title: Effect of vitamin D receptor knockout on cornea epithelium wound healing and tight junctions.
abstract: OBJECTIVE
  Our laboratory previously determined that vitamin D3, the vitamin D receptor (VDR), and 1α hydroxylase are present and active in the eye. In this study, we examined the effects of VDR knockout on wound healing, the tight junction-associated proteins occludin and ZO-1, and tight junction numbers in mouse corneas.
  
  
  METHODS
  Epithelial wounds (2-mm) were made with an agar brush on 4-week-old and 10-week-old wild-type, heterozygous, and VDR knockout mouse corneas. Mice were on a normal or high lactose, Ca(2+), and PO₄(-) diet. Wound-healing area was measured over time. Real-time PCR was used to quantify occludin and ZO-1 message expression. Western blot was used for protein expression. Transmission electron microscopy was used to examine corneal epithelium and endothelium tight junctions. Immunofluorescence was used to examine epithelial ZO-1 distribution.
  
  
  RESULTS
  Results showed a decreased healing rate in 10-week-old VDR knockout mice compared with wild-types. Vitamin D receptor knockout mice on the special diet had no difference in healing rate compared with wild-types. Real-time PCR showed decreased expression of occludin and ZO-1 in 10-week-old VDR knockout mice compared with wild-types. Western blot of 10-week-old knockout mouse corneas showed decreased occludin expression compared with wild-types. Transmission electron microscopy showed a significant difference in tight junction numbers in VDR knockouts versus wild-types. Immunofluorescence showed a change in ZO-1 distribution among genotypes.
  
  
  CONCLUSIONS
  Vitamin D receptor knockout affects mouse corneal epithelium wound healing and tight junction integrity.
authors: Department of Cellular Biology and Anatomy, Georgia Regents University, Augusta, Georgia, United States.
authors: Rodolfo A
authors: RA
authors: Elizondo
authors: Department of Anatomy and Neuroscience, University of Tennessee Health Science Center, Memphis, Tennessee, United States.
authors: Zhaohong
authors: Z
authors: Yin
authors: Department of Cellular Biology and Anatomy, Georgia Regents University, Augusta, Georgia, United States.
authors: Xiaowen
authors: X
authors: Lu
authors: Department of Cellular Biology and Anatomy, Georgia Regents University, Augusta, Georgia, United States.
authors: Mitchell A
authors: MA
authors: Watsky
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004728:Endothelium, Corneal / Q000166:cytology / Q000502:physiology; D019573:Epithelium, Corneal / Q000166:cytology / Q000502:physiology*; D018345:Mice, Knockout; D062793:Occludin / Q000378:metabolism; D018167:Receptors, Calcitriol / Q000172:deficiency / Q000502:physiology*; D019108:Tight Junctions / Q000502:physiology*; D014945:Wound Healing / Q000502:physiology*; D062826:Zonula Occludens-1 Protein / Q000378:metabolism
chemical_list: D062793:Occludin; D018167:Receptors, Calcitriol; D062826:Zonula Occludens-1 Protein
keywords: corneal epithelium; tight junctions; vitamin D; wound healing