Endocrinology of the Single Cell. Tools and Insights.

Whether all cells ascribed to the same type are indeed identical and the related question, "How are signals integrated at tissue and cell levels?" are fundamental issues in biological research and are responsible, in part, for the acceleration of activity in single-cell research. Also contributing are the major advances in single cell methodology. The capability to interrogate, manipulate with spatiotemporal specificity, and acquire data on multiple activities in the same cell can be powerful for understanding normal function and also dysfunction and drug targeting. Reviewed here are examples of how the emergent field of single-cell analysis and its tools are being used to understand the dynamics of the multiple components in regulatory networks for genes, intracellular signaling molecules, and secretion. For more in-depth consideration, the pancreatic β-cell and the pituitary gonadotrope are reviewed as parallel examples for application of single-cell analysis in the examination of one component of regulated secretion.