title: The single fgf receptor gene in the beetle Tribolium castaneum codes for two isoforms that integrate FGF8- and Branchless-dependent signals.
abstract: The precise regulation of cell-cell communication by numerous signal-transduction pathways is fundamental for many different processes during embryonic development. One important signalling pathway is the evolutionary conserved fibroblast-growth-factor (FGF)-pathway that controls processes like cell migration, axis specification and mesoderm formation in vertebrate and invertebrate animals. In the model insect Drosophila, the FGF ligand / receptor combinations of FGF8 (Pyramus and Thisbe) / Heartless (Htl) and Branchless (Bnl) / Breathless (Btl) are required for the migration of mesodermal cells and for the formation of the tracheal network respectively with both the receptors functioning independently of each other. However, only a single fgf-receptor gene (Tc-fgfr) has been identified in the genome of the beetle Tribolium. We therefore asked whether both the ligands Fgf8 and Bnl could transduce their signal through a common FGF-receptor in Tribolium. Indeed, we found that the function of the single Tc-fgfr gene is essential for mesoderm differentiation as well as for the formation of the tracheal network during early development. Ligand specific RNAi for Tc-fgf8 and Tc-bnl resulted in two distinct non-overlapping phenotypes of impaired mesoderm differentiation and abnormal formation of the tracheal network in Tc-fgf8- and Tc-bnl(RNAi) embryos respectively. We further show that the single Tc-fgfr gene encodes at least two different receptor isoforms that are generated through alternative splicing. We in addition demonstrate through exon-specific RNAi their distinct tissue-specific functions. Finally, we discuss the structure of the fgf-receptor gene from an evolutionary perspective.
authors: University of Rostock, Biological Sciences, Department of Genetics, Albert-Einsteinstr. 3, 18059 Rostock, Germany.
authors: Rahul
authors: R
authors: Sharma
authors: University of Rostock, Biological Sciences, Department of Genetics, Albert-Einsteinstr. 3, 18059 Rostock, Germany.
authors: Katharina
authors: K
authors: Beer
authors: University of Rostock, Biological Sciences, Department of Genetics, Albert-Einsteinstr. 3, 18059 Rostock, Germany.
authors: Katharina
authors: K
authors: Iwanov
authors: University of Rostock, Biological Sciences, Department of Genetics, Albert-Einsteinstr. 3, 18059 Rostock, Germany.
authors: Felix
authors: F
authors: Schmöhl
authors: University of Rostock, Biological Sciences, Department of Genetics, Albert-Einsteinstr. 3, 18059 Rostock, Germany.
authors: Paula Indigo
authors: PI
authors: Beckmann
authors: University of Rostock, Biological Sciences, Department of Genetics, Albert-Einsteinstr. 3, 18059 Rostock, Germany. Electronic address: reinhard.schroeder@uni-rostock.de.
authors: Reinhard
authors: R
authors: Schröder
mesh_terms: D000818:Animals; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D004625:Embryo, Nonmammalian / Q000378:metabolism / Q000648:ultrastructure; D019143:Evolution, Molecular; D051524:Fibroblast Growth Factor 8 / Q000378:metabolism*; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D007814:Larva / Q000378:metabolism / Q000648:ultrastructure; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000235:genetics / Q000502:physiology*; D034622:RNA Interference; D017468:Receptors, Fibroblast Growth Factor / Q000235:genetics*; D017422:Sequence Analysis, DNA; D012795:Sialoglycoproteins / Q000235:genetics*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D014231:Tribolium / Q000235:genetics*
chemical_list: D017931:DNA Primers; D019476:Insect Proteins; D020033:Protein Isoforms; D017468:Receptors, Fibroblast Growth Factor; D012795:Sialoglycoproteins; C086711:cysteine-rich fibroblast growth factor receptor; D051524:Fibroblast Growth Factor 8
keywords: Evolution; Exon-specific RNAi; FGFR; Signalling; Tribolium