| Abstract: | It has recently been suggested that the Arg-Gly-Asp sequence (RGD) forms part of a widespread cell-extracellular matrix recognition system. Analysis of the cell binding sites of vertebrate fibronectin and other extracellular proteins that interact with cell surfaces implicate the same amino acid triplet. Peptides containing this sequence inhibit certain developmental events such as cell-matrix adhesion or cellular migration in vitro and in vivo. The RGD-sequence is also part of the cellular recognition site of the aggregation protein discoidin I in Dictyostelium suggesting that the RGD-recognition system could be universally used. In Drosophila, despite its advanced genetics, very little is known about the extracellular components that are involved in cell movements and morphogenesis. We report here that peptides containing the RGD-sequence prevent gastrulation of Drosophila embryos. The phenotypic effect is similar to that observed in the dorsal-group mutants: no ventral furrow is formed and the embryos lack dorsal-ventral polarity. The specificity of the inhibiting action suggests that the RGD-sequence may also be used by invertebrates to mediate cell-attachment phenomena. |
