Integrin expression in developing human salivary glands.

The development and complete differentiation of salivary glands is a complex process that involves a large number of co-ordinated events. Little is known about the molecular basis for salivary gland development. However, we have reported previously that integrins appear to play a role. Integrins are heterodimeric transmembrane receptors consisting of one alpha and one beta subunit that play a pivotal role in the interaction of cells with the extracellular matrix. Such interactions regulate the organisation of cells of tissues and organs during development as well as cell proliferation and differentiation. Using immunohistochemistry and Western and Northern blot analysis, we mapped the localisation and expression of integrins beta1, beta3 and beta4 in human salivary glands obtained from foetuses ranging from weeks 4-24 of gestation and compared it with adult salivary glands. Integrin beta1 first appeared during the canalisation stage and during the differentiation stage. A message first appeared at week 6 of development. The expression of beta4 integrin protein and message was observed only in the late stage of differentiation. Integrin beta3 was not detected in the developing glands; however, integrins beta1, beta3 and beta4 were all expressed in adult salivary gland tissues. The data suggest that integrins, particularly beta1, have a role to play in salivary gland development and differentiation.