Decaying and Expanding ERK Gradients Process Memory of Skeletal Size During Zebrafish Fin Regeneration

This study investigates the role of Erk signaling in zebrafish fin regeneration, focusing on how positional memory influences tissue growth. Researchers found that Erk activity in osteoblasts is dependent on Fgf receptor signaling and forms gradients from the distal tip to the amputation site. These gradients, which scale with the amount of tissue amputated, predict osteoblast cycling and the size of regenerated skeletal structures. Mathematical modeling suggests that these gradients are established by long-lived ligands transported by tissue growth. The study highlights the importance of localized, scaled expression of pro-regenerative ligands, such as <i>fgf20a</i>, in directing long-range signaling and controlling skeletal size during regeneration.