Dataset Information

SHIP-1 Couples to the Dectin-1 hemITAM and Selectively Modulates Reactive Oxygen Species Production in Dendritic Cells in Response to Candida albicans.

ABSTRACT: Dectin-1 (Clec7a) is a paradigmatic C-type lectin receptor that binds Syk through a hemITAM motif and couples sensing of pathogens such as fungi to induction of innate responses. Dectin-1 engagement triggers a plethora of activating events, but little is known about the modulation of such pathways. Trying to define a more precise picture of early Dectin-1 signaling, we explored the interactome of the intracellular tail of the receptor in mouse dendritic cells. We found unexpected binding of SHIP-1 phosphatase to the phosphorylated hemITAM. SHIP-1 colocalized with Dectin-1 during phagocytosis of zymosan in a hemITAM-dependent fashion. Moreover, endogenous SHIP-1 relocated to live or heat-killed Candida albicans-containing phagosomes in a Dectin-1-dependent manner in GM-CSF-derived bone marrow cells (GM-BM). However, SHIP-1 absence in GM-BM did not affect activation of MAPK or production of cytokines and readouts dependent on NF-?B and NFAT. Notably, ROS production was enhanced in SHIP-1-deficient GM-BM treated with heat-killed C. albicans, live C. albicans, or the specific Dectin-1 agonists curdlan or whole glucan particles. This increased oxidative burst was dependent on Dectin-1, Syk, PI3K, phosphoinositide-dependent protein kinase 1, and NADPH oxidase. GM-BM from CD11c?SHIP-1 mice also showed increased killing activity against live C. albicans that was dependent on Dectin-1, Syk, and NADPH oxidase. These results illustrate the complexity of myeloid C-type lectin receptor signaling, and how an activating hemITAM can also couple to intracellular inositol phosphatases to modulate selected functional responses and tightly regulate processes such as ROS production that could be deleterious to the host.

SUBMITTER: Blanco-Menendez N

PROVIDER: S-EPMC4641325 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

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SHIP-1 Couples to the Dectin-1 hemITAM and Selectively Modulates Reactive Oxygen Species Production in Dendritic Cells in Response to Candida albicans.

Blanco-Menéndez Noelia N Del Fresno Carlos C Fernandes Sandra S Calvo Enrique E Conde-Garrosa Ruth R Kerr William G WG Sancho David D

Journal of immunology (Baltimore, Md. : 1950) 20150928 9

Dectin-1 (Clec7a) is a paradigmatic C-type lectin receptor that binds Syk through a hemITAM motif and couples sensing of pathogens such as fungi to induction of innate responses. Dectin-1 engagement triggers a plethora of activating events, but little is known about the modulation of such pathways. Trying to define a more precise picture of early Dectin-1 signaling, we explored the interactome of the intracellular tail of the receptor in mouse dendritic cells. We found unexpected binding of SHIP ...[more]

PMID: 26416276

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Project description:At host-pathogen contact sites with Candida albicans, Dectin-1 activates pro-inflammatory signaling, while DC-SIGN promotes adhesion to the fungal surface. We observed that Dectin-1 and DC-SIGN collaborate to enhance capture/retention of C. albicans under fluid shear culture conditions. Therefore, we devised a cellular model system wherein we could investigate the interaction between these two receptors during the earliest stages of host-pathogen interaction. In cells expressing both receptors, DC-SIGN was quickly recruited to contact sites (103.15% increase) but Dectin-1 did not similarly accumulate. Once inside the contact site, FRAP studies revealed a strong reduction in lateral mobility of DC-SIGN (but not Dectin-1), consistent with DC-SIGN engaging in multivalent adhesive binding interactions with cell wall mannoprotein ligands. Interestingly, in the absence of Dectin-1 co-expression, DC-SIGN recruitment to the contact was much poorer-only 35.04%. These data suggested that Dectin-1 promotes the active recruitment of DC-SIGN to the contact site. We proposed that Dectin-1 signaling activates the RHOA pathway, leading to actomyosin contractility that promotes DC-SIGN recruitment, perhaps via the formation of a centripetal actomyosin flow (AMF) directed into the contact site. Indeed, RHOA pathway inhibitors significantly reduced Dectin-1-associated DC-SIGN recruitment to the contact site. We used agent-based modeling to predict DC-SIGN transport kinetics with ("Directed + Brownian") and without ("Brownian") the hypothesized actomyosin flow-mediated transport. The Directed + Brownian transport model predicted a DC-SIGN contact site recruitment (106.64%), similar to that we observed experimentally under receptor co-expression. Brownian diffusive transport alone predicted contact site DC-SIGN recruitment of only 55.60%. However, this value was similar to experimentally observed DC-SIGN recruitment in cells without Dectin-1 or expressing Dectin-1 but treated with RHOA inhibitor, suggesting that it accurately predicted DC-SIGN recruitment when a contact site AMF would not be generated. TIRF microscopy of nascent cell contacts on glucan-coated glass revealed Dectin-1-dependent DC-SIGN and F-actin (LifeAct) recruitment kinetics to early stage contact site membranes. DC-SIGN entry followed F-actin with a temporal lag of 8.35 ± 4.57 s, but this correlation was disrupted by treatment with RHOA inhibitor. Thus, computational and experimental evidence provides support for the existence of a Dectin-1/RHOA-dependent AMF that produces a force to drive DC-SIGN recruitment to pathogen contact sites, resulting in improved pathogen capture and retention by immunocytes. These data suggest that the rapid collaborative response of Dectin-1 and DC-SIGN in early contact sties might be important for the efficient acquisition of yeast under flow conditions, such as those that prevail in circulation or mucocutaneous sites of infection.

Dataset Information

SHIP-1 Couples to the Dectin-1 hemITAM and Selectively Modulates Reactive Oxygen Species Production in Dendritic Cells in Response to Candida albicans.

Publications

SHIP-1 Couples to the Dectin-1 hemITAM and Selectively Modulates Reactive Oxygen Species Production in Dendritic Cells in Response to Candida albicans.

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