Phosphorylation of phospholemman (PLM) on ser68 has been proposed to at least partially mediate cyclic AMP (cAMP) mediated relaxation of arterial smooth muscle. We evaluated the time course of the phosphorylation of phospholemman (PLM) on ser68, myosin regulatory light chains (MRLC) on ser19, and heat shock protein 20 (HSP20) on ser16 during a transient forskolininduced relaxation of histamine-stimulated swine carotid artery. We also evaluated the dose response for forskolin- and nitroglycerin-induced relaxation in phenylephrine-stimulated PLM-/- and PLM+/+ mice. The time course for changes in ser19 MRLC dephosphorylation and ser16 HSP20 phosphorylation was appropriate to explain the forskolin-induced relaxation and the recontraction observed upon washout of forskolin. However, the time course for changes in ser68 PLM phosphorylation was too slow to explain forskolin-induced changes in force. There was no difference in the phenylephrine contractile dose response or in forskolin-induced relaxation dose response observed in PLM-/- and PLM+/+ aortae. In aortae precontracted with phenylephrine, nitroglycerin induced a slightly, but significantly greater relaxation in PLM-/- compared to PLM+/+ aortae. These data are consistent with the hypothesis that ser19 MRLC dephosphorylation and ser16 HSP20 phosphorylation are involved in forskolininduced relaxation. Our data suggest that PLM phosphorylation is not significantly involved in forskolin-induced arterial relaxation.

• Klíčová slova
• Cyclic AMP, FXYD protein, HSP20, Myosin light chain, Vascular smooth muscle,
• MeSH
• AMP cyklický metabolismus   MeSH
• aorta metabolismus   účinky léků   MeSH
• arteriae carotides metabolismus   účinky léků   MeSH
• časové faktory MeSH
• fosfoproteiny genetika   metabolismus   nedostatek   MeSH
• fosforylace MeSH
• kolforsin farmakologie   MeSH
• lehké řetězce myosinu metabolismus   MeSH
• membránové proteiny genetika   metabolismus   nedostatek   MeSH
• myši knockoutované MeSH
• myši MeSH
• nitroglycerin farmakologie   MeSH
• prasata MeSH
• proteiny tepelného šoku HSP20 metabolismus   MeSH
• vazodilatace účinky léků   MeSH
• vazodilatancia farmakologie   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH

Combination of fluorescence techniques and molecular docking was used to monitor interaction of Na,K-ATPase and its large cytoplasmic loop connecting fourth and fifth transmembrane helices (C45) with fluorone dyes (i.e. eosin Y, 5(6)-carboxyeosin, rose bengal, fluorescein, and erythrosine B). Our data suggested that there are at least two binding sites for all used fluorone dyes, except of 5(6)-carboxyeosin. The first binding site is located on C45 loop, and it is sensitive to the presence of nucleotide. The other site is located on the extracellular part of the enzyme, and it is sensitive to the presence of Na(+) or K(+) ions. The molecular docking revealed that in the open conformation of C45 loop (which is obtained in the presence of ATP) all used fluorone dyes occupy position directly inside the ATP-binding pocket, while in the closed conformation (i.e. in the absence of any ligand) they are located only near the ATP-binding site depending on their different sizes. On the extracellular part of the protein, the molecular docking predicts two possible binding sites with similar binding energy near Asp897(α) or Gln69(β). The former was identified as a part of interaction site between α- and β-subunits, the latter is in contact with conserved FXYD sequence of the γ-subunit. Our findings provide structural explanation for numerous older studies, which were performed with fluorone dyes before the high-resolution structures were known. Further, fluorone dyes seem to be good probes for monitoring of intersubunit interactions influenced by Na(+) and K(+) binding.

• MeSH
• adenosintrifosfát chemie   MeSH
• červeň bengálská chemie   MeSH
• chemické modely MeSH
• cytoplazma metabolismus   MeSH
• draslík chemie   MeSH
• eosin chemie   MeSH
• erythrosin chemie   MeSH
• Escherichia coli metabolismus   MeSH
• fluorescein chemie   MeSH
• fluoresceiny chemie   farmakologie   MeSH
• fluorescenční barviva farmakologie   MeSH
• konformace proteinů MeSH
• lidé MeSH
• molekulární konformace MeSH
• sodík chemie   MeSH
• sodíko-draslíková ATPasa chemie   MeSH
• terciární struktura proteinů MeSH
• vazebná místa MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The cardiac glycosides are a group of compounds isolated from plants and some animals. They have been used in therapy for heart failure for many years. The cytotoxic effect of many cardiac glycosides has been demonstrated, but the mechanism of action is very complicated and complex, and Na+/K+-ATPase surely plays a crucial role in it. On the other hand, Na+/K+-ATPase is regulated by many endogenous factors, such as hormones or FXYD proteins, whose role in regulating the cell cycle has been studied intensively. This review focuses on the role of Na+/K+-ATPase in regulating the cell growth, the cell cycle and the cell proliferation and on the involvement of cardiac glycosides in regulating Na+/K+-ATPase. The cytotoxic effect of cardiac glycosides is discussed with respect to the apoptotic mechanisms possibly induced by these compounds. Novel strategies in cancer therapy based on cardiac glycosides are discussed as are possibilities for counteracting multidrug resistance by using cardiac glycosides. The aim of this review is to present cardiac glycosides not only as pharmaceuticals used in the management of heart failure, but also as potent cytotoxic agents with potential uses in cancer treatment.

• MeSH
• antitumorózní látky farmakologie   terapeutické užití   MeSH
• cytotoxiny farmakologie   terapeutické užití   MeSH
• kardiotonika farmakologie   terapeutické užití   MeSH
• lidé MeSH
• nádory farmakoterapie   enzymologie   metabolismus   MeSH
• sodíko-draslíková ATPasa metabolismus   MeSH
• srdeční glykosidy farmakologie   terapeutické užití   MeSH
• srdeční selhání farmakoterapie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH