Erythropoietin-dependent suppression of the expression of the beta subunits of the interleukin-3 receptor during erythroid differentiation.
To clarify how erythroid cells lose their response to interleukin-3 (IL-3), we analyzed the expression of the alpha (alpha(IL-3)) and beta (beta(IL-3)/beta(com)) subunits of its receptor in a panel of murine cell lines immortalized at different stages of hemopoietic differentiation. The panel was composed by the mast cell line 32D and by its granulo-monocytic (32D GM), granulocytic (32D G), and erythroid (32D Epo1.1 and Epo) subclones. The 32D Epo cells grow only in erythropoietin (EPO) while the Epo1.1 subclone grows in either EPO or IL-3. The phenotype of these cells is that of early (expression of globins and erythroid-specific carbonic anhydrase II) and late (also expression of the erythroid-specific band 4.1 mRNA) erythroblasts when they grow in IL-3 or EPO, respectively. All the cell lines expressed comparable levels of alpha(IL-3). In contrast, the expression of beta(IL-3)/beta(com) was restricted to cells growing in IL-3 and was barely detectable in 32D Epo and 32D Epo1.1 cells growing in EPO. When switched from EPO to IL-3, 32D Epo1.1 cells expressed 10 times more beta(IL-3)/beta(com) by rapidly activating (within 1 h) their transcription rate. When reexposed to EPO, 32D Epo1.1 cells first expressed (1-6 h) more beta(IL-3)/beta(com) (2 times) but suppressed such an expression at later time points (by 48 h). The beta(IL-3)/beta(com) mRNA half-life was also different when 32D Epo1.1 cells grew in EPO or IL-3 (2-3 h vs >5 h, respectively). These results indicate that EPO specifically induces transcriptional and posttranscriptional downmodulation of beta(IL-3)/beta(com) expression in late erythroid cells.
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Laboratory of Cell Biology, Istituto Superiore di Sanità, Rome, Italy.
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D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D003609:Dactinomycin / Q000494:pharmacology; D004912:Erythrocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004921:Erythropoietin / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D021122:Protein Subunits; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012313:RNA / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics; D016185:Receptors, Interleukin-3 / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014407:Tumor Cells, Cultured
D007377:Interleukin-3; D021122:Protein Subunits; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D016185:Receptors, Interleukin-3; D004921:Erythropoietin; D003609:Dactinomycin; D012313:RNA