Notch signaling induces apoptosis in primary human CD34+ hematopoietic progenitor cells.
Notch signaling regulates diverse cell fate decisions during development and is reported to promote murine hematopoietic stem cell (HSC) self-renewal. The purpose of this study was to define the functional consequences of activating the Notch signaling pathway on self-renewal in human HSCs. Subsets of human umbilical cord blood CD34(+) cells were retrovirally transduced with the constitutively active human Notch 1 intracellular domain (N1ICD). N1ICD-transduced cells proliferated to a lesser extent in vitro than cells transduced with vector alone, and this was accompanied by a reduction in the percentage and absolute number of CD34(+) cell populations, including CD34(+)Thy(+)Lin(-) HSCs. Ectopic N1ICD expression inhibited cell cycle kinetics concurrent with an upregulation of p21 mRNA expression and induced apoptosis. Transduction of cells with HES-1, a known transcriptional target of Notch signaling and a mediator of Notch function, had no effect on HSC proliferation, indicating that the mechanism of the Notch-induced effect is HES-1-independent. The results of this study show that activation of the Notch signaling pathway has an inhibitory effect on the proliferation and survival of human hematopoietic CD34(+) cells populations. These findings have important implications for strategies aimed at promoting self-renewal of human HSCs.
Chadwick
Nicholas
N
Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom.
Nostro
Maria Cristina
MC
Baron
Martin
M
Mottram
Rachel
R
Brady
Gerard
G
Buckle
Anne-Marie
AM
D018952:Antigens, CD34 / Q000276:immunology*; D017209:Apoptosis / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology*; D002469:Cell Separation; D018920:Coculture Techniques; D018076:DNA, Complementary / Q000235:genetics; D017930:Genes, Reporter; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008156:Luciferases / Q000235:genetics; D016133:Polymerase Chain Reaction; D051880:Receptors, Notch / Q000502:physiology*; D012190:Retroviridae / Q000235:genetics; D017154:Stromal Cells / Q000166:cytology / Q000502:physiology; D014161:Transduction, Genetic
D018952:Antigens, CD34; D018076:DNA, Complementary; D051880:Receptors, Notch; D008156:Luciferases