Kinetic Analysis of PDGF Receptor Signaling Pathways in Fibroblasts

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dc.contributor.advisor Steven W. Peretti, Committee Member en_US
dc.contributor.advisor Robert M. Kelly, Committee Member en_US
dc.contributor.advisor Jason M. Haugh, Committee Chair en_US
dc.contributor.advisor Carla Mattos, Committee Member en_US Park, Chang Shin en_US 2010-04-02T18:35:06Z 2010-04-02T18:35:06Z 2005-01-24 en_US
dc.identifier.other etd-10252004-133645 en_US
dc.description.abstract Living cells perceive information about their surroundings and decode it in order to decide how to respond. All of this information flow is processed through intracellular signaling pathways. However, research on these intracellular processes is difficult because signaling pathways are connected to each other in numerous ways. Due to the complicated nature of the interactions among signaling molecules, the overall signal transduction network has hardly been investigated quantitatively or systematically. In order to reveal the underlying control of the signaling network, we designed mechanistic experiments to quantitatively measure the activity of signaling molecules and formulated a mathematical model consistent with these data. In this manner, we approached the study of the platelet-derived growth factor (PDGF) receptor mediated phosphoinositide (PI) 3-kinase/Akt signaling pathway and crosstalk between Ras and PI 3-kinase. The linear signaling pathway, PDGF receptor/PI 3-kinase/Akt, was systematically investigated by using biochemical assays and mathematical modeling. We find that PDGF receptor phosphorylation shows positive cooperativity with respect to PDGF concentration, and the receptor dimerization process is consistent with association of two 1:1 ligand-receptor intermediate complexes. The kinetics of receptor phosphorylation are transient at high PDGF concentrations. Activation of PI 3-kinase, and thus Akt, are saturated with respect to the number of activated receptors. At higher PDGF concentrations, the kinetics of 3¡¯ PI production are governed by the first-order turnover rate constant and those of Akt are further controlled by its deactivation rate constant. To investigate the crosstalk between Ras and PI 3-kinase, we systematically designed experiments to assess the effect of Ras on PI 3-kinase activation and developed a simple mathematical model to describe the molecular assembly of complexes involving PDGF receptors, PI 3-kinase, and Ras. From the experimental results, we find that the Ras effectively enhances the affinity of PI 3-kinase towards the receptor. In our model, this can only be explained if a ternary receptor/PI 3-kinase/Ras complex forms in two steps, where the second step is greatly enhanced through induced proximity and possibly allosteric effects. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject Ras en_US
dc.subject PI 3-kinase en_US
dc.subject PDGF Receptor en_US
dc.subject PDGF en_US
dc.subject Mathematical Modeling en_US
dc.subject Signal Transduction en_US
dc.title Kinetic Analysis of PDGF Receptor Signaling Pathways in Fibroblasts en_US PhD en_US dissertation en_US Chemical Engineering en_US

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