H. pylori infection blocks DNA damage induced apoptosis by T4SS-dependent upregulation of miR-155

ABSTRACT: The innate immune response against Helicobacter pylori is mainly controlled by pattern recognition receptors that lead to the up-regulation of pro-inflammatory cytokines. A new player in this field is the miR-155 being regulated by TLR ligands in monocytic derived cells influencing certain intracellular pathways by down-regulating targets involved in signaling and development. By using primary bone marrow derived macrophages (BMMs) from mice deficient in the key TLR signals the regulation of miR-155 was explored. Further on the biological impact of a lack of miR-155 in BMMs was analyzed by micro-array studies and apoptosis assays. We observed that miR-155 is up-regulated in response to H. pylori via TLR2 and TLR4 in a NF-M-NM-:B dependent manner, but also identified a TLR2/TLR4 independent mechanism that was strongly connected to a functional TypeIV secretion system. Down-stream the high expression of miR-155 down-regulated many mRNA targets during H. pylori infection. Thereby we could validate Tspan14, Lpin1, and Pmaip1 as new targets of miR-155 and identified their binding site. These and other already published targets showed a substantial pro-apoptotic potential. We observed that H. pylori infected wild type BMMs were much more resistant to DNA damage induced apoptosis by cisplatin when compared to their respective miR-155-/- BMMs. Our data strongly suggests that there is an additional innate immune mechanism of BMMs leading to the upregulation of the anti-apoptotic miR-155 that causes resistance to DNA damage in BMMs. Microarray experiments were performed as dual-color hybridizations. To compensate for dye-specific effects, an independent dye-reversal color-swap was applied. Bone marrow derived macrophages were 'in vitro' infected with H.pylori P12 and the expression changes were measured.

ORGANISM(S): Mus musculus

SUBMITTER: Hans-Joachim Mollenkopf 

PROVIDER: E-GEOD-29388 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress