NF-κB signalling regulates the growth of neural processes in the developing PNS and CNS

Abstract

The proper growth and elaboration of neural processes is essential for the establishment of a functional nervous system during development and is an integral feature of neural plasticity throughout life. Nuclear factor-kappa B (NF-κB) is classically known for its ubiquitous roles in inflammation, immune and stress-related responses and regulation of cell survival in all tissues, including the nervous system. NF-κB participation in other cellular processes remains poorly understood. Here we report a mechanism for controlling the growth of neural processes in developing peripheral and central neurons involving the transcription factor NF-κB. Inhibiting NF-κB activation with super-repressor IκB-α, BAY 11 7082 (IκB-α phosphorylation inhibitor) or N-acetyl-Leu-Leu-norleucinal (proteosomal degradation inhibitor), or inhibiting NF-κB transcriptional activity with κB decoy DNA substantially reduced the size and complexity of the neurite arbors of sensory neurons cultured with brain-derived neurotrophic factor while having no effect on their survival. NF-κB exerted this effect during a restricted period of development following the phase of naturally occurring neuronal death when the processes and connections of the remaining neurons are extensively modified and refined. Inhibiting NF-κB activation or NF-κB transcriptional activity in layer 2 pyramidal neurons in postnatal somatosensory cortical slices reduced dendritic arbor size and complexity. This function of NF-κB has important implications for neural development and may provide an explanation for reported involvement of NF-κB in learning and memory.