Abstract 12967: Deletion of G Protein-Coupled Receptor 39 Protects Angiogenesis in Hyperglycemia

Abstract

Introduction: Endothelial cells (ECs) are essential to vascular homeostasis and angiogenesis. Endothelial dysfunction significantly contributes to critical limb ischemia in patients with diabetes. G protein-coupled receptor (GPR) 39 is an orphan receptor whose role in EC functions is unknown. We hypothesize that inhibition of GPR 39 protects angiogenesis under hyperglycemic conditions. Methods and Results: Healthy human aortic endothelial cells (H-HAECs) and diabetic human aortic endothelial cells (D-HAECs) were cultured in vitro . The migration (Modified Boyden Chamber assay) and tube formation capacity of H-HAECs were impaired by the transfection of adenovirus carrying human GPR39 or by a GPR39 agonist, TC-G-1008 (both n=5, p<0.05). Conversely, GPR39 siRNA improved D-HAEC migration (n=4 per group, p<0.05). In an angiogenesis protein profiler array, GPR39 overexpression has significantly reduced vascular endothelial growth factor (VEGF), Interleukin-8, monocyte Chemoattractant Protein-1 (MCP1), and Angiopoietin-2 in H-HAECs (n=5 per group, p<0.05). Adult male GPR39 global knockout (GPR39 KO ) mice and age- and sex-matched wild-type (GPR39 WT ) litters were rendered diet-induced obese (DIO) by a 10-week high-fat and an add-on 8-week hyperglycemia by low-dose streptozotocin (STZ) injections chow as they reflect the human condition where obesity is closely linked to type 2 diabetes development. Hind limb ischemia was created by left femoral artery ligation. Laser Doppler imaging showed that GPR39 KO mice had a faster blood perfusion recovery from ischemia than GPR39 WT mice (n=5 per group, p<0.05). In adult male C57BL/6 with DIO-STZ, intramuscular injection of EC-affinitive AAV-mediated shRNA against GPR39 significantly accelerated blood perfusion recovery and prevented tissue necrosis compared to empty AAV treatment (n=5 per group, p<0.05). Conclusion: Our data indicated that genetic inhibition of GPR39 improved EC functions and accelerated angiogenesis from ischemia. We believe that the investigations in endothelial GPR39 may help better identify the novel therapeutic potential of targeting GPR39 in treating vascular complications in hyperglycemia.