High impact information on bap

• We focus on the regulation of two mesodermal genes: bagpipe (bap), which defines the anlagen of the visceral musculature of the midgut, and serpent (srp), which marks the anlagen of the fat body [1].
• Here, we describe two homeo box genes, tinman (tin) and bagpipe (bap), which spatially subdivide the mesoderm and determine cell fates in the dorsal mesoderm [2].
• In embryos mutant for bap, visceral mesoderm formation is strongly disrupted [2].
• The mouse Bapx1 gene is homologous to the Drosophila homeobox containing bagpipe (bap) gene [3].
• Our present study addresses how positive Dpp signals and antagonistic Wg inputs are integrated at the enhancer level of bagpipe (bap), a NK homeobox gene that serves as an early regulator of visceral mesoderm development [4].

Biological context of bap

• In addition, we show that binding sites for yet unknown repressors are essential to prevent the induction of the bap enhancer by Dpp in the dorsal ectoderm [4].
• The haplotype structure of bap is more complex: about half of the sequences are identical (or virtually so), while the rest are fairly heterogeneous [5].
• Recombination rate and gene conversion are also higher for bap than for tin [5].
• There is strong linkage disequilibrium, with the highest values in the introns of both genes and exon II of bap [5].
• Mtn transcription is not altered in homozygous mutants of four genes (lab, wg, dpp, bap) known to be involved in midgut morphogenesis [6].

Anatomical context of bap

• An evolutionarily conserved vertebrate homologue of the Drosophila NK-3 homeodomain gene bagpipe, Nkx3-1, is expressed in vascular and visceral mesoderm-derived muscle tissues and may influence smooth muscle cell differentiation [7].

Physical interactions of bap

• We show that an evolutionarily conserved bap enhancer element requires combinatorial binding sites for Tin and Dpp-activated Smad proteins for its activity [4].

References