NEURONAL DIFFERENTIATION OF PC12 CELLS AS A RESULT OF PREVENTION OF CELL-DEATH BY BCL-2

Rat pheochromocytoma PC12 cells die when cultured in serum-free medium . Neurotrophic factors can rescue PC12 cells from cell death, and indu ce neuronal differentiation. To further investigate the relationship a mong cell death, survival, and differentiation, the bcl-2 cDNA, which is known to prevent apoptosis in various types of cells, was transfect ed into PC12 cells. Six monoclonal bcl-2-transfected cell lines were i solated and confirmed to express mRNA and protein product of bcl-2. Th e wildtype and bcl-2-transfected PC12 cells were kept to adhere to col lagen-coated dishes at the inintiation of serum-free experiments to av oid cellular damage due to detachment of the cells by trituration. Eve n under the conditions, the control PC12 cells mostly died within 24 h , when cultured in serum-free medium, whereas those expressing Bcl-2 s urvived even for 7 days in serum-free medium. Moreover, outgrowth of l ong processes in the bcl-2-transfected cells was only observed under t he condition to keep the cells attached to the dishes in serum-free me dium without any additive neurotrophic or growth factors. Neurofilamen t medium protein, which is a neuron-specific cytoskeletal component, w as also expressed in the differentiated cells, suggesting that the lon g processes in bcl-2-transfected PC12 cells are neurites. However, neu ronal differentiation of PC12 cells expressing Bcl-2 was not observed when cultured in serum-containing medium. Accordingly, survival of PC1 2 cells expressing Bcl-2 under the condition which cells usually die m ay be accompanied with neuronal differentiation. (C) 1994 John Wiley a nd Sons, Inc.