THE TRIBOLIUM DECAPENTAPLEGIC GENE IS SIMILAR IN SEQUENCE, STRUCTURE,AND EXPRESSION TO THE DROSOPHILA DPP GENE

We are characterizing members of the Transforming Growth Factor-beta ( TGF-beta) superfamily in the red flour beetle, Tribolium castaneum, in order to examine the evolutionary conservation of the structure and f unction of TGF-beta-like genes during insect development. A decapentap legic-like gene of the TGF-beta superfamily was isolated in Tribolium (Tc dpp) that is similar in sequence, organization, and expression to the Drosophila melanogaster dpp gene (Dm dpp). Conserved features incl ude a high degree of sequence similarity in both the pro-domain and ma ture domains of the encoded polypeptide. In addition, the position of an intron within the protein-coding region is conserved in Tc dpp, Dm dpp, and two bone morphogenetic protein genes of the TGF-beta superfam ily in humans, BMP2 and BMP4. Consensus binding sites for the dorsal t ranscription factor are found within this intron in Tc dpp similar to the intronic location of several dorsal binding sites in Dm dpp. Durin g embryogenesis, Tc dpp is expressed in an anterior cap of serosa cell s at the blastoderm stage, in the dorsal ectoderm at the lateral edges of the developing and extended germ band, and in the distal tips of d eveloping embryonic appendages. Several aspects of embryonic expressio n, similar in both flies and beetles, suggest conserved roles for dpp in cellular communication during the development of these distantly re lated insects.