Browse
Submit Data
Databases
API
Help

Dataset Information

27 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

The NK cell granule protein NKG7 regulates cytotoxic granule exocytosis and inflammation.

ABSTRACT: Immune-modulating therapies have revolutionized the treatment of chronic diseases, particularly cancer. However, their success is restricted and there is a need to identify new therapeutic targets. Here, we show that natural killer cell granule protein 7 (NKG7) is a regulator of lymphocyte granule exocytosis and downstream inflammation in a broad range of diseases. NKG7 expressed by CD4⁺ and CD8⁺ T cells played key roles in promoting inflammation during visceral leishmaniasis and malaria-two important parasitic diseases. Additionally, NKG7 expressed by natural killer cells was critical for controlling cancer initiation, growth and metastasis. NKG7 function in natural killer and CD8⁺ T cells was linked with their ability to regulate the translocation of CD107a to the cell surface and kill cellular targets, while NKG7 also had a major impact on CD4⁺ T cell activation following infection. Thus, we report a novel therapeutic target expressed on a range of immune cells with functions in different immune responses.

SUBMITTER: Ng SS

PROVIDER: S-EPMC7965849 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

VAMP4- and VAMP7-expressing vesicles are both required for cytotoxic granule exocytosis in NK cells.

Project description:NK cells eliminate cancer and virus-infected cells through their cytolytic activity. The last step in NK-cell cytotoxicity, resulting in exocytosis of granule content, requires fusion of lytic granules with the plasma membrane. Proteins from the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) family mediate membrane fusion events in the cell. Here, we show that NK cells express all members of the R-SNARE subgroup. Two of these R-SNARE proteins, VAMP4 and VAMP7, colocalize with lytic granules during cytotoxic interactions. However, only VAMP7 associates with perforin-containing granules in nonactivated cells, indicating that the two VAMPs have different functions in exocytosis. Using both the tumor NK-cell line YTS and the peripheral NK cells, we show that the disruption of expression of either VAMP4 or VAMP7 inhibits the release of lytic granules and severely impairs NK-cell cytotoxic activity. Furthermore, VAMP7 but not VAMP4 is involved in IFN-γ secretion in NK cells, indicating that VAMP7 is involved in many fusion processes and thus plays a more general function in NK-cell activity than VAMP4.

| S-EPMC3438144 | biostudies-literature

No specific subcellular localization of protein kinase C is required for cytotoxic T cell granule exocytosis.

Project description:Cytotoxic T cells kill virus-infected cells and tumor cells by releasing lytic granules that contain cell-killing contents. Exocytosis requires calcium influx and protein kinase C (PKC) activation. Here, we extend our previous finding regarding the lack of isoform specificity of PKCs in the granule release step, showing that mutant constitutively active PKCdelta can substitute for phorbol esters and support exocytosis. PKCdelta, a novel PKC isoform, was recently shown to play a role in lytic granule reorientation. Surprisingly, however, our results suggested that mutant PKCdelta did not localize to the plasma membrane (PM). To test directly whether PKC has to be in the PM to drive exocytosis, we generated mutants of various PKC isoforms that were tethered either to the outer mitochondrial membrane or to the PM. Tethered mutant PKCdeltas were able to promote exocytosis as effectively as the untethered version. The substrates of PKCs involved in lytic granule exocytosis are currently unknown, but subcellular localization is believed to be a critical factor in determining PKC accessibility to substrates. That there is no requirement for specific PKC localization in lytic granule exocytosis may have important implications for the identity of PKC substrates.

| S-EPMC2757214 | biostudies-literature

VASP Regulates NK Cell Lytic Granule Convergence.

Project description:NK cells eliminate viral-infected and malignant cells through a highly orchestrated series of cytoskeletal rearrangements, resulting in the release of cytolytic granule contents toward the target cell. Central to this process is the convergence of cytolytic granules to a common point, the microtubule-organizing center (MTOC), before delivery to the synapse. In this study, we show that vasodialator-stimulated phosphoprotein (VASP), an actin regulatory protein, localizes to the cytolytic synapse, but surprisingly, shows no impact on conjugate formation or synaptic actin accumulation despite being required for human NK cell-mediated killing. Interestingly, we also find that a pool of VASP copurifies with lytic granules and localizes with lytic granules at the MTOC. Significantly, depletion of VASP decreased lytic granule convergence without impacting MTOC polarization. Using the KHYG-1 cell line in which lytic granules are in a constitutively converged state, we find that either VASP depletion or F-actin destabilization promoted spreading of formerly converged granules. Our results demonstrate a novel requirement for VASP and actin polymerization in maintaining lytic granule convergence during NK cell-mediated killing.

| S-EPMC6317751 | biostudies-literature

Munc18-2 deficiency causes familial hemophagocytic lymphohistiocytosis type 5 and impairs cytotoxic granule exocytosis in patient NK cells.

Project description:Familial hemophagocytic lymphohistiocytosis (FHL) is a genetically heterogeneous autosomal recessive immune disorder characterized by the occurrence of uncontrolled activation of lymphocytes and macrophages infiltrating multiple organs. Disease-causing mutations in the perforin (PRF1; also known as FHL2), Munc13-4 (UNC13D; also known as FHL3), and syntaxin-11 (STX11; also known as FHL4) genes have been identified in individuals with FHL. These genes all encode proteins involved in the cytotoxic activity of lymphocytes. Here, we show that the gene encoding syntaxin-binding protein 2 (Munc18-2; official gene symbol STXBP2) is mutated in another subset of patients with FHL (designated by us as "FHL5"). Lymphoblasts isolated from these patients had strongly decreased STXBP2 protein expression, and NK cells exhibited impaired cytotoxic granule exocytosis, a defect that could be overcome by ectopic expression of wild-type STXBP2. Furthermore, we provide evidence that syntaxin-11 is the main partner of STXBP2 in lymphocytes, as its expression required the presence of STXBP2. Our work shows that STXBP2 deficiency causes FHL5. These data indicate that STXBP2 is required at a late step of the secretory pathway for the release of cytotoxic granules by binding syntaxin 11, another component of the intracellular membrane fusion machinery.

| S-EPMC2786810 | biostudies-literature

Cytotoxic Granule Exocytosis From Human Cytotoxic T Lymphocytes Is Mediated by VAMP7.

Project description:Cytotoxic T lymphocytes kill infected or malignant cells through the directed release of cytotoxic substances at the site of target cell contact, the immunological synapse. While genetic association studies of genes predisposing to early-onset life-threatening hemophagocytic lymphohistiocytosis has identified components of the plasma membrane fusion machinery, the identity of the vesicular components remain enigmatic. Here, we identify VAMP7 as an essential component of the vesicular fusion machinery of primary, human T cells. VAMP7 co-localizes with granule markers throughout all stages of T cell maturation and simultaneously fuses with granule markers at the IS. Knock-down of VAMP7 expression significantly decreased the killing efficiency of T cells, without diminishing early T cell receptor signaling. VAMP7 exerts its function in a SNARE complex with Syntaxin11 and SNAP-23 on the plasma membrane. The identification of the minimal fusion machinery in T cells provides a starting point for the development of potential drugs in immunotherapy.

| S-EPMC6692471 | biostudies-literature

Differences in Granule Morphology yet Equally Impaired Exocytosis among Cytotoxic T Cells and NK Cells from Chediak-Higashi Syndrome Patients.

Project description:Chediak-Higashi syndrome (CHS) is caused by autosomal recessive mutations in LYST, resulting in enlarged lysosomal compartments in multiple cell types. CHS patients display oculocutaneous albinism and may develop life-threatening hemophagocytic lymphohistiocytosis (HLH). While NK cell-mediated cytotoxicity has been reported to be uniformly defective, variable defects in T cell-mediated cytotoxicity has been observed. The latter has been linked to the degree of HLH susceptibility. Since the discrepancies in NK cell- and T cell-mediated cellular cytotoxicity might result from differences in regulation of cytotoxic granule release, we here evaluated perforin-containing secretory lysosome size and number in freshly isolated lymphocytes from CHS patients and furthermore compared their exocytic capacities. Whereas NK cells from CHS patients generally contained a single, gigantic perforin-containing granule, cytotoxic T cells predominantly contained several smaller granules. Nonetheless, in a cohort of 21 CHS patients, cytotoxic T cell and NK cell granule exocytosis were similarly impaired upon activating receptor stimulation. Mechanistically, polarization of cytotoxic granules was defective in cytotoxic lymphocytes from CHS patients, with EEA1, a marker of early endosomes, mislocalizing to lysosomal structures. The results leads to the conclusion that lysosome enlargement corresponds to loss of distinct organelle identity in the endocytic pathway, which on a subcellular level more adversely affects NK cells than T cells. Hence, vesicular size or numbers do not per se dictate the impairment of lysosomal exocytosis in the two cell types studied.

| S-EPMC5394158 | biostudies-literature

Myosin IIA is required for cytolytic granule exocytosis in human NK cells.

Project description:Natural killer (NK) cell cytotoxicity involves the formation of an activating immunological synapse (IS) between the effector and target cell through which granzymes and perforin contained in lytic granules are delivered to the target cell via exocytosis. Inhibition of nonmuscle myosin II in human NK cells with blebbistatin or ML-9 impaired neither effector-target cell conjugation nor formation of a mature activating NK cell IS (NKIS; formation of an actin ring and polarization of the microtubule-organizing center and cytolytic granules to the center of the ring). However, membrane fusion of lytic granules, granzyme secretion, and NK cell cytotoxicity were all effectively blocked. Specific knockdown of the myosin IIA heavy chain by RNA interference impaired cytotoxicity, membrane fusion of lytic granules, and granzyme secretion. Thus, myosin IIA is required for a critical step between NKIS formation and granule exocytosis.

| S-EPMC2118468 | biostudies-literature

NKG7 Enhances CD8+ T Cell Synapse Efficiency to Limit Inflammation.

Project description:Cytotoxic lymphocytes are essential for anti-tumor immunity, and for effective responses to cancer immunotherapy. Natural killer cell granule protein 7 (NKG7) is expressed at high levels in cytotoxic lymphocytes infiltrating tumors from patients treated with immunotherapy, but until recently, the role of this protein in cytotoxic lymphocyte function was largely unknown. Unexpectedly, we found that highly CD8+ T cell-immunogenic murine colon carcinoma (MC38-OVA) tumors grew at an equal rate in Nkg7+/+ and Nkg7-/- littermate mice, suggesting NKG7 may not be necessary for effective CD8+ T cell anti-tumor activity. Mechanistically, we found that deletion of NKG7 reduces the ability of CD8+ T cells to degranulate and kill target cells in vitro. However, as a result of inefficient cytotoxic activity, NKG7 deficient T cells form a prolonged immune synapse with tumor cells, resulting in increased secretion of inflammatory cytokines, including tumor necrosis factor alpha (TNF). By deleting the TNF receptor, TNFR1, from MC38-OVA tumors, we demonstrate that this hyper-secretion of TNF compensates for reduced synapse-mediated cytotoxic activity against MC38-OVA tumors in vivo, via increased TNF-mediated tumor cell death. Taken together, our results demonstrate that NKG7 enhances CD8+ T cell immune synapse efficiency, which may serve as a mechanism to accelerate direct cytotoxicity and limit potentially harmful inflammatory responses.

| S-EPMC9299089 | biostudies-literature

Syntaxin 4 mediates endosome recycling for lytic granule exocytosis in cytotoxic T-lymphocytes.

Project description:Adaptive and innate immunity utilize the perforin-killing pathway to eliminate virus-infected or cancer cells. Cytotoxic T-lymphocytes (CTLs) and natural killer cells mediate this process by releasing toxic proteins at the contact area with target cells known as immunological synapse (IS). Formation of a stable IS and exocytosis of toxic proteins requires persistent fusion of Rab11a recycling endosomes with the plasma membrane (PM) that may assure the delivery of key effector proteins. Despite the importance of the recycling endosomal compartment, the membrane fusion proteins that control this process at the IS remain elusive. Here, by performing knockdown experiments we found that syntaxin 4 (STX4) is necessary for cytotoxic activity and CD107a degranulation against target cells in a similar fashion to syntaxin 11, which is involved in lytic granule (LG) exocytosis and immunodeficiency when it is mutated. Using total internal reflection fluorescent microscopy we identified that STX4 mediates fusion of EGFP-Rab11a vesicles at the IS. Immunoprecipitation experiments in lysates of activated CTLs indicate that endogenous STX4 may drive this fusion step by interacting with cognate proteins: Munc18-3/SNAP23/VAMP7 and/or VAMP8. These results reveal the role of STX4 in mediating fusion of Rab11a endosomes upstream of lytic granules (LGs) exocytosis and further demonstrate the importance of this pathway in controlling CTL-mediated cytotoxicity.

| S-EPMC5513838 | biostudies-literature

Flow cytometry enables a high-throughput homogeneous fluorescent antibody-binding assay for cytotoxic T cell lytic granule exocytosis.

Project description:We developed a homogeneous phenotypic fluorescence end-point assay for cytotoxic T lymphocyte lytic granule exocytosis. This flow cytometric assay measures binding of an antibody to a luminal epitope of a lysosomal membrane protein (LAMP-1) that is exposed by exocytosis to the extracellular solution. Washing to remove unbound antibody is not required. Confirming the assay's ability to detect novel active compounds, we screened at a concentration of 50 µM a synthetic diversity library of 91 compounds in a 96-well plate format, identifying 17 compounds that blocked by 90% or more. The actions of six structurally related tetracyano-hexahydroisoindole compounds that inhibited by ~90% at a concentration of 10 µM were investigated further. Four reduced elevations in intracellular Ca(2+); it is likely that depolarization of the cells' membrane potential underlies the effect for at least two of the compounds. Another compound was found to be a potent inhibitor of the activation of the mitogen-activated protein (MAP) kinase ERK. Finally, we transferred the assay to a 384-well format and screened the Prestwick Compound Library using high-throughput flow cytometry. Our results indicate that our assay will likely be a useful means of screening libraries for novel compounds with important biological activities.

| S-EPMC4043149 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data