Opposing Roles of Wnt and BMP signaling in Zebrafish caudal fin regeneration

Presenter: Alan Gomez (Biology)

Mentor: Kryn Stankunas

Facilitator: Chris Moe

Zebrafish and many other vertebrates possess an incredible ability to regenerate damaged or amputated body parts including the retina, spinal chord, fins and limbs. The zebrafish caudal fin is a widely studied system because of its simple anatomy, accessibility, and robust ability to completely and consistently regenerate after amputation in under two weeks. Regeneration of the zebrafish caudal fin is dependent upon the formation of a proliferating mass of cells that grow at the amputation site called the blastema. The cells that line the bone rays in the mature zebrafish contribute to the blastema along with other cell types and are responsible for rebuilding the lost bone. These osteoblasts become activated after a fin injury through dramatic changes in their genetic program. Two signaling pathways called Wnt and BMP are particularly important for inducing these genetic changes and for organizing the spatial localization of osteoblasts in the blastema. BMP and Wnt are proteins that cause changes in gene expression programs of the cells that they physically interact with at the cell surface. Proper expression of Wnt and BMP in the blastema is essential for regeneration to occur. By examining the genes activated by Wnt and BMP during regeneration we have concluded that the gene expression programs activated by BMP work to counteract those of Wnt signaling. Investigating this feedback between BMP and Wnt has helped to characterize the specific roles that these signaling pathways play during the process of bone regeneration.