title: Characterization of myeloid cells derived from the anterior ventral mesoderm in the Xenopus laevis embryo.
abstract: A recent study revealed the presence of a unique population of myeloid cells in the anterior ventral (AV) mesoderm of Xenopus laevis embryo, as characterized by the expression of peroxidase 2 (POX2), which encodes for a leukocyte-specific enzyme. The current report further characterized the POX2-positive cells in terms of their contribution to hematopoiesis in tadpole and regulatory mechanism in differentiation. Grafting experiments with cytogenetically labeled tissues revealed that AV-derived mesoderm supplies a transient population of migrating leukocytes in the mesenchyme of early tadpole. These cells were rarely found in blood vessels at any stages. Using a ventral marginal zone explant system, we demonstrated that dkk1, shown as a heart inducer in this system, has a strong ability to induce the expression of POX2. Injection of a high dose dkk1 RNA induced a heart marker while a low dose of dkk1 preferentially induced the expression of POX2, suggesting that dkk1 works as a morphogen to determine the different lineages. Overall results indicate that wnt signal inhibitors induce leukocytes at the early neurula stage and that these cells spread to the entire body and exist until the ventral blood island-derived leukocytes appear in the body.
authors.affiliation: Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan.
authors.forename: Sumihisa
authors.initials: S
authors.lastname: Tashiro
authors.forename: Ayako
authors.initials: A
authors.lastname: Sedohara
authors.forename: Makoto
authors.initials: M
authors.lastname: Asashima
authors.forename: Yumi
authors.initials: Y
authors.lastname: Izutsu
authors.forename: Mitsugu
authors.initials: M
authors.lastname: Maéno
mesh_terms: D000818:Animals; D019070:Cell Lineage / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D007814:Larva / Q000201:enzymology; D008648:Mesoderm / Q000201:enzymology*; D022423:Myeloid Cells / Q000201:enzymology*; D009195:Peroxidase / Q000096:biosynthesis*; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D029867:Xenopus Proteins; C110182:dkk1 protein, Xenopus; D009195:Peroxidase