Overexpressing STAMP2 attenuates adipose tissue angiogenesis and insulin resistance in diabetic ApoE

The aim of this study was to investigate whether overexpression of STAMP2 improves insulin resistance by regulating angiogenesis in adipose tissues. The characteristics of diabetic mice were measured by serial metabolite and pathology tests. Samples were obtained from epididymal, subcutaneous and brown adipose tissues. Histological and morphological analysis demonstrated that STAMP2 gene overexpression reduced adipocyte size, angiogenesis in epididymal and brown adipose tissues. On aortic ring assay, microvessels sprouting from aortas were significantly inhibited after STAMP2 gene overexpression. The cellular effect of STAMP2 on angiogenesis was explored in human umbilical vein endothelial cells (HUVECs) model. Correlation of STAMP2 and angiogenesis was validated by Ad-STAMP2 transfection and STAMP2 siRNA inhibition. In vitro, overexpression of STAMP2 significantly inhibited endothelial cell migration, tube formation. The effects of Ad-STAMP2 transfection on HUVECs were abolished by treatment with PPARγ antagonist GW9662 (2.5 μM), and the roles of STAMP2 siRNA on HUVECs were also reversed by treatment with PPARγ agonist rosiglitazone (RSG) (0.1 mM). RT-PCR indicated that STAMP2 could regulate levels of adhesion molecules, vascular endothelial growth factor A and CD36. The expression of PPARγ and CD36 was decreased when STAMP2 was inhibited by siRNA, while PPARγ and CD36 were highly expressed after overexpression of STAMP2. Our results suggested that STAMP2 gene overexpression may improve insulin resistance via attenuating angiogenesis in epididymal and brown adipose tissues through the PPARγ/CD36 signalling pathway.