Hsp70-GlcNAc-binding activity is released by stress, proteasome inhibition, and protein misfolding.
Numerous recent works strengthen the idea that the nuclear and cytosolic-specific O-GlcNAc glycosylation protects cells against injuries. We have first investigated O-GlcNAc level and Hsp70-GlcNAc-binding activity (HGBA) behaviour after exposure of HeLa and HepG(2) cells to a wide variety of stresses. O-GlcNAc and HGBA responses were different according to the stress and according to the cell. HGBA was released for almost all stresses, while O-GlcNAc level was modified either upwards or downwards, depending to the stress. Against all expectations, we demonstrated that energy charge did not significantly vary with stress whereas UDP-GlcNAc pools were more dramatically affected even if differences in UDP-GlcNAc contents were not correlated with O-GlcNAc variations suggesting that O-GlcNAc transferase is itself finely regulated during cell injury. Finally, HGBA could be triggered by proteasome inhibition and by L-azetidine-2-carboxylic acid (a proline analogue) incorporation demonstrating that protein misfolding is one of the key-activator of this Hsp70 property.
Guinez
Céline
C
UMR-CNRS 8576, UGSF, IFR 147, 59655 Villeneuve d'Ascq, France.
Mir
Anne-Marie
AM
Leroy
Yves
Y
Cacan
René
R
Michalski
Jean-Claude
JC
Lefebvre
Tony
T
D000117:Acetylglucosamine / Q000378:metabolism*; D001383:Azetidinecarboxylic Acid / Q000737:chemistry / Q000494:pharmacology; D002852:Chromatography, Ion Exchange; D000431:Ethanol / Q000494:pharmacology; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D037102:Lectins / Q000378:metabolism; D007976:Leupeptins / Q000494:pharmacology; D011392:Proline / Q000737:chemistry; D061988:Proteasome Inhibitors; D011485:Protein Binding / Q000187:drug effects; D017510:Protein Folding; D012965:Sodium Chloride / Q000494:pharmacology*; D013816:Thermodynamics; D014537:Uridine Diphosphate N-Acetylglucosamine / Q000302:isolation & purification / Q000378:metabolism
D018840:HSP70 Heat-Shock Proteins; D037102:Lectins; D007976:Leupeptins; D061988:Proteasome Inhibitors; D000431:Ethanol; D012965:Sodium Chloride; D014537:Uridine Diphosphate N-Acetylglucosamine; D001383:Azetidinecarboxylic Acid; D011392:Proline; D006861:Hydrogen Peroxide; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde; D000117:Acetylglucosamine