Nerve Growth Factor-induced p75-mediated Death of Cultured Hippocampal Neurons Is Age-dependent and Transduced through Ceramide Generated by Neutral Sphingomyelinase

Adi B Brann,Marianna Tcherpakov,Ian M Williams,Anthony H Futerman,Mike Fainzilber

doi:10.1074/jbc.m109862200

Adi B Brann, Marianna Tcherpakov + Show 3 more

Open Access

https://doi.org/10.1074/jbc.m109862200

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Abstract

Binding of nerve growth factor (NGF) to the p75 neurotrophin receptor (p75) in cultured hippocampal neurons has been reported to cause seemingly contrasting effects, namely ceramide-dependent axonal outgrowth of freshly plated neurons, versus Jun kinase (Jnk)-dependent cell death in older neurons. We now show that the apoptotic effects of NGF in hippocampal neurons are observed only from the 2nd day of culture onward. This switch in the effect of NGF is correlated with an increase in p75 expression levels and increasing levels of ceramide generation as the cultures mature. NGF application to neuronal cultures from p75(exonIII-/-) mice had no effect on ceramide levels and did not affect neuronal viability. The neutral sphingomyelinase inhibitor, scyphostatin, inhibited NGF-induced ceramide generation and neuronal death, whereas hippocampal neurons cultured from acid sphingomyelinase(-/-) mice were as susceptible to NGF-induced death as wild type neurons. The acid ceramidase inhibitor, (1S,2R)-d-erythro-2-(N-myristoylamino)-1-phenyl-1-propanol, enhanced cell death, supporting a role for ceramide itself and not a downstream lipid metabolite. Finally, scyphostatin inhibited NGF-induced Jnk phosphorylation in hippocampal neurons. These data indicate an initiating role of ceramide generated by neutral sphingomyelinase in the diverse neuronal responses induced by binding of neurotrophins to p75.

Highlights

The p75 neurotrophin receptor (p75)1 is the shared receptor for all four mammalian neurotrophins [1] as well as other unrelated ligands [2,3,4,5,6]
We show that in addition to its ability to stimulate axonal outgrowth [17], ceramide generated via binding of nerve growth factor (NGF) to p75 can induce cell death in hippocampal neurons only from the 2nd day of culture onward, which parallels an increase in p75 expression levels
In our current and previous studies, we demonstrate that cultured hippocampal neurons undergo a switch in their response to NGF after the first 24 h in culture, from acceleration of the rate of axonal outgrowth [17] to apoptotic cell death

Summary

Introduction

The p75 neurotrophin receptor (p75)1 is the shared receptor for all four mammalian neurotrophins [1] as well as other unrelated ligands [2,3,4,5,6]. Binding of nerve growth factor (NGF) to the p75 neurotrophin receptor (p75) in cultured hippocampal neurons has been reported to cause seemingly contrasting effects, namely ceramide-dependent axonal outgrowth of freshly plated neurons, versus Jun kinase (Jnk)-dependent cell death in older neurons.

Results

Conclusion