Abstract

We recently reported that the age-induced apoptotic death of cultured cerebellar neurons is correlated with an increased expression of a particulate-bound 38-kDa protein that we identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). To determine whether this phenomenon of GAPDH overexpression occurs in other cell types, we selected primary cultures of cerebrocortical cells for testing, because under normal culture conditions, cortical neurons die progressively after 15 days in vitro. As with cerebellar neurons, this age-induced neuronal death involves ultrastructural changes and internucleosomal DNA fragmentation characteristic of apoptosis and is effectively prevented by actinomycin-D and cycloheximide. Moreover, a GAPDH antisense oligodeoxyribonucleotide arrested this cortical neuronal death for about 4 to 5 days and thus was more effective than cycloheximide. By contrast, its corresponding sense oligonucleotide had no effect. Additionally, the age-induced apoptosis of cortical neuronal cultures is effectively protected by aurintricarboxylic acid and tetrahy-droaminoacridine (an antidementia drug). Before cell death, GAPDH mRNA levels increased by about 2-fold and the increase was blocked by the above-mentioned neuroprotective agents and the GAPDH antisense, but not sense, oligonucleotide. The effects of antisense oligonucleotide are more robust in the present case than those found with cerebellar neurons, and they indicate a significant, though at present not defined, role of GAPDH in the apoptotic process occurring in these two types of neurons.