Activation of the AMP-activated protein kinase (AMPK) by nitrated lipids in endothelial cells
Authors: Yong Wu
Yunzhou Dong
Ming-Hui Zou
Ping Song
Journal: PloS one (2012)
Discipline: Multidisciplinary
Keywords: AMP-activated protein kinase; endothelial function; nitrated oleic acid; heme oxygenase-1; hypoxia-inducible factor-1α
Affiliations: Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America.

Abstract:  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-NO(2)) and investigated the implications in endothelial function. Treatment of bovine aortic endothelial cells (BAECs) with OA-NO(2) 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)-1α. Pharmacologic inhibition or genetic ablation of HO-1 or HIF-1α abolished OA-NO(2)-induced AMPK phosphorylation. OA-NO(2) 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-NO(2)-induced HIF-1α upregulation, suggesting that OA-NO(2)/HO-1-initiated HIF-1α induction is partially dependent on ERK1/2 activity. In addition, OA-NO(2) enhanced endothelial intracellular Ca(2+), an effect that was inhibited by the HIF-1α inhibitor, YC-1, and by HIF-1α siRNA. These results implicate the involvement of HIF-1α. Experiments using the Ca(2+)/calmodulin-dependent protein kinase kinase (CaMKK) inhibitor STO-609, the selective CaMKII inhibitor KN-93, and an isoform-specific siRNA demonstrated that OA-NO(2)-induced AMPK phosphorylation was dependent on CaMKKβ. Together, these results demonstrate that OA-NO(2) activates AMPK in endothelial cells via an HO-1-dependent mechanism that increases HIF-1α protein expression and Ca(2+)/CaMKKβ activation. 

Retracted: Yes

PubPeer comments:
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 Figure 5A. ![file] , 
 https: retractionwatch.com 2019 07 08 georgia-state-researcher-has-two-papers-retracted-eight-flagged-hes-not-happy-about-it , 
 #4 Additional problematic data figure 5A. See inside yellow boxes. ![file] , 
 2020 retraction. https: journals.plos.org plosone article?id=10.1371 journal.pone.0233408 Following the publication of this article [1], concerns were raised regarding the western blot data reported in Figs 1, 3, 4, 5, 6 and 7: Lanes 1 and 4u20138 of the p-AMPK panel of Fig 1E appear similar to lanes 1u20136 of the p-AMPK panel of Fig 7C. The panels represent data from the same experiment. Lanes 1 and 4u20138 of the AMPK panel of Fig 1E appear similar to lanes 1u20136 of the AMPK panel of Fig 7C. The panels represent data from the same experiment. Lanes 1u20136 of the u03b2-actin panel of Fig 1A appear similar to lanes 1u20136 of the u03b2-actin panel of Fig 7C. Lane 1 of the HIF-1u03b1 lane of Fig 3A appears similar to lane 1 of the HIF-1u03b1 lane of Fig 4C. Both bands represent the same control sample. However, the appearance of similar bands in otherwise different panels suggests the control band for one of the figures may have been spliced from a separate blot. In the u03b2-actin panel of Fig 3A, the following bands appear similar: lanes 3, 7, and 11; lanes 4 and 8; lanes 5 and 9; lanes 6 and 10. Lanes 1u20136 of the u03b2-actin panel of Fig 3A appear similar to lanes 1u20136 of the u03b2-actin panel of Fig 4C. In the AMPK panel of Fig 5A, the bands in lanes 6u20138 appear similar to the bands in lanes 9u201311 respectively. In the p-AMPK panel of Fig 5A, the bands in lanes 1u20133 appear similar to the bands in lanes 9u201311 respectively. In the u03b2-actin panel of Fig 5A, the bands in lanes 6u20138 appear similar to the bands in lanes 9u201311 respectively. Lanes 2u20137 of the u03b2-actin panel of Fig 5A appear similar to lanes 1u20136 of the u03b2-actin panel of Fig 7B. In the p-AMPK panel of Fig 6A, the band in lane 1 appears similar to the band in lane 6. In the eNOS panel of Fig 6B, the bands in lanes 1 and 2 appear similar to the bands in lanes 3 and 4 respectively. In the p-eNOS panel of Fig 7A, the band in lane 3 appears similar to the band in lane 4. In the p-eNOS panel of Fig 7B, the band in lane 1 appears similar to the band in lane 2. The authors have indicated that the underlying data for Figs 3 and 4 are unavailable. Cropped panels and replicate experiment data for Figs 1, 5, 6 and 7 have been provided, but these do not resolve the image concerns outlined. In light of the concerns affecting multiple figure panels that question the integrity of these data, the PLOS ONE Editors retract this article. PS and M-HZ agreed with the retraction. YW did not agree with the retraction. YD either did not respond directly or could not be reached. Reference 1.Wu Y, Dong Y, Song P, Zou M-H (2012) Activation of the AMP-Activated Protein Kinase (AMPK) by Nitrated Lipids in Endothelial Cells. PLoS ONE , 
 https: retractionwatch.com 2020 05 20 associate-vp-for-research-at-georgia-state-is-up-to-10-retractions ,