Exportin 1-independent nuclear export of GAPDH.
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a key enzyme of the glycolytic pathway. Recent studies have demonstrated an additional role in apoptosis: GAPDH is targeted to the nucleus during apoptotic signalling. This nuclear transport has also been observed in serum-depleted cells, but it is reversible in fibroblasts, in contrast to apoptotic-induced transport (Eur J Cell Biol 80 (2001) 419). Here, we analyse the serum depletion-induced transport processes of GAPDH in NIH 3T3 cells. Prolonged serum depletion did not cause cell death, nuclear fragmentation (hoechst staining) or a significant increase in DNA strand-breaks (comet assay). Using cells expressing green fluorescent protein (GFP)-tagged GAPDH allowed us to monitor its intracellular localisation by confocal laser scanning microscopy (CLSM). Treatment of cells with the exportin1 inhibitor leptomycin B (LMB) did not influence cytoplasmic localisation of GFP-GAPDH, indicating that nuclear targeting of GAPDH is not constitutive and may be altered via a serum-dependent regulatory export process. Suprisingly, the export of nuclear GFP-GAPDH after re-addition of serum to starved cells was not prevented by LMB. Thus, nuclear export of GAPDH upon serum depletion is not mediated by exportin1.
Schmitz
Hans-Dirk
HD
Kinematic Cell Research Group, Biocentre, Goethe University of Frankfurt/Main, Marie-Curie-Str. 9, D-60439 Frankfurt, Germany.
Dutiné
Christine
C
Bereiter-Hahn
Jürgen
J
D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism*; D028884:Karyopherins / Q000502:physiology*; D051379:Mice; D041681:NIH 3T3 Cells; D018160:Receptors, Cytoplasmic and Nuclear; D000097606:Exportin 1 Protein
D016895:Culture Media, Serum-Free; D005231:Fatty Acids, Unsaturated; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D028884:Karyopherins; D018160:Receptors, Cytoplasmic and Nuclear; D000097606:Exportin 1 Protein; C038753:leptomycin B