Identification of protein disulfide isomerase as an endothelial hypoxic stress protein.
Endothelial cells (EC) exposed to hypoxia upregulate a unique set of five stress proteins. These proteins are upregulated in human and bovine aortic and pulmonary artery EC and are distinct from heat shock or glucose-regulated proteins. We previously identified two of these proteins as the glycolytic enzymes glyceraldehyde-3-phosphate dehydrogenase and enolase and postulated that the remaining proteins were also glycolytic enzymes. Using SDS-PAGE, tryptic digestion, and NH(2)-terminal amino acid sequencing, we report here the identification of the 56-kDa protein as protein disulfide isomerase (PDI). PDI is upregulated by hypoxia at the mRNA level and follows a time course similar to that of the protein, with maximal upregulation detected after exposure to 18 h of 0% O(2). Neither smooth muscle cells nor fibroblasts upregulate PDI to the same extent as EC, which correlates with their decreased hypoxia tolerance. Upregulation of PDI specifically in EC may contribute to their ability to tolerate hypoxia and may occur through PDI's functions as a prolyl hydroxylase subunit, protein folding catalyst, or molecular chaperone.
Graven
Krista K
KK
Department of Medicine, University of Wisconsin Medical School, Madison, Wisconsin 53706, USA. kkg@mdicine.wisc.edu
Molvar
Christopher
C
Roncarati
Jill S
JS
Klahn
Brian D
BD
Lowrey
Shawna
S
Farber
Harrison W
HW
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic; D005947:Glucose / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism; D000860:Hypoxia / Q000378:metabolism*; D051793:Hypoxia-Inducible Factor 1; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D009687:Nuclear Proteins / Q000378:metabolism; D019704:Protein Disulfide-Isomerases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D011651:Pulmonary Artery / Q000166:cytology / Q000201:enzymology*; D012333:RNA, Messenger / Q000032:analysis; D014157:Transcription Factors
D004268:DNA-Binding Proteins; D006360:Heat-Shock Proteins; D051793:Hypoxia-Inducible Factor 1; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D019704:Protein Disulfide-Isomerases; D005947:Glucose