Spatio-temporal regulation of concurrent developmental processes by generic signaling downstream of chemokine receptors.

Chemokines are secreted proteins that regulate a range of processes in eukaryotic organisms. Interestingly, different chemokine receptors control distinct biological processes, and the same receptor can direct different cellular responses, but the basis for this phenomenon is not known. To understand this property of chemokine signaling, we examined the function of the chemokine receptors Cxcr4a, Cxcr4b, Ccr7, Ccr9 in the context of diverse processes in embryonic development in zebrafish. Our results reveal that the specific response to chemokine signaling is dictated by cell-type-specific chemokine receptor signal interpretation modules (CRIM) rather than by chemokine-receptor-specific signals. Thus, a generic signal provided by different receptors leads to discrete responses that depend on the specific identity of the cell that receives the signal. We present the implications of employing generic signals in different contexts such as gastrulation, axis specification and single-cell migration.