| Popis: |
In order to investigate the mechanisms by which cytokines and tumor promoters stimulate cell growth, the expression of genes implicated in the regulation of cellular proliferation were examined in an interleukin-3 (IL-3) dependent hematopoietic cell line. Upon stimulation of factor-deprived cells with IL-3, mRNA transcripts encoding the immediate-early genes: c-myc, jun-B, krox-20, beta-actin, and the cytokine genes: IL-4 and IL-6 were detected within 1 h. In contrast mRNA transcripts encoding the delayed-early genes: ornithine decarboxylase, p53, the IL-2 receptor-alpha, IL-4 receptor, and the T cell receptor c-gamma chains were observed at highest levels later. The tumor promoter, phorbol 12-myristate 13-acetate also stimulated the expression of many immediate-early genes, however, c-myc and the delayed-early genes were only detected when IL-3 was present. We conclude that cytokines and tumor promoters have distinct effects on proto-oncogene expression in hematopoietic cells which may affect the ability of these agents to promote cellular growth versus differentiation. |
