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 Ca2+/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.
Footnotes
This work was supported by the National Research Foundation of Korea, funded by the Korean government [Grant 2010-0001707]; and the Ministry of Education Science and Technology of the Korean government [Post 21st Frontier Research Program Grant 2010-0026355].
Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.
doi:10.1124/mol.111.073502.
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ABBREVIATIONS:
- eNOS
- endothelial nitric-oxide synthase
- AICAR
- 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside
- AMPK
- AMP-activated protein kinase
- HUVEC
- human umbilical vein endothelial cell
- Akt
- protein kinase B
- ERK
- extracellular signal regulated kinase
- JNK
- c-Jun N-terminal kinase
- ER
- estrogen receptor
- ACC
- acetyl CoA carboxylase
- CaMK
- Ca2+/calmodulin-dependent protein kinase
- LY294002
- 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
- PD98059
- 2′-amino-3′-methoxyflavone
- B203580
- 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole
- SP600125
- 1,9-pyrazoloanthrone
- ICI 182780
- fulvestrant
- A3281
- N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride
- PPT
- 4,4′,4″-(4-Propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol
- DPN
- diarylpropionitrile
- MPP
- methyl-piperidino-pyrazole
- THC
- tetrahydrochrysene
- siRNA
- small interfering RNA
- DN
- dominant-negative
- CA
- constitutive active
- MTT
- 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide
- DAF-2 DA
- 4,5-diaminofluorescein diacetate
- TE
- Tris-EDTA
- PI3K
- phosphatidylinositol 3-kinase
- LKB
- liver kinase B1
- compound C
- 6-[4-(2-piperidin-1-yl-ethoxy)-phenyl)]-3-pyridin-4-yl-pyrrazolo[1,5-a]-pyrimidine.
- Received May 9, 2011.
- Accepted September 22, 2011.
- Copyright © 2011 The American Society for Pharmacology and Experimental Therapeutics
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