During the development of the vertebrate nervous system, a balance is maintained between the formation of neurons and their synapses and neuronal death and synaptic remodeling. Neurotrophic cytokines are known to promote the survival of certain classes of neurons during development. The signaling pathways activated by these cytokines, however, have not been defined. In this issue, Middleton et al. 2000 provides evidence that neurotrophic cytokines activate the transcription factor nuclear factor kappa B (NFκB), which is crucial for the survival of cytokine dependent neurons.
In many populations of developing neurons, more than half of the neurons generated die by apoptosis. This is believed to ensure that the correct number and type of neurons innervate target cells. The survival or death decision of neurons appears not to be predetermined, but is instead the consequence of the integration of multiple intracellular...
