The Unfolded-Protein Response Triggers the Arthropod Immune Deficiency Pathway

Sidak-Loftis, Lindsay C; Rosche, Kristin L.; Pence, Natasha; Ujczo, Jessica K; Hurtado, Joanna; Fisk, Elis A; Goodman, Alan G.; Noh, Susan M.; Peters, John W.; Shaw, Dana K.

doi:10.1128/mbio.00703-22

Cited by 10 publications

(21 citation statements)

References 141 publications

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“…Seven days post infection 25-50 μl of blood was collected from the lateral saphenous vein. Levels of A. phagocytophilum in the blood was measured by qPCR (16S rRNA relative to mouse β-actin (51, 54)) (Table S1). Uninfected I. scapularis larval ticks were purchased from Oklahoma State University (Stillwater, OK, USA).…”

Section: Methodsmentioning

confidence: 99%

“…The Verso cDNA Synthesis Kit (ThermoFisher) was used to generate cDNA. Levels of viable A. phagocytophilum in the ticks were measured by quantifying A. phagocytophilum 16S rRNA relative to I. scapularis β-actin transcripts by qRT-PCR (Table S1) by absolute quantification (51, 54). All animal use protocols were approved by the Washington State University Institutional Animal Care and Use Committee (ASAF #6630).…”

Section: Methodsmentioning

confidence: 99%

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AnAnaplasma phagocytophilumT4SS effector, AteA, is essential for tick infection

Park

Genera

Fahy

et al. 2023

Preprint

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Pathogens must adapt to disparate environments in permissive host species, a feat that is especially pronounced for vector-borne microbes, which transition between vertebrate hosts and arthropod vectors to complete their lifecycles. Most knowledge about arthropod-vectored bacterial pathogens centers on their life in the mammalian host, where disease occurs. However, disease outbreaks are driven by the arthropod vectors. Adapting to the arthropod is critical for obligate intracellular rickettsial pathogens, as they depend on eukaryotic cells for survival. To manipulate the intracellular environment, these bacteria use Type IV Secretion Systems (T4SS) to deliver effectors into the host cell. To date, few rickettsial T4SS translocated effectors have been identified and have only been examined in the context of mammalian infection. We identified an effector from the tick-borne rickettsial pathogenAnaplasma phagocytophilum, HGE1_02492, as critical for survival in tick cells and acquisition by ticks in vivo. Conversely, HGE1_02492 was dispensable during mammalian cell culture and murine infection. We show HGE1_02492 is translocatable in a T4SS-dependent manner to the host cell cytosol. In eukaryotic cells, the HGE1_02492 localized with cortical actin filaments, which is dependent on multiple sub-domains of the protein. HGE1_02492 is the first arthropod-vector specific T4SS translocated effector identified from a rickettsial pathogen. Moreover, the subcellular target of HGE1_02492 suggests thatA. phagocytophilumis manipulating actin to enable arthropod colonization. Based on these findings, we propose the name AteA forAnaplasma(phagocytophilum) tick effector A. Altogether, we show thatA. phagocytophilumuses distinct strategies to cycle between mammals and arthropods.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

AnAnaplasma phagocytophilumT4SS effector, AteA, is essential for tick infection

Park

Genera

Fahy

et al. 2023

Preprint

Self Cite

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“…Ticks and other non-insect arthropods lack genes encoding key molecules such as transmembrane peptidoglycan recognition proteins that initiate the IMD pathway, and the signaling molecules IMD and FADD 10,18,19 . Instead, the tick IMD pathway responds to multiple cues such as infection-derived lipids that are sensed by the receptor Croquemort 10,11,17 and to cellular stress that is caused by infection 20,21 .…”

Section: Introductionmentioning

confidence: 99%

“…Recently, the unfolded protein response (UPR) has been linked to arthropod immunity 20 . The UPR is a specialized cellular response pathway that is activated when the endoplasmic reticulum (ER) is under stress [22][23][24] .…”

Section: Introductionmentioning

confidence: 99%

“…Three ER receptors orchestrate the UPR and function to restore cellular homeostasis: ATF6 (activating transcription factor 6), PERK (PKR-like ER kinase), and IRE1α (inositol-requiring enzyme 1α). When Ixodes scapularis ticks are colonized by Borrelia burgdorferi (Lyme disease) or Anaplasma phagocytophilum (granulocytic anaplasmosis), the IRE1α receptor undergoes self-phosphorylation and pairs with TRAF2 (TNF receptor associated factor 2) to activate the IMD pathway 20 . During this process, reactive oxygen species (ROS) are also potentiated.…”

Section: Introductionmentioning

confidence: 99%

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PERK-mediated antioxidant response is key for pathogen persistence in ticks

Rosche,

Hurtado,

Fisk

et al. 2023

Preprint

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A crucial phase in the lifecycle of tick-borne pathogens is the time spent colonizing and persisting within the arthropod. Tick immunity is emerging as a key force shaping how transmissible pathogens interact with the vector. How pathogens remain in the tick despite immunological pressure remains unknown. In persistently infected Ixodes scapularis, we found that Borrelia burgdorferi (Lyme disease) and Anaplasma phagocytophilum (granulocytic anaplasmosis) activate a cellular stress pathway mediated by the endoplasmic reticulum receptor PERK and the central regulatory molecule, eIF2α. Disabling the PERK pathway through pharmacological inhibition and RNAi significantly decreased microbial numbers. In vivo RNA interference of the PERK pathway not only reduced the number of A. phagocytophilum and B. burgdorferi colonizing larvae after a bloodmeal, but also significantly reduced the number of bacteria that survive the molt. An investigation into PERK pathway-regulated targets revealed that A. phagocytophilum and B. burgdorferi induce activity of the antioxidant response regulator, Nrf2. Tick cells deficient for nrf2 expression or PERK signaling showed accumulation of reactive oxygen and nitrogen species in addition to reduced microbial survival. Supplementation with antioxidants rescued the microbicidal phenotype caused by blocking the PERK pathway. Altogether, our study demonstrates that the Ixodes PERK pathway is activated by transmissible microbes and facilitates persistence in the arthropod by potentiating an Nrf2-regulated antioxidant environment.

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Anaplasma phagocytophilum effector EgeA facilitates infection by hijacking TANGO1 and SCFD1 from ER–Golgi exit sites to pathogen-occupied inclusions

Wang,

Lin,

Hou

et al. 2024

Proc. Natl. Acad. Sci. U.S.A.

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The obligatory intracellular bacterium Anaplasma phagocytophilum causes human granulocytic anaplasmosis, an emerging zoonosis. Anaplasma has limited biosynthetic and metabolic capacities, yet it effectively replicates inside of inclusions/vacuoles of eukaryotic host cells. Here, we describe a unique Type IV secretion system (T4SS) effector, E R– G olgi e xit site protein of A naplasma (EgeA). In cells infected by Anaplasma , secreted native EgeA, EgeA-GFP, and the C-terminal half of EgeA (EgeA-C)-GFP localized to Anaplasma- containing inclusions. In uninfected cells, EgeA-C-GFP localized to cis-Golgi, whereas the N-terminal half of EgeA-GFP localized to the ER. Pull-down assays identified EgeA-GFP binding to a transmembrane protein in the ER, Transport and Golgi organization protein 1 (TANGO1). By yeast two-hybrid analysis, EgeA-C directly bound Sec1 family domain-containing protein 1 (SCFD1), a host protein of the cis-Golgi network that binds TANGO1 at ER–Golgi exit sites (ERES). Both TANGO1 and SCFD1 localized to the Anaplasma inclusion surface. Furthermore, knockdown of Anaplasma EgeA or either host TANGO1 or SCFD1 significantly reduced Anaplasma infection. TANGO1 and SCFD1 prevent ER congestion and stress by facilitating transport of bulky or unfolded proteins at ERES. A bulky cargo collagen and the ER-resident chaperon BiP were transported into Anaplasma inclusions, and several ER stress marker genes were not up-regulated in Anaplasma- infected cells. Furthermore, EgeA transfection reduced collagen overexpression-induced BiP upregulation. These results suggest that by binding to the two ERES proteins, EgeA redirects the cargo-adapted ERES to pathogen-occupied inclusions and reduces ERES congestion, which facilitates Anaplasma nutrient acquisition and reduces ER stress for Anaplasma survival and proliferation.

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The Unfolded-Protein Response Triggers the Arthropod Immune Deficiency Pathway

Abstract: The ability of an arthropod to harbor and transmit pathogens is termed “vector competency.” Many factors influence vector competency, including how arthropod immune processes respond to the microbe. Divergences in innate immunity between arthropods are increasingly being reported.

Cited by 10 publications

References 141 publications

AnAnaplasma phagocytophilumT4SS effector, AteA, is essential for tick infection

AnAnaplasma phagocytophilumT4SS effector, AteA, is essential for tick infection

PERK-mediated antioxidant response is key for pathogen persistence in ticks

Anaplasma phagocytophilum effector EgeA facilitates infection by hijacking TANGO1 and SCFD1 from ER–Golgi exit sites to pathogen-occupied inclusions

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