Regeneration of Amputated Zebrafish Fin Rays from De Novo Osteoblasts

摘要

Determining the cellular source of new skeletal elements is critical for understanding appendage regeneration in amphibians and fish. Recent lineage-tracing studies indicated that zebrafish fin ray bone regenerates through the dedifferentiation and proliferation of spared osteoblasts, with limited if any contribution from other cell types. Here, we examined the requirement for this mechanism by using genetic ablation techniques to destroy virtually all skeletal osteoblasts in adult zebrafish fins. Animals survived this injury and restored the osteoblast population within 2 weeks. Moreover, amputated fins depleted of osteoblasts regenerated new fin ray structures at rates indistinguishable from fins possessing a resident osteoblast population. Inducible genetic fate mapping confirmed that new bone cells do not arise from dedifferentiated osteoblasts under these conditions. Our findings demonstrate diversity in the cellular origins of appendage bone and reveal that de novo osteoblasts can fully support the regeneration of amputated zebrafish fins. Following conventional amputation, zebrafish fins regenerate osteoblasts via dedifferentiation and proliferation of existing osteoblasts. Singh et al. find that transgenic ablation of osteoblasts unexpectedly allows normal regeneration via new osteoblasts emerging from nonosteoblasts. This regenerative plasticity of cell origin suggests that osteoblasts prevent other cells from becoming osteoblasts during regeneration.