Activation of the AMP-Activated Protein Kinase (AMPK) by Nitrated Lipids in Endothelial Cells

作者：Wu Yong^*; Dong Yunzhou; Song Ping; Zou Ming Hui

来源：PLos One, 2012, 7(2): e31056.

DOI：10.1371/journal.pone.0031056

The AMP-activated protein kinase (AMPK) is an important regulator of endothelial metabolic and functional homeostasis. Here, we examined the regulation of AMPK by nitrated oleic acid (OA-NO2) and investigated the implications in endothelial function. Treatment of bovine aortic endothelial cells (BAECs) with OA-NO2 induced a significant increase in both AMPK-Thr172 phosphorylation and AMPK activity as well as upregulation of heme oxygenase (HO)-1 and hypoxia-inducible factor (HIF)-1 alpha. Pharmacologic inhibition or genetic ablation of HO-1 or HIF-1 alpha abolished OA-NO2-induced AMPK phosphorylation. OA-NO2 induced a dramatic increase in extracellular signal-regulated kinase (ERK) 1/2 phosphorylation that was abrogated by the HO-1 inhibitor, zinc deuteroporphyrin IX 2,4-bis-ethylene glycol (ZnBG). Inhibition of ERK1/2 using UO126 or PD98059 reduced but did not abolish OA-NO2-induced HIF-1 alpha upregulation, suggesting that OA-NO2/HO-1-initiated HIF-1 alpha induction is partially dependent on ERK1/2 activity. In addition, OA-NO2 enhanced endothelial intracellular Ca2+, an effect that was inhibited by the HIF-1 alpha inhibitor, YC-1, and by HIF-1 alpha siRNA. These results implicate the involvement of HIF-1 alpha. Experiments using the Ca2+/calmodulin-dependent protein kinase kinase ( CaMKK) inhibitor STO-609, the selective CaMKII inhibitor KN-93, and an isoform-specific siRNA demonstrated that OA-NO2-induced AMPK phosphorylation was dependent on CaMKK beta. Together, these results demonstrate that OA-NO2 activates AMPK in endothelial cells via an HO-1-dependent mechanism that increases HIF-1 alpha protein expression and Ca2+/CaMKK beta activation.

• 出版日期2012-2-17