Hypoxia-inducible factor-1a mRNA contains an internal ribosome entry site that allows efficient translation during normoxia and hypoxia
Date
2002
Authors
Lang, K.
Kappel, A.
Goodall, G.
Editors
Wickens, M.P.
Advisors
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Type:
Journal article
Citation
Molecular Biology of the Cell, 2002; 13(5):1792-1801
Statement of Responsibility
Kenneth J. D. Lang, Andreas Kappel, and Gregory J. Goodall
Conference Name
Abstract
HIF-1α is the regulated subunit of the HIF-1 transcription factor, which induces transcription of a number of genes involved in the cellular response to hypoxia. The HIF-1α protein is rapidly degraded in cells supplied with adequate oxygen but is stabilized in hypoxic cells. Using polysome profile analysis, we found that translation of HIF-1α mRNA in NIH3T3 cells is spared the general reduction in translation rate that occurs during hypoxia. To assess whether the 5'UTR of the HIF-1α mRNA contains an internal ribosome entry site (IRES), we constructed a dicistronic reporter with the HIF-1α 5'UTR inserted between two reporter coding regions. We found that the HIF-1α 5'UTR promoted translation of the downstream reporter, indicating the presence of an IRES. The IRES had activity comparable to that of the well-characterized c-myc IRES. IRES activity was not affected by hypoxic conditions that caused a reduction in cap-dependent translation, and IRES activity was less affected by serum-starvation than was cap-dependent translation. These data indicate that the presence of an IRES in the HIF-1α 5'UTR allows translation to be maintained under conditions that are inhibitory to cap-dependent translation.
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Copyright © 2002 by The American Society for Cell Biology