Quynh Ton - The Roles of Semaphorin3d (Sema3d) Signaling in Fin Regeneration

 

The zebrafish fin is composed of multiple bony fin rays. Each fin ray is comprised of multiple segments separated by joints. Regulatory mechanisms that control joint morphogenesis and ray segment length in zebrafish fins are not fully understood. We found that the semaphorin3d (sema3d) gene is expressed during fin regeneration in a cx43-dependent manner. Semaphorins are signaling molecules involved in different signaling pathways, especially in axon guidance cues during pattering of the central nervous system. Interestingly, sema3d is found at the lateral compartment of the regenerating fin consistent with the location of precursor cells for bones and joints. Moreover, sema3d knock-down recapitulates the cx43 phenotype including reduced in growth and reduced in segments. Studies show that depending on the cell-type, Sema3s interact with neurophilin receptors (Nrps) either physically or indirectly via other receptor complexes. During fin regeneration, we found expression of only nrp2a. Interestingly, nrp2a is expressed in the skeletal precursors where sema3d expression was identified. We hypothesize that sema3d signaling through nrp2a regulates cell proliferation and inhibits joint formation.