Wnt signaling regulates immunomodulatory functions during infection and inflammation. Employing NCCIT and HCT116 cells, having high endogenous Wnt signaling, we observed elevated levels of low-density lipoprotein receptor-related protein 5/6 (LRP5/6) and Frizzled class receptor 10 (FZD10) and increases in β-catenin, doublecortin-like kinase 1 (DCLK1), CD44 molecule (CD44), and aldehyde dehydrogenase 1 family member A1 (ALDH1A1). siRNA-induced knockdown of these receptors antagonized TOPflash reporter activity and spheroid growth in vitro and elevated Wnt-inhibitory factor 1 (WIF1) activity. Elevated mRNA and protein levels of LRP5/6 and FZD10 paralleled expression of WNT2b and WNT4 in colonic crypts at days 6 and 12 post-infection with Citrobacter rodentium (CR) and tended to decline at days 20-34. The CR mutant escV or the tankyrase inhibitor XAV939 attenuated these responses. A three-dimensional organoid assay in colonic crypts isolated from CR-infected mice revealed elevated levels of LRP5/6 and FZD10 and β-catenin co-localization with enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2). Co-immunoprecipitation in the membrane fraction revealed that axin associates with LRP5/6 in CR-infected crypts, and this association was correlated with increased β-catenin. Colon tumors from either CR-infected ApcP Min/+ or azoxymethane/dextran sodium sulfate (AOM/DSS)-treated mice had high LRP5/6 or FZD10 levels, and chronic Notch blockade through the γ-secretase inhibitor dibenzazepine down-regulated LRP5/6 and FZD10 expression. In CR-responsive CT-26 cells, siRNA-induced LRP5/6 or FZD10 knockdown antagonized TOPflash reporter activity. Elevated miR-153-3p levels correlated with LRP5/6 and FZD10, and miR-153-3p sequestration via a plasmid-based miR inhibitor system attenuated Wnt signaling. We conclude that infection-induced signals from the plasma membrane epigenetically regulate Wnt signaling.
The Journal of biological chemistry
Cell Membrane; Citrobacter rodentium; Enterobacteriaceae Infections; Epigenesis, Genetic; Frizzled Receptors; HCT116 Cells; HEK293 Cells; Humans; Ligands; Low Density Lipoprotein Receptor-Related Protein-5; Low Density Lipoprotein Receptor-Related Protein-6; Male; MicroRNAs; Organoids; Receptors, Notch; Wnt Signaling Pathway
Citrobacter rodentium; Fzd10; LRP5; LRP6; Notch; Notch pathway; Wnt; bacterial infection; bacterial pathogenesis; beta-catenin; cancer stem cells; inflammation; miR-153–3p; microRNA (miRNA); β-catenin
Ahmed I, Roy BC, Rao Jakkula LUM, et al. Infection-induced signals generated at the plasma membrane epigenetically regulate Wnt signaling in vitro and in vivo. J Biol Chem. 2020;295(4):1021-1035. doi:10.1074/jbc.RA119.010285