title: The ActR-I activin receptor protein is expressed in notochord, lens placode and pituitary primordium cells in the mouse embryo.
abstract: ActR-I is a type I serine/threonine kinase receptor which has been shown to bind activin and bone morphogenetic proteins (BMPs). To study the function of ActR-I, we have generated novel monoclonal antibodies that specifically recognize the extracellular domain of mouse ActR-I. We examined the level of ActR-I protein during mouse development by immunohistochemistry. We found that in the embryonic body, ActR-I protein first appears in a restricted part of the primitive streak region and is present throughout the length of notochord. Furthermore, ActR-I protein is expressed in the facial sensory organ primordia, including eye area, otic vesicle and olfactory placode, which all contain invaginating ectoderm. In addition, ActR-I is produced in pituitary primordium (Rathke's pouch), mammary buds and the epithelial layer of branchial arches. Interestingly, in the lens placodes and in early Rathke's pouch, ActR-I protein is transiently localized at the apical surface of the epithelial cells, indicating the presence of an apical-basal asymmetry in these cells.
authors.affiliation: Department of Molecular Biology, Biomolecular Engineering Research Institute, 6-2-3 Furuedai, Suita, Osaka, Japan.
authors.forename: S I
authors.initials: SI
authors.lastname: Yoshikawa
authors.forename: S
authors.initials: S
authors.lastname: Aota
authors.forename: Y
authors.initials: Y
authors.lastname: Shirayoshi
authors.forename: K
authors.initials: K
authors.lastname: Okazaki
mesh_terms: D030201:Activin Receptors, Type I; D000818:Animals; D007908:Lens, Crystalline / Q000196:embryology* / Q000378:metabolism; D051379:Mice; D009672:Notochord / Q000196:embryology / Q000378:metabolism; D010902:Pituitary Gland / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis*; D017978:Receptors, Growth Factor / Q000096:biosynthesis*; D014407:Tumor Cells, Cultured
chemical_list: D017978:Receptors, Growth Factor; D017346:Protein Serine-Threonine Kinases; D030201:Activin Receptors, Type I