The Expression of MHC Class II Genes in Macrophages Is Cell Cycle Dependent

• Published in: The Journal of immunology (1950) Vol. 165; no. 11; pp. 6364 - 6371
• Main Authors: Xaus, Jordi, Comalada, Monica, Barrachina, Marta, Herrero, Carmen, Gonalons, Eduard, Soler, Concepcio, Lloberas, Jorge, Celada, Antonio
• Format: Journal Article
• Language: English
• Published: United States Am Assoc Immnol 01.12.2000
• Subjects: Animals; Blotting, Northern; Bone Marrow Cells - cytology; Bone Marrow Cells - immunology; Bone Marrow Cells - metabolism; Cell Cycle - drug effects; Cell Cycle - genetics; Cell Cycle - immunology; Cells, Cultured; DNA - analysis; Flow Cytometry; G1 Phase - drug effects; G1 Phase - genetics; G1 Phase - immunology; Gene Expression Regulation - drug effects; Gene Expression Regulation - immunology; Genes, MHC Class II - drug effects; Growth Inhibitors - pharmacology; Interferon-gamma - pharmacology; Macrophage Activation - drug effects; Macrophage Activation - genetics; Macrophages - cytology; Macrophages - enzymology; Macrophages - immunology; Macrophages - metabolism; Mice; Mice, Inbred BALB C; Nitric Oxide Synthase - biosynthesis; Nitric Oxide Synthase - genetics; Nitric Oxide Synthase Type II; Protein Processing, Post-Translational - genetics; Protein Processing, Post-Translational - immunology; Receptors, IgG - biosynthesis; RNA, Messenger - biosynthesis
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.165.11.6364

Using different drugs, we stopped the cell cycle of bone marrow-derived macrophages at different points. After IFN-gamma stimulation, macrophages arrested at the G(1) phase of the cell cycle did not increase cell surface expression of the MHC class II IA. This inhibition is specific, because, under the same conditions, IFN-gamma induces the expression of Fcgamma receptors and the inducible NO synthase mRNA. Treatments that inhibit macrophage proliferation by blocking the cell cycle at the G(1) phase, such as adenosine, forskolin, or LPS, blocked the IFN-gamma induction of IA. Under IFN-gamma treatment, the steady-state levels of IAalpha and IAss mRNA did not increase in cells arrested at the G(1) phase and the half-life of the MHC mRNA was not modified. These data suggest that the cell cycle modulation of IFN-gamma-induced MHC II gene expression occurs at the transcriptional level. The expression of the class II transactivator mRNA induced by IFN-gamma was also blocked when macrophages were arrested at the G(1) phase of the cell cycle, suggesting that the lack of IFN-gamma response occurs at the early steps of MHC class II expression. Finally, macrophages arrested at the G(1) phase showed increased basal levels of cell surface IA due to an increase of the translational efficiency. These data show that the expression of MHC class II genes is regulated by the cell cycle.