Rate Distortion Theory in Cellular Signaling

Summary form only given. Cells often use signal transduction networks to make decisions critical to proper cell functioning. However, the performance and efficiency of many cellular decision-making systems is relatively unclear. Here we use rate distortion theory as theoretical tool for studying performance-cost tradeoffs in cellular decision making. The rate distortion function provides a lower bound on the rate at which information must be transmitted through the cellular signal transduction network in order to achieve a given performance criterion. To study gradient sensing performance of D. discoideum cells, we developed a model of the cell´s directional response to a chemoattractant gradient that arises from a random direction. The distribution of the gradient angle represents a priori knowledge of the chemoattractant source location from the perspective of the cell. Using a distortion function closely related to the chemotactic index - a widely used measure of chemotactic performance - we computed the rate distortion function that minimizes the mutual information between the gradient angle and the directional response of the cell. We found that the input-output maps that optimally achieve the rate distortion function closely match published models that capture key characteristics of the signaling network in D. discoideum, implying that these cells have evolved to respond to chemoattractant sources in an efficient manner.