Detailed Instructions: Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.
Problem:Context: Reactive oxygen species have been implicated as signaling molecules modulating the activity of redox-sensitive transcription factors such as nuclear factor kappa B (NF-kappaB). Recently, the transcription factor hypoxia-inducible factor-1 (HIF-1), known to mediate gene expression by hypoxia, has been found to be also activated by nonhypoxic factors in a redox-sensitive manner. We therefore aimed to elucidate the link between these 2 important redox-sensitive transcription factors.', 'In pulmonary artery smooth muscle cells, reactive oxygen species generated either by exogenous H2O2 or by a NOX4-containing NADPH oxidase stimulated by thrombin activated or induced NF-kappaB and HIF-1alpha. The reactive oxygen species-mediated HIF-1alpha induction occurred on the transcriptional level and was dependent on NF-kappaB. Transfection experiments with wild-type or mutant HIF-1alpha promoter constructs revealed the presence of a yet unidentified NF-kappaB binding element. Gel shift analyses and chromatin immunoprecipitation verified binding of NF-kappaB to this site. Furthermore, reactive oxygen species enhanced expression of plasminogen activator inhibitor-1, which was prevented by dominant-negative IkappaB or mutation of the HIF-1 binding site within the plasminogen activator inhibitor-1 promoter.
Answer: These findings show for the first time to our knowledge that reactive oxygen species directly link HIF-1alpha and NF-kappaB, implicating an important pathophysiological role of this novel pathway in disorders associated with elevated levels of reactive oxygen species.
Solution:
Do reactive oxygen species activate the HIF-1alpha promoter via a functional NFkappaB site?