On 9 May 2022, a new research article titled ‘Identification of oleoylethanolamide as an endogenous ligand for HIF-induced transcription factor research’ was published online in Nature Communications. Wulab, in collaboration with Cheng Luo’s team from Shanghai Institute of Materia Medica Chinese Academy of Sciences and Fraydoon Rastinejad’s team from the University of Oxford published it. Xiaotong Diao, a PhD student of Wulab, and Prof. Fei Ye of Zhejiang Sci-Tech University were the co-first authors of the paper, while Profs. Dalei Wu, Cheng Luo and Fraydoon Rastinejad were the co-corresponding authors. And Shandong University was the first and corresponding author’s affiliation of the paper.

Hypoxia-inducible factors (HIFs) are an important class of transcription factors that enable cells to adapt to changes in oxygen concentration and regulate physiological functions. Three scientists, Kaelin, Ratcliffe and Semenza, were awarded the Nobel Prize in Physiology and Medicine in 2019 for their discovery of HIFs and their mechanism of action. Under normoxic conditions, prolyl hydroxylase hydroxylates proline at HIF-α-specific sites using oxygen as a substrate, allowing it to be degraded via the ubiquitin pathway, whereas under hypoxic conditions, HIF-α maintains its stability due to the blockage of hydroxylation, thereby activating the HIF pathway. In addition to oxygen-dependent regulation of protein stability, HIF-α can be directly bound by synthetic small-molecule ligands and regulate its transcriptional activity. Such as the renal clear cell carcinoma drug Belzutifan, which was available in 2021, a variant inhibitor of HIF-2α. However, endogenous small molecules that directly target the HIF-α protein and regulate its activity have not been previously identified, and the search for endogenous ligands has been one of the hot issues in the field of HIF research.

This study for the first time identified oleoylethanolamide (OEA), an endogenous lipid ligand that directly binds to the HIF-3α protein. The specific molecular mechanism of how OEA enters HIF-3α, promotes the stability of the HIF-3α-ARNT heterodimer, and enhances the transcriptional activity of HIF-3α on downstream genes was revealed by resolving the crystal structure of the HIF-3α-ARNT-OEA complex, combined with molecular dynamics simulations, hydrogen-deuterium exchange mass spectrometry analysis, and cell - level functional experiments, etc. It was demonstrated that, in addition to the oxygen-dependent post-translational modification mechanism of proteins, there are endogenous ligands (especially metabolites) involved in regulating the activity of the HIF pathway. The existence of natural or endogenous ligands not only enriches the physiological functions and activity regulation methods of HIF-α, but also increases the success probability of developing HIF-α-targeted drugs, just as many nuclear receptor-targeted drugs are developed from their endogenous ligands. It was worth mentioning that HIF-3α can bind to small molecules of microbial origin. This study implied that HIF-3α is expected to be one of the key receptors through which gut microbiota regulate the host transcription factor signaling pathway via metabolites.

This research work was supported by grants from National Natural Science Foundation of China, Shandong Provincial Natural Science Foundation, Taishan Scholars Program of Shandong Province, and Interdisciplinary Innovative Research Group Program of Shandong University. It was provided important support for this work by Core Facilities for Life and Environmental Sciences of Shandong University, National Facility for Protein Science in Shanghai and Shanghai Synchrotron Radiation Facility.

Full text link: https://doi.org/10.1038/s41467-022-30338-z

Figure source & Editor: Xiaotong Diao