Abstract
Abstract: :
Purpose: The c-Jun N-terminal kinase (JNK; also known as SAPK, stress activated protein kinase) signaling pathway is activated by cytotoxic stress. To investigate in vivo ultraviolet (UV) irradiation induced JNK pathway activation in corneal epithelial cells, the expression of JNK, apoptosis signal-regulating kinase 1 (ASK1), SAPK/ERK kinase (SEK1) and cytochrome c was analyzed in the cornea. Methods: Eyes of anaesthetized rats were exposed to 0.47J/cm2 of ultraviolet radiation (302nm), and expression of JNK1/2, ASK1, SEK1, and cytochrome C in corneal epithelial cells was examined by protein immunoblot analysis. Histopathology (TUNEL method) and immunohistochemistry for JNK were also performed. Results: Corneas exposed to UV radiation showed TUNEL positive staining in epithelial cells and superficial keratocytes at 1 hours after irradiation. After UV radiation, substantial expression of activated JNK1/2 was observed in corneal epithelial cells, whereas no expression of activated JNK1/2 was seen in non-irradiated contralateral corneas. The expression of ASK1, SEK1, and cytochrome C was also quickly upregulated in corneal epithelial cells after UV exposure. Conclusions: These data suggest that JNK and cytochrome c mediated death pathway may play an important role in UV-induced apoptosis of corneal epithelial cells.
Keywords: cornea: epithelium • apoptosis/cell death • signal transduction