An Isoaurone and Other Constituents fromTrichosanthes kirilowiiSeeds Inhibit Hypoxia-Inducible Factor-1 and Nuclear Factor-κB

Hypoxia-inducible factor-1 (HIF-1) is a regulator of metabolic adaptation to hypoxia. It is now appreciated that HIF-1α accumulation is achieved under normoxic conditions by various factors, such as TNF-α. Here, it was our intention to gain insight into the signaling mechanisms used by TNF-α to stimulate HIF-1α. In tubular LLC-PK1or human embryonic kidney cells, TNF-α induced accumulation of HIF-1α protein but not HIF-1α mRNA. Blocking nuclear factor (NF)-κB with sulfasalazine or expression of an IκB superrepressor attenuated HIF-1α accumulation, whereas transfection of active p50/p65-NF-κB subunits mimicked a TNF-α response. Experiments with actinomycin D and cycloheximide also pointed to a transcriptional and translational process in facilitating the TNF-α response. Interestingly, and in contrast to established hypoxic signaling concepts, TNF-α elicited HIF-1α accumulation in a ubiquitinated form that still bound the von Hippel-Lindau (pVHL) protein. These data indicate that HIF-1α accumulation by TNF-α demands the NF-κB pathway, preserves ubiquitination of HIF-1α, and allows the HIF-1α-pVHL interaction.

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Upregulated Signaling Pathways in Ruptured Human Saccular Intracranial Aneurysm Wall: An Emerging Regulative Role of Toll-Like Receptor Signaling and Nuclear Factor-κB, Hypoxia-Inducible Factor-1A, and ETS Transcription Factors

Neurosurgery ◽

10.1227/neu.0b013e318210f001 ◽

2011 ◽

Vol 68 (6) ◽

pp. 1667-1676 ◽

Cited By ~ 59

Author(s):

Mitja I. Kurki ◽

Sanna-Kaisa Häkkinen ◽

Juhana Frösen ◽

Riikka Tulamo ◽

Mikael von und zu Fraunberg ◽

...

Keyword(s):

Transcription Factor ◽

Intracranial Aneurysm ◽

Signaling Pathways ◽

Binding Sites ◽

Hypoxia Inducible Factor ◽

Transcription Factor Binding Sites ◽

Nuclear Factor Κb ◽

Nuclear Factor ◽

Toll Like Receptor ◽

Factor Binding

Abstract BACKGROUND: Aneurysmal subarachnoid hemorrhage, almost always from saccular intracranial aneurysm (sIA), is a devastating form of stroke that affects the working-age population. Cellular and molecular mechanisms predisposing to the rupture of the sIA wall are largely unknown. This knowledge would facilitate the design of novel diagnostic tools and therapies for the sIA disease. OBJECTIVE: To investigate gene expression patterns distinguishing ruptured and unruptured sIA. METHODS: We compared the whole-genome expression profile of 11 ruptured sIA wall samples with that of 8 unruptured ones using oligonucleotide microarrays. Signaling pathways enriched in the ruptured sIA walls were identified with bioinformatic analyses. Their transcriptional control was predicted in silico by seeking the enrichment of conserved transcription factor binding sites in the promoter regions of differentially expressed genes. RESULTS: Overall, 686 genes were significantly upregulated and 740 were downregulated in the ruptured sIA walls. Significantly upregulated biological processes included response to turbulent blood flow, chemotaxis, leukocyte migration, oxidative stress, vascular remodeling; and extracellular matrix degradation. Toll-like receptor signaling and nuclear factor-κB, hypoxia-inducible factor-1A, and ETS transcription factor binding sites were significantly enriched among the upregulated genes. CONCLUSION: We identified pathways and candidate genes associated with the rupture of human sIA wall. Our results may provide clues to the molecular mechanism in sIA wall rupture and insight for novel therapeutic strategies to prevent rupture.

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