title: BMP-2 induces ectopic expression of cardiac lineage markers and interferes with somite formation in chicken embryos.
abstract: In Drosophila induction of the homeobox gene tinman and subsequent heart formation are dependent on dpp signaling from overlying ectoderm. In order to define vertebrate heart-inducing signals we screened for dpp-homologues expressed in HH stage 4 chicken embryos. The majority of transcripts were found to be BMP-2 among several other members of the BMP family. From embryonic HH stage 4 onwards cardiogenic mesoderm appeared to be in close contact to BMP-2 expressing cells which initially were present in lateral mesoderm and subsequently after headfold formation in the pharyngeal endoderm. In order to assess the role of BMP-2 for heart formation, gastrulating chick embryos in New culture were implanted with BMP-2 producing cells. BMP-2 implantation resulted in ectopic cardiac mesoderm specification. BMP-2 was able to induce Nkx2-5 expression ectopically within the anterior head domain, while GATA-4 was also induced more caudally. Cardiogenic induction by BMP-2, however remained incomplete, since neither Nkx2-8 nor the cardiac-restricted structural gene VMHC-1 became ectopically induced. BMP-2 expressing cells implanted adjacent to paraxial mesoderm resulted in impaired somite formation and blocked the expression of marker genes, such as paraxis, Pax-3, and the forkhead gene cFKH-1. These results suggest that BMP-2 is part of the complex of cardiogenic signals and is involved in the patterning of early mesoderm similar to the role of dpp in Drosophila.
authors.affiliation: Department of Cell and Molecular Biology, Institute for Biochemistry and Biotechnology, Technical University of Braunschweig, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Andrée
authors.forename: D
authors.initials: D
authors.lastname: Duprez
authors.forename: B
authors.initials: B
authors.lastname: Vorbusch
authors.forename: H H
authors.initials: HH
authors.lastname: Arnold
authors.forename: T
authors.initials: T
authors.lastname: Brand
mesh_terms: D000818:Animals; D001483:Base Sequence; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000494:pharmacology*; D002642:Chick Embryo; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D005775:Gastrula / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D005819:Genetic Markers; D006321:Heart / Q000187:drug effects / Q000196:embryology*; D017403:In Situ Hybridization; D008648:Mesoderm / Q000166:cytology / Q000187:drug effects; D016133:Polymerase Chain Reaction; D019170:Somites / Q000166:cytology / Q000187:drug effects*; D016212:Transforming Growth Factor beta
chemical_list: D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D017931:DNA Primers; D005819:Genetic Markers; D016212:Transforming Growth Factor beta