Oxygen‐dependent regulation of β3‐adrenoceptor in the retina: Another piece in the puzzle of the pathological neovascularization

Abstract

AbstractPurpose: Hypoxia‐inducible factor (HIF)‐1 is the major transcriptional regulator involved in the adaptive responses to hypoxia in health and disease. In the retina, HIF‐1 controls the hypoxia‐driven vascular proliferation by inducing the overexpression of neoangiogenic factors. The HIF‐1‐mediated neoangiogenesis is strongly promoted by β‐adrenoceptors overstimulation following the hypoxia‐driven surge of catecholamines. Among them, β3‐adrenoceptor (β3‐AR) appears strictly linked to hypoxia, resulting overexpressed in proliferating vessels parallelly with increased HIF‐1. However, whether β3‐AR undergoes HIF‐1 direct regulation remains to be established.Methods: The mouse model of oxygen‐induced retinopathy (OIR) was used to test the influence of the HIF‐1 stabilization with DMOG on the oxygen‐dependent modulation of β3‐AR expression in the retina. Hence, the mouse β3‐AR gene was analysed to search for putative HIF binding sites (HBSs), which then underwent in silico simulations to predict their suitability for the binding with HIF‐1. Finally, the oxygen‐dependent physical interaction of the best scored HBS with HIF‐1 was tested using ChIP‐qPCR in retinas of OIR mice and correlated with the β3‐AR gene expression.Results: In OIR retinas, β3‐AR expression inversely correlated with the oxygen tension. The inhibition of HIF‐1 drop under hyperoxia abolished the oxygen‐dependent β3‐AR modulation, indicating that β3‐AR expression might depend on HIF‐1 levels. The β3‐AR gene analysis and the HIF‐1 docking simulations revealed 6 possible HBS, of which HBS#1 resulted the most suitable region for HIF‐1 binding. The ChIP‐qPCR analysis on OIR retinas demonstrated the actual oxygen‐dependent HIF‐1/HBS#1 physical interaction, which correlated with the β3‐AR gene transactivation.Conclusions: This evidence allows to establish the β3‐AR as a member of the HIF‐1 target genes, thus paving the way to the further characterization of its role in oxygen‐dependent retinal abnormalities.