Role of STAT1 in Chlamydia-Induced Type-1 Interferon Production in Oviduct Epithelial Cells.
We previously reported that Chlamydia muridarum-infected murine oviduct epithelial cells (OE cells) secrete interferon β (IFN-β) in a mostly TLR3-dependent manner. However, C. muridarum-infected TLR3-deficient OE cells were still able to secrete detectable levels of IFN-β into the supernatants, suggesting that other signaling pathways contribute to Chlamydia-induced IFN-β synthesis in these cells. We investigated the role of STAT1 as a possible contributor in the Chlamydia-induced type-1 IFN production in wild-type (WT) and TLR3-deficient OE cells to ascertain its putative role at early- and late-times during Chlamydia infection. Our data show that C. muridarum infection significantly increased STAT1 gene expression and protein activation in WT OE cells; however, TLR3-deficient OE cells showed diminished STAT1 protein activation and gene expression. There was significantly less IFN-β detected in the supernatants of C. muridarum-infected OE cells derived from mice deficient in STAT1 when compared with WT OE cells, which suggest that STAT1 is required for the optimal synthesis of IFN-β during infection. Real-time quantitative polymerase chain reaction analyses of signaling components of the type-1 IFN signaling pathway demonstrated equal upregulation in the expression of STAT2 and IRF7 genes in the WT and TLR3-deficient OE cells, but no upregulation in these genes in the STAT1-deficient OE cells. Finally, experiments in which INFAR1 was blocked with neutralizing antibody revealed that IFNAR1-mediated signaling was critical to the Chlamydia-induced upregulation in IFN-α gene transcription, but had no role in the Chlamydia-induced upregulation in IFN-β gene transcription.
1 Department of Microbiology and Immunology, Indiana University School of Medicine , Indianapolis, Indiana.
Kristen Lynette
KL
Hosey
1 Department of Microbiology and Immunology, Indiana University School of Medicine , Indianapolis, Indiana.|2 College of Veterinary Medicine, Huazhong Agricultural University , Wuhan, People's Republic of China .
Sishun
S
Hu
1 Department of Microbiology and Immunology, Indiana University School of Medicine , Indianapolis, Indiana.
Wilbert Alfred
WA
Derbigny
D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology; D002460:Cell Line; D002690:Chlamydia Infections / Q000276:immunology* / Q000382:microbiology; D023502:Chlamydia muridarum / Q000276:immunology*; D004847:Epithelial Cells / Q000166:cytology / Q000276:immunology*; D005187:Fallopian Tubes / Q000166:cytology / Q000276:immunology*; D005260:Female; D005786:Gene Expression Regulation / Q000276:immunology; D050839:Interferon Regulatory Factor-7 / Q000096:biosynthesis / Q000235:genetics; D016898:Interferon-alpha / Q000096:biosynthesis; D016899:Interferon-beta / Q000096:biosynthesis* / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053633:Receptor, Interferon alpha-beta / Q000037:antagonists & inhibitors / Q000235:genetics; D050794:STAT1 Transcription Factor / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology; D015398:Signal Transduction / Q000276:immunology; D051196:Toll-Like Receptor 3 / Q000235:genetics; D015533:Transcriptional Activation / Q000276:immunology; D015854:Up-Regulation
D057134:Antibodies, Neutralizing; D050839:Interferon Regulatory Factor-7; D016898:Interferon-alpha; C494235:Irf7 protein, mouse; D050794:STAT1 Transcription Factor; C494080:Stat1 protein, mouse; C519703:TLR3 protein, mouse; D051196:Toll-Like Receptor 3; D053633:Receptor, Interferon alpha-beta; D016899:Interferon-beta