TY  - JOUR
A1  - Wangorsch, Gaby
A1  - Butt, Elke
A1  - Mark, Regina
A1  - Hubertus, Katharina
A1  - Geiger, Jörg
A1  - Dandekar, Thomas
A1  - Dittrich, Marcus
T1  - Time-resolved in silico modeling of fine-tuned cAMP signaling in platelets: feedback loops, titrated phosphorylations and pharmacological modulation
N2  - Background: Hemostasis is a critical and active function of the blood mediated by platelets. Therefore, the prevention of pathological platelet aggregation is of great importance as well as of pharmaceutical and medical interest. Endogenous platelet inhibition is predominantly based on cyclic nucleotides (cAMP, cGMP) elevation and subsequent cyclic nucleotide-dependent protein kinase (PKA, PKG) activation. In turn, platelet phosphodiesterases (PDEs) and protein phosphatases counterbalance their activity. This main inhibitory pathway in human platelets is crucial for countervailing unwanted platelet activation. Consequently, the regulators of cyclic nucleotide signaling are of particular interest to pharmacology and therapeutics of atherothrombosis. Modeling of pharmacodynamics allows understanding this intricate signaling and supports the precise description of these pivotal targets for pharmacological modulation. Results: We modeled dynamically concentration-dependent responses of pathway effectors (inhibitors, activators, drug combinations) to cyclic nucleotide signaling as well as to downstream signaling events and verified resulting model predictions by experimental data. Experiments with various cAMP affecting compounds including antiplatelet drugs and their combinations revealed a high fidelity, fine-tuned cAMP signaling in platelets without crosstalk to the cGMP pathway. The model and the data provide evidence for two independent feedback loops: PKA, which is activated by elevated cAMP levels in the platelet, subsequently inhibits adenylyl cyclase (AC) but as well activates PDE3. By multi-experiment fitting, we established a comprehensive dynamic model with one predictive, optimized and validated set of parameters. Different pharmacological conditions (inhibition, activation, drug combinations, permanent and transient perturbations) are successfully tested and simulated, including statistical validation and sensitivity analysis. Downstream cyclic nucleotide signaling events target different phosphorylation sites for cAMP- and cGMP-dependent protein kinases (PKA, PKG) in the vasodilator-stimulated phosphoprotein (VASP). VASP phosphorylation as well as cAMP levels resulting from different drug strengths and combined stimulants were quantitatively modeled. These predictions were again experimentally validated. High sensitivity of the signaling pathway at low concentrations is involved in a fine-tuned balance as well as stable activation of this inhibitory cyclic nucleotide pathway. Conclusions: On the basis of experimental data, literature mining and database screening we established a dynamic in silico model of cyclic nucleotide signaling and probed its signaling sensitivity. Thoroughly validated, it successfully predicts drug combination effects on platelet function, including synergism, antagonism and regulatory loops.
KW  - Vasodilatator-stimuliertes Phosphoprotein
KW  - VASP
KW  - cyclic nucleotide signaling
KW  - silico model
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-69145
ER  - 
TY  - THES
A1  - Hubertus, Katharina
T1  - Regulation des cAMP Spiegel und der Signaltransduktion in humanen Thrombozyten durch Prostanoid-Rezeptoren
T1  - Regulation of cAMP level and signaltransduction in human platelets by prostanoid-receptors
N2  - Prostanoide wirken über Prostanoid-Rezeptoren auf die Aktivierung oder Hemmung der Thrombozyten. In dieser Arbeit wurde die Existenz und Funktionsweise der Prostanoid-Rezeptoren anhand synthetischer Agonisten und Antagonisten in humanen Thrombozyten nachgewiesen. Weiter wurde untersucht, über welche Prostanoid-Rezeptoren die Signaltransduktion der natürlichen Agonisten wie PGE2, PGE1 und PGA1 vermittelt wird, sowie das Zusammenspiel der Prostanoid-Rezeptoren auf die Aktivierung oder Hemmung der Thrombozyten gezeigt. Das Vorhandensein der Prostaglandin E2 Synthase 3 wurde nachgewiesen sowie erste Anhaltspunkte für die Existenz eines Komplexes aus Prostaglandin E2 Synthase 3, Hitzeschockprotein-90 sowie Casein Kinase 2 gezeigt.
N2  - Prostanoids act to platelet activation or inhibition via prostanoid-receptors. In this work, the existence and function of prostanoid receptors in human platelets was shown by using sythetic agonists and antagonists. Further, the prostanoid receptors taking part at the signaltransduction induced by endogen prostanoids like PGE2, PGE1 and PGA1 were examinated. The interactions of the prostanoid receptors in platelet activation and inhibition were shown. The existence of prostaglandin E2 synthase 3 in human platelets was shown and first evidence for a complexe of prostaglandin E2 synthase 3, heat shock protein 90 and casein kinase 2 was given.
KW  - Prostaglandine
KW  - Rezeptor
KW  - Cyclo-AMP
KW  - Prostanoid-Rezeptor
KW  - cAMP
KW  - Prostanoide
KW  - Thrombozyt
KW  - prostanoid receptor
KW  - platelets
KW  - cAMP
KW  - prostanoids
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-71996
ER  -