INTEGRIN SUBUNIT EXPRESSION ASSOCIATED WITH EPITHELIAL-MESENCHYMAL INTERACTIONS DURING MURINE TOOTH DEVELOPMENT

The initial information for patterning of early tooth development resi des in the epithelium. Later, this is shifted to the mesenchyme. The p rocess is governed by multiple epithelial-mesenchymal interactions, In tegrins are cell surface receptors for extracellular matrix components . Expression of the beta(5) integrin subunit alternates between epithe lium and mesenchyme during early tooth development (Yamada et al, [199 4] Int, J. Dev. Biol, 38: 553-556), By immunofluorescence and in situ hybridization we show here a remarkably similar oscillating expression pattern of the alpha(v) integrin subunit. This subunit is known to as sociate with beta(5), and we therefore suggest that integrin alpha(v) beta(5) is involved in epithelial-mesenchymal interactions during toot h development, We also demonstrate that the developing tooth epitheliu m expresses the alpha(6), beta(1) and beta(4) subunits. The laminin re ceptors alpha(6) beta(1) and alpha(6) beta(4) may thus in part mediate the effect of basement membranes on tooth epithelial development. Int erestingly, the enamel knot region expressed very little alpha(6) inte grin subunit, whereas some expression was seen transiently in the cond ensing mesenchyme, During early tooth development, integrins possessin g the alpha(6), subunit might also be involved in cell-cell interactio ns independently of laminins. (C) 1996 Wiley-Liss, Inc.