BACKGROUND: Oxidative stress plays a causal role in vascular injury in diabetes mellitus, but the mechanisms and targets remain poorly understood. METHODS AND RESULTS: Exposure of cultured human umbilical vein endothelial cells to either peroxynitrite (ONOO-) or high glucose significantly inhibited both basal and insulin-stimulated Akt phosphorylation at Ser473 and Akt activity in parallel with increased apoptosis, phosphorylation, and activity of phosphatase and tensin homologue deleted on chromosome 10 (PTEN). Furthermore, protein kinase B/Akt inhibition induced by ONOO- or high glucose and apoptosis triggered by high glucose could be abolished by transfection of PTEN-specific small interfering RNA, suggesting that PTEN mediated the Akt inhibition by ONOO-. In addition, exposure of human umbilical vein endothelial cells to ONOO- or high glucose remarkably increased Ser428 phosphorylation of LKB1, a tumor suppressor. Interestingly, the ONOO(-)-enhanced PTEN phosphorylation and Akt inhibition can be blocked by LKB1-specific small interfering RNA. Consistently, LKB1 phosphorylated PTEN at Ser380/Thr382/383 in vitro, suggesting that LKB1 might act as an upstream kinase for PTEN. Compared with nondiabetic mice, the levels of PTEN, LKB1-Ser428 phosphorylation, and 3-nitrotyrosine (a biomarker of ONOO-) were significantly increased in the aortas of streptozotocin-induced diabetic mice, which was in parallel with a reduction in Akt-Ser473 phosphorylation and an increase in apoptosis. Furthermore, administration of PTEN-specific small interfering RNA suppressed diabetes-enhanced apoptosis and Akt inhibition. Finally, treatment with Tempol, a superoxide dismutase mimetic, and insulin, both of which reduced the ONOO- formation, markedly reduced diabetes-enhanced LKB1-Ser428 phosphorylation, PTEN, and apoptosis in the endothelium of mouse aortas. CONCLUSION: We conclude that hyperglycemia triggers apoptosis by inhibiting Akt signaling via ONOO(-)-mediated LKB1-dependent PTEN activation.
BACKGROUND: Oxidative stress plays a causal role in vascular injury in diabetes mellitus, but the mechanisms and targets remain poorly understood. METHODS AND RESULTS: Exposure of cultured human umbilical vein endothelial cells to either peroxynitrite (ONOO-) or high glucose significantly inhibited both basal and insulin-stimulated Akt phosphorylation at Ser473 and Akt activity in parallel with increased apoptosis, phosphorylation, and activity of phosphatase and tensin homologue deleted on chromosome 10 (PTEN). Furthermore, protein kinase B/Akt inhibition induced by ONOO- or high glucose and apoptosis triggered by high glucose could be abolished by transfection of PTEN-specific small interfering RNA, suggesting that PTEN mediated the Akt inhibition by ONOO-. In addition, exposure of human umbilical vein endothelial cells to ONOO- or high glucose remarkably increased Ser428 phosphorylation of LKB1, a tumor suppressor. Interestingly, the ONOO(-)-enhanced PTEN phosphorylation and Akt inhibition can be blocked by LKB1-specific small interfering RNA. Consistently, LKB1 phosphorylated PTEN at Ser380/Thr382/383 in vitro, suggesting that LKB1 might act as an upstream kinase for PTEN. Compared with nondiabetic mice, the levels of PTEN, LKB1-Ser428 phosphorylation, and 3-nitrotyrosine (a biomarker of ONOO-) were significantly increased in the aortas of streptozotocin-induced diabeticmice, which was in parallel with a reduction in Akt-Ser473 phosphorylation and an increase in apoptosis. Furthermore, administration of PTEN-specific small interfering RNA suppressed diabetes-enhanced apoptosis and Akt inhibition. Finally, treatment with Tempol, a superoxide dismutase mimetic, and insulin, both of which reduced the ONOO- formation, markedly reduced diabetes-enhanced LKB1-Ser428 phosphorylation, PTEN, and apoptosis in the endothelium of mouse aortas. CONCLUSION: We conclude that hyperglycemia triggers apoptosis by inhibiting Akt signaling via ONOO(-)-mediated LKB1-dependent PTEN activation.
Authors: Raluca Marcu; Surya Kotha; Zhongwei Zhi; Wan Qin; Christopher K Neeley; Ruikang K Wang; Ying Zheng; Brian J Hawkins Journal: Circ Res Date: 2015-02-26 Impact factor: 17.367
Authors: G Mangialardi; A Monopoli; E Ongini; G Spinetti; O Fortunato; C Emanueli; P Madeddu Journal: Br J Pharmacol Date: 2011-09 Impact factor: 8.739
Authors: Saurabh Aggarwal; Christine M Gross; Sanjiv Kumar; Sanjeev Datar; Peter Oishi; Gokhan Kalkan; Christian Schreiber; Sohrab Fratz; Jeffrey R Fineman; Stephen M Black Journal: J Cell Physiol Date: 2011-12 Impact factor: 6.384