Nuclear translocation of GAPDH-GFP fusion protein during apoptosis.

Increased expression and nuclear accumulation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) are early, critical events in several forms of apoptosis. In order to investigate the subcellular trafficking of GAPDH in vivo, the localization of a GAPDH-green fluorescent protein (GFP) fusion was studied in PC12, HEK 293 and COS-1 cells. In control cells, fusion protein autofluorescence was largely restricted to the cytoplasm, rather than the nuclear concentration favored by GFP alone. In contrast, as early as 30 min after an insult, nuclear fluorescence increased in all cell lines studied. The fusion protein redistribution paralleled the dynamics of endogenous GAPDH. These data suggest that some nuclear GAPDH observed during apoptosis represents protein previously resident in the cytosol. This construct provides an in vivo monitor for an early change in apoptosis.