Interferon‐γ activates multiple pathways to regulate the expression of the genes for major histocompatibility class II I‐Aβ, tumor necrosis factor and complement component C3 in mouse macrophages

Abstract

The purpose of this study was to obtain additional information on the mechanism by which interferon-gamma (IFN-gamma) is able to regulate gene expression in macrophages. The expression of the genes for class II histocompatibility I-A beta, tumor necrosis factor (TNF) and complement component C3 was assayed after treating bone marrow macrophages with IFN-gamma. Each gene displayed a characteristic pattern of regulation. First, the increase in the level of RNA for each gene followed different kinetics. The level of TNF RNA increased within 15 min after IFN-gamma treatment and reached a plateau after 4 h. In contrast, there was a lag of about 4 h before the level of I-A beta RNA began to rise and a plateau was not reached until 48 h after the IFN-gamma treatment began. C3 gene expression followed an intermediate time course between that for TNF and I-A beta. Second, the expression of I-A beta was inhibited when cells were treated with both IFN-gamma and cycloheximide, while the expression of TNF and C3 was not. Interestingly, the sensitivity to cycloheximide only lasted 30 min following the addition of IFN-gamma, after which cycloheximide had no effect on the expression of I-A beta. Third, lipopolysaccharide abolished the IFN-gamma-induced expression of I-A beta, but enhanced the expression of TNF. Based on these observations, we conclude that IFN-gamma must activate multiple pathways to regulate gene expression in macrophages.

Regulation of murine Tap1 and Lmp2 genes in macrophages by interferon gamma is mediated by STAT1 and IRF-1

“…This treatment produced a 490% reduction in the incorporation of [ 3 H]leucine into trichloroacetic acid-precipitable material. 23 Raw 264.7 cells were treated with cycloheximide 30 min before and during stimulation for 1 h with IFN-g, then cells were incubated in normal media and gene expression was analyzed by Northern Blot. The short treatment with cycloheximide was carried out because it is very toxic for macrophages.…”

“…Actinomycin D was then added at a concentration (5 mg/ml) sufficient to block all further mRNA synthesis, as determined by [ 3 H]UTP incorporation, 23 and mRNA was isolated from aliquots of cells at distinct intervals thereafter. Determination of the relative levels of Tap1 and Lmp2 mRNA after the addition of actinomycin D allowed us to estimate the half-life of these mRNAs.…”

Deacetylase Activity Is Required for STAT5-Dependent GM-CSF Functional Activity in Macrophages and Differentiation to Dendritic Cells

“…There is an apparent discrepancy between the levels of CIITA mRNA, which was completely inhibited by TSA, and those of I-A ␤, which was only partially inhibited. This discrepancy can be attributed to the distinct mRNA half-lives; for CIITA mRNA the half-life is short (between 30 and 60 min) (41) whereas I-A ␤ mRNA is stable (Ͼ10 h) (42,43), as is the I-A ␤ protein (39).…”

IL-12 induced modulation of tumor derived myeloid cell inflammatory responsiveness.

“…IFNγ is the sole member of the type II interferon group (44). Th1 lymphocytes, NK cells, and macrophages produce IFNγ, which is a potent endogenous activator of macrophages (45)(46)(47)(48). Genes that are upregulated in macrophages in response to IFNγ include MHC class I and II, anti-viral proteins, inflammatory cytokines and chemokines (46,49).…”

“…Th1 lymphocytes, NK cells, and macrophages produce IFNγ, which is a potent endogenous activator of macrophages (45)(46)(47)(48). Genes that are upregulated in macrophages in response to IFNγ include MHC class I and II, anti-viral proteins, inflammatory cytokines and chemokines (46,49). IFNγ binds to its receptor to form a heterodimer of type II cytokine receptors, interferon gamma receptor gamma 1 and 2 (IFNGR1 and 2) that leads to the activation of JAK1 and JAK2 that subsequently phosphorylate IFNGR1 (50,51).…”