title: Expression, regulation, and requirement of the toll transmembrane protein during dorsal vessel formation in Drosophila melanogaster.
abstract: Early heart development in Drosophila and vertebrates involves the specification of cardiac precursor cells within paired progenitor fields, followed by their movement into a linear heart tube structure. The latter process requires coordinated cell interactions, migration, and differentiation as the primitive heart develops toward status as a functional organ. In the Drosophila embryo, cardioblasts emerge from bilateral dorsal mesoderm primordia, followed by alignment as rows of cells that meet at the midline and morph into a dorsal vessel. Genes that function in coordinating cardioblast organization, migration, and assembly are integral to heart development, and their encoded proteins need to be understood as to their roles in this vital morphogenetic process. Here we prove the Toll transmembrane protein is expressed in a secondary phase of heart formation, at lateral cardioblast surfaces as they align, migrate to the midline, and form the linear tube. The Toll dorsal vessel enhancer has been characterized, with its activity controlled by Dorsocross and Tinman transcription factors. Consistent with the observed protein expression pattern, phenotype analyses demonstrate Toll function is essential for normal dorsal vessel formation. Such findings implicate Toll as a critical cell adhesion molecule in the alignment and migration of cardioblasts during dorsal vessel morphogenesis.
authors.affiliation: Department of Biochemistry and Molecular Biology, Box 117, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
authors.forename: Jianbo
authors.initials: J
authors.lastname: Wang
authors.forename: Ye
authors.initials: Y
authors.lastname: Tao
authors.forename: Ingolf
authors.initials: I
authors.lastname: Reim
authors.forename: Kathleen
authors.initials: K
authors.lastname: Gajewski
authors.forename: Manfred
authors.initials: M
authors.lastname: Frasch
authors.forename: Robert A
authors.initials: RA
authors.lastname: Schulz
mesh_terms: D000818:Animals; D001483:Base Sequence; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology* / Q000235:genetics*; D004742:Enhancer Elements, Genetic / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D006321:Heart / Q000196:embryology*; D008648:Mesoderm / Q000378:metabolism; D008969:Molecular Sequence Data; D009024:Morphogenesis; D032386:Myoblasts, Cardiac / Q000166:cytology* / Q000378:metabolism*; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D010641:Phenotype; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism; D051193:Toll-Like Receptors; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation / Q000235:genetics
chemical_list: C476237:Doc1 protein, Drosophila; D029721:Drosophila Proteins; D011956:Receptors, Cell Surface; D012097:Repressor Proteins; C068721:Tl protein, Drosophila; D051193:Toll-Like Receptors; D015534:Trans-Activators; D014157:Transcription Factors; C102933:tin protein, Drosophila