Translational repression during chronic hypoxia is dependent on glucose levels.
Translation is often repressed in cell lines that are exposed to hypoxic conditions (0.5% - 1.5% O2) but this repression requires prolonged exposure (> 16 h). We report here that prolonged exposure to hypoxia results in the depletion of glucose from the media and that the loss of glucose correlates with the shut down in translation. Furthermore, we show that the addition of glucose or reoxygenation restores translation in hypoxic PC3 cells. This indicates that both glucose depletion and hypoxia are required for translational repression. We also show that eIF2alpha phosphorylation is reversed by glucose addition. Moreover, we present data that strongly indicate that eIF2alpha phosphorylation as well as the translational inhibition that occurs when cells are grown under conditions of glucose depletion and hypoxia is pancreatic eIF2alpha kinase (PERK) independent. We believe this is the first report to show that glucose depletion is required for translational repression under hypoxic conditions and that this explains why prolonged exposure to hypoxia is required for this inhibition. Since the physiological conditions that lead to tumor hypoxia would also likely lead to reduced glucose levels, understanding the interplay of glucose and hypoxia in regulating tumor metabolism will provide important information on the growth and development of solid tumors.
Thomas
Jeff D
JD
Department of Pathology and Laboratory Medicine, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, USA.
Dias
Lizalynn M
LM
Johannes
Gregg J
GJ
D015687:Cell Hypoxia / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*; D045744:Cell Line, Tumor; D017077:Culture Media, Conditioned; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D005973:Glutamine / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008297:Male; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes; D010766:Phosphorylation; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects; D011506:Proteins; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012334:RNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D058570:TOR Serine-Threonine Kinases; D014157:Transcription Factors / Q000378:metabolism; D019892:eIF-2 Kinase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
D017077:Culture Media, Conditioned; D015852:Eukaryotic Initiation Factor-2; D005947:Glucose; D005973:Glutamine; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes; D011506:Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D034741:RNA, Small Interfering; D058570:TOR Serine-Threonine Kinases; D014157:Transcription Factors; D019892:eIF-2 Kinase