15(S)-HETE-induced angiogenesis in adipose tissue is mediated through activation of PI3K/Akt/mTOR signaling pathway

Abstract

Chronic low-grade inflammation underlies obesity and associated metabolic dysfunctions. Lipoxygenase pathways are activated in adipose tissue during obese conditions. Since adipogenesis is associated with angiogenesis, the present study was designed to examine the role of 15-lipoxygenase metabolite, 15(S)-hydroxyeicosatetraenoic acid [15(S)-HETE] on angiogenesis in adipose tissue. Results showed that 15(S)-HETE induced sprouting in fat pad stromovascular tissues, induced morphological changes relevant to angiogenesis in endothelial cells derived from adipose tissue, upregulated the production of CD31, upregulated the gene level expression and production of vascular endothelial growth factor (VEGF), indicating the pro-angiogenic effect of 15(S)-HETE. LY294002, an inhibitor of PI3K-Akt pathway, and rapamycin, inhibitor of mammalian target of rapamycin (mTOR), significantly reversed the effect of 15(S)-HETE. 15(S)-HETE also induced activation of Akt and mTOR. These observations suggest that 15(S)-HETE stimulates angiogenesis in adipose tissue through activation of PI3K/Akt/mTOR signaling.