title: Cellular stress amplifies TLR3/4-induced CXCL1/2 gene transcription in mononuclear phagocytes via RIPK1.
abstract: The impact of environmental stressors on the magnitude of specific chemokine gene expression was examined in mouse bone marrow-derived macrophages stimulated through various TLRs. Levels of TLR-stimulated CXCL1 and CXCL2 but not CXCL10 or CCL5 mRNAs were selectively enhanced (>10-fold) in stressed macrophages. The amplification was also manifested for other proinflammatory cytokines, including TNF-α, IL-1α, and IL-6. Responses through TLR3 and TLR4 exhibited the greatest sensitivity, reflecting a requirement for Toll/IL-IR domain-containing adaptor-inducing IFN-β (TRIF), the adaptor protein selectively associated with these TLRs. IFN regulatory factor 3, a transcription factor that is downstream of TLR4/TRIF signaling, was not required for sensitivity to stress-induced chemokine amplification. c/EBP homologous protein and X box binding protein 1 have been reported to enhance inflammatory cytokine responses but are not required for amplification of TLR3/4-induced CXCL1 expression. Rather, receptor-interacting protein kinase 1, a kinase also linked with TLR3/4/TRIF signaling, is required and involves a stress-dependent increase in its abundance and ubiquitination. Whereas NF-κB activation is necessary for TLR-induced chemokine gene transcription, this factor does not appear to be the primary mechanistic target of environmental stress. The application of stress also enhanced chemokine expression in macrophages infiltrating the peritoneal cavity but was not observed in the resident peritoneal cells or in the liver. These findings identify novel mechanisms for modulating the magnitude and duration of selective TLR-induced chemokine and cytokine gene expression and further establish the importance of cell stress pathways in coordinating the outcomes of cellular and tissue injury.
authors.affiliation: Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195.
authors.forename: Chenyang
authors.initials: C
authors.lastname: Zhao
authors.affiliation: Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Pavicic
authors.affiliation: Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195.
authors.forename: Shyamasree
authors.initials: S
authors.lastname: Datta
authors.affiliation: Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195.
authors.forename: Dongxu
authors.initials: D
authors.lastname: Sun
authors.affiliation: Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195.
authors.forename: Michael
authors.initials: M
authors.lastname: Novotny
authors.affiliation: Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195 hamiltt@ccf.org.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Hamilton
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002478:Cells, Cultured; D054360:Chemokine CXCL1 / Q000235:genetics* / Q000378:metabolism; D054426:Chemokine CXCL2 / Q000235:genetics* / Q000378:metabolism; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D022423:Myeloid Cells / Q000187:drug effects / Q000378:metabolism; D034622:RNA Interference; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D000071701:Regulatory Factor X Transcription Factors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D051196:Toll-Like Receptor 3 / Q000235:genetics* / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014415:Tunicamycin / Q000494:pharmacology
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D054360:Chemokine CXCL1; D054426:Chemokine CXCL2; D016207:Cytokines; D004268:DNA-Binding Proteins; D004121:Dimethyl Sulfoxide; D008070:Lipopolysaccharides; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; D000071701:Regulatory Factor X Transcription Factors; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; D014157:Transcription Factors; D014415:Tunicamycin; C476286:Ticam1 protein, mouse; C506251:Ripk1 protein, mouse