title: Wnt/β-Catenin Signaling Mediates Regeneration of Retinal Pigment Epithelium After Laser Photocoagulation in Mouse Eye.
abstract: OBJECTIVE
  Laser photocoagulation of retinal pigment epithelium (RPE) is used to stimulate the regenerative processes of the RPE. However, the molecular mechanisms that control RPE proliferation and the epithelial-mesenchymal transition (EMT) during regeneration remain poorly understood. We investigated the role of Wnt/β-catenin signaling in the regeneration of mouse RPE after laser photocoagulation.
  
  
  METHODS
  C57BL/6J mice were photocoagulated unilaterally. To determine the β-catenin-dependent Wnt signal transduction in the photocoagulated RPE, the expression levels of Wnts, β-catenin, and their target genes were analyzed using real time-PCR and Western blotting. Retinal pigment epithelium proliferation and EMT were determined by 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay and by profiling expression of EMT markers, respectively, in eyes injected intravitreally with a Wnt/β-catenin signaling antagonist, Dkk-1, after laser photocoagulation.
  
  
  RESULTS
  Expression of several of the 19 Wnt genes was significantly increased in laser-treated RPE. The expression levels of β-catenin signaling target genes cyclin D1, Otx2, and Mitf were higher in laser-treated RPE than in control RPE. The number of EdU-positive cells in the laser-treated area was significantly lower in the Dkk-1-injected group than in the laser-treated group or laser-treated + vehicle-injected group. There were more Otx2- and Mitf-positive cells after laser photocoagulation and markedly fewer in the Dkk-1-injected group. Otx2- and Mitf-positive cells were colocalized with EdU-positive cells. The EMT markers vimentin and α-smooth muscle actin (α-SMA) were upregulated in the laser-treated area and significantly downregulated in the Dkk-1-injected group.
  
  
  CONCLUSIONS
  Laser photocoagulation activates a Wnt/β-catenin signal transduction pathway, promoting both RPE proliferation and EMT. Wnt/β-catenin signaling also upregulates the expression of Otx2 and Mitf, key transcription factors in RPE formation. Our results demonstrate an important role for Wnt/β-catenin signaling in RPE proliferation and EMT, and suggest that manipulating Wnt/β-catenin signaling may have therapeutic potential for RPE regeneration.
authors.affiliation: Department of Ophthalmology, Soonchunhyang University, College of Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea.
authors.forename: Jung Woo
authors.initials: JW
authors.lastname: Han
authors.affiliation: Myung-Gok Eye Research Institute, Department of Medical Science, Konyang University, Daejeon, Korea.
authors.forename: Jungmook
authors.initials: J
authors.lastname: Lyu
authors.affiliation: Laboratory for Translational Research on Retinal and Macular Degeneration, Soonchunhyang University, College of Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea.
authors.forename: Yeo Jin
authors.initials: YJ
authors.lastname: Park
authors.affiliation: Department of Ophthalmology, Soonchunhyang University, College of Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea.
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Jang
authors.affiliation: Department of Ophthalmology, Soonchunhyang University, College of Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea 3Laboratory for Translational Research on Retinal and Macular Degeneration, Soonchunhyang University, College of Medicine.
authors.forename: Tae Kwann
authors.initials: TK
authors.lastname: Park
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation; D004195:Disease Models, Animal; D005451:Fluorescein Angiography; D005654:Fundus Oculi; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D017075:Laser Coagulation; D008268:Macular Degeneration / Q000175:diagnosis / Q000235:genetics* / Q000601:surgery; D051379:Mice; D008810:Mice, Inbred C57BL; D012313:RNA / Q000235:genetics; D012038:Regeneration; D055213:Retinal Pigment Epithelium / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051153:Wnt Proteins / Q000096:biosynthesis / Q000235:genetics*; D060449:Wnt Signaling Pathway / Q000235:genetics*; D051176:beta Catenin / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D051153:Wnt Proteins; D051176:beta Catenin; D012313:RNA