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Harmonic oscillator model of the insulin and IGF1 receptors' allosteric binding and activation.

Kiselyov VV, Versteyhe S, Gauguin L, De Meyts P - Mol. Syst. Biol. (2009)

Bottom Line: On the basis of the available structural and biochemical information, we develop a physically plausible model of the receptor binding and activation, which is based on the concept of a harmonic oscillator.Modelling a network of interactions among all possible receptor intermediaries arising in the context of the model (35, for the insulin receptor) accurately reproduces for the first time all the kinetic properties of the receptor, and provides unique and robust estimates of the kinetic parameters.The harmonic oscillator model may be adaptable for many other dimeric/dimerizing receptor tyrosine kinases, cytokine receptors and G-protein-coupled receptors where ligand crosslinking occurs.

View Article: PubMed Central - PubMed

Affiliation: Receptor Systems Biology Laboratory, Hagedorn Research Institute, Gentofte, Denmark. vkis@novonordisk.com

ABSTRACT
The insulin and insulin-like growth factor 1 receptors activate overlapping signalling pathways that are critical for growth, metabolism, survival and longevity. Their mechanism of ligand binding and activation displays complex allosteric properties, which no mathematical model has been able to account for. Modelling these receptors' binding and activation in terms of interactions between the molecular components is problematical due to many unknown biochemical and structural details. Moreover, substantial combinatorial complexity originating from multivalent ligand binding further complicates the problem. On the basis of the available structural and biochemical information, we develop a physically plausible model of the receptor binding and activation, which is based on the concept of a harmonic oscillator. Modelling a network of interactions among all possible receptor intermediaries arising in the context of the model (35, for the insulin receptor) accurately reproduces for the first time all the kinetic properties of the receptor, and provides unique and robust estimates of the kinetic parameters. The harmonic oscillator model may be adaptable for many other dimeric/dimerizing receptor tyrosine kinases, cytokine receptors and G-protein-coupled receptors where ligand crosslinking occurs.

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Fitting of the model to the experimental data for the insulin/IGF1 binding. (A, B) Competition experiments for the insulin and IGF1 binding, respectively (shown also as Scatchard plots in the insets). (C, D) Percentages of hot insulin and IGF1, respectively, remaining after dissociation for 20 and 60 min in the presence of various concentrations of the respective cold ligand. (E, F) Simulation of the ligand dependence of the receptor dissociation for insulin and IGF1, respectively, using the estimated parameter values.
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f5: Fitting of the model to the experimental data for the insulin/IGF1 binding. (A, B) Competition experiments for the insulin and IGF1 binding, respectively (shown also as Scatchard plots in the insets). (C, D) Percentages of hot insulin and IGF1, respectively, remaining after dissociation for 20 and 60 min in the presence of various concentrations of the respective cold ligand. (E, F) Simulation of the ligand dependence of the receptor dissociation for insulin and IGF1, respectively, using the estimated parameter values.

Mentions: Two sets of data were used for modelling. In the first one (a competition experiment), IM9 and 293 EBN cells were incubated for 2.5 h with hot insulin and 4 h with hot IGF1, respectively, in the presence of various concentrations of the respective cold ligand. Concentration of the hot ligand was 7 pM in both cases. Thereafter, the amount of bound radioactivity was measured (Figure 5A and B). In the second set (quantification of the ligand dependence of the dissociation rate), IM9 and 293 EBN cells were pre-incubated for 2 h with 24 pM hot insulin and IGF1, respectively. Thereafter, the hot ligand was removed and cells were incubated in a 40-fold dilution for various periods of time with various concentrations of the respective cold ligand (De Meyts et al, 1973). The amount of the remaining pre-bound radioactivity was then measured (Figure 5C and D). To minimize the effect of receptor recycling on the apparent kinetics, the data were obtained at 15°C. The recycling rate at 15°C is expected to be reduced 50- to 100-fold compared with that at 37°C. The reduced rate is still too high to be totally ignored because of long incubation times (up to 4 h). Modelling receptor recycling is described in the Supplementary information.


Harmonic oscillator model of the insulin and IGF1 receptors' allosteric binding and activation.

Kiselyov VV, Versteyhe S, Gauguin L, De Meyts P - Mol. Syst. Biol. (2009)

Fitting of the model to the experimental data for the insulin/IGF1 binding. (A, B) Competition experiments for the insulin and IGF1 binding, respectively (shown also as Scatchard plots in the insets). (C, D) Percentages of hot insulin and IGF1, respectively, remaining after dissociation for 20 and 60 min in the presence of various concentrations of the respective cold ligand. (E, F) Simulation of the ligand dependence of the receptor dissociation for insulin and IGF1, respectively, using the estimated parameter values.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2657531&req=5

f5: Fitting of the model to the experimental data for the insulin/IGF1 binding. (A, B) Competition experiments for the insulin and IGF1 binding, respectively (shown also as Scatchard plots in the insets). (C, D) Percentages of hot insulin and IGF1, respectively, remaining after dissociation for 20 and 60 min in the presence of various concentrations of the respective cold ligand. (E, F) Simulation of the ligand dependence of the receptor dissociation for insulin and IGF1, respectively, using the estimated parameter values.
Mentions: Two sets of data were used for modelling. In the first one (a competition experiment), IM9 and 293 EBN cells were incubated for 2.5 h with hot insulin and 4 h with hot IGF1, respectively, in the presence of various concentrations of the respective cold ligand. Concentration of the hot ligand was 7 pM in both cases. Thereafter, the amount of bound radioactivity was measured (Figure 5A and B). In the second set (quantification of the ligand dependence of the dissociation rate), IM9 and 293 EBN cells were pre-incubated for 2 h with 24 pM hot insulin and IGF1, respectively. Thereafter, the hot ligand was removed and cells were incubated in a 40-fold dilution for various periods of time with various concentrations of the respective cold ligand (De Meyts et al, 1973). The amount of the remaining pre-bound radioactivity was then measured (Figure 5C and D). To minimize the effect of receptor recycling on the apparent kinetics, the data were obtained at 15°C. The recycling rate at 15°C is expected to be reduced 50- to 100-fold compared with that at 37°C. The reduced rate is still too high to be totally ignored because of long incubation times (up to 4 h). Modelling receptor recycling is described in the Supplementary information.

Bottom Line: On the basis of the available structural and biochemical information, we develop a physically plausible model of the receptor binding and activation, which is based on the concept of a harmonic oscillator.Modelling a network of interactions among all possible receptor intermediaries arising in the context of the model (35, for the insulin receptor) accurately reproduces for the first time all the kinetic properties of the receptor, and provides unique and robust estimates of the kinetic parameters.The harmonic oscillator model may be adaptable for many other dimeric/dimerizing receptor tyrosine kinases, cytokine receptors and G-protein-coupled receptors where ligand crosslinking occurs.

View Article: PubMed Central - PubMed

Affiliation: Receptor Systems Biology Laboratory, Hagedorn Research Institute, Gentofte, Denmark. vkis@novonordisk.com

ABSTRACT
The insulin and insulin-like growth factor 1 receptors activate overlapping signalling pathways that are critical for growth, metabolism, survival and longevity. Their mechanism of ligand binding and activation displays complex allosteric properties, which no mathematical model has been able to account for. Modelling these receptors' binding and activation in terms of interactions between the molecular components is problematical due to many unknown biochemical and structural details. Moreover, substantial combinatorial complexity originating from multivalent ligand binding further complicates the problem. On the basis of the available structural and biochemical information, we develop a physically plausible model of the receptor binding and activation, which is based on the concept of a harmonic oscillator. Modelling a network of interactions among all possible receptor intermediaries arising in the context of the model (35, for the insulin receptor) accurately reproduces for the first time all the kinetic properties of the receptor, and provides unique and robust estimates of the kinetic parameters. The harmonic oscillator model may be adaptable for many other dimeric/dimerizing receptor tyrosine kinases, cytokine receptors and G-protein-coupled receptors where ligand crosslinking occurs.

Show MeSH
Related in: MedlinePlus