High impact information on gbb

• The BMP homolog Gbb provides a retrograde signal that regulates synaptic growth at the Drosophila neuromuscular junction [1].
• Both decapentaplegic (dpp) protein and 60A protein have been implicated in pattern formation during Drosophila melanogaster embryogenesis [2].
• Given its high affinity for Gbb, this dual function of Sax impacts the function of Gbb in the Bmp activity gradient more profoundly than does Dpp [3].
• Gbb/Bmp signaling is essential for maintaining germline stem cells and for repressing bam transcription in the Drosophila testis [4].
• Retrograde Gbb signaling through the Bmp type 2 receptor wishful thinking regulates systemic FMRFa expression in Drosophila [5].

Biological context of gbb

• This sog misexpression phenotype is very similar to that of viable mutants of glass-bottom boat (gbb), which encodes a BMP family member [6].
• 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 [7].
• 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 [7].
• As the germ band retracts, and throughout later stages of embryonic development, the 60A transcript and protein are most readily detected in cells of the developing foregut and hindgut [8].
• Because of its localization on the polytene chromosome map, we refer to this gene as 60A [8].

Anatomical context of gbb

• 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 [7].
• We show that Gbb, a Bmp ligand expressed in the neurohemal organ provides a retrograde signal that helps specify the peptidergic phenotype of the Tv neurons [5].
• We present evidence that when dpp signaling is compromised, lowering the level of 60A impairs several dpp-dependent developmental processes examined, including the patterning of the visceral mesoderm, the embryonic ectoderm and the imaginal discs [9].
• Here, by contrast, we show that the maintenance and proliferation of germ line stem cells and their progeny depends upon their ability to transduce the activity of a somatically expressed TGF-beta ligand, the BMP5/8 ortholog Glass Bottom Boat [10].

Physical interactions of gbb

• We also confirm that Tsg and Cv have similar biochemical activities: Sog/Cv complex binds a Dpp/Gbb heterodimer with high affinity [11].

Other interactions of gbb

• TGF-beta/BMP superfamily members, Gbb-60A and Dpp, cooperate to provide pattern information and establish cell identity in the Drosophila wing [12].
• Furthermore, the critical ratio of Gbb-60A to Dpp signaling appears to be mediated by both Tkv and Sax type I receptors [12].
• These features strongly suggest that Crossveinless 2 acts extracelluarly or in the secretory pathway to directly potentiate Dpp or Gbb signaling [13].
• Our data indicate that Wit and Gbb function via the downstream transcription factor Mad and that Mad-mediated signaling is continuously required during development to confer competence of motoneurons to express synaptic homeostasis [14].

Analytical, diagnostic and therapeutic context of gbb

• Sequence analysis suggests that the Drosophila 60A gene is the dipteran homolog of this BMP subfamily and may provide clues to the physiologic functions of the products of these genes in human biology [15].

References