Abstract
Purpose: :
The purpose of the study is to investigate hyperosmotic stress-induced activation of c-Jun/AP-1 through a novel Polo-like kinase 3 (Plk3) pathway in human corneal epithelial cells.
Methods: :
Human corneal epithelial (HCE) cells were cultured in DMEM/F12 medium containing 10% FBS and 5 µg/ml insulin at 37°C, 5% CO2. Hyperosmotic stress was applied with various concentrations of sorbitol to cultured cells for 1 h. Immunoprecipitation and kinase assays were employed to measure hyperosmotic stress-induced Plk3 kinase activity. Cell viability was detected by MTT assay and Immunoblot was performed to analyze the expression of protein with specific antibody.
Results: :
1) Hyperosmotic stress induced activation of Plk3 in a dose-dependent manner in HCE cells. 2)Cell growth significantly decreased after exposed HCE cells to hyperosmotic stress. 3)Hyperosmotic stress induced site-specific phosphorylation of c-jun at serine 63 and serine 73 in HCE cells. 4) Osmotic stress-induced activation of signaling cascades was detected by measuring p38 activities. 5) Effect of osmotic stress-induced Plk3 activation on cell viability was examined with various assays.
Conclusions: :
Our results, for the first time, provide a novel signaling mechanism that involves hyperosmotic stress-induced activation of Plk3 pathway in addition to p38 MAPK pathway to deregulate c-Jun activity resulting in control of HCE cell proliferation and apoptosis.
Keywords: stress response • cornea: epithelium • signal transduction