Institution: | a Department of Mathematics, Vanderbilt University, 1326 Stevenson Center, Nashville, TN 37240, USA b Division of Mathematical Sciences, National Science Foundation, 4201 Wilson Blvd., Room 1025, Arlington, VA 22230, USA c Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park, Dallas, TX 75390-9041, USA d Department of Pharmacology, Vanderbilt University School of Medicine, 23rd Ave. South & Pierce, Nashville, TN 37232-6600, USA e Department of Chemistry, Vanderbilt University School of Medicine, 23rd Ave. South & Pierce, Nashville, TN 37232-6600, USA |
Abstract: | A mathematical model of the G protein signaling pathway in RAW 264.7 macrophages downstream of P2Y6 receptors activated by the ubiquitous signaling nucleotide uridine 5’-diphosphate is developed. The model, which is based on time-course measurements of inositol trisphosphate, cytosolic calcium, and diacylglycerol, focuses particularly on differential dynamics of multiple chemical species of diacylglycerol. When using the canonical pathway representation, the model predicted that key interactions were missing from the current network structure. Indeed, the model suggested that accurate depiction of experimental observations required an additional branch to the signaling pathway. An intracellular pool of diacylglycerol is immediately phosphorylated upon stimulation of an extracellular receptor for uridine 5’-diphosphate and subsequently used to aid replenishment of phosphatidylinositol. As a result of sensitivity analysis of the model parameters, key predictions can be made regarding which of these parameters are the most sensitive to perturbations and are therefore most responsible for output uncertainty. |