Sensing your surroundings: how transcription-regulatory networks of the cell discern environmental signals.

Accumulating evidence indicates that cells differentially regulate parts of their biochemical networks in various environmental conditions. Two recent studies, focused on the yeast transcription-regulatory network, have identified the characteristics and some of the regulatory logic that defines such conditional regulation on a system level. But what is the underlying basis of such environment-dependent dynamic network utilization? We propose that with simultaneous changes in many environmental variables, cells detect and process the incoming pieces of information individually with the use of receptors and sensor transcription factors specialized to a given type of signal. In turn, transcriptional subnetworks affected by the activity of these proteins reassemble the processed signals deeper inside the network, ultimately resulting in the development of an integrated cellular response.