Systems biology. How information theory handles cell signaling and uncertainty

Abstract

Information theory allows analyses of cell signaling capabilities without necessarily requiring detailed knowledge of the signaling networks.

Figure. Inverse ecology

To determine the frequency with which a stimulus (such as a ligand) occurs in a cell’s natural environment, a population of cells (genetically identical) can be exposed to the ligand in an experimental setting. Individual cell responses can be measured at a range of doses; that information can be used to discover information about a cell’s natural environment. There is variation in response at each dose (noise). Mathematically, such experimental measurements provide a conditional probability distribution [P (response|signal)]. It is assumed that a cell is “optimized” to obtain the most information about the frequency of doses it encounters in its natural environment [P(signal)]. Information theory (IT) determines the P(signal) that maximizes the information capacity of the signaling network that is responsive to the particular ligand; this reflects the dose frequency in the cell’s natural environment.