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Signal response sensitivity in the yeast mitogen-activated protein kinase cascade.

Thalhauser CJ, Komarova NL - PLoS ONE (2010)

Bottom Line: At the basis of our theory is an analytical result that weak interactions make the response biphasic while tight interactions lead to a graded response.We then show via an analysis of the kinetic binding rate constants how the results of experimental manipulations, modeled as changes to certain of these binding constants, lead to predictions of pathway output consistent with experimental observations.We demonstrate how the results of these experimental manipulations are consistent within the framework of our theoretical treatment of this scaffold-dependent MAPK cascades, and how future efforts in this style of systems biology can be used to interpret the results of other signal transduction observations.

View Article: PubMed Central - PubMed

Affiliation: Department of Mathematics, University of California Irvine, Irvine, California, United States of America.

ABSTRACT
The yeast pheromone response pathway is a canonical three-step mitogen activated protein kinase (MAPK) cascade which requires a scaffold protein for proper signal transduction. Recent experimental studies into the role the scaffold plays in modulating the character of the transduced signal, show that the presence of the scaffold increases the biphasic nature of the signal response. This runs contrary to prior theoretical investigations into how scaffolds function. We describe a mathematical model of the yeast MAPK cascade specifically designed to capture the experimental conditions and results of these empirical studies. We demonstrate how the system can exhibit either graded or ultrasensitive (biphasic) response dynamics based on the binding kinetics of enzymes to the scaffold. At the basis of our theory is an analytical result that weak interactions make the response biphasic while tight interactions lead to a graded response. We then show via an analysis of the kinetic binding rate constants how the results of experimental manipulations, modeled as changes to certain of these binding constants, lead to predictions of pathway output consistent with experimental observations. We demonstrate how the results of these experimental manipulations are consistent within the framework of our theoretical treatment of this scaffold-dependent MAPK cascades, and how future efforts in this style of systems biology can be used to interpret the results of other signal transduction observations.

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Signal response of the scaffold-MAPK complex as a function of scaffold-membrane binding and alignment rate.(left) Representative Hill plots for  (dashed) and  (solid). (right) Dependence of the Hill coefficient on . All other parameters as in table 4.
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pone-0011568-g007: Signal response of the scaffold-MAPK complex as a function of scaffold-membrane binding and alignment rate.(left) Representative Hill plots for (dashed) and (solid). (right) Dependence of the Hill coefficient on . All other parameters as in table 4.

Mentions: We can use model (2) to model this experimental system and gain understanding of how membrane binding affects ultrasensitivity. By varying the complex-membrane association rate we can simulate a scaffold which is either tethered to the membrane (high ) or a scaffold which is free to dissociate and diffuse throughout the cytoplasm (low ). As seen in figure 7, increasing leads to a decrease in the Hill coefficient and therefore a more graded signal response.


Signal response sensitivity in the yeast mitogen-activated protein kinase cascade.

Thalhauser CJ, Komarova NL - PLoS ONE (2010)

Signal response of the scaffold-MAPK complex as a function of scaffold-membrane binding and alignment rate.(left) Representative Hill plots for  (dashed) and  (solid). (right) Dependence of the Hill coefficient on . All other parameters as in table 4.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2909145&req=5

pone-0011568-g007: Signal response of the scaffold-MAPK complex as a function of scaffold-membrane binding and alignment rate.(left) Representative Hill plots for (dashed) and (solid). (right) Dependence of the Hill coefficient on . All other parameters as in table 4.
Mentions: We can use model (2) to model this experimental system and gain understanding of how membrane binding affects ultrasensitivity. By varying the complex-membrane association rate we can simulate a scaffold which is either tethered to the membrane (high ) or a scaffold which is free to dissociate and diffuse throughout the cytoplasm (low ). As seen in figure 7, increasing leads to a decrease in the Hill coefficient and therefore a more graded signal response.

Bottom Line: At the basis of our theory is an analytical result that weak interactions make the response biphasic while tight interactions lead to a graded response.We then show via an analysis of the kinetic binding rate constants how the results of experimental manipulations, modeled as changes to certain of these binding constants, lead to predictions of pathway output consistent with experimental observations.We demonstrate how the results of these experimental manipulations are consistent within the framework of our theoretical treatment of this scaffold-dependent MAPK cascades, and how future efforts in this style of systems biology can be used to interpret the results of other signal transduction observations.

View Article: PubMed Central - PubMed

Affiliation: Department of Mathematics, University of California Irvine, Irvine, California, United States of America.

ABSTRACT
The yeast pheromone response pathway is a canonical three-step mitogen activated protein kinase (MAPK) cascade which requires a scaffold protein for proper signal transduction. Recent experimental studies into the role the scaffold plays in modulating the character of the transduced signal, show that the presence of the scaffold increases the biphasic nature of the signal response. This runs contrary to prior theoretical investigations into how scaffolds function. We describe a mathematical model of the yeast MAPK cascade specifically designed to capture the experimental conditions and results of these empirical studies. We demonstrate how the system can exhibit either graded or ultrasensitive (biphasic) response dynamics based on the binding kinetics of enzymes to the scaffold. At the basis of our theory is an analytical result that weak interactions make the response biphasic while tight interactions lead to a graded response. We then show via an analysis of the kinetic binding rate constants how the results of experimental manipulations, modeled as changes to certain of these binding constants, lead to predictions of pathway output consistent with experimental observations. We demonstrate how the results of these experimental manipulations are consistent within the framework of our theoretical treatment of this scaffold-dependent MAPK cascades, and how future efforts in this style of systems biology can be used to interpret the results of other signal transduction observations.

Show MeSH
Related in: MedlinePlus