The mitogenic response of T cells to interleukin-2 requires Raf-1

✍ Scribed by Detlev Riedel; Ulrich Brennscheidt; Michael Kiehntopf; Marion Brach; Friedhelm Herrmann

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 790 KB
• Volume: 23
• Category: Article
• ISSN: 0014-2980
• DOI: 10.1002/eji.1830231216

✦ Synopsis

The mitogenic response of T cells to interleukin-2 requires Raf-l*

The product of the c-raf-1 proto-oncogene, Raf-1, is known to encode a 74-kDa ubiquitously expressed cytoplasmic serinehhreonine kinase. Various growth factors such as epidermal growth factor, acidic fibroblast growth factor, platelet-derived growth factor, insulin, granulocyte-macrophage colony-stimulating factor, interleukin (1L)-2, IL-3 and erythropoietin have been shown to induce phosphorylation of Raf-1, thereby activating Raf-1 kinase. Raf-1 is, thus, believed to play a role in coupling growth factor receptors to proliferation. We have examined the role of Raf-1 in the mitogenic response of human peripheral blood-derived IL-2 receptor expressing T cells to human recombinant IL-2 employing c-raf antisense (AS) oligodeoxyribonucleotide. Uptake studies of oligonucleotides indicated that incorporation of oligomers was maximal at 4 h and oligdeoxynucleotides remained stable in these cells for up to 24 h.Treatment of T cells with the AS oligodeoxyribonucleotide in intracellular duplex formation followed by efficient translation blockade of c-raf-1. In contrast, sense (S) and nonsense (NS) oligodeoxynucleotides failed to form intracellular duplexes and did not interfere with translation of c-raf-1, suggesting specific elimination of c-raf-1 by the AS oligomer. Proliferation of T cells ([3H]thymidine incorporation) following exposure to IL-2 was substantially reduced when the c-raf-1 AS oligodeoxyribonucleotide was added to cultures, while the mitogenic response to this factor remained almost unaffected in the presence of S and NS oligodeoxyribonucleotides.