AP-1 (c-Fos/c-Jun) is required for corneal epithelial spreading

Purpose: We previously demonstrated that the AP-1 components c-fos/c-jun are up-regulated in healing rat corneal epithelium in a relatively early phase following epithelial debridement, implicating the AP-1 function in the initiation of cell movement. To explore this hypothesis, we examined the effect of lack of c-Fos and c-Jun protein expressions on the spreading of corneal epithelium and in situ in organ culture. Antisense-oligonucleotide (AS) c-fos-null mice were used for this purpose. Methods: A rectangular piece of corneal tissue (2 x 2 mm) was obtained from each eye of recently killed adult C57BL/6 mice and was incubated for 11 h in culture medium with 8 muM c-fos AS or c-jun AS probe. Sense probes were used for negative control. A rectangular section of corneal tissue was also obtained from each eye of c-fos(-/-), c-fos(+/-) and c-fos(+/+) mice and was organ-cultured for 11 h. The length of the path of epithelial spreading on stromal cut surface (both sides) was measured in hematoxylin-eosinstained specimens. Data were analyzed by unpaired Student's t-test. Results: Addition of c-fos AS to the medium decreased the length of epithelial spread to 40.36% of that in the control with the S probe. Addition of c-jun AS decreased the length of epithelial spreading rate to 42.71% of control with S probe. Lacking c-Fos decreased the epithelial spreading to 17.73% of control data from c-fos(+/-) and c-fos(+/+) mice. Conclusion: AP-1 (c-Fos/c-Jun) is required for the corneal epithelial spreading.