Oxygen-dependent changes in binding partners and post-translational modifications regulate the abundance and activity of HIF-1 alpha/2 alpha

Daly, Leonard A ORCID: 0000-0001-9712-9676, Brownridge, Philip J, Batie, Michael ORCID: 0000-0002-7508-6641, Rocha, Sonia, See, Violaine ORCID: 0000-0001-6384-8381 and Eyers, Claire E ORCID: 0000-0002-3223-5926 (2021) Oxygen-dependent changes in binding partners and post-translational modifications regulate the abundance and activity of HIF-1 alpha/2 alpha. SCIENCE SIGNALING, 14 (692). eabf6685-.

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Abstract

Cellular adaptation to low-oxygen environments is mediated in part by the hypoxia-inducible factors (HIFs). Like other transcription factors, the stability and transcriptional activity of HIFs-and consequently, the hypoxic response-are regulated by post-translational modifications (PTMs) and changes in protein-protein interactions. Our current understanding of PTM-mediated regulation of HIFs is primarily based on in vitro protein fragment-based studies typically validated in fragment-expressing cells treated with hypoxia-mimicking compounds. Here, we used immunoprecipitation-based mass spectrometry to characterize the PTMs and binding partners for full-length HIF-1α and HIF-2α under normoxic (21% oxygen) and hypoxic (1% oxygen) conditions. Hypoxia substantially altered the complexity and composition of the HIFα protein interaction networks, particularly for HIF-2α, with the hypoxic networks of both isoforms being enriched for mitochondrial proteins. Moreover, both HIFα isoforms were heavily covalently modified. We identified ~40 PTM sites composed of 13 different types of modification on both HIFα isoforms, including multiple cysteine modifications and an unusual phosphocysteine. More than 80% of the PTMs identified were not previously known and about half exhibited oxygen dependency. We further characterized an evolutionarily conserved phosphorylation of Ser³¹ in HIF-1α as a regulator of its transcriptional function, and we propose functional roles for Thr⁴⁰⁶, Thr⁵²⁸, and Ser⁵⁸¹ in HIF-2α. These data will help to delineate the different physiological roles of these closely related isoforms in fine-tuning the hypoxic response.

Item Type:	Article
Uncontrolled Keywords:	Humans, Oxygen, Protein Isoforms, Protein Processing, Post-Translational, Basic Helix-Loop-Helix Transcription Factors, Hypoxia-Inducible Factor 1, alpha Subunit, Hypoxia
Divisions:	Faculty of Health and Life Sciences Faculty of Health and Life Sciences > Institute of Systems, Molecular and Integrative Biology
Depositing User:	Symplectic Admin
Date Deposited:	16 Aug 2021 07:50
Last Modified:	18 Jan 2023 21:33
DOI:	10.1126/scisignal.abf6685
Open Access URL:	https://doi.org/10.1101/2020.11.12.379768
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3133614