The ''cell-matrix attachment complex'' (CMAX) in embryonic epithelia contains zyxin and vinculin.
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Zyxin, vinculin and paxillin are components of focal adhesions. We describe areas of cell-matrix interaction, the CMAX, along basal lateral membranes of whole epithelia which contain zyxin and vinculin. Previous studies have shown that epithelia isolated without basal lamina (-BL) have F-actin localized in basal cell cytoplasmic blebs. These blebs respond to laminin (LM) by reorganizing F-actin into a filamentous network, the actin cortical mat (ACM), to tissue cultured with cytochalasin D (CD), P-actin is disrupted into aggregates. We asked: What is the intracellular distribution of zyxin, vinculin, and paxillin in embryonic Avian corneal epithelia? Do zyxin, vinculin, or paxillin colocalizc with F-actin in cytoplasmic blebs, in LM induced reorganized ACM, or CD induced actin aggregates? The 6-day embryonic Avian comeal epithelia was isolated with the BL or -BL and cultured in the presence of control media, +10 ng/ml LM, or +LM and 2M CD for 2hrs. Immunohistochemistry and confocal microscopy was used to analyze intracellular protein distribution. In epithelia with an ACM, zyxin and vinculin were localized to discrete areas along superior and inferior basal lateral membranes at the ends of P-actin in the ACM optical plane. In epithelia isolated -BL and in CD treated epithelia, zyxin and vinculin did not localize to discrete areas along the inferior basal lateral membranes and appeared diffuse throughout the epithelia. Paxillin was punctate in the basal cells in all treatment groups. In our whole tissue model, zyxin and vinculin appear to anchor F-actin at the CMAX of corneal epithelial tissue and are involved in cell-cell attachment in the periderm cells. Supported by NTH grant EY-08886.
