Using Microfluidics and Live Cell Reporters to Dissect the Dynamics of TGF-β Signaling in Mouse Embryonic Stem Cells.

The TGF-β pathway is known to behave as a classical morphogen, meaning that it can dictate cell fate decisions in a dose-dependent manner. Recent observations however showed that in addition to the absolute value of morphogen concentration, cells could also extract information from its temporal variations. In the present article we describe how to use automated microfluidics cell culture to stimulate cells with precisely defined temporal profiles of morphogens and how to engineer mouse embryonic stem cells with fluorescent reporters of pathway activity to record in real time their response to the applied stimulations. The combination of automated cell culture and of live cell reporter provides a complete toolbox to study how cells encode the information carried by time-varying TGF-β signals.