Abstract

The failure of the CNS neurons to regenerate axons after injury or stroke is a major clinical problem. Transcriptional regulators like Set-ß are well positioned to regulate intrinsic axon regeneration capacity, which declines developmentally in maturing CNS neurons. Set-ß also functions at cellular membranes and its subcellular localization is disrupted in Alzheimer's disease, but many of its biological mechanisms have not been explored in neurons. We found that Set-ß was upregulated postnatally in CNS neurons, and was primarily localized to the nucleus but was also detected in the cytoplasm and adjacent to the plasma membrane. Remarkably, nuclear Set-ß suppressed, whereas Set-ß localized to cytoplasmic membranes promoted neurite growth in rodent retinal ganglion cells and hippocampal neurons. Mimicking serine 9 phosphorylation, as found in Alzheimer's disease brains, delayed nuclear import and furthermore blocked the ability of nuclear Set-ß to suppress neurite growth. We also present data on gene regulation and protein binding partner recruitment by Set-ß in primary neurons, raising the hypothesis that nuclear Set-ß may preferentially regulate gene expression whereas Set-ß at cytoplasmic membranes may regulate unique cofactors, including PP2A, which we show also regulates axon growth in vitro. Finally, increasing recruitment of Set-ß to cellular membranes promoted adult rat optic nerve axon regeneration after injury in vivo. Thus, Set-ß differentially regulates axon growth and regeneration depending on subcellular localization and phosphorylation.

View details for DOI 10.1523/JNEUROSCI.3658-13.2014

View details for Web of Science ID 000336895200030

View details for PubMedID 24849368

View details for PubMedCentralID PMC4028506