title: Non-neuronal enolase is an endothelial hypoxic stress protein.
abstract: The hypoxia-associated proteins (HAPs) are five cell-associated stress proteins (M(r) 34, 36, 39, 47, and 57) up-regulated in cultured vascular endothelial cells (EC) exposed to hypoxia. While hypoxic exposure of other cell types induces heat shock and glucose-regulated proteins, EC preferentially up-regulate HAPs. In order to identify the 47-kDa HAP, protein from hypoxic bovine EC lysates was isolated, digested with trypsin, and sequenced. Significant identity was found with enolase, a glycolytic enzyme. Western analyses confirmed that non-neuronal enolase (NNE) is up-regulated in hypoxic EC. Western analysis of subcellular fractions localized NNE primarily to the cytoplasm and confirmed that it was up-regulated 2.3-fold by hypoxia. Interestingly, NNE also appeared in the nuclear fraction of EC but was unchanged by hypoxia. Northern analyses revealed that NNE mRNA hypoxic up-regulation began at 1-2 h, peaked at 18 h, persisted for 48 h, and returned to base line after return to 21% O2 for 24 h. Hypoxia maximally up-regulated NNE mRNA levels 3.4-fold. While hypoxic up-regulation of NNE may have a protective effect by augmenting anaerobic metabolism, we speculate that enolase may contribute to EC hypoxia tolerance through one or more of its nonglycolytic functions.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001011:Aorta; D015153:Blotting, Western; D002417:Cattle; D015687:Cell Hypoxia; D002467:Cell Nucleus / Q000201:enzymology; D002478:Cells, Cultured; D003600:Cytosol / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic; D006360:Heat-Shock Proteins / Q000096:biosynthesis* / Q000737:chemistry; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D010751:Phosphopyruvate Hydratase / Q000096:biosynthesis* / Q000737:chemistry; D011651:Pulmonary Artery; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D017386:Sequence Homology, Amino Acid; D013997:Time Factors
chemical_list: D006360:Heat-Shock Proteins; D012333:RNA, Messenger; D010751:Phosphopyruvate Hydratase