title: Thromboxane A2 receptor activates a Rho-associated kinase/LKB1/PTEN pathway to attenuate endothelium insulin signaling.
abstract: This study was conducted to elucidate the molecular mechanisms of thromboxane A2 receptor (TP)-induced insulin resistance in endothelial cells. Exposure of human umbilical vein endothelial cells (HUVECs) or mouse aortic endothelial cells to either IBOP or U46619, two structurally related thromboxane A(2) mimetics, significantly reduced insulin-stimulated phosphorylation of endothelial nitric-oxide synthase (eNOS) at Ser(1177) and Akt at Ser(473). These effects were abolished by pharmacological or genetic inhibitors of TP. TP-induced suppression of both eNOS and Akt phosphorylation was accompanied by up-regulation of PTEN (phosphatase and tension homolog deleted on chromosome 10), Ser(380)/Thr(382/383) PTEN phosphorylation, and PTEN lipid phosphatase activity. PTEN-specific small interference RNA restored insulin signaling in the face of TP activation. The small GTPase, Rho, was also activated by TP stimulation, and pretreatment of HUVECs with Y27632, a Rho-associated kinase inhibitor, rescued TP-impaired insulin signaling. Consistent with this result, pertussis toxin abrogated IBOP-induced dephosphorylation of both Akt and eNOS, implicating the G(i) family of G proteins in the suppressive effects of TP. In mice, high fat diet-induced diabetes was associated with aortic PTEN up-regulation, PTEN-Ser(380)/Thr(382/383) phosphorylation, and dephosphorylation of both Akt (at Ser(473)) and eNOS (at Ser(1177)). Importantly, administration of TP antagonist blocked these changes. We conclude that TP stimulation impairs insulin signaling in vascular endothelial cells by selectively activating the Rho/Rho-associated kinase/LKB1/PTEN pathway.
authors.affiliation: From the Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
authors.forename: Ping
authors.initials: P
authors.lastname: Song
authors.affiliation: From the Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
authors.forename: Miao
authors.initials: M
authors.lastname: Zhang
authors.affiliation: From the Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
authors.forename: Shuangxi
authors.initials: S
authors.lastname: Wang
authors.affiliation: From the Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
authors.forename: Jian
authors.initials: J
authors.lastname: Xu
authors.affiliation: From the Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
authors.forename: Hyoung Chul
authors.initials: HC
authors.lastname: Choi
authors.affiliation: From the Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104. Electronic address: ming-hui-zou@ouhsc.edu.
authors.forename: Ming-Hui
authors.initials: MH
authors.lastname: Zou
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases; D000818:Animals; D001483:Base Sequence; D040761:Biomimetic Materials / Q000494:pharmacology; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002478:Cells, Cultured; D004041:Dietary Fats / Q000008:administration & dosage; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D008024:Ligands; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D051059:PTEN Phosphohydrolase / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D044244:Receptors, Thromboxane A2, Prostaglandin H2 / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D054460:rho-Associated Kinases / Q000378:metabolism*
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D004041:Dietary Fats; D005231:Fatty Acids, Unsaturated; D007328:Insulin; D008024:Ligands; D034741:RNA, Small Interfering; D044244:Receptors, Thromboxane A2, Prostaglandin H2; C061750:7-(3-(3-hydroxy-4-(4'-iodophenoxy)-1-butenyl)-7-oxabicyclo(2.2.1)heptan-2-yl)-5-heptenoic acid; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; C109790:STK11 protein, human; C491654:Stk11 protein, mouse; D054460:rho-Associated Kinases; D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; C487757:Pten protein, mouse