DIFFERENTIAL DISTRIBUTION OF STATHMIN AND SCG10 IN DEVELOPING NEURONSIN CULTURE

The neuron-specific protein SCG10 and the ubiquitous protein stathmin are two members of a family of microtubule-destabilizing factors that may regulate microtubule dynamics in response to extracellular signals . To gain insight into the function of these proteins in the nervous s ystem, we have compared their intracellular distribution in cortical n eurons developing in culture, We have used double-immunofluorescence m icroscopy with specific antibodies for stathmin and SCG10 in combinati on with antibodies for axonal, microtubule, and synaptic marker protei ns, Stathmin and SCG10 were coexpressed in individual neurons, While b oth proteins were highly expressed in developing cultures during diffe rentiation, their subcellular localization was strikingly different, S tathmin showed a cytosolic distribution, mainly in cell bodies, wherea s SCG10 strongly labeled the growth cones of axons and dendrites, Duri ng neurite outgrowth, SCG10 appeared as a single concentrated spot in a region of the growth cone where the microtubules are known to be par ticularly dynamic, Disassembly of labile microtubules by nocodazole ca used a dispersal of the SCG10 staining into punctate structures, indic ating that its subcellular localization is microtubule-dependent. Upon maturation and synapse formation, the levels of both stathmin and SCG 10 decreased to become undetectable. These observations demonstrate th at the expression of both proteins is associated with neurite outgrowt h and suggest that they perform their roles in this process in distinc t subcellular compartments. (C) 1997 Wiley-Liss, Inc.