MiR-155 induction by microbes/microbial ligands requires NF-kB-dependent de novo protein synthesis

• Main Authors: Susheela eTridandapani, Thomas John Cremer, Kavin eFatehchand, Prexy eShah, Devyn eGillette, Hemal ePatel, Rachel L Marsh, Beth Y Besecker, Murugesan VS Rajaram, Thirumala-Devi eKanneganti, Larry eSchlesinger, Jonathan P Butchar
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2012-06-01
• Series: Frontiers in Cellular and Infection Microbiology
• Subjects: Bacteria; Burkholderia; Infection; Mycobacterium; microRNA; TLR
• Online Access: http://journal.frontiersin.org/Journal/10.3389/fcimb.2012.00073/full

MiR-155 regulates numerous aspects of innate and adaptive immune function. This miR is induced in response to toll-like receptor ligands, cytokines, and microbial infection. We have previously shown that miR-155 is induced in monocytes/macrophages infected with Francisella tularensis and suppresses expression of the inositol phosphatase SHIP to enhance activation of the PI3K/Akt pathway, which in turn promotes favorable responses for the host. Here we examined how miR-155 expression is regulated during infection. First, our data demonstrate that miR-155 can be induced through soluble factors of bacterial origin and not the host. Second, miR-155 induction is not a direct effect of infection and it requires NF-κB signaling to up-regulate fos/jun transcription factors. Finally, we demonstrate that the requirement for NF-κB-dependent de novo protein synthesis is globally shared by microbial ligands and live bacteria. This study provides new insight into the complex regulation of miR-155 during microbial infection.