates when used as a coated substrate but not in the soluble form. The F3 effect on neurite elongation is highly specific for neuronal cell types since under the same experimental conditions it did not modify neurite outgrowth of h ippocampal neurons and was shown to stimulate elongation of neurites f rom sensory neurons in both membrane-anchored and soluble form. Our re sults provide evidence to extend the proposed role of F3 and strongly suggest that axonal-growth-controlling molecules may quite generally e xert dual actions which are likely to depend on the receptor repertoir e of the responding neuron.