NeuroD6 genomic signature bridging neuronal differentiation to survival via the molecular chaperone network

J Neurosci Res. 2010 Jan;88(1):33-54. doi: 10.1002/jnr.22182.

Abstract

During neurogenesis, expression of the basic helix-loop-helix NeuroD6/Nex1/MATH-2 transcription factor parallels neuronal differentiation and is maintained in differentiated neurons in the adult brain. To dissect NeuroD6 differentiation properties further, we previously generated a NeuroD6-overexpressing stable PC12 cell line, PC12-ND6, which displays a neuronal phenotype characterized by spontaneous neuritogenesis, accelerated NGF-induced differentiation, and increased regenerative capacity. Furthermore, we reported that NeuroD6 promotes long-term neuronal survival upon serum deprivation. In this study, we identified the NeuroD6-mediated transcriptional regulatory pathways linking neuronal differentiation to survival, by conducting a genome-wide microarray analysis using PC12-ND6 cells and serum deprivation as a stress paradigm. Through a series of filtering steps and a gene-ontology analysis, we found that NeuroD6 promotes distinct but overlapping gene networks, consistent with the differentiation, regeneration, and survival properties of PC12-ND6 cells. By using a gene-set-enrichment analysis, we provide the first evidence of a compelling link between NeuroD6 and a set of heat shock proteins in the absence of stress, which may be instrumental in conferring stress tolerance on PC12-ND6 cells. Immunocytochemistry results showed that HSP27 and HSP70 interact with cytoskeletal elements, consistent with their roles in neuritogenesis and preserving cellular integrity. HSP70 also colocalizes with mitochondria located in the soma, growing neurites, and growth cones of PC12-ND6 cells prior to and upon stress stimulus, consistent with its neuroprotective functions. Collectively, our findings support the notion that NeuroD6 links neuronal differentiation to survival via the network of molecular chaperones and endows the cells with increased stress tolerance.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Analysis of Variance
  • Animals
  • Basic Helix-Loop-Helix Transcription Factors / genetics*
  • Basic Helix-Loop-Helix Transcription Factors / metabolism
  • Blotting, Western
  • Cell Line
  • Cell Survival / genetics*
  • Cells, Cultured
  • Fluorescent Antibody Technique
  • Microscopy, Confocal
  • Molecular Chaperones / genetics*
  • Molecular Chaperones / metabolism
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism
  • Neurogenesis / genetics*
  • Neurons / metabolism
  • Oligonucleotide Array Sequence Analysis
  • PC12 Cells
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rats
  • Transcriptional Activation

Substances

  • Basic Helix-Loop-Helix Transcription Factors
  • Molecular Chaperones
  • Nerve Tissue Proteins
  • Neurod6 protein, rat
  • RNA, Messenger