Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA342

Poster Communications

Histone deacetylases are differentially oxidized by NADPH oxidases

T. Schader1, O. Löwe1, J. Backs2, K. Schröder1

1. Institut für Kardiovaskuläre Physiologie, Frankfurt/Main, Germany. 2. Molecular Cardiology and Epigenetics, Heidelberg, Germany.

NADPH oxidases produce reactive oxygen species differing in localization, type and concentration. Only Nox4 directly produces H2O2 while the others such as Nox5 produce superoxide anions. In contrast to superoxide, H2O2 can directly oxidize cysteine residues, a post-translational modification that influences activity, stability, localization and protein-protein interactions of the affected protein. Importantly, knock down of Nox4, but not of other Noxes, reduces angiogenesis after hindlimb ischemia in mice1. Moreover, class IIa histone deacetylases (HDACs) also regulate angiogenesis through deacetylation and repression of target proteins2,3. We hypothesize that Nox4 derived H2O2 specifically oxidizes HDACs which disrupts repressor complexes. Thereby, Nox4 positively influences endothelial function and angiogenesis. Here we aim to analyze if HDACs can be differentially oxidized by Nox4. As an artificial system inducible Nox4 and Nox5 overexpressing HEK cells were generated. Nox4 expression and activity is achieved in a tetracycline dependent manner, while Nox5 is stably overexpressed and acutely activated by PMA. As target proteins we analyzed class IIa HDACs 4 and 5. BIAM switch assays revealed enhanced oxidation of HDAC4 and 5 upon Nox4 upregulation in a DPI sensitive manner. In contrast, Nox5 derived superoxide did not affect HDAC oxidation. Moreover, tube formation assays with HUVECs were performed to assess the angiogenic function of HDAC4. Overexpression of HDAC4 reduced the tube formation ability which was restored using a redox dead HDAC4 mutant. We conclude that Nox4 oxidizes class IIa HDACs which potentially leads to activation of repressed pro-angiogenic factors.

Where applicable, experiments conform with Society ethical requirements