Role of members of the Wnt gene family in human hematopoiesis.
The hematopoietic system is derived from ventral mesoderm. A number of genes that are important in mesoderm development have been identified including members of the transforming growth factor-beta (TGF-beta) superfamily, the fibroblast growth factor (FGF) family, and the Wnt gene family. Because TGF-beta plays a pleiotropic role in hematopoiesis, we wished to determine if other genes that are important in mesoderm development, specifically members of the Wnt gene family, may play a role in hematopoiesis. Three members of the Wnt gene family (Wnt-5A, Wnt-2B, and Wnt-10B) were identified and cloned from human fetal bone stromal cells. These genes are expressed to varying levels in hematopoietic cell lines derived from T cells, B cells, myeloid cells, and erythroid cells; however, only Wnt-5A was expressed in CD34(+)Lin- primitive progenitor cells. The in vitro biological activity of these Wnt genes on CD34(+)Lin- hematopoietic progenitors was determined in a feeder cell coculture system and assayed by quantitating progenitor cell numbers, CD34(+) cell numbers, and numbers of differentiated cell types. The number of hematopoietic progenitor cells was markedly affected by exposure to stromal cell layers expressing Wnt genes with 10- to 20-fold higher numbers of mixed colony-forming units (CFU-MIX), 1.5- to 2. 6-fold higher numbers of CFU-granulocyte macrophage (CFU-GM), and greater than 10-fold higher numbers of burst-forming units-erythroid (BFU-E) in the Wnt-expressing cocultures compared with the controls. Colony formation by cells expanded on the Wnt-expressing cocultures was similar for each of the three genes, indicating similar action on primitive progenitor cells; however, Wnt-10B showed differential activity on erythroid progenitors (BFU-E) compared with Wnt-5A and Wnt-2B. Cocultures containing Wnt-10B alone or in combination with all three Wnt genes had threefold to fourfold lower BFU-E colony numbers than the Wnt-5A- or Wnt-2B-expressing cocultures. The frequency of CD34(+) cells was higher in Wnt-expressing cocultures and cellular morphology indicated that coculture in the presence of Wnt genes resulted in higher numbers of less differentiated hematopoietic cells and fewer mature cells than controls. These data indicate that the gene products of the Wnt family function as hematopoietic growth factors, and that they may exhibit higher specificity for earlier progenitor cells.
Van Den Berg
D J
DJ
Center for Molecular Hematopoiesis and the Section of Hematology/Oncology, the Department of Medicine, University of Illinois at Chicago, USA. dvdb@uic.edu
Sharma
A K
AK
Bruno
E
E
Hoffman
R
R
D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis; D001853:Bone Marrow / Q000196:embryology; D001854:Bone Marrow Cells / Q000737:chemistry; D002454:Cell Differentiation / Q000235:genetics; D002460:Cell Line; D019070:Cell Lineage; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D003114:Colony-Forming Units Assay; D029721:Drosophila Proteins; D051157:Frizzled Receptors; D018507:Gene Expression Regulation, Developmental; D006023:Glycoproteins; D006133:Growth Substances / Q000235:genetics* / Q000502:physiology; D006410:Hematopoiesis / Q000235:genetics* / Q000502:physiology; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D008648:Mesoderm / Q000166:cytology; D008969:Molecular Sequence Data; D005810:Multigene Family; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D043562:Receptors, G-Protein-Coupled; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D017154:Stromal Cells / Q000737:chemistry; D014162:Transfection; D051153:Wnt Proteins; D000071818:Wnt-5a Protein
D018952:Antigens, CD34; D029721:Drosophila Proteins; D051157:Frizzled Receptors; D006023:Glycoproteins; D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D043562:Receptors, G-Protein-Coupled; D011993:Recombinant Fusion Proteins; C491119:WNT10B protein, human; C115496:WNT2B protein, human; C085389:WNT5A protein, human; D051153:Wnt Proteins; D000071818:Wnt-5a Protein; C492031:Wnt2b protein, mouse; C058784:fz protein, Drosophila