Programmed cell death (apoptosis) is of central importance in many age-related degenerative processes. We demonstrate apoptosis in PC12 cells deprived of extracellular matrix adhesion and that nerve growth factor (NGF) treatment greatly accelerates this process. Both NGF and fibroblast growth factor induced apoptosis while epidermal growth factor (which induces proliferation but not neuronal differentiation of PC12 cells was less potent. Immunoblotting with anti-phosphotyrosine antibodies revealed striking differences in the pattern of tyrosine phosphorylation induced by NGF in adherent as compared to nonadherent PC12 cells, suggesting that NGF signaling is altered in nonadherent PC12 cells. We developed a variation of the differential display cloning approach that specifically targets members of multigene families. This method resulted in the amplification of a PCR product that showed an apparent specificity of tissue distribution. Sequencing showed a 99% match with the known murine ICE sequence, and the pattern of brain distribution we observed is consistent with published studies of murine ICE. These results validate the general method of PCR amplification with biotinylated targeting primers coupled with arbitrary primers.
