Assessment of information in biological tissues proper to ligands or receptors: A quantitative evaluation in the transgenic animal era

Abstract Objective Transgenic technology has enabled the visualization of signal transduction via ligand—receptor interactions. By using ubiquitous or intrinsic promoters, the impacts of ligand availability and receptor expression on signal transduction can be measured. However, methods for evaluating reporter expression gaps by using these promoters are poorly documented. Here, we applied entropy analysis in an in silico imaginary cell field for future transgenic animal experiments. Results Ligand availability is the bottleneck in signal transduction when intrinsic promoter-driven reporter expression is almost equivalent to ubiquitous promoter-driven reporter expression. Indeed, the mutual information of ubiquitous promoter-driven and intrinsic promoter-driven reporter expression increased as the latter increased. Conversely, receptor expression is the bottleneck when there is a large gap between ubiquitous promoter-driven or intrinsic promoter-driven reporter expression. Importantly, the value of mutual information is dependent on the proportion of ubiquitous promoter-driven reporter expression in the total cells, suggesting that it is necessary to consider ubiquitous promoter-driven reporter expression before evaluating the intrinsic promoter-driven reporter expression and the mutual information. Therefore, the generation of ubiquitous promoter-driven reporter transgenic animals may be useful in the future. In summary, a quantitative method for analyzing the contribution of ligands and receptors in signal transduction that is potentially useful in future transgenic animal experiments is proposed.