C/EBPalpha and G-CSF receptor signals cooperate to induce the myeloperoxidase and neutrophil elastase genes.
To assess cooperation between G-CSF signals and C/EBPalpha, we characterized Ba/F3 pro-B cell lines expressing C/EBPalphaWT-ER and the G-CSF receptor (GCSFR). In these lines, GCSFR signals can be evaluated independent of their effect on C/EBPalpha levels. G-CSF alone did not induce the MPO, NE, LF, or PU.1 RNAs, and C/EBPalphaWT-ER alone stimulated low-level MPO and high-level PU.1 expression. Simultaneous activation of the GCSFR and C/EBPalphaWT-ER markedly increased MPO and NE induction at 24 h, and LF mRNA was detected at 48 h. G-CSF did not increase endogenous GCSFR, endogenous C/EBPalpha or exogenous C/EBPalphaWT-ER levels, and C/EBPalphaWT-ER did not induce endogenous or exogenous GCSFR. Several GCSFR mutants were also co-expressed with C/EBPalphaYWT-ER. Mutation of all four cytoplasmic tyrosines prevented NE induction but enhanced MPO induction. Mutation of Y704 was required for increased MPO induction. Consistent with this finding, removing IL-3 without G-CSF addition enabled MPO, but not NE, induction by C/EBPalphaWT-ER. GCSFR signals or related signals from other receptors may cooperate with C/EBPalpha to direct differentiation of normal myeloid stem cells.
Wang
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The Johns Hopkins Oncology Center, Division of Pediatric Oncology, Baltimore, MD 21231, USA.
Wang
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Ward
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Touw
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Friedman
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D000818:Animals; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000502:physiology*; D002455:Cell Division; D002460:Cell Line; D015971:Gene Expression Regulation, Enzymologic; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D019272:Leukocyte Elastase / Q000235:genetics*; D051379:Mice; D009195:Peroxidase / Q000235:genetics*; D016188:Receptors, Granulocyte Colony-Stimulating Factor / Q000502:physiology*; D019076:Transgenes
D022763:CCAAT-Enhancer-Binding Protein-alpha; D016188:Receptors, Granulocyte Colony-Stimulating Factor; D016179:Granulocyte Colony-Stimulating Factor; D009195:Peroxidase; D019272:Leukocyte Elastase