391C Poster - 04. Stem cells, regeneration and tissue injury
Saturday April 09, 1:30 PM - 3:30 PM

Authors:
James White; Kimi LaFever Hodge; Ivy Han; Jasmine Su; M. Shane Hutson; Andrea Page-McCaw

Affiliation: Vanderbilt University

Keywords:
o. wound healing; y. live imaging

In the past decade, there has been increased awareness of cellular polyploidy in development, homeostasis, and cancer. In addition to being a conserved developmentally programmed behavior, polyploidy is also induced in response to injury. Work by Vicki Losick has shown adult Drosophila epithelia repair by becoming polyploid through endoreplication and cell-cell fusion. In Zebrafish epicardial explants, regeneration is led by a wavefront of polyploid cells. We have found that both endocycling and cell fusions occur after laser wounding in the pupal notum, a system that supports live imaging. By imaging living tissue, we find that syncytia are able to close wounds faster than non-syncytial neighboring cells, and when syncytia formation is blocked, wounds close more slowly. Live imaging also allowed us to determine that cell-cell fusions occur within the first 20-30 minutes after wounding, and cell borders break down within the first 3 rows of cells from the wound. Thus, multinuclear syncytia form very rapidly and are positioned at the front lines of wound repair. The majority of fusion events occur between cells at different distances from the wound, as opposed to neighbors in the same row. Given this new spatial-temporal information I hypothesize fusions of sequential rows of cells allows distal cellular resources to be pooled at the leading edge of wound repair allowing for the construction of large actin-rich contractile structures. Preliminary live-imaging studies of actin support this hypothesis, as actin label in fused cells aggregates at the wound margin in large filipodia like structures. These large structures likely allow for rapid migration during the early stages of wound repair.