Notch signaling enhances survival and alters differentiation of 32D myeloblasts.
The Notch transmembrane receptors play important roles in precursor survival and cell fate specification during hematopoiesis. To investigate the function of Notch and the signaling events activated by Notch in myeloid development, we expressed truncated forms of Notch1 or Notch2 proteins that either can or cannot activate the core binding factor 1 (CBF1) in 32D (clone 3) myeloblasts. 32D cells proliferate as blasts in the presence of the cytokines, GM-CSF or IL-3, but they initiate differentiation and undergo granulopoiesis in the presence of granulocyte CSF (G-CSF). 32D cells expressing constitutively active forms of Notch1 or Notch2 proteins that signal through the CBF1 pathway maintained significantly higher numbers of viable cells and exhibited less cell death during G-CSF induction compared with controls. They also displayed enhanced entry into granulopoiesis, and inhibited postmitotic terminal differentiation. In contrast, Notch1 constructs that either lacked sequences necessary for CBF1 binding or that failed to localize to the nucleus had little effect. Elevated numbers of viable cells during G-CSF treatment were also observed in 32D cells overexpressing the basic helix-loop-helix protein (bHLH), HES1, consistent with activation of the CBF1 pathway. Taken together, our data suggest that Notch signaling enhances 32D cell survival, promotes entry into granulopoiesis, and inhibits postmitotic differentiation through a CBF1-dependent pathway.
Tan-Pertel
H T
HT
Division of Hematology-Oncology, Department of Medicine, University of California at Los Angeles School of Medicine and Jonsson Comprehensive Cancer Center, Los Angeles, CA 90095, USA.
Walker
L
L
Browning
D
D
Miyamoto
A
A
Weinmaster
G
G
Gasson
J C
JC
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D002470:Cell Survival / Q000235:genetics / Q000502:physiology; D017353:Gene Deletion; D005822:Genetic Vectors / Q000096:biosynthesis / Q000138:chemical synthesis; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics; D007424:Intracellular Fluid / Q000502:physiology; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D051379:Mice; D023461:Myeloid Progenitor Cells / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D010446:Peptide Fragments / Q000096:biosynthesis / Q000235:genetics; D010641:Phenotype; D051881:Receptor, Notch1; D051883:Receptor, Notch2; D011956:Receptors, Cell Surface / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D051880:Receptors, Notch; D015398:Signal Transduction / Q000502:physiology*; D013347:Subcellular Fractions / Q000378:metabolism; D000072056:Transcription Factor HES-1; D014157:Transcription Factors
D051792:Basic Helix-Loop-Helix Proteins; D016179:Granulocyte Colony-Stimulating Factor; D018398:Homeodomain Proteins; D008565:Membrane Proteins; D010446:Peptide Fragments; D051881:Receptor, Notch1; D051883:Receptor, Notch2; D011956:Receptors, Cell Surface; D051880:Receptors, Notch; D000072056:Transcription Factor HES-1; D014157:Transcription Factors; C489734:Hes1 protein, mouse; C497762:Notch1 protein, mouse; C497765:Notch2 protein, mouse