title: Enhanced megakaryocyte and erythroid development from normal human CD34(+) cells: consequence of enforced expression of SCL.
abstract: The product of the SCL gene is a basic helix-loop-helix (bHLH) transcription factor that is essential for the development of hematopoietic stem cells in both the embryo and the adult. However, once the stem cell compartment is established, the function of SCL in subsequent differentiation and commitment events within normal hematopoietic cells remains undefined. The aim of the current study was to investigate this role using purified normal human hematopoietic CD34(+) cells. An SCL retrovirus was used to transduce CD34(+) cells isolated from human bone marrow, peripheral blood, and umbilical cord blood. Enforced expression of SCL increased by a median of twofold the number of erythroid colonies, with an increase in both colony size and the rate of hemoglobinization. Unexpectedly, enforced expression in CD34(+) cells also significantly increased the number of megakaryocyte colonies, but with no impact on the size of colonies. There was no consistent effect on the number nor size of granulocyte-macrophage (GM) colonies. The proliferative effect of enforced SCL expression on erythroid cells was attributed to a shortened cell cycle time; the self-renewal capacity of erythroid or GM progenitors was unchanged, as was survival of cells within colonies. These results demonstrate a role for SCL in determining erythroid and megakaryocyte differentiation from normal human hematopoietic CD34(+) cells.
authors.affiliation: Rotary Bone Marrow Research Laboratories, Victoria, Australia. elwood@wehi.edu.au
authors.forename: N J
authors.initials: NJ
authors.lastname: Elwood
authors.forename: H
authors.initials: H
authors.lastname: Zogos
authors.forename: D S
authors.initials: DS
authors.lastname: Pereira
authors.forename: J E
authors.initials: JE
authors.lastname: Dick
authors.forename: C G
authors.initials: CG
authors.lastname: Begley
mesh_terms: D000328:Adult; D018952:Antigens, CD34 / Q000032:analysis; D017209:Apoptosis; D051792:Basic Helix-Loop-Helix Proteins; D001773:Blood Cells / Q000166:cytology; D001854:Bone Marrow Cells / Q000166:cytology; D002453:Cell Cycle; D002454:Cell Differentiation; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D015672:Erythroid Precursor Cells / Q000166:cytology* / Q000378:metabolism; D005312:Fetal Blood / Q000166:cytology; D005786:Gene Expression Regulation; D005822:Genetic Vectors / Q000235:genetics; D006098:Granulocytes / Q000166:cytology; D006410:Hematopoiesis / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006454:Hemoglobins / Q000096:biosynthesis; D006801:Humans; D007231:Infant, Newborn; D008264:Macrophages / Q000166:cytology; D008533:Megakaryocytes / Q000166:cytology*; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins / Q000502:physiology; D012190:Retroviridae / Q000235:genetics; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D014157:Transcription Factors; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D018952:Antigens, CD34; D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D006454:Hemoglobins; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D014157:Transcription Factors; C067143:TAL1 protein, human