title: Nectandrin B activates endothelial nitric-oxide synthase phosphorylation in endothelial cells: role of the AMP-activated protein kinase/estrogen receptor α/phosphatidylinositol 3-kinase/Akt pathway.
abstract: We revealed previously that nectandrin B isolated from Myristica fragrans (nutmeg, Myristicaceae) functions as a potent AMP-activated protein kinase (AMPK) activator and showed its antiobesity effect. In this study, we investigated whether nectandrin B affects phosphorylation of endothelial nitric-oxide synthase (eNOS) in human endothelial cells. Nectandrin B increased the phosphorylation of eNOS and nitric oxide (NO) production in a concentration-dependent manner and maximal effect was found at 10 μg/ml. Nectandrin B activates AMPK, presumably via Ca(2+)/calmodulin kinase II activation and nectandrin B-stimulated eNOS phosphorylation was reversed by AMPK inhibition. Both the enzyme activity of phosphatidylinositol 3-kinase (PI3K) and the estrogen receptor (ER)-dependent reporter gene transcription were enhanced by nectandrin B. ERα inhibition by specific antagonist or small interfering siRNA (siRNA) suppressed nectandrin B-mediated eNOS phosphorylation. Moreover, AMPK inhibition significantly reversed the activation of ER-dependent transcription and PI3K activation in response to nectandrin B. Nectandrin B evoked endothelium-dependent relaxation in rat aortic rings, and this was blocked by inhibition of AMPK, ER, or PI3K. These results suggest that potent AMPK activator nectandrin B enhances NO production via eNOS phosphorylation in endothelial cells and ERα-dependent PI3K activity is required.
authors.affiliation: BK21 Project Team, College of Pharmacy, Chosun University, Gwangju, Republic of Korea.
authors.forename: Tran Thi
authors.initials: TT
authors.lastname: Hien
authors.forename: Won Keun
authors.initials: WK
authors.lastname: Oh
authors.forename: Phi Hung
authors.initials: PH
authors.lastname: Nguyen
authors.forename: Seok Jeong
authors.initials: SJ
authors.lastname: Oh
authors.forename: Moo Yeol
authors.initials: MY
authors.lastname: Lee
authors.forename: Keon Wook
authors.initials: KW
authors.lastname: Kang
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000502:physiology*; D000818:Animals; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D047628:Estrogen Receptor alpha / Q000502:physiology*; D006801:Humans; D017705:Lignans / Q000302:isolation & purification / Q000494:pharmacology*; D008297:Male; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D009924:Organ Culture Techniques; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
chemical_list: D047628:Estrogen Receptor alpha; D017705:Lignans; D010936:Plant Extracts; C524653:nectandrin-B; D052250:Nitric Oxide Synthase Type III; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D055372:AMP-Activated Protein Kinases