Differential expression of the integrin subunits in human fetal membranes.

The distribution of the alpha 1, alpha 3-alpha 6, beta 1, beta 3 and beta 4 integrin subunits in fetal membranes at term was examined using an indirect immunofluorescence technique and confocal laser scanning microscopy. In the amniotic epithelium, beta 4 integrin (alpha 6 beta 4) exhibited distinct basal localization, whereas beta 1 integrins (alpha 3 beta 1, alpha 5 beta 1) were localized basolaterally. This finding suggests that integrins, especially alpha 6 beta 4 which is a structural component of the hemidesmosomes, may function as basement membrane receptors. Integrins localized laterally may play a role in cell-cell interactions. beta 1 (alpha 1 beta 1, alpha 5 beta 1) integrins are probably involved in cell-matrix interactions in the connective tissue layers which are rich in collagens and fibronectin. Cytotrophoblasts, located predominantly towards the chorionic basement membrane, mainly expressed alpha 6 beta 4, while those located predominantly in the vicinity of decidua expressed alpha 5 beta 1, alpha 3 beta 1 and alpha 1 beta 1. Decidual cells expressed alpha 3 beta 1 and alpha 1 beta 1, whereas alpha 1, alpha 5, alpha 6, beta 1 and beta 4 were expressed in blood vessels. This pattern of integrin expression reflects the reported difference in composition of the extracellular matrix at these locations and obviates an important role for alpha 5 beta 1 at the chorio-decidual interface. The differential integrin expression at the cell-basement membrane interfaces demonstrated in this study (at amniotic epithelium, cytotrophoblasts, decidual cells and blood vessels) indicated a differential recognition of basement membranes by these cells.(ABSTRACT TRUNCATED AT 250 WORDS)