CHARACTERIZATION OF APOPTOSIS IN A MOTOR-NEURON CELL-LINE

Study Design. Serum withdrawal was introduced to a spinal cord motor n euron cell line to investigate the mode of cell death. Objectives. To characterize the death of motor neurons in culture, to gain insight in to mechanisms that could be important in spinal cord diseases. Summary of Background Data, Normal reduction of cell number during central ne rvous system development is brought about by programmed cell death. Th ese same apoptotic processes probably play a role in a variety of cent ral nervous system disorders, including traumatic injury. Although cer tain proteolytic processes are involved, the molecular details involve d in the apoptotic induction have not been fully elucidated, Methods. To identify apoptosis, several criteria were used, including analysis of chromatin condensation with DNA-specific stains (propidium iodide a nd Hoechst 33342); in situ end-labeling of DNA fragments in apoptotic nuclei with terminal deoxynucleotidyl transferase; fragmentation of DN A separated on agarose gel electrophoresis; and cleavage of a characte ristic substrate for apoptotic proteases, alpha-fodrin, into signature cleavage fragments. Results. The NSC19 cell line exhibited motor neur on characteristics morphologically, with typical cellular structure, a nd biochemically, by synthesizing choline acetyl transferase, Under va rious treatments including serum withdrawal (loss of trophic factors), cell loss occurred through an apoptotic cell death pathway. Conclusio ns. A murine motor neuron cell line, NSC19, has been used to investiga te apoptosis in this in vitro system. Cell death occurs by apoptosis, suggesting that this cell line may provide a useful model for studying apoptotic mechanisms in spinal cord degeneration and injury.