Evidence for a role of the Na+/H+ exchanger in the colony-stimulating-factor-induced ornithine decarboxylase activity and proliferation of the human cell line M-07e.
The subclone M-07e, derived from the interleukin-3 (IL-3)-responsive human myeloid cell line M-07, is strictly dependent on either IL-3 or granulocyte-macrophage-colony-stimulating factor (GM-CSF) for its growth and survival. This cell line may be regarded as a candidate model to investigate the poorly understood events triggered by growth factors binding to human hemopoietic cells. Both IL-3 and GM-CSF induce in M-07e cells an increase of ornithine decarboxylase (ODC) activity, which reaches its maximum at 24-30 h and fully depends on de novo protein synthesis. The growth factors do not elicit translocation of protein kinase C to the membrane; thus a role of the kinase in ODC induction is ruled out. An amiloride-inhibitable Na+/H+ exchanger is present in the membrane of M-07e cells; its apparent Km for extracellular Na+ is 47.77 mM; and its activity is greatly enhanced when the cytoplasm is acidified. Growth-factor-evoked ODC activation and DNA synthesis are blocked in a dose- and time-dependent manner when M-07e cells are incubated with ethylisopropylamiloride, a specific inhibitor of Na+/H+ exchanger. The exchanger does not appear to be directly activated by IL-3 or GM-CSF, but its operation is strictly required for the biological effects of these growth factors on M-07e cell line.
Ghigo
D
D
Dipartimento di Genetica, Biologia e Chimica Medica, Università di Torino, Italy.
Brizzi
M F
MF
Avanzi
G C
GC
Bussolino
F
F
Garbarino
G
G
Costamagna
C
C
Pegoraro
L
L
Bosia
A
A
D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D002352:Carrier Proteins / Q000502:physiology*; D002455:Cell Division / Q000502:physiology; D002460:Cell Line; D004261:DNA Replication / Q000187:drug effects; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000502:physiology*; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007377:Interleukin-3 / Q000502:physiology*; D009955:Ornithine Decarboxylase / Q000378:metabolism*; D011493:Protein Kinase C / Q000502:physiology*; D017923:Sodium-Hydrogen Exchangers; D013347:Subcellular Fractions / Q000201:enzymology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013936:Thymidine / Q000378:metabolism; D014316:Tritium
D002352:Carrier Proteins; D007377:Interleukin-3; D017923:Sodium-Hydrogen Exchangers; D014316:Tritium; D000584:Amiloride; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D011493:Protein Kinase C; D009955:Ornithine Decarboxylase; D013755:Tetradecanoylphorbol Acetate; D013936:Thymidine; C039614:ethylisopropylamiloride