title: Polyploidization and cell fusion contribute to wound healing in the adult Drosophila epithelium.
abstract: BACKGROUND
  Reestablishing epithelial integrity and biosynthetic capacity is critically important following tissue damage. The adult Drosophila abdominal epithelium provides an attractive new system to address how postmitotic diploid cells contribute to repair.
  
  
  RESULTS
  Puncture wounds to the adult Drosophila epidermis close initially by forming a melanized scab. We found that epithelial cells near the wound site fuse to form a giant syncytium, which sends lamellae under the scab to re-epithelialize the damaged site. Other large cells arise more peripherally by initiating endocycles and becoming polyploid, or by cell fusion. Rac GTPase activity is needed for syncytium formation, while the Hippo signaling effector Yorkie modulates both polyploidization and cell fusion. Large cell formation is functionally important because when both polyploidization and fusion are blocked, wounds do not re-epithelialize.
  
  
  CONCLUSIONS
  Our observations indicate that cell mass lost upon wounding can be replaced by polyploidization instead of mitotic proliferation. We propose that large cells generated by polyploidization or cell fusion are essential because they are better able than diploid cells to mechanically stabilize wounds, especially those containing permanent acellular structures, such as scar tissue.
authors.affiliation: Department of Embryology, Carnegie Institution for Science, Howard Hughes Medical Institute, 3520 San Martin Drive, Baltimore, MD 21218, USA.
authors.forename: Vicki P
authors.initials: VP
authors.lastname: Losick
authors.affiliation: Department of Pharmacology and Cancer Biology and Department of Cell Biology, Duke University Medical Center, C318 LSRC Box 3813, Durham, NC 27710, USA.
authors.forename: Donald T
authors.initials: DT
authors.lastname: Fox
authors.affiliation: Department of Embryology, Carnegie Institution for Science, Howard Hughes Medical Institute, 3520 San Martin Drive, Baltimore, MD 21218, USA. Electronic address: spradling@ciwemb.edu.
authors.forename: Allan C
authors.initials: AC
authors.lastname: Spradling
mesh_terms: D000007:Abdominal Injuries / Q000473:pathology; D000367:Age Factors; D000818:Animals; D030801:Animals, Genetically Modified; D002453:Cell Cycle; D002459:Cell Fusion; D019927:Cyclin E / Q000235:genetics / Q000378:metabolism; D004330:Drosophila / Q000166:cytology / Q000502:physiology*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011123:Polyploidy; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014945:Wound Healing / Q000502:physiology*; D000091102:YAP-Signaling Proteins; D020744:rac GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D000099317:Hippo Kinases
chemical_list: D019927:Cyclin E; D029721:Drosophila Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D017346:Protein Serine-Threonine Kinases; D015534:Trans-Activators; D000091102:YAP-Signaling Proteins; D020744:rac GTP-Binding Proteins; C503814:Yki protein, Drosophila; C499474:hpo protein, Drosophila; D000099317:Hippo Kinases