title: Melk-like kinase plays a role in hematopoiesis in the zebra fish.
abstract: A serine/threonine kinase, Melk, was initially cloned in mouse oocytes as a maternal gene, but whose function was unknown. In adult mice, Melk was strongly expressed in the thymus and bone marrow, suggesting a role for Melk in hematopoiesis. We cloned a Melk-like gene from zebra fish (zMelk). zMelk-like gene was expressed in the brain and lateral mesoderm at 12 hours postfertilization (hpf) and in several tissues of adult fish, including the kidney and spleen, both of which are known to be hematopoietic tissues in zebra fish. Abrogation of zMelk-like gene function by zMelk-like gene-specific Morpholino (MO) resulted in abnormal swelling around the tectum region. In addition, the start of blood circulation was severely delayed but, in contrast, the vessel formation seemed normal. Expression of scl, gata-1, and lmo-2 was down regulated at 12 to 14 hpf in the zMelk-like gene MO-injected embryos, and the coexpression of gata-1 rescued the anemic phenotype induced by zMelk-like gene MO. Expression of the zMelk-like gene in embryos enhanced gata-1 promoter-dependent enhanced green fluorescent protein expression, suggesting that the zMelk-like gene affects gata-1 expression at the transcriptional level. Taken together, our data suggest that the zMelk-like gene may play a role in primitive hematopoiesis by affecting the expression of genes critical for hematopoiesis.
authors: Institute of Medical Science, University of Tokyo, Department of Molecular and Developmental Biology, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
authors: Rika
authors: R
authors: Saito
authors: Yoko
authors: Y
authors: Tabata
authors: Akihiko
authors: A
authors: Muto
authors: Ken-Ichi
authors: K
authors: Arai
authors: Sumiko
authors: S
authors: Watanabe
mesh_terms: D000740:Anemia / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D050981:Erythroid-Specific DNA-Binding Factors; D005123:Eye / Q000196:embryology; D020869:Gene Expression Profiling; D006410:Hematopoiesis / Q000235:genetics / Q000502:physiology*; D016350:Leucine Zippers / Q000502:physiology*; D008969:Molecular Sequence Data; D018919:Neovascularization, Physiologic / Q000235:genetics; D016376:Oligonucleotides, Antisense; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology; D029961:Zebrafish Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D016376:Oligonucleotides, Antisense; D014157:Transcription Factors; D029961:Zebrafish Proteins; C503578:Melk protein, zebrafish; D017346:Protein Serine-Threonine Kinases