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Resistin-like molecule ? is a bactericidal protein that promotes spatial segregation of the microbiota and the colonic epithelium.

ABSTRACT: The mammalian intestine is colonized by trillions of bacteria that perform essential metabolic functions for their hosts. The mutualistic nature of this relationship depends on maintaining spatial segregation between these bacteria and the intestinal epithelial surface. This segregation is achieved in part by the presence of a dense mucus layer at the epithelial surface and by the production of antimicrobial proteins that are secreted by epithelial cells into the mucus layer. Here, we show that resistin-like molecule ? (RELM?) is a bactericidal protein that limits contact between Gram-negative bacteria and the colonic epithelial surface. Mouse and human RELM? selectively killed Gram-negative bacteria by forming size-selective pores that permeabilized bacterial membranes. In mice lacking RELM?, Proteobacteria were present in the inner mucus layer and invaded mucosal tissues. Another RELM family member, human resistin, was also bactericidal, suggesting that bactericidal activity is a conserved function of the RELM family. Our findings thus identify the RELM family as a unique family of bactericidal proteins and show that RELM? promotes host-bacterial mutualism by regulating the spatial segregation between the microbiota and the intestinal epithelium.

SUBMITTER: Propheter DC

PROVIDER: S-EPMC5651776 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

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Resistin-like molecule β is a bactericidal protein that promotes spatial segregation of the microbiota and the colonic epithelium.

Propheter Daniel C DC Chara Andrew L AL Harris Tamia A TA Ruhn Kelly A KA Hooper Lora V LV

Proceedings of the National Academy of Sciences of the United States of America 20170925 42

The mammalian intestine is colonized by trillions of bacteria that perform essential metabolic functions for their hosts. The mutualistic nature of this relationship depends on maintaining spatial segregation between these bacteria and the intestinal epithelial surface. This segregation is achieved in part by the presence of a dense mucus layer at the epithelial surface and by the production of antimicrobial proteins that are secreted by epithelial cells into the mucus layer. Here, we show that ...[more]

PMID: 28973871

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Project description:Salmonella infections can become chronic and increase the risk of cancer. The mechanisms by which specific Salmonella organisms contribute to cancer, however, are still unknown. Live and attenuated Salmonella are used as vectors to target cancer cells, but there have been no systematic studies of the oncogenic potential of chronic Salmonella infections in cancer models. AvrA, a pathogenic product of Salmonella, is inserted into host cells during infection and influences eukaryotic cell pathways. In the current study, we colonized mice with Salmonella AvrA-sufficient or AvrA-deficient Salmonella typhimirium strains and induced inflammation-associated colon cancer by azoxymethane/dextran sulfate sodium (AOM/DSS). We confirmed Salmonella persisted in the colon for up to 45 weeks. Salmonella was identified not only in epithelial cells on the colonic luminal surface and base of the crypts but also in invading tumors. Tumor incidence in the AvrA+infected group was 100% compared with 51.4% in the AOM/DSS group without bacterial gavage and 56.3% in mice infected with the AvrA- strain. Infection with AvrA+ strain also altered tumor distribution from the distal to proximal colon that might reflect changes in the microbiome. AvrA-expressing bacteria also upregulated beta-catenin signaling as assessed by decreased beta-catenin ubiquitination, increased nuclear beta-catenin and increased phosphorylated-beta-catenin (Ser552), a marker of proliferating stem-progenitor cells. Other β-catenin targets increased by AvrA included Bmi1, a cancer stem cell marker, matrix metalloproteinase-7, and cyclin D1. In summary, AvrA-expressing Salmonella infection activates β-catenin signals and enhances colonic tumorigenesis. Our findings provide important new mechanistic insights into how a bacterial protein targets proliferating stem-progenitor cells and contributes to cancer development. Our observations also raise a note of caution regarding the use of mutant Salmonella organisms as vectors for anti-cancer therapy. Finally, these studies could suggest biomarkers (such as AvrA level in gut) to assess cancer risk in susceptible individuals and infection-related dysregulation of β-catenin signaling in cancer.

Dataset Information

Resistin-like molecule ? is a bactericidal protein that promotes spatial segregation of the microbiota and the colonic epithelium.

Publications

Resistin-like molecule β is a bactericidal protein that promotes spatial segregation of the microbiota and the colonic epithelium.

Similar Datasets

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