IFN-gamma/lipopolysaccharide activation of macrophages is associated with protein kinase C-dependent down-modulation of the colony-stimulating factor-1 receptor. |
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Authors: | M Baccarini P Dello Sbarba D Buscher A Bartocci E R Stanley |
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Institution: | Department of Developmental Biology and Cancer, Albert Einstein College of Medicine New York, NY 10461. |
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Abstract: | IFN gamma/LPS treatment increases macrophage tumoricidal and microbicidal activity and inhibits CSF-1-induced macrophage proliferation. The mechanism underlying the latter effect was investigated in the CSF-1-dependent mouse macrophage cell line, BAC-1.2F5. IFN-gamma and LPS together dramatically reduced the total number of CSF-1 receptors (CSF-1R) via selective degradation of the cell surface form. Processing and transport of intracellular CSF-1R to the cell surface were unaffected. IFN-gamma alone had no effect but significantly enhanced LPS-induced CSF-1R down-regulation. The reduction in CSF-1R number was protein kinase C-dependent and involved changes in serine phosphorylation of the receptor at different sites. CSF-1R down-modulation by this mechanism may be important in switching off the energy-consuming processes of CSF-1R-mediated proliferation and chemotaxis in activated macrophages. |
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