title: Functions of flt3 in zebrafish hematopoiesis and its relevance to human acute myeloid leukemia.
abstract: FMS-like tyrosine kinase 3 (FLT3) is expressed in human hematopoietic stem and progenitor cells (HSPCs) but its role during embryogenesis is unclear. In acute myeloid leukemia (AML), internal tandem duplication (ITD) of FLT3 at the juxtamembrane (JMD) and tyrosine kinase (TKD) domains (FLT3-ITD(+)) occurs in 30% of patients and is associated with inferior clinical prognosis. TKD mutations (FLT3-TKD(+)) occur in 5% of cases. We made use of zebrafish to examine the role of flt3 in developmental hematopoiesis and model human FLT3-ITD(+) and FLT3-TKD(+) AML. Zebrafish flt3 JMD and TKD were remarkably similar to their mammalian orthologs. Morpholino knockdown significantly reduced the expression of l-plastin (pan-leukocyte), csf1r, and mpeg1 (macrophage) as well as that of c-myb (definitive HSPCs), lck, and rag1 (T-lymphocyte). Expressing human FLT3-ITD in zebrafish embryos resulted in expansion and clustering of myeloid cells (pu.1(+), mpo(+), and cebpα(+)) which were ameliorated by AC220 and associated with stat5, erk1/2, and akt phosphorylation. Human FLT3-TKD (D835Y) induced significant, albeit modest, myeloid expansion resistant to AC220. This study provides novel insight into the role of flt3 during hematopoiesis and establishes a zebrafish model of FLT3-ITD(+) and FLT3-TKD(+) AML that may facilitate high-throughput screening of novel and personalized agents.
authors.affiliation: Division of Haematology, Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong;
authors.forename: Bai-Liang
authors.initials: BL
authors.lastname: He
authors.forename: Xiangguo
authors.initials: X
authors.lastname: Shi
authors.forename: Cheuk Him
authors.initials: CH
authors.lastname: Man
authors.forename: Alvin C H
authors.initials: AC
authors.lastname: Ma
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Ekker
authors.forename: Howard C H
authors.initials: HC
authors.lastname: Chow
authors.forename: Chi Wai Eric
authors.initials: CW
authors.lastname: So
authors.forename: William W L
authors.initials: WW
authors.lastname: Choi
authors.forename: Wenqing
authors.initials: W
authors.lastname: Zhang
authors.forename: Yiyue
authors.initials: Y
authors.lastname: Zhang
authors.forename: Anskar Y H
authors.initials: AY
authors.lastname: Leung
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D017124:Conserved Sequence; D004625:Embryo, Nonmammalian; D006410:Hematopoiesis / Q000235:genetics*; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics*; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D020080:Tandem Repeat Sequences; D059467:Transcriptome; D015027:Zebrafish / Q000196:embryology / Q000502:physiology*; D029961:Zebrafish Proteins / Q000737:chemistry / Q000502:physiology*; D051941:fms-Like Tyrosine Kinase 3 / Q000737:chemistry / Q000502:physiology*
chemical_list: D029961:Zebrafish Proteins; C000588719:flt3 protein, zebrafish; D051941:fms-Like Tyrosine Kinase 3