Prolyl-4-hydroxylase domain 3 (PHD3) is a critical terminator for cell survival of macrophages under stress conditions. Mus musculus

On molecular level cells sense changes in oxygen availability through the prolyl-4-hydroxylase domain enzymes (PHDs), which regulate the protein stability of the α-subunit of the transcription factor hypoxia inducible factor (HIF). Especially PHD3 has been additionally associated with apoptotic cell death. We hypothesized that PHD3 plays a role in cell-fate decisions in macrophages. Therefore myeloid-specific PHD3 knock out mice (PHD3-/-) were created and analysed. PHD3-deficient bone marrow-derived macrophages (BMDM) showed no altered HIF-1alpha or HIF-2alpha stabilization or increased HIF target genes expression in normoxia or hypoxia. Macrophage M1 and M2-polarization was unchanged likewise. Compared to macrophages from wild type littermates PHD3-/- BMDM exhibited a significant reduction in TUNEL positive cells after serum withdrawal or treatment with staurosporine and s-nitroso-N-acetylpenicillamine (SNAP). Under the same conditions PHD3-/- BMDM also showed less Annexin V staining which is representative for membrane disruption and indicated a reduced early apoptosis. In an unbiased transcriptome screen we found that angiopoietin like protein 2 (Angptl2) expression was reduced in PHD3-/- BMDM under stress conditions. Addition of recombinant Angptl2 rescued the anti-apoptotic phenotype demonstrating that it is involved in the PHD3-mediated response towards apoptotic stimuli in macrophages. Overall design: 3 mice each for control wildtype and knockout mice, low/normal oxygen concentration, starved/normal feeding