Abstract
Purpose: :
The purpose of the study is to investigate the interaction between c–Jun and Polo–like kinase 3 (Plk3) in UV irradiation–induced corneal epithelial cell apoptosis. Previous studies showed that Plk3 is responsive to DNA damage and regulates M phase in the cell cycle. We hypothesize that Plk3 interacts with UV–sensitive AP–1 that is composed of Jun, Fos and ATF dimmers to regulate corneal epithelial cell fate.
Methods: :
rabbit and human cornea epithelial cell were cultured in DMEM/F12 medium containing 10% FBS and 5 µg/ml insulin at 37°C, 5% CO2. Western blot, immunoprecipitation and kinase assays were employed to measure UV–induced Plk3 kinase activity. Protein interactions were detected by using protein pull down assay and immunofluorescence analysis with special antibodies.
Results: :
1) UV irradiation activated Plk3 kinase and induced c–Jun phosphorylation in corneal epithelial cells. 2) UV–activated Plk3 phosphorylated c–Jun protein in vitro. 3) The exclusion of JNK kinase, the phosphorylation of c–Jun by Plk3 is not changed. 4) Direct protein–protein interaction between Plk3 and c–Jun was detected in normal and UV irradiated corneal epithelial cells. 5) Plk3 and c–Jun were collocated in nuclei of corneal epithelial cells detected by immunofluorescence analysis.
Conclusions: :
Our results provided for the first time that Plk3 mediates UV irradiation–induced c–Jun phosphorylation in corneal epithelial cells. It suggests that Plk3 plays an important role in mediating UV–induced DNA damage to activation of c–Jun.
Keywords: cornea: epithelium • phosphorylation • radiation damage: light/UV