ABSTRACT
In the zebrafish lateral line, non-sensory supporting cells readily re-enter the cell cycle to generate new hair cells and supporting cells during homeostatic maintenance and following damage to hair cells. This contrasts with supporting cells from mammalian vestibular and auditory sensory epithelia which rarely re-enter the cell cycle, and hence loss of hair cells results in permanent sensory deficit. Lateral line supporting cells are derived from multipotent progenitor cells that migrate down the trunk midline as a primordium and are deposited to differentiate into a neuromast. We have found that we can revert zebrafish support cells back to a migratory progenitor state by pharmacologically altering the signaling environment to mimic that of the migratory primordium, with active Wnt signaling and repressed FGF signaling. The reverted supporting cells migrate anteriorly and posteriorly along the horizontal myoseptum and will re-epithelialize to form an increased number of neuromasts along the midline when the pharmacological agents are removed. These data demonstrate that supporting cells can be readily reprogrammed to a migratory multipotent progenitor state that can form new sensory neuromasts, which has important implications for our understanding of how the lateral line system matures and expands in fish and also suggest avenues for returning mammalian supporting cells back to a proliferative state.
