title: Gene duplication of zebrafish JAK2 homologs is accompanied by divergent embryonic expression patterns: only jak2a is expressed during erythropoiesis.
abstract: Members of the JAK family of protein tyrosine kinase (PTK) proteins are required for the transmission of signals from a variety of cell surface receptors, particularly those of the cytokine receptor family. JAK function has been implicated in hematopoiesis and regulation of the immune system, and recent data suggest that the vertebrate JAK2 gene may play a role in leukemia. We have isolated and characterized jak cDNAs from the zebrafish Danio rerio. The zebrafish genome possesses 2 jak2 genes that occupy paralogous chromosome segments in the zebrafish genome, and these segments conserve syntenic relationships with orthologous genes in mammalian genomes, suggesting an ancient duplication in the zebrafish lineage. The jak2a gene is expressed at high levels in erythroid precursors of primitive and definitive waves and at a lower level in early central nervous system and developing fin buds. jak2b is expressed in the developing lens and nephritic ducts, but not in hematopoietic tissue. The expression of jak2a was examined in hematopoietic mutants and found to be disrupted in cloche and spadetail, suggesting an early role in hematopoiesis. Taken together with recent gene knockout data in the mouse, we suggest that jak2a may be functionally equivalent to mammalian Jak2, with a role in early erythropoiesis.
authors.affiliation: Ludwig Institute for Cancer Research, Melbourne Tumour Biology Branch, Royal Melbourne Hospital, Victoria, Australia. aoates@molbio.princeton.edu
authors.forename: A C
authors.initials: AC
authors.lastname: Oates
authors.forename: A
authors.initials: A
authors.lastname: Brownlie
authors.forename: S J
authors.initials: SJ
authors.lastname: Pratt
authors.forename: D V
authors.initials: DV
authors.lastname: Irvine
authors.forename: E C
authors.initials: EC
authors.lastname: Liao
authors.forename: B H
authors.initials: BH
authors.lastname: Paw
authors.forename: K J
authors.initials: KJ
authors.lastname: Dorian
authors.forename: S L
authors.initials: SL
authors.lastname: Johnson
authors.forename: J H
authors.initials: JH
authors.lastname: Postlethwait
authors.forename: L I
authors.initials: LI
authors.lastname: Zon
authors.forename: A F
authors.initials: AF
authors.lastname: Wilks
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D004331:Drosophila melanogaster / Q000201:enzymology / Q000235:genetics; D004790:Enzyme Induction; D015672:Erythroid Precursor Cells / Q000201:enzymology; D004920:Erythropoiesis / Q000235:genetics; D019143:Evolution, Molecular; D018507:Gene Expression Regulation, Developmental; D005796:Genes; D006410:Hematopoiesis / Q000235:genetics; D006412:Hematopoietic Stem Cells / Q000201:enzymology; D006801:Humans; D053614:Janus Kinase 2; D008322:Mammals / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D011505:Protein-Tyrosine Kinases / Q000235:genetics* / Q000502:physiology; D011518:Proto-Oncogene Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014158:Transcription, Genetic; D015027:Zebrafish / Q000196:embryology / Q000235:genetics*
chemical_list: D011518:Proto-Oncogene Proteins; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2