AUF1 isoform-specific regulation of anti-inflammatory IL10 expression in monocytes.
IL-10 is an immunomodulatory cytokine that regulates inflammatory responses of mononuclear phagocytes (monocytes and macrophages). Mononuclear cells exposed to microbes or microbial products secrete a host of proinflammatory cytokines followed by delayed onset of anti-inflammatory IL-10. IL-10 suppresses immune responses by inhibiting cytokine production by mononuclear phagocytes. Using THP-1, a human promonocytic leukemia cell line, we show that endotoxin/lipopolysaccharide (LPS) exposure induces IL10 expression while IFN-gamma blocks this LPS-mediated effect. IFN-gamma is an important modulator of IL-10 production during infectious diseases. We show that LPS and IFN-gamma regulate IL10 expression in THP-1 cells in part through posttranscriptional mechanisms. Our results demonstrate that 3'-untranslated region (3'-UTR) AU-rich elements (AREs) decrease expression of a chimeric luciferase reporter gene in THP-1 cells. The ARE-binding protein AUF1 binds the IL10 3'-UTR. Depletion of AUF1 by RNAi suppresses LPS-mediated induction of IL10 mRNA and protein without affecting LPS-mediated stabilization of IL10 mRNA. Upon complementation with either RNAi-refractory p37 or p40 AUF1 plasmids, only p40 restores LPS-mediated induction of IL10 mRNA and protein to near normal levels. Thus, the p40 AUF1 isoform selectively plays a critical, positive role in IL10 expression upon LPS exposure.
Department of Molecular Genetics, Microbiology, and Immunology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA. pestka@umdnj.edu
Srijata
S
Sarkar
Kristina S
KS
Sinsimer
Randi L
RL
Foster
Gary
G
Brewer
Sidney
S
Pestka
D002460:Cell Line; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D016753:Interleukin-10 / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000378:metabolism; D008262:Macrophage Activation; D009000:Monocytes / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000276:immunology / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics
C000630986:HNRNPD protein, human; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D; D008070:Lipopolysaccharides; D020033:Protein Isoforms; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016753:Interleukin-10; D007371:Interferon-gamma