Decaying and expanding Erk gradients process memory of skeletal size during zebrafish fin regeneration [Fin tip]

Although appreciated for centuries, the identity of position-dependent cues and how they control tissue growth are not resolved. Here, we quantify Erk signaling events in populations of osteoblasts during zebrafish fin regeneration.

We find osteoblast Erk activity depends on Fgf receptor signaling and organizes into millimeter-long gradients spanning the distal tip to the amputation site. Erk activity scales with amount of tissue amputated, predicts likelihood of osteoblast cycling, and predicts size of regenerated skeletal structures. Mathematical modeling suggests gradients are established by transient deposition of long-lived ligands that are transported by tissue growth.