Distribution of integrins alpha 6 and beta 4 in the rabbit corneal epithelium after anterior keratectomy.

Integrins are heterodimeric cell-surface receptor glycoproteins involved in cell-matrix and also in cell-cell interactions. The alpha 6 beta 4 integrin heterodimer has been shown to be a component of the hemidesmosome. In response to wounding, hemidesmosomes are disassembled, the epithelium migrates to cover the denuded area, and eventually the hemidesmosomes reappear. In the present investigation the distribution of the integrin alpha 6 and beta 4 subunits after anterior keratectomy was studied by indirect immunohistochemistry. Labeling for the alpha 6 subunit was observed around the entire cell surface, right to the leading edge. The immunoreaction for the beta 4 subunit was confined to the basal cell membrane facing the basement membrane as in the normal cornea. Cells at the leading edge of the migrating epithelium did not show any labeling for beta 4. Patchy labeling for beta 4 was first observed in the region midway between the wound margin and the leading edge. Because integrins are only expressed as heterodimers, the alpha 6 subunit may be complexed with the beta 1 subunit, instead of with beta 4, at the leading edge of the migrating epithelium. We also suggest that this alpha 6 beta 1 heterodimer may play a role in the reformation of the adhesion complex.