ABSTRACT
Pathogenic mycobacteria employ several immune evasion strategies such as inhibition of class II transactivator (CIITA) and MHC-II expression, to survive and persist in host macrophages. However, precise roles for specific signaling components executing down-regulation of CIITA/MHC-II have not been adequately addressed. Here, we demonstrate that Mycobacterium bovis bacillus Calmette-Guérin (BCG)-mediated TLR2 signaling-induced iNOS/NO expression is obligatory for the suppression of IFN-γ-induced CIITA/MHC-II functions. Significantly, NOTCH/PKC/MAPK-triggered signaling cross-talk was found critical for iNOS/NO production. NO responsive recruitment of a bifunctional transcription factor, KLF4, to the promoter of CIITA during M. bovis BCG infection of macrophages was essential to orchestrate the epigenetic modifications mediated by histone methyltransferase EZH2 or miR-150 and thus calibrate CIITA/MHC-II expression. NO-dependent KLF4 regulated the processing and presentation of ovalbumin by infected macrophages to reactive T cells. Altogether, our study delineates a novel role for iNOS/NO/KLF4 in dictating the mycobacterial capacity to inhibit CIITA/MHC-II-mediated antigen presentation by infected macrophages and thereby elude immune surveillance.
Subject(s)
Histocompatibility Antigens Class II/immunology , Kruppel-Like Transcription Factors/immunology , Nitric Oxide/immunology , Nuclear Proteins/immunology , Trans-Activators/immunology , Tuberculosis/immunology , Animals , Cell Line , Cells, Cultured , Enhancer of Zeste Homolog 2 Protein , Epigenesis, Genetic/immunology , Gene Expression/drug effects , Gene Expression/immunology , Histocompatibility Antigens Class II/genetics , Histocompatibility Antigens Class II/metabolism , Host-Pathogen Interactions/genetics , Host-Pathogen Interactions/immunology , Immunoblotting , Interferon-gamma/immunology , Interferon-gamma/pharmacology , Kruppel-Like Factor 4 , Kruppel-Like Transcription Factors/genetics , Kruppel-Like Transcription Factors/metabolism , Macrophages/immunology , Macrophages/metabolism , Macrophages/microbiology , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Knockout , MicroRNAs/genetics , MicroRNAs/immunology , MicroRNAs/metabolism , Microscopy, Confocal , Mycobacterium bovis/immunology , Mycobacterium bovis/physiology , Nitric Oxide/metabolism , Nitric Oxide Synthase Type II/genetics , Nitric Oxide Synthase Type II/immunology , Nitric Oxide Synthase Type II/metabolism , Nuclear Proteins/genetics , Nuclear Proteins/metabolism , Polycomb Repressive Complex 2/genetics , Polycomb Repressive Complex 2/immunology , Polycomb Repressive Complex 2/metabolism , RNA Interference , Reverse Transcriptase Polymerase Chain Reaction , Trans-Activators/genetics , Trans-Activators/metabolism , Tuberculosis/microbiology , Tuberculosis/veterinaryABSTRACT
We isolated and characterized two lytic bacteriophages against Staphylococcus aureus named TANUVAS_MVC-VPHSA1 and TANUVAS_MVC-VPHSA2, with the aim of investigating their genomic and structural features. The bacteriophages belong to the Caudoviricetes, and their genomes have sizes of 50,505 and 50,516 base pairs with a GC content of 41.4%.