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Updated: May 4, 2026
Co-immunoprecipitation Assay Using Endogenous Nuclear Proteins from Cells Cultured Under Hypoxic Conditions
Published on: August 2, 2018
EAF2 suppresses hypoxia-induced factor 1α transcriptional activity by disrupting its interaction with coactivator
Zhu Chen1, Xing Liu, Zhichao Mei
1Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, People's Republic of China.
Abstract:
Previous studies revealed that the potential tumor suppressor EAF2 binds to and stabilizes pVHL, suggesting that EAF2 may function by disturbing the hypoxia signaling pathway. However, the extent to which EAF2 affects hypoxia and the mechanisms underlying this activity remain largely unknown. In this study, we found that EAF2 is a hypoxia response gene harboring the hypoxia response element (HRE) in its promoter. By taking advantage of the pVHL-null cell lines RCC4 and 786-O, we demonstrated that hypoxia-induced factor 1α (HIF-1α), but not HIF-2α, induced EAF2 under hypoxia. Subsequent experiments showed that EAF2 bound to and suppressed HIF-1α but not HIF-2α transactivity. In addition, we observed that EAF2 inhibition of HIF-1α activity resulted from the disruption of p300 recruitment and that this occurred independently of FIH-1 (factor inhibiting HIF-1) and Sirt1. Furthermore, we found that EAF2 protected cells against hypoxia-induced cell death and inhibited cellular uptake of glucose under hypoxic conditions, suggesting that EAF2 indeed may act by modulating the hypoxia-signaling pathway. Our findings not only uncover a unique feedback regulation loop between EAF2 and HIF-1α but also provide a novel insight into the mechanism of EAF2 tumor suppression.
Insights
The tumor suppressor EAF2 is induced by hypoxia and suppresses hypoxia-induced factor 1-alpha (HIF-1α) activity. EAF2 protects cells from hypoxia-induced death and regulates glucose uptake, revealing a feedback loop.
Area of Science:
- Molecular Biology
- Cancer Research
- Cellular Signaling
Background:
- EAF2 (Ellison-11) is a potential tumor suppressor that interacts with pVHL.
- EAF2's role in the hypoxia signaling pathway is not well understood.
- Hypoxia signaling is crucial in cancer development and progression.
Purpose of the Study:
- To investigate the role of EAF2 in the hypoxia signaling pathway.
- To elucidate the mechanism by which EAF2 affects hypoxia-induced factor 1-alpha (HIF-1α).
- To determine the functional consequences of EAF2 modulation under hypoxic conditions.
Main Methods:
- Analysis of EAF2 promoter for hypoxia response elements (HREs).
- Experiments using pVHL-null cell lines (RCC4, 786-O) to study HIF-1α and HIF-2α effects on EAF2.
- Assessment of EAF2 binding to and suppression of HIF-1α and HIF-2α transactivity.
- Investigation of EAF2's effect on p300 recruitment, FIH-1, and Sirt1.
- Evaluation of EAF2's impact on cell death and glucose uptake under hypoxia.
Main Results:
- EAF2 is a hypoxia-responsive gene regulated by HIF-1α, not HIF-2α.
- EAF2 directly binds and suppresses HIF-1α transactivity independently of FIH-1 and Sirt1.
- EAF2 inhibits HIF-1α activity by disrupting p300 recruitment.
- EAF2 confers protection against hypoxia-induced cell death.
- EAF2 inhibits glucose uptake under hypoxic conditions.
Conclusions:
- EAF2 acts as a negative regulator of the hypoxia signaling pathway by targeting HIF-1α.
- A novel feedback loop exists between EAF2 and HIF-1α.
- EAF2's tumor-suppressive function may be mediated through its modulation of hypoxia signaling and cellular metabolism.
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