Abstract
Purpose: :
Previous study found that UV irradiation activates the JNK signaling pathway resulting in apoptosis. In the present study, we investigate further that the early events of UV stress-induced Kv channel hyperactivity linked to activation of the MEKK-JNK signaling pathway through cytoskeletal reorganizations.
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. UV irradiation experiments were performed by exposure of cell to UV-C light at a dosage of 42 µJ/cm2. ELISA and western analysis were performed to detect focal adhesion kinase (FAK) and Src activities, respectively. Integrin activation and cytoskeletal rearrangements were detected by immunostaining using specific antibodies.
Results: :
1) Exposed cells to UV irradiation resulted in markedly increased FAK and Src activities. 2) UV stress-induced activations of FAK and Src were abolished by inhibition of Kv channels with specific blocker, 4-aminopyridine (4-AP). 3) UV stress-induced a rapid and transient activation of integrin β5 detected by formations of integrin clustering in immunostaining experiments. 4) Cytoskeletal microfiber rearrangements were observed in UV exposed cells, suggesting that there were changed cell shape and leading edge detachment of these cells.
Conclusions: :
UV stress-induced corneal epithelial cell apoptosis involves cytoskeletal rearrangements through stimulating Kv channel hyperactivity and scaffold kinase activations, resulting in activation of the JNK signaling pathway.
Keywords: stress response • cornea: epithelium • cytoskeleton