Functional expression of the macrophage colony-stimulating factor receptor in human THP-1 monocytic leukemia cells.
Macrophage colony-stimulating factor (M-CSF) is required for the proliferation, differentiation, and activation of monocytes. High-affinity receptors for M-CSF are encoded by the c-fms proto-oncogene. In the present study, we show that c-fms transcripts are detectable in human THP-1 myeloid leukemia cells. Furthermore, radiolabeled 125I-M-CSF is rapidly internalized into THP-1 cells and then degraded intracellularly. The results also show that treatment of THP-1 cells with M-CSF is associated with the activation of protein kinase C (PKC) and the induction of tumor necrosis factor (TNF) gene expression. TNF transcript levels were low to undetectable in uninduced THP-1 cells, reached maximal levels by 1 hour of exposure to M-CSF, and returned to those of control cells by 24 hours. Transcriptional run-on analysis showed that a low level of TNF transcription is detectable in untreated THP-1 cells, and M-CSF treatment increased the rate of TNF transcription. Pretreatment of THP-1 cells with pertussis toxin inhibited the increase in PKC activity but not the induction of TNF transcripts by M-CSF. Moreover, exposure of THP-1 cells to inhibitors of protein kinase activity blocked the increase in TNF messenger RNA. These findings suggest that at least two M-CSF- mediated signaling pathways exist in THP-1 cells and that the induction of TNF may be regulated by a protein kinase-dependent mechanism distinct from PKC.[1]References
- Functional expression of the macrophage colony-stimulating factor receptor in human THP-1 monocytic leukemia cells. Datta, R., Imamura, K., Goldman, S.J., Dianoux, A.C., Kufe, D.W., Sherman, M.L. Blood (1992) [Pubmed]
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