<i>Wilms Tumor 1b</i> defines a wound-specific sheath cell subpopulation associated with notochord repair.

Abstract

Regenerative therapy for degenerative spine disorders requires the identification of cells that can slow down and possibly reverse degenerative processes. Here, we identify an unanticipated wound-specific notochord sheath cell subpopulation that expresses Wilms Tumor (WT) 1b following injury in zebrafish. We show that localized damage leads to Wt1b expression in sheath cells, and that <i>wt1b</i>⁺cells migrate into the wound to form a stopper-like structure, likely to maintain structural integrity. <i>Wt1b</i>⁺sheath cells are distinct in expressing cartilage and vacuolar genes, and in repressing a Wt1b-p53 transcriptional programme. At the wound, <i>wt1b</i>⁺and <i>entpd5⁺</i> cells constitute separate, tightly-associated subpopulations. Surprisingly, <i>wt1b</i> expression at the site of injury is maintained even into adult stages in developing vertebrae, which form in an untypical manner via a cartilage intermediate. Given that notochord cells are retained in adult intervertebral discs, the identification of novel subpopulations may have important implications for regenerative spine disorder treatments.