Genetic Analysis of the Bone Morphogenetic Protein-Related Gene, gbb, Identifies Multiple Requirements During Drosophila Development

Abstract We have isolated mutations in the Drosophila melanogaster gene glass bottom boat (gbb), which encodes a TGF-β signaling molecule (formerly referred to as 60A) with highest sequence similarity to members of the bone morphogenetic protein (BMP) subgroup including vertebrate BMPs 5-8. Genetic analysis of both null and hypomorphic gbb alleles indicates that the gene is required in many developmental processes, including embryonic midgut morphogenesis, patterning of the larval cuticle, fat body morphology, and development and patterning of the imaginal discs. In the embryonic midgut, we show that gbb is required for the formation of the anterior constriction and for maintenance of the homeotic gene Antennapedia in the visceral mesoderm. In addition, we show a requirement for gbb in the anterior and posterior cells of the underlying endoderm and in the formation and extension of the gastric caecae. gbb is required in all the imaginal discs for proper disc growth and for specification of veins in the wing and of macrochaete in the notum. Significantly, some of these tissues have been shown to also require the Drosophila BMP2/4 homolog decapentaplegic (dpp), while others do not. These results indicate that signaling by both gbb and dpp may contribute to the development of some tissues, while in others, gbb may signal independently of dpp.

Download Full-text

Characterization of a homolog of human bone morphogenetic protein 1 in the embryo of the sea urchin, Strongylocentrotus purpuratus

Development ◽

10.1242/dev.120.3.559 ◽

1994 ◽

Vol 120 (3) ◽

pp. 559-568 ◽

Cited By ~ 1

Author(s):

S.P. Hwang ◽

J.S. Partin ◽

W.J. Lennarz

Keyword(s):

Bone Morphogenetic Protein ◽

Sea Urchin ◽

Sequence Similarity ◽

Human Bone ◽

Blastula Stage ◽

Morphogenetic Protein ◽

Sea Urchin Embryo ◽

Human Bone Morphogenetic Protein ◽

Maximal Expression ◽

Bone Morphogenetic Protein 1

A cDNA clone encoding a protein homologous to human bone morphogenetic protein 1 (huBMP1) was isolated from a sea urchin embryo cDNA library. This sea urchin gene, named suBMP, encodes a protein of M(r) of 72 × 10(3). The deduced amino acid sequence of suBMP shares 72% sequence similarity (55% identity) with that of huBMP1. Like huBMP1 it also contains an N-terminal metalloendoprotease domain that shares sequence similarity with the astacin protease from crayfish, a C-terminal domain that is similar to the repeat domain found in C1r or C1s serine proteases, and an EGF-like segment. Although suBMP mRNA was detectable at a low level in the unfertilized egg, maximal expression of mRNA was observed at hatched blastula stage, with only a modest decrease in level at later stages of development. In situ hybridization studies revealed that suBMP mRNA is found in both ectodermal and primary mesenchyme cells in hatched blastula-stage embryos. Maximal expression of suBMP was observed at mesenchyme blastula, just before the onset of primitive skeleton (spicule) formation. SuBMP was found by immunoelectronmicroscopy in all cell types in late gastrula stage embryos. The antibody gold particles appeared in small clusters in the cytoplasm, on the surface of the cells and within the blastocoel. This distribution of suBMP, coupled with the finding that it was associated with membranes but was released by sodium carbonate treatment, suggests that the protein is secreted, and subsequently associates with a cell surface component. Two models for the possible function of suBMP in spiculogenesis in the sea urchin embryo are discussed.

Download Full-text