Nuclear translocation of glyceraldehyde-3-phosphate dehydrogenase: a role in high glucose-induced apoptosis in retinal Müller cells.

PURPOSE: A recent study demonstrated that retinal Müller cells undergo hyperglycemia-induced apoptosis in vitro. Translocation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from the cytosol to the nucleus is a critical step in the induction of apoptosis in neuronal cells. R-(-)-deprenyl prevents nuclear translocation of GAPDH and subsequent apoptosis in neuronal cells. In this study, the role of nuclear translocation of GAPDH in hyperglycemia-induced apoptosis in retinal Müller cells and the ability of R-(-)-deprenyl to inhibit the translocation of GAPDH and apoptosis were investigated.
METHODS: Transformed rat Müller cells (rMC-1) and isolated human Müller cells were cultured in normal glucose, high glucose, and high glucose plus R-(-)-deprenyl for up to 5 days. Subcellular distribution of GAPDH was determined in vitro and in vivo by immunocytochemistry. Apoptosis in tissue cultures was determined by annexin-V staining and caspase-3 activity.
RESULTS: Hyperglycemia significantly increased the amount of GAPDH protein in the nucleus above normal within the first 48 hours in rMC-1 and human Müller cells. The addition of R-(-)-deprenyl to these cells incubated in high glucose reduced the amount of GAPDH protein in the nucleus and decreased hyperglycemia-induced apoptosis in both cell types. In vivo studies confirmed the accumulation of GAPDH in nuclei of Müller cells in diabetes.
CONCLUSIONS: The nuclear translocation of GAPDH in rMC-1 and human Müller cells is closely associated with the induction of apoptosis. R-(-)-deprenyl inhibits nuclear accumulation of GAPDH and subsequent apoptosis in these cells. Therefore, R-(-)-deprenyl offers a strategy to explore the role of GAPDH translocation into the nucleus in the development of diabetic retinopathy.