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MicroRNA-155 Is Required for Mycobacterium bovis BCG-Mediated Apoptosis of Macrophages

Ghorpade, Devram Sampat and Leyland, Rebecca and Kurowska-Stolarska, Mariola and Patil, Shripad A and Balaji, Kithiganahalli Narayanaswamy (2012) MicroRNA-155 Is Required for Mycobacterium bovis BCG-Mediated Apoptosis of Macrophages. In: MOLECULAR AND CELLULAR BIOLOGY, 32 (12). pp. 2239-2253.

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Official URL: http://dx.doi.org/10.1125/MCB.06597-11


Pathogenic rnycobacteria, including Mycobacterium tuberculosis and Mycobacterium bovis, cause significant morbidity and mortality worldwide. However, the vaccine strain Mycobacterium bovis BCG, unlike virulent strains, triggers extensive apoptosis of infected macrophages, a step necessary for the elicitation of robust protective immunity. We here demonstrate that M. bovis BCG triggers Toll-like receptor 2 (TLR2)-dependent microRNA-155 (miR-155) expression, which involves signaling cross talk among phosphatidylinositol 3-kinase (PI3K), protein kinase C delta (PKC delta), and mitogen-activated protein kinases (MAPKs) and recruitment of NF-kappa B and c-ETS to miR-155 promoter. Genetic and signaling perturbations presented the evidence that miR-155 regulates PKA signaling by directly targeting a negative regulator of PKA, protein kinase inhibitor alpha (PKI-alpha). Enhanced activation of PKA signaling resulted in the generation of PKA C-alpha; phosphorylation of MSK1, cyclic AMP response element binding protein (CREB), and histone H3; and recruitment of phospho-CREB to the apoptotic gene promoters. The miR-155-triggered activation of caspase-3, BAK1, and cytochrome c translocation involved signaling integration of MAPKs and epigenetic or posttranslational modification of histones or CREB. Importantly, M. bovis BCG infection-induced apoptosis was severely compromised in macrophages derived from miR-155 knockout mice. Gain-of-function and loss-of-function studies validated the requirement of miR-155 for M. bovis BCG's ability to trigger apoptosis. Overall, M. bovis BCG-driven miR-155 dictates cell fate decisions of infected macrophages, strongly implicating a novel role for miR-155 in orchestrating cellular reprogramming during immune responses to mycobacterial infection.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to the American Society for Microbiology
Department/Centre: Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited: 05 Jul 2012 12:33
Last Modified: 05 Jul 2012 12:37
URI: http://eprints.iisc.ac.in/id/eprint/44766

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