Human-specific induction of glutathione peroxidase-3 by proteasome inhibition in cardiovascular cells.
Glutathione peroxidase-3 (GPx-3) is a key antioxidant enzyme in the plasma. GPx-3 was previously identified as the major antioxidative enzyme that was induced upon nontoxic proteasome inhibition in endothelial cells. Here, we investigated the determinants of the proteasome inhibitor-induced expression of GPx-3. Nontoxic proteasome inhibition massively upregulates GPx-3 RNA and protein in human umbilical cord vein cells within 24 h. Surprisingly, induction of GPx-3 was species-specific for human cells. The exponential upregulation of GPx-3 is mediated by transcriptional activation of the human GPx-3 promoter and, in addition, stabilization of GPx-3 mRNA: in reporter gene assays with full-length and deleted variants of the human GPx-3 promoter we identified a putative antioxidative response element (ARE) as essential and also sufficient for transcriptional activation of GPx-3 by proteasome inhibition. However, the ARE-specific antioxidative transcription factor Nrf2 is not involved in the activation of GPx-3. UV-crosslinking using the 3'UTR of GPx-3 revealed an altered protein binding pattern in the presence of proteasome inhibitors, thus indicating regulation of mRNA stability of human GPx-3. As GPx-3 is secreted into the plasma, our data point toward a borderline defense mechanism of endothelial cell-derived GPx-3 to protect the vasculature from oxidative stress.
Westphal
Kera
K
Medizinische Klinik für Kardiologie und Angiologie, Charite-Universitaetsmedizin Berlin, 10117 Berlin, Germany.
Stangl
Verena
V
Fähling
Michael
M
Dreger
Henryk
H
Weller
Andrea
A
Baumann
Gert
G
Stangl
Karl
K
Meiners
Silke
S
D000818:Animals; D001897:Boronic Acids / Q000494:pharmacology*; D002417:Cattle; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D005979:Glutathione Peroxidase / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D007976:Leupeptins / Q000494:pharmacology*; D009154:Mutation; D018384:Oxidative Stress; D011401:Promoter Regions, Genetic; D061988:Proteasome Inhibitors; D011485:Protein Binding / Q000187:drug effects; D020871:RNA Stability / Q000187:drug effects; D051381:Rats; D020218:Response Elements / Q000235:genetics; D013045:Species Specificity; D015533:Transcriptional Activation / Q000187:drug effects
D001897:Boronic Acids; D007976:Leupeptins; C423917:MG 262; D061988:Proteasome Inhibitors; C486484:GPX3 protein, human; D005979:Glutathione Peroxidase; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde