Exploring the role of actinotrichia during fin regeneration
Date
2024
Authors
Thomason, Madeline
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
Zebrafish are capable of robustly regenerating injured limbs and organs. After amputation of zebrafish fins, a blastema is formed which is subsequently populated by Wnt-producing "niche" cells beginning at 3 days post amputation (dpa). This coincides with the timeline of actinotrichia production, as actinotrichia collagens begin to be produced between 2 and 3 dpa. Actinotrichia are unique spoke-like collagen structures that stabilize the fin tip while bony rays are still forming. It is thought that actinotrichia treadmill proximally and are degraded as they come into proximity of newly mineralizing bone. Actinotrichia remain present in the distal tips of unamputated fins, and it is thought that they act in support of fin tissue in areas without mature bone. In larval zebrafish, fin mesenchymal cells produce and orient actinotrichia through cellular protrusions. We sought to determine whether, in the regenerating adult fin, Wnt-producing "niche" cells similarly wrap actinotrichia in actin-rich protrusions, and to determine pathways that directly regulate these interactions. We explored two lines of inquiry; (1) How do actinotrichia and niche cells interact? And (2) What factors promote actinotrichia formation? Through time course imaging of a regenerating fin, we concluded that actinotrichia components appear at 2dpa, which is earlier than previously recorded. To explore actinotrichia-niche cell interactions, we stained and imaged fin sections. We observed niche cells colocalizing with actinotrichia, as well as actinotrichia appearing to wrap around dach-positive niche cells. In our exploration of the factors promoting actinotrichia formation, we used Wnt RNA-seq data and drug treatments to conclude that the Wnt and TGF-β pathways are not directly upstream of actinotrichia production. Our findings provide contributions toward a better understanding of regeneration, which has exciting implications for improving human healing.
Description
Keywords
Zebrafish, Actinotrichia, Stankunas Lab, Regeneration, Mesenchymal Cells