Interferon receptor-deficient mice are susceptible to eschar-associated rickettsiosis

Burke, Thomas; Engström, Patrik; Tran, Cuong J; Glasner, Dustin R.; Espinosa, Diego A.; Harris, Eva; Welch, Matthew

doi:10.1101/2020.09.23.310409

Cited by 4 publications

(8 citation statements)

References 62 publications

(103 reference statements)

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“…The ability of Rickettsia species to escape the vacuole and avoid host membranes Our work shows that Pat1 is important for virulence upon i.v. infection in a mouse model that succumbs to R. parkeri infection (8,61). This is consistent with other bacterial factors involved in vacuolar escape being important virulence factors in animal models of disease.…”

Section: Discussionsupporting

confidence: 84%

“…We next examined the contribution of Pat1 to virulence in vivo using mice lacking the receptors for both IFN-I (Ifnar1) or IFN-γ (Ifngr1) (Ifnar1 -/-;Ifngr1 -/double knock out mice), which succumb to infection with WT R. parkeri and can be used to investigate the importance of bacterial genes to virulence (8,61). Mice infected intravenously (i.v.)…”

Section: Pat1 Is Important For Infection Of Host Cells and Contributes To Virulence In Micementioning

confidence: 99%

“…Because R. parkeri can be studied under biosafety level 2 (BSL2) conditions, it is emerging as a model for understanding the molecular determinants of SFG Rickettsia pathogenicity. (4)(5)(6)(7)(8) as well as endothelial cells (6,7,9) during infection in humans and animal models. Upon invasion of host cells, bacteria escape from the primary vacuole into the cytosol, where they replicate (10,11).…”

Section: Introductionmentioning

confidence: 99%

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A patatin-like phospholipase mediatesRickettsia parkeriescape from host membranes

Borgo

Burke

Tran

et al. 2021

Preprint

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Spotted fever group Rickettsia species are arthropod-borne obligate intracellular bacteria that can cause mild to severe human disease. These bacteria invade host cells, replicate in the cell cytosol, and then spread from cell to cell. To access the host cytosol and avoid detection by immune surveillance mechanisms, these pathogens must have evolved efficient ways to escape membrane-bound vacuoles. Although Rickettsia are predicted to express factors that disrupt host membranes, little is known about how and when these proteins function during infection. Here, we investigated the role of a Rickettsia patatin-like phospholipase A2 enzyme (Pat1) during host cell infection by characterizing a Rickettsia parkeri mutant with a transposon insertion in the pat1 gene. We show that Pat1 is important for infection in a mouse model and in host cells. We further show that Pat1 is critical for efficiently escaping from the single and double membrane-bound vacuoles into the host cytosol, and for avoiding host galectins that mark damaged membranes. In the host cytosol, Pat1 is important for avoiding host polyubiquitin, preventing recruitment of autophagy receptor p62, and promoting actin-based motility and cell-cell spread. Our results show that Pat1 plays critical roles in escaping host membranes and promoting cell-cell spread during R. parkeri infection and suggest diverse roles for patatin-like phospholipases in facilitating microbial infection.ImportanceSpotted fever group Rickettsia are bacteria that reside in ticks and can be transmitted to mammalian hosts, including humans. Severe disease is characterized by high fever, headache, and rash, and results in occasional mortality despite available treatment. Rickettsia interact with host cell membranes while invading cells, escaping into the cytosol, and evading cellular defenses. Bacterial phospholipase enzymes have been proposed as critical factors for targeting host cell membranes, however the specific roles of rickettsial phospholipases are not well defined. We investigated the contribution of one conserved patatin-like phospholipase, Pat1, in Rickettsia parkeri. We observed that Pat1 is important for virulence in an animal model. Moreover, Pat1 plays critical roles in host cells by facilitating access to the cell cytosol, inhibiting detection by host defense pathways, and promoting cell-cell spread. Our study indicates that Pat1 performs several critical functions, suggesting a broad role for phospholipases throughout the Rickettsia lifecycle.

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Section: Discussionsupporting

confidence: 84%

Section: Pat1 Is Important For Infection Of Host Cells and Contributes To Virulence In Micementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A patatin-like phospholipase mediatesRickettsia parkeriescape from host membranes

Borgo

Burke

Tran

et al. 2021

Preprint

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“…2B). We further analyzed the roles of PKMT1 and PKMT2 by intradermal inoculations in Ifnar −/− Ifngr −/− mice, which result in skin lesion formation after infection with WT R. parkeri (24), similar to what is observed in humans after a tick bite (25). Mice infected with the pkmt1::tn displayed no or reduced skin lesion formation (Fig.…”

Section: Pkmt1 and Pkmt2 Are R Parkeri Virulence Factorsmentioning

confidence: 70%

“…To initiate infection, 30% purified bacteria were diluted in cell culture media at RT to reach a multiplicity of infection (MOI) of 0.01 for Vero and HMEC cells [for 1 hpi in Fig. 1F, an MOI of 2 was used; for other time points (24,48, and 72 hpi) in Fig. 1F, an MOI of 0.01 was used] and an MOI of 0.1 for BMDMs.…”

Section: Western Blottingmentioning

confidence: 99%

Lysine methylation shields an intracellular pathogen from ubiquitylation and autophagy

et al. 2021

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Many intracellular pathogens avoid detection by their host cells. However, it remains unknown how they avoid being tagged by ubiquitin, an initial step leading to antimicrobial autophagy. Here, we show that the intracellular bacterial pathogen Rickettsia parkeri uses two protein-lysine methyltransferases (PKMTs) to modify outer membrane proteins (OMPs) and prevent their ubiquitylation. Mutants deficient in the PKMTs were avirulent in mice and failed to grow in macrophages because of ubiquitylation and autophagic targeting. Lysine methylation protected the abundant surface protein OmpB from ubiquitin-dependent depletion from the bacterial surface. Analysis of the lysine-methylome revealed that PKMTs modify a subset of OMPs, including OmpB, by methylation at the same sites that are modified by host ubiquitin. These findings show that lysine methylation is an essential determinant of rickettsial pathogenesis that shields bacterial proteins from ubiquitylation to evade autophagic targeting.

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Identification of common sequence motifs shared exclusively among selectively packed exosomal pathogenic microRNAs during rickettsial infections

Bei¹,

Qiu²,

Cockrell

et al. 2023

Preprint

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We previously reported that microRNA (miR)23a and miR30b are selectively sorted into rickettsia-infected, endothelial cell-derived exosomes (R-ECExos). Yet, the mechanism remains unknown. The number of cases of spotted fever rickettsioses has been increasing in recent years, and infections with these bacteria cause life-threatening diseases by targeting brain and lung tissues. Therefore, the aim of the present study is to continue to dissect the molecular mechanism underlying R-ECExos-induced barrier dysfunction of normal recipient microvascular endothelial cells (MECs), depending on their exosomal RNA cargos. Rickettsiae are transmitted to human hosts by the bite of an infected tick into the skin. In the present study we demonstrate that treatment with R-ECExos, which were derived from spotted fever group R parkeri infected human dermal MECs, induced disruptions of the paracellular adherens junctional protein VE-cadherin and breached the paracellular barrier function in recipient pulmonary MECs (PMECs) in an exosomal RNA-dependent manner. Similarly, we did not detect different levels of miRs in parent dermal MECs following rickettsial infections. However, we demonstrated that the microvasculopathy-relevant miR23a-27a-24 cluster and miR30b are selectively enriched in R-ECExos. Bioinformatic analysis revealed that common sequence motifs are shared exclusively among the exosomal, selectively-enriched miR23a cluster and miR30b at different levels. Taken together, these data warrant further functional identification and characterization of a single, bipartition, or tripartition among ACA, UCA, and CAG motifs that guide recognition of microvasculopathy-relevant miR23a-27a-24 and miR30b, and subsequently results in their selective enrichments in R-ECExos.

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Interferon receptor-deficient mice are susceptible to eschar-associated rickettsiosis

Cited by 4 publications

References 62 publications

A patatin-like phospholipase mediatesRickettsia parkeriescape from host membranes

A patatin-like phospholipase mediatesRickettsia parkeriescape from host membranes

Lysine methylation shields an intracellular pathogen from ubiquitylation and autophagy

Identification of common sequence motifs shared exclusively among selectively packed exosomal pathogenic microRNAs during rickettsial infections

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