Phosphorylation at S345 Converts HIF-2α from a Transcription Factor to an RNA binding protein

Albanese, A.; Daly, L. A.; Prost-Fingerle, K.; Elliott, L. G.; Oswald, S. O.; Ecclestone, G. B.; Bell, G.; Batie, M.; Rigden, D. J.; Eyers, C.; Fandrey, J.; Kenneth, N. S.; See, V. S.; Rocha, S.

doi:10.64898/2026.04.28.721420

bioRxiv · 10.64898/2026.04.28.721420

Phosphorylation at S345 Converts HIF-2α from a Transcription Factor to an RNA binding protein

Albanese, A.·Daly, L. A.·Prost-Fingerle, K.·Elliott, L. G.·Oswald, S. O.·Ecclestone, G. B.·Bell, G.·Batie, M.·Rigden, D. J.·Eyers, C.·Fandrey, J.·Kenneth, N. S.·See, V. S.·Rocha, S.

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Abstract

Oxygen sensing and adaptation are vital for metazoan survival. At the cellular level the response to hypoxia is characterised by a switch in transcriptional programming, primarily mediated by hypoxia-inducible factors (HIFs). HIFs comprise an obligatory heterodimer between an oxygen-sensitive HIF- subunit and an oxygen-insensitive HIF-1{beta} subunit, which together regulate gene expression in response to hypoxia. Among the three HIF- proteins in vertebrates (HIF-1, HIF-2, and HIF-3), post-translational modifications (PTMs) play a crucial role in modulating their stability, localisation, and activity. While many modifications have been investigated on HIF-1, our knowledge of HIF-2 regulation is very limited. Here, we investigated the function of the recently identified HIF-2 S345 phosphorylation site and demonstrate that this disrupts the interaction between HIF-2 and HIF-1{beta}, thereby silencing the HIF-2 transcriptional response. Additionally, our findings suggest that this modification redirects HIF-2 from its normal transcription factor function towards a role in mRNA fate control, as indicated by mass spectrometry interactome analysis and RNA-immunoprecipitation. Our discoveries highlight a new regulatory mechanism of HIF-2 activity, where S345 phosphorylation impedes HIF-2/HIF-1{beta} heterodimer formation, creating a switch in HIF-2 function. As HIF-2 is the only HIF- isoform with a clinically approved inhibitor, these insights are crucial for advancing therapeutic strategies targeting hypoxia signalling.

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Albanese, A., Daly, L. A., Prost-Fingerle, K., Elliott, L. G., Oswald, S. O., Ecclestone, G. B., Bell, G., Batie, M., Rigden, D. J., Eyers, C., Fandrey, J., Kenneth, N. S., See, V. S., Rocha, S.. 2026-04-30. Phosphorylation at S345 Converts HIF-2α from a Transcription Factor to an RNA binding protein. https://doi.org/10.64898/2026.04.28.721420

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