This article requires a subscription to view the full text. If you have a subscription you may use the login form below to view the article. Access to this article can also be purchased.
Graphical Abstract
Highlights
Identification of endogenous SUMO1,SUMO2/3 conjugates and their response to hypoxia.
TFAP2A is a target of sumoylation and its modification is inhibited under hypoxia.
TFAP2A enhances the transcriptional activity of HIF-1 in a sumo-dependent manner.
TFAP2A interacts physically with HIF-1 and HIF-2 in a sumo-independent manner.
Abstract
Hypoxia occurs in pathological conditions, such as cancer, as a result of the imbalance between oxygen supply and consumption by proliferating cells. HIFs are critical molecular mediators of the physiological response to hypoxia but also regulate multiple steps of carcinogenesis including tumor progression and metastasis. Recent data support that sumoylation, the covalent attachment of the Small Ubiquitin-related MOdifier (SUMO) to proteins, is involved in the activation of the hypoxic response and the ensuing signaling cascade. To gain insights into differences of the SUMO1 and SUMO2/3 proteome of HeLa cells under normoxia and cells grown for 48 h under hypoxic conditions, we employed endogenous SUMO-immunoprecipitation in combination with quantitative mass spectrometry (SILAC). The group of proteins whose abundance was increased both in the total proteome and in the SUMO IPs from hypoxic conditions was enriched in enzymes linked to the hypoxic response. In contrast, proteins whose SUMOylation status changed without concomitant change in abundance were predominantly transcriptions factors or transcription regulators. Particularly interesting was transcription factor TFAP2A (Activating enhancer binding Protein 2 alpha), whose sumoylation decreased on hypoxia. TFAP2A is known to interact with HIF-1 and we provide evidence that deSUMOylation of TFAP2A enhances the transcriptional activity of HIF-1 under hypoxic conditions. Overall, these results support the notion that SUMO-regulated signaling pathways contribute at many distinct levels to the cellular response to low oxygen.
- Hypoxia
- SILAC
- Post-translational modifications*
- Cell biology*
- Mass Spectrometry
- Molecular biology*
- Transcriptional Regulation*
- HIF
- HIF-1α
- SUMO
- TFAP2A
Footnotes
Author contributions: G.C., F.M., and G.S. designed research; G.C., A.K., A.B., and U.P. performed research; G.C., N.S.-V., U.P., and H.U. analyzed data; G.C. wrote the paper; H.U., F.M., and G.S. contributed new reagents/analytic tools; N.S.-V. helped writing the paper; F.M. and G.S. supervised experiments and helped writing the paper.
↵* This project was partially funded by A.V. Humboldt foundation (fellowship to G.C.). G.C. acknowledges funding by the Research Committee of The University of Thessaly (5600.03.04.13.01). F.M. acknowledges funding by the German Research Society (SFB 1036-TP15/SFB-TRR186 A18).
↵
This article contains supplemental Figures and Table. We declare that they have no competing or financial interest.
- Received February 18, 2019.
- Revision received March 14, 2019.
- © 2019 Chachami et al.
Published under exclusive license by The American Society for Biochemistry and Molecular Biology, Inc.