A member of the Met/HGF-receptor family is expressed in a BMP-4-like pattern in the ectoderm of Xenopus gastrulae.
The importance and involvement of growth factors and their corresponding receptors in embryonic induction has been more and more recognized during the past decade, in particular by loss-of-function experiments using dominant negative receptors. Here, we report the isolation of XHR, a Xenopus receptor-type tyrosine kinase, with homology to members of the Met/hepatocyte growth factor (HGF)-receptor family. Sequence comparison of XHR with other members of the Met/HGF-receptor family as well as in situ expression analyses suggest that XHR represents a novel member of this family of receptor-type tyrosine kinases. As could be shown by whole-mount in situ analysis, XHR transcripts are first expressed in the entire ectoderm at the onset of gastrulation. As gastrulation proceeds, XHR-transcription is turned off in cells induced by dorsal mesoderm to form neural tissue and thus, becomes predominantly confined to prospective epidermis. The strikingly similar expression patterns of XHR and Bone Morphogenetic Protein-4 (BMP-4), an inducer of epidermis and inhibitor of neural development, suggest an involvement of XHR signalling in the early cell-fate decision of ectodermal cells to form either neural derivatives or epidermis.
Aberger
F
F
University of Salzburg, Institute of Genetics, Austria. fritz.aberger@sbg.ac.at
Weidinger
G
G
Richter
K
K
D000818:Animals; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000235:genetics*; D004475:Ectoderm / Q000378:metabolism*; D004627:Embryonic Induction; D005775:Gastrula / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D017228:Hepatocyte Growth Factor / Q000378:metabolism; D008969:Molecular Sequence Data; D019859:Proto-Oncogene Proteins c-met; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics*; D014158:Transcription, Genetic; D014981:Xenopus; D029867:Xenopus Proteins
D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D029867:Xenopus Proteins; C525812:bmp4 protein, Xenopus; D017228:Hepatocyte Growth Factor; D019859:Proto-Oncogene Proteins c-met; D020794:Receptor Protein-Tyrosine Kinases