Abstract
Programmed cell death, or apoptosis, occurs asynchronously in neuronal cells. To overcome this asynchrony, rat pheochromocytoma (PC12) cells were separated at different stages of apoptosis on the basis of cell density. Live cells that exhibited no apoptotic features floated to the top of density gradients. The most dense cells showed extensive loss of cytochrome c from mitochondria, caspase activation, chromatin condensation, and DNA fragmentation. These cells were committed to apoptosis and could not be rescued by reculturing in with nerve growth factor (NGF). Cells of intermediate density displayed no DNA fragmentation, but had begun to show cytochrome c loss, caspase activation, and chromatin condensation. This population displayed upregulation of the prodeath factor, c-Jun, and downregulation of prosurvival kinase, Akt. Importantly, apoptosis was reversible by NGF in this population. These studies suggest that increased cell density correlates with an initial step in the apoptosis mechanism that precedes irreversible commitment to suicide.
| Original language | English |
|---|---|
| Pages (from-to) | 347-362 |
| Number of pages | 16 |
| Journal | Molecular and Cellular Neuroscience |
| Volume | 18 |
| Issue number | 4 |
| DOIs | |
| State | Published - 2001 |
Funding
We thank Gretchen McCaffrey for helpful suggestions during the course of this work, Carolyn Young for technical assistance with the PFGE, Marshall Walton for technical assistance with the c-Jun immunocytochemical studies, Janice Valetta and W. C. Mobley for NGF, and Michael Comb and Cell Signalling Technologies for antibodies to Akt and cleaved caspase-9. F.F. was supported by a Health Research Council of New Zealand Postgraduate Scholarship, New Zealand Vice-Chancellors’ Committee Georgetti and Shirtcliffe Fellowships. This work was supported by the Whitehall Foundation, Cancer Society of New Zealand, Health Research Council, New Zealand Lottery Health and Lottery Science, the Palmerston North Medical Research Foundation, the National Child Health Research Foundation, and the Real Kids Charitable Trust.
