title: Stimulator of IFN gene is critical for induction of IFN-beta during Chlamydia muridarum infection.
abstract: Type I IFN signaling has recently been shown to be detrimental to the host during infection with Chlamydia muridarum in both mouse lung and female genital tract. However, the pattern recognition receptor and the signaling pathways involved in chlamydial-induced IFN-beta are unclear. Previous studies have demonstrated no role for TLR4 and a partial role for MyD88 in chlamydial-induced IFN-beta. In this study, we demonstrate that mouse macrophages lacking TLR3, TRIF, TLR7, or TLR9 individually or both TLR4 and MyD88, still induce IFN-beta equivalent to wild type controls, leading to the hypothesis that TLR-independent cytosolic pathogen receptor pathways are crucial for this response. Silencing nucleotide-binding oligomerization domain 1 in HeLa cells partially decreased chlamydial-induced IFN-beta. Independently, small interfering RNA-mediated knockdown of the stimulator of IFN gene (STING) protein in HeLa cells and mouse oviduct epithelial cells significantly decreased IFN-beta mRNA expression, suggesting a critical role for STING in chlamydial-induced IFN-beta induction. Conversely, silencing of mitochondria-associated antiviral signaling proteins and the Rig-I-like receptors, RIG-I, and melanoma differentiation associated protein 5, had no effect. In addition, induction of IFN-beta depended on the downstream transcription IFN regulatory factor 3, and on activation of NF-kappaB and MAPK p38. Finally, STING, an endoplasmic reticulum-resident protein, was found to localize in close proximity to the chlamydial inclusion membrane during infection. These results indicate that C. muridarum induces IFN-beta via stimulation of nucleotide-binding oligomerization domain 1 pathway, and TLR- and Rig-I-like receptor-independent pathways that require STING, culminating in activation of IFN regulatory factor 3, NF-kappaB, and p38 MAPK.
authors.affiliation: Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Prantner
authors.forename: Toni
authors.initials: T
authors.lastname: Darville
authors.forename: Uma M
authors.initials: UM
authors.lastname: Nagarajan
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000172:deficiency / Q000235:genetics; D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D023502:Chlamydia muridarum / Q000235:genetics* / Q000502:physiology; D005260:Female; D006367:HeLa Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D016899:Interferon-beta / Q000235:genetics / Q000378:metabolism*; D017737:Macrophages, Peritoneal / Q000166:cytology / Q000378:metabolism* / Q000382:microbiology; D008297:Male; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88 / Q000172:deficiency / Q000235:genetics; D034622:RNA Interference; D051196:Toll-Like Receptor 3 / Q000172:deficiency / Q000235:genetics; D051197:Toll-Like Receptor 4 / Q000172:deficiency / Q000235:genetics; D051199:Toll-Like Receptor 7 / Q000172:deficiency / Q000235:genetics; D051217:Toll-Like Receptor 9 / Q000172:deficiency / Q000235:genetics; D000099197:STING Protein
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D016899:Interferon-beta; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D053594:Myeloid Differentiation Factor 88; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; D051199:Toll-Like Receptor 7; D051217:Toll-Like Receptor 9; C507780:Myd88 protein, mouse; C530855:Sting1 protein, mouse; D000099197:STING Protein; C476286:Ticam1 protein, mouse; C519703:TLR3 protein, mouse; C493487:Tlr4 protein, mouse; C477038:Tlr7 protein, mouse; C495370:Tlr9 protein, mouse