Role of zinc in p53‐mediated proliferation and apoptosis of human neuronal precursor cells

Abstract

Recent reports have established stem cell proliferation and neurogenesis in the adult human brain, primarily localized in the subventricular zone and the subgranular zone of the dentate gyrus. While the trace element zinc is clearly important for normal central nervous system function, no work has explored the role that this essential nutrient plays in adult stem cell proliferation and differentiation. To test this, we employed a model of chelator-induced zinc deficiency in the human stem-cell like neuronal precursor line, Ntera-2 (NT-2). Addition of the zinc chelator TPEN to growth media at concentrations above 7 μM resulted in a significant reduction in cell number compared to untreated control cells. BrdU uptake and labeling, used a marker of cell proliferation, was reduced from approximately 50% in untreated cells over the course of 18 h, to 3% in cells treated with 8 μM TPEN (p<0.001). Additionally, there was both morphological and molecular evidence of apoptosis in TPEN-treated NT-2 cells. Nuclear staining with DAPI showed that zinc deficient cells exhibited classical signs of apoptosis including nuclear shrinkage, chromatin aggregation, and nuclear blebbing. Immunocytochemistry revealed TPEN-induced increases in abundance and nuclear translocation of the tumor suppressor protein p53. Because p53 has been shown to regulate the cell cycle and apoptotic pathways, it is likely that this transcription factor plays a role in the mechanisms regulating zinc deficient NT-2 cells. On-going work is using oligonucleotide array to identify p53-target genes responsible for the regulation of proliferation, survival, and death of neuronal precursors when zinc availability is limited. Supported by FSU Council on Research and Creativity.