Effect of hypoxic stress-activated Polo-like kinase 3 on corneal epithelial wound healing.
OBJECTIVE
Hypoxia/reoxygenation conditions can generate oxidative stresses resulting in the suppression of cell proliferation and the delay of corneal epithelial wound healing. The purpose of this study was to investigate the cellular mechanism involving the role of the stress-responsive Polo-like kinase 3 (Plk3) in hypoxic stress-induced delay of corneal epithelial wound healing.


METHODS
Plk3 activities were determined by immunochemistry and immunocomplex kinase assay approaches. Corneal epithelial wound healing was evaluated by a whole-eye organ culture model and by scratch-induced wound closure assay. Corneal epithelial layer was removed by using a corneal rust-ring-remover in wild-type and Plk3(-/-) mice. Wound healing was analyzed using a confocal imaging system. Cell growth was measured by MTT assays.


RESULTS
The effect of hypoxic stress on early stages of corneal epithelial wound healing was compared with other oxidative stresses, including UV, CoCl(2), and H(2)O(2) treatments. Hypoxic stress-induced delay of corneal epithelial wound healing was further evaluated in human corneal epithelial cells and in the corneas of wild-type and Plk3 knockout (Plk3(-/-)) mice. Hypoxic stress-induced Plk3 activation resulted in growth attenuation and delay of wound healing. Further evidence demonstrated that the increase in Plk3 activity in constitutively active Plk3-expressed cells significantly enhanced stress-induced delay of wound healing. In contrast, hypoxic stress-induced delay of wound healing was markedly diminished in the corneas of Plk3 deficient Plk3(-/-) mice.


CONCLUSIONS
These results provide for the first time important evidence that Plk3 plays a significant role in hypoxic stress-induced attenuation of cell growth and delay of corneal epithelial wound healing.
Lu
Jiawei
J
Division of Molecular Medicine, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Torrance, California 90502, USA.
Wang
Ling
L
Dai
Wei
W
Lu
Luo
L
D000818:Animals; D015153:Blotting, Western; D049109:Cell Proliferation; D002478:Cells, Cultured; D003035:Cobalt / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D019573:Epithelium, Corneal / Q000187:drug effects / Q000201:enzymology* / Q000528:radiation effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D000860:Hypoxia / Q000378:metabolism*; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D009924:Organ Culture Techniques; D018384:Oxidative Stress / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D014945:Wound Healing / Q000502:physiology*
D003035:Cobalt; D006861:Hydrogen Peroxide; C093328:Plk3 protein, mouse; D017346:Protein Serine-Threonine Kinases; C018021:cobaltous chloride