Differential expression of Raf-1 protooncogene in resting and activated human leukocyte populations.
In this study we examined by Northern blot analysis the expression of Raf-1 protooncogene in normal human peripheral blood leukocytes. Unlike thymocytes, circulating lymphocytes did not express appreciable levels of Raf-1 mRNA. In contrast, polymorphonuclear cells (PMN) had high levels of Raf-1 transcripts. Also density gradient separated monocytes showed Raf-1 mRNA but at lower levels compared to PMN. Expression of Raf-1 was constitutive inasmuch as it was not induced by the purification procedure. The half-life of Raf-1 mRNA in PMN was greater than 4 h. Functional activation of PMN and monocytes with various stimuli (phorbol esters, tumor necrosis factor, colony stimulating factors, LPS) did not affect Raf-1 expression. By contrast, density gradient purified monocytes allowed to adhere to plastic for 1 h expressed augmented levels of Raf-1. Monocytes cultivated in suspension or allowed to adhere to plastic showed an half-life of Raf-1 transcripts of, respectively, more than 4 h and less than 30 min. Circulating lymphocytes stimulated with mitogens (PHA, conA, anti-CD3 antibodies, and Staphylococcus aureus) also expressed high levels of transcripts of this protooncogene. PHA-induced transcripts in lymphocytes had an half-life greater than 4 h. The pattern of expression of Raf-1 in resting and activated leukocytes suggests that this protooncogene may play a role in expression of differentiated functions and activation of these cells.
Colotta
F
F
Centro Catullo e Daniela Borgomainerio, Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.
Polentarutti
N
N
Mantovani
A
A
D002460:Cell Line; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007962:Leukocytes / Q000187:drug effects / Q000502:physiology*; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000302:isolation & purification; D019908:Proto-Oncogene Proteins c-raf; D011519:Proto-Oncogenes; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D008070:Lipopolysaccharides; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D003609:Dactinomycin; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D003513:Cycloheximide; D011505:Protein-Tyrosine Kinases; D019908:Proto-Oncogene Proteins c-raf; D013755:Tetradecanoylphorbol Acetate