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The E3 ubiquitin ligase RNF115 regulates phagosome maturation and host response to bacterial infection

ABSTRACT: Phagocytosis is a key process in innate immunity and homeostasis. After particle uptake, newly formed phagosomes mature by acquisition of endo-lysosomal enzymes. Macrophage activation by interferon gamma (IFN-γ) increases microbicidal activity, but delays phagosomal maturation by an unknown mechanism. Using quantitative proteomics, we show that phagosomal proteins harbour high levels of typical and atypical ubiquitin chain types. Moreover, phagosomal ubiquitylation of vesicle trafficking proteins is substantially enhanced upon IFN-γ activation of macrophages, suggesting a role in regulating phagosomal functions. We identified the E3 ubiquitin ligase RNF115, which is enriched on phagosomes of IFN-γ activated macrophages, as an important regulator of phagosomal maturation. Loss of RNF115 protein or ligase activity enhanced phagosomal maturation and increased cytokine responses to bacterial infection, suggesting that both innate immune signalling from the phagosome and phagolysosomal trafficking are controlled through ubiquitylation. RNF115 knock-out mice show less tissue damage in response to S. aureus infection, indicating a role of RNF115 in inflammatory responses in vivo. In conclusion, RNF115 and phagosomal ubiquitylation are important regulators of innate immune functions during bacterial infections.

SUBMITTER: Dr. Orsolya Bilkei-Gorzo

PROVIDER: S-SCDT-10_15252-EMBJ_2021108970 | biostudies-other |

REPOSITORIES: biostudies-other

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The E3 ubiquitin ligase RNF115 regulates phagosome maturation and host response to infection

Project description:Phagocytosis is an essential process for the microbicidal function of professional phagocytes, in which phagosome maturation plays a critical role. Macrophage activation by interferons (IFN) increases their microbicidal activity, but delays phagosomal maturation. Here, we investigated the role of ubiquitylation in phagosome functions. We show that phagosomal proteins are ubiquitylated and that phagosomes contain diverse ubiquitin chain types, including atypical ubiquitin chains. IFN-γ activation of macrophages substantially enhanced phagosomal ubiquitylation of both innate immune response proteins and vesicle trafficking proteins. We identified the E3 ubiquitin ligase RNF115, which is enriched on phagosomes of IFN-γ activated macrophages, as an important regulator of phagosomal maturation. Loss of RNF115 protein or ubiquitin ligase activity facilitated enhanced phagosomal maturation, and increased cytokine responses to Staphylococcus aureus. Our data suggests that both innate immune signalling and phagolysosomal trafficking are controlled through ubiquitylation. In conclusion, we identify RNF115 and ubiquitylation as important regulators of innate immune signalling from the phagosome during bacterial infections.

2022-07-20 | PXD026843 | Pride

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