A dominant-negative mutant of C/EBPalpha, associated with acute myeloid leukemias, inhibits differentiation of myeloid and erythroid progenitors of man but not mouse.
The CCAAT/enhancer binding protein alpha (C/EBPalpha) is an essential transcription factor for granulocytic differentiation. C/EBPalpha mutations are found in approximately 8% of acute myeloid leukemia (AML) patients. Most of these mutations occur in the N-terminal coding region, resulting in a frame shift and the enhanced translation of a dominant-negative 30-kDa protein, which may be responsible for the differentiation block observed in AML. To test this hypothesis, we introduced a cDNA encoding an N-terminal mutated C/EBPalpha (mut10) into primary hematopoietic progenitors using a retroviral vector. Expression of mut10 in human CD34+ cord blood cells dramatically inhibited differentiation of both myeloid and erythroid lineages. Immunohistochemical analysis demonstrated coexpression of both myeloid and erythroid markers in the immature transformed cells. Surprisingly, mut10 did not block myelocytic differentiation in murine progenitors but did alter their differentiation kinetics and clonogenicity. Experiments were performed to confirm that the differential effect of mut10 on murine and human progenitors was not due to species-specific differences in C/EBPalpha protein sequences, expression levels, or inefficient targeting of relevant cells. Taken together, our results underline the intrinsic differences between hematopoietic controls in mouse and human and support the hypothesis that mutations in CEBPA are critical events in the disruption of myeloid differentiation in AMLs.
Schwieger
Maike
M
Molecular Pathology Group, Heinrich-Pette-Institut für Experimentelle Immunologie und Virologie, Hamburg, Germany.
Löhler
Jürgen
J
Fischer
Meike
M
Herwig
Uwe
U
Tenen
Daniel G
DG
Stocking
Carol
C
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000235:genetics* / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D002478:Cells, Cultured; D003001:Cloning, Molecular; D015672:Erythroid Precursor Cells / Q000166:cytology / Q000187:drug effects* / Q000473:pathology; D005260:Female; D005312:Fetal Blood / Q000166:cytology; D005799:Genes, Dominant; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects; D006801:Humans; D007231:Infant, Newborn; D015470:Leukemia, Myeloid, Acute / Q000235:genetics* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D023461:Myeloid Progenitor Cells / Q000166:cytology / Q000187:drug effects* / Q000473:pathology; D011994:Recombinant Proteins / Q000494:pharmacology; D013045:Species Specificity
D022763:CCAAT-Enhancer-Binding Protein-alpha; D011994:Recombinant Proteins