title: Expression of erythropoietin receptor-like molecule in Xenopus laevis and erythrocytopenia upon administration of its recombinant soluble form.
abstract: The regulation of hematopoiesis in non-mammalian vertebrates is poorly understood. This is partly because the structures and effects of most hematopoietic regulators have not been identified. As a first step towards studies on the key mechanism of hematopoietic regulation among phyla as well as the diversity of organisms, we have focused on amphibian hematopoiesis. A cDNA sharing the highest degree of homology with mammalian erythropoietin (EPO) receptors, tentatively named xlEPOR, was cloned from a cDNA library of Xenopus laevis immature erythrocytes. The comparative identities of the deduced entire amino acid sequence to mammalian EPO receptors were quite low, although functional domains indispensable for erythropoietic activities were found in the molecule. Northern analysis revealed that xlEPOR were expressed in peripheral blood cells. In the peripheral blood of phenylhydrazine-treated adult Xenopus, immature erythrocytes expressing xlEPOR were identified by in situ hybridization and immunostaining with polyclonal antibodies to xlEPOR. To confirm the biological functions of this molecule, the extracellular domain of xlEPOR (i.e., soluble xlEPOR) was administered to adult Xenopus by consecutive intracardiac injection. The peripheral erythrocyte counts were decreased gradually; meanwhile, immature erythrocytes appeared in the circulation, demonstrating that xlEPOR plays a significant physiological role in erythropoiesis in Xenopus laevis.
authors.affiliation: Major in Integrative Bioscience and Biomedical Engineering, Graduate School of Science and Engineering, and Department of Biology, School of Education, Waseda University, Shinjuku-ku, Tokyo.
authors.forename: Youichi
authors.initials: Y
authors.lastname: Aizawa
authors.forename: Nami
authors.initials: N
authors.lastname: Nogawa
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Kosaka
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Maeda
authors.forename: Takafumi
authors.initials: T
authors.lastname: Watanabe
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miyazaki
authors.forename: Takashi
authors.initials: T
authors.lastname: Kato
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004920:Erythropoiesis / Q000502:physiology*; D015723:Gene Library; D008297:Male; D008969:Molecular Sequence Data; D017467:Receptors, Erythropoietin / Q000096:biosynthesis / Q000737:chemistry / Q000502:physiology*; D011994:Recombinant Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014982:Xenopus laevis / Q000502:physiology*
chemical_list: D017467:Receptors, Erythropoietin; D011994:Recombinant Proteins