Differential actions of neurotrophins on apoptosis mediated by the low affinity neurotrophin receptor p75(NTR) in immortalised neuronal cell lines

The low affinity neurotrophin receptor (p75(NTR)) mediates apoptosis of a n umber of neuronal and non-neuronal cells but the signals leading to the apo ptosis remain obscure. To reveal the mechanism of p75(NTR)-mediated apoptos is, a neural cell line expressing human p75(NTR) was established. The human cDNA fragment encoding for p75(NTR) was PCR-amplified, cloned into the ret rovirus expression vector pXT-1 and transfected into the rat cerebellum cel l line R2. The expression of p75(NTR) in the R2 cell line was demonstrated by both Northern blotting analysis and immunocytochemistry. Serum withdrawa l induced dramatic apoptosis in p75(NTR)-expressing R2 cells (R2L1) but not in pXT-1 transfected control R2 cells (R2P). Reverse transcription polymer ase chain reaction (RT-PCR) revealed that these cell lines express trkA and trkB but not trkC. The apoptosis of R2L1 cells triggered by the serum depr ivation for 48 h was completely prevented by neurotrophin-3 and the antibod y to p75(NTR) but only partially prevented by the nerve growth factor and b rain derived neurotrophic factor. We conclude that the p75(NTR) mediates ap optosis of R2L1 cells by its intrinsic receptor effects requiring an unboun d status of this receptor and that the apoptosis is prevented by neurotroph ins or the antibody to p75(NTR) through distinct mechanisms. (C) 1999 Elsev ier Science Ltd. All rights reserved.