Odoroside A and ouabain inhibit Na+/K+-ATPase and prevent NF-kappaB-inducible protein expression by blocking Na+-dependent amino acid transport.
Inflammatory cytokines, such as tumor necrosis factor (TNF)-alpha and interleukin-1 (IL-1), trigger the activation of transcription factor NF-kappaB that induces the expression of a variety of genes, including intercellular adhesion molecule (ICAM)-1. Odoroside A [3beta-O-(beta-D-diginosyl)-14-hydroxy-5beta,14beta-card-20(22)-enolide] was found to inhibit the cell-surface expression of ICAM-1 induced by TNF-alpha and IL-1 at comparable concentrations in human lung carcinoma A549 cells. In this study, the molecular mechanism underlying the inhibition of TNF-alpha-induced cell-surface ICAM-1 expression by odoroside A together with the specific Na(+)/K(+)-ATPase inhibitor ouabain was further investigated. Odoroside A and ouabain neither prevented IkappaBalpha degradation nor NF-kappaB translocation to the nucleus upon TNF-alpha stimulation. While odoroside A and ouabain had no inhibitory effect on the induction of ICAM-1 mRNA, they inhibited the TNF-alpha-induced ICAM-1 expression at the protein level. Consistent with these results, odoroside A and ouabain potently reduced de novo protein synthesis, largely due to its ability to block Na(+)-dependent transport of amino acids across the plasma membrane, but not to interfering with the translation machinery. As a direct molecular target, odoroside A was found to inhibit the ATP-hydrolyzing activity of Na(+)/K(+)-ATPase as potently as ouabain. These results clearly demonstrate that odoroside A and ouabain prevent NF-kappaB-inducible protein expression by blocking the Na(+)-dependent amino acid transport.
Takada
Yohei
Y
Center for Biological Resources and Informatics, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Japan.
Matsuo
Kentaro
K
Ogura
Hirotsugu
H
Bai
Liming
L
Toki
Asami
A
Wang
Liyan
L
Ando
Masayoshi
M
Kataoka
Takao
T
D000596:Amino Acids / Q000378:metabolism*; D001483:Base Sequence; D001692:Biological Transport / Q000187:drug effects*; D015153:Blotting, Western; D002298:Cardenolides / Q000494:pharmacology*; D045744:Cell Line, Tumor; D017931:DNA Primers; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D007375:Interleukin-1 / Q000378:metabolism; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D000596:Amino Acids; D002298:Cardenolides; D017931:DNA Primers; D007375:Interleukin-1; D016328:NF-kappa B; D011506:Proteins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; C415148:odoroside; D018799:Intercellular Adhesion Molecule-1; D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase