Cytoskeletal and cell adhesion defects in wounded and Pax6+/- corneal epithelia.

PURPOSE

PAX6 heterozygosity (PAX6(+/-)) causes aniridia and aniridia-related keratopathy (ARK) in humans, but the pathway from gene dosage deficiency to clinical disease has not been fully characterized. Recently, the authors suggested a model of a chronic wound state exacerbated by oxidative stress, showed the barrier function of Pax6(+/-) corneas is compromised and suggested Pax6(+/-) corneas show the molecular signature of a perpetual wound-healing state.

METHODS

Pax6(+/-) mice were used as a model for Pax6-related corneal diseases and in vivo wound-healing assays. Immunohistochemistry and electron microscopy analyses were performed on mutant and wounded corneas.

RESULTS

This work reports defects in keratin, desmoplakin, and actin-based cytoskeletal structures in Pax6(+/-) cells. During wild-type corneal reepithelialization, cell fissures and desquamation, intracellular vesicles, intercellular gaps, and filopodialike structures were apparent, similar to the phenotypes seen in "unwounded" Pax6(+/-) corneal epithelia. Pax6(+/-) cells and wounded wild-type cells showed changed patterns of desmoplakin and actin localization. Protein oxidation and ERK1/2 and p38 MAPK phosphorylation were barely detected in the basal cells of intact wild-type corneal epithelia, but they were found in basal wild-type cells near the wound edge and throughout Pax6(+/-) corneal epithelia.

CONCLUSIONS

These data show that cell junctions and cytoskeleton organization are dynamically remodeled in vivo by wounding and in Pax6(+/-) corneas. This apparent wound-healing phenotype contributes to the clinical aspects of ARK.