ALTERNATIVE EXPRESSION OF SHC FAMILY MEMBERS IN NERVE-INJURED MOTONEURONS

Expression of Shc family protein (Shc/ShcA, SCK/ShcB and N-Shc/ShcC) a nd Grb2 mRNAs in the hypoglossal motoneurons after axotomy was examine d by in situ hybridization. In normal hypoglossal motor neurons, N-Shc mRNA was expressed predominantly, whereas the Shc mRNA level is very low. Rat hypoglossal nerve injury reversed the expressions of these tw o molecules in hypoglossal motoneurons. Shc mRNA expression was up-reg ulated markedly whereas N-Shc was down-regulated after nerve injury. E xpression levels of SCK, another Shc family member, and Grb2 were unaf fected by nerve injury. These results suggest that, whereas the N-Shc- mediated pathway dominates under normal conditions, an alternative She -mediated pathway is utilized in the event of nerve injury. By changin g the expression of the Shc family members, the signaling pathway can be altered and various responses induced for nerve regeneration. (C) 1 998 Elsevier Science B.V.