70-kDa-heat shock protein presents an adjustable lectinic activity towards O-linked N-acetylglucosamine.
Numerous works demonstrated that the dynamic O-GlcNAc glycosylation could protect against the proteasomal degradation by modifying the target proteins and the proteasome itself. Considering that Hsp70 is a crucial component in the quality control of protein conformation in the proteasomal pathway, we investigated the possibility that Hsp70 physically interacts with O-GlcNAc proteins through a lectinic activity. First, we demonstrate that in HepG2 cells, Hsp70 can specifically bind to O-GlcNAc residues but also is itself modified by O-GlcNAc. Second, when cells were deprived of glucose (nutrient stress), Hsp70 lectinic activity markedly increased whereas its glycosylation dramatically decreased. On the other hand, a 42 degrees C thermic stress did not affect any of these features. Lastly, the nature of O-GlcNAc modified proteins co-immunoprecipitating with Hsp70 was similar for cells submitted to the thermic and to nutrient stress. These results strongly suggest that O-GlcNAc influences protein stability through specific interaction with 70-kDa-heat shock protein members.
Guinez
Céline
C
UMR 8576 du CNRS, IFR 118, Unité de Glycobiologie Structurale et Fonctionnelle, Bâtiment C9, Cité Scientifique, 59655 Villeneuve d'Ascq cedex, France.
Lemoine
Jérôme
J
Michalski
Jean-Claude
JC
Lefebvre
Tony
T
D000117:Acetylglucosamine / Q000737:chemistry*; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D004591:Electrophoresis, Polyacrylamide Gel; D005947:Glucose / Q000737:chemistry; D006031:Glycosylation; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D037102:Lectins / Q000737:chemistry*; D008956:Models, Chemical; D011233:Precipitin Tests; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013312:Stress, Physiological
D018840:HSP70 Heat-Shock Proteins; D037102:Lectins; D005947:Glucose; D000117:Acetylglucosamine