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The GTPase Rab39a promotes phagosome maturation into MHC-I antigen-presenting compartments

ABSTRACT: For CD8 T lymphocytes to mount responses to cancer and virally-infected cells, dendritic cells must capture antigens present in tissues and display them as peptides bound to MHC-I molecules. This is most often accomplished through a pathway called antigen cross-presentation (XPT). Here, we report that the vesicular trafficking protein Rab39a is needed for optimal cross-presentation by dendritic cells in vitro, and cross-priming of CD8 T cells in vivo. Without Rab39a, MHC-I presentation of intraphagosomal peptides is inhibited, indicating that Rab39a converts phagosomes into peptide-loading compartments. In this process, Rab39a promotes the delivery of MHC-I molecules from the endoplasmic reticulum (ER) to phagosomes, and increases the levels of peptide-empty MHC-I conformers that can be loaded with peptide in this compartment. Rab39a also increases the levels of Sec22b and NOX2, previously recognized to participate in cross-presentation, on phagosomes, thereby filling in a missing link into how phagosomes mature into cross-presenting vesicles.

SUBMITTER: Freidrich, M Cruz

PROVIDER: S-SCDT-EMBOJ-2019-102020 | biostudies-other |

REPOSITORIES: biostudies-other

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The GTPase Rab39a promotes phagosome maturation into MHC-I antigen-presenting compartments.

Project description:For CD8 T lymphocytes to mount responses to cancer and virally-infected cells, dendritic cells must capture antigens present in tissues and display them as peptides bound to MHC-I molecules. This is most often accomplished through a pathway called antigen cross-presentation (XPT). Here, we report that the vesicular trafficking protein Rab39a is needed for optimal cross-presentation by dendritic cells in vitro and cross-priming of CD8 T cells in vivo. Without Rab39a, MHC-I presentation of intraphagosomal peptides is inhibited, indicating that Rab39a converts phagosomes into peptide-loading compartments. In this process, Rab39a promotes the delivery of MHC-I molecules from the endoplasmic reticulum (ER) to phagosomes, and increases the levels of peptide-empty MHC-I conformers that can be loaded with peptide in this compartment. Rab39a also increases the levels of Sec22b and NOX2, previously recognized to participate in cross-presentation, on phagosomes, thereby filling in a missing link into how phagosomes mature into cross-presenting vesicles.

| S-EPMC6960445 | biostudies-literature

The GTPase Rab39a matures phagosomes into MHC-I antigen-presenting compartments.

Project description:We have found Rab39a to be important in dendritic cells to promote antigen crosspresentation. As Rab39a is a Rab GTPase, we sought to determine how it influenced the contents of phagosomes. Thus we used SILAC using Rab39a CRISPR KO or reconstituted cells to determine phagosomal protein differences using a proteomics based approach.

2019-12-11 | PXD016394 | Pride

The GTPase Rab39a matures phagosomes into MHC-I antigen-presenting compartments.

Project description:This is the mass spec data from phagosomes of Rab39a deficient or Rab39a induced dendritic cell lines. For reference, see: Cruz FM, Colbert JD, Rock KL: The GTPase Rab39a matures phagosomes into MHC-I antigen-presenting compartments. . EMBO J (in press). Silac: Rab39a KO (Light), Rab39a induced (Heavy) Samples: 3 biological replicates each run with 3 technical replicates.

2019-11-21 | MSV000084611 | MassIVE

TLR-dependent phagosome tubulation in dendritic cells promotes phagosome cross-talk to optimize MHC-II antigen presentation.

Project description:Dendritic cells (DCs) phagocytose large particles like bacteria at sites of infection and progressively degrade them within maturing phagosomes. Phagosomes in DCs are also signaling platforms for pattern recognition receptors, such as Toll-like receptors (TLRs), and sites for assembly of cargo-derived peptides with major histocompatibility complex class II (MHC-II) molecules. Although TLR signaling from phagosomes stimulates presentation of phagocytosed antigens, the mechanisms underlying this enhancement and the cell surface delivery of MHC-II-peptide complexes from phagosomes are not known. We show that in DCs, maturing phagosomes extend numerous long tubules several hours after phagocytosis. Tubule formation requires an intact microtubule and actin cytoskeleton and MyD88-dependent phagosomal TLR signaling, but not phagolysosome formation or extensive proteolysis. In contrast to the tubules that emerge from endolysosomes after uptake of soluble ligands and TLR stimulation, the late-onset phagosomal tubules are not essential for delivery of phagosome-derived MHC-II-peptide complexes to the plasma membrane. Rather, tubulation promotes MHC-II presentation by enabling maximal cargo transfer among phagosomes that bear a TLR signature. Our data show that phagosomal tubules in DCs are functionally distinct from those that emerge from lysosomes and are unique adaptations of the phagocytic machinery that facilitate cargo exchange and antigen presentation among TLR-signaling phagosomes.

| S-EPMC4217451 | biostudies-literature

Dendritic cell maturation in HCV infection: altered regulation of MHC class I antigen processing-presenting machinery.

Project description:Background & aimsModulation of dendritic cell (DC) function has been theorized as one of the mechanisms used by hepatitis C virus (HCV) to evade the host immune response and cause persistent infection.MethodsWe used a range of cell and molecular biology techniques to study DC subsets from uninfected and HCV-infected individuals.ResultsWe found that patients with persistent HCV infection have lower numbers of circulating myeloid DC and plasmacytoid DC than healthy controls or patients who spontaneously recovered from HCV infection. Nonetheless, DC from patients with persistent HCV infection display normal phagocytic activity, typical expression of the class I and II HLA and co-stimulatory molecules, and conventional cytokine production when stimulated to mature in vitro. In contrast, they do not display the strong switch from immunoproteasome to standard proteasome subunit expression and the upregulation of the transporter-associated proteins following stimulation, which were instead observed in DC from uninfected individuals. This different modulation of components of the HLA class I antigen processing-presenting machinery results in a differential ability to present a CD8(+) T cell epitope whose generation is dependent on the LMP7 immunoproteasome subunit.ConclusionsOverall, these findings establish that under conditions of persistent HCV antigenemia, HLA class I antigen processing and presentation are distinctively regulated during DC maturation.

| S-EPMC8759579 | biostudies-literature

Glycogene expression during maturation of human antigen-presenting cells

Project description:Dr. van Kooyk's laboratory is exploring the function of antigen presenting cells, such as dendritic cells (DC), that regulate viral-antigen recognition, DC trafficking and T cell binding--all processes that initiate immunity or tolerance. Essential in this is the recognition of ligands by C-type lectins and the functional consequences of differential terminal glycosylation that may regulate DC function. In this study, the gene expression profile of glycosylation-related genes is examined in relation to the maturation of human antigen-presenting cells. Two pooled RNA samples, one each from immature and mature human monocyte-derived dendritic cells, were prepared and sent to Microarray Core (E). The RNA was amplified, labeled, and hybridized to the GLYCOv3 microarrays.

2011-04-29 | E-GEOD-28946 | biostudies-arrayexpress

Glycogene expression during maturation of human antigen-presenting cells

2011-04-29 | GSE28946 | GEO

Ubiquitination of the PI3-kinase VPS-34 promotes VPS-34 stability and phagosome maturation.

Project description:Apoptotic cells generated by programmed cell death are engulfed by phagocytes and enclosed within membrane-bound phagosomes. Maturation of apoptotic cell-containing phagosomes leads to formation of phagolysosomes where cell corpses are degraded. The class III phosphatidylinositol 3-kinase (PI3-kinase) VPS-34 coordinates with PIKI-1, a class II PI3-kinase, to produce PtdIns3P on phagosomes, thus promoting phagosome closure and maturation. Here, we identified UBC-13, an E2 ubiquitin-conjugating enzyme that functions in the same pathway with VPS-34 but in parallel to PIKI-1 to regulate PtdIns3P generation on phagosomes. Loss of ubc-13 affects early steps of phagosome maturation, causing accumulation of cell corpses. We found that UBC-13 functions with UEV-1, a noncatalytic E2 variant, and CHN-1, a U-box-containing E3 ubiquitin ligase, to catalyze K63-linked poly-ubiquitination on VPS-34 both in vitro and in Caenorhabditis elegans Loss of ubc-13, uev-1, or chn-1 disrupts ubiquitin modification of VPS-34 and causes significantly reduced VPS-34 protein levels. Our data suggest that K63-linked ubiquitin modification serves as a general mechanism to modulate VPS-34 stability in multiple processes.

| S-EPMC5748982 | biostudies-literature

SNX10 promotes phagosome maturation in macrophages and protects mice against <i>Listeria monocytogenes</i> infection.

Project description:Listeria monocytogenes (L. monocytogenes), which is a facultative intracellular bacterial pathogen that causes listeriosis, is widely used to study the mammalian immune response to infection. After phagocytosis by professional phagocytes, L. monocytogenes is initially contained within phagosomes, which mature into phagolysosomes, where the bacteria are degraded. Although phagocytosis and subsequent phagosome maturation is essential for the clearance of infectious microbial pathogens, the underlying regulatory mechanisms are still unclear. SNX10 (Sorting nexin 10) has the simplest structure of the SNX family and has been reported to regulate endosomal morphology, which might be crucial for macrophage function, including phagocytosis and digestion of pathogens, inflammatory response, and antigen presentation. Our results showed that SNX10 expression was upregulated following L. monocytogenes infection in macrophages. It was also revealed that SNX10 promoted phagosome maturation by recruiting the Mon1-Ccz1 complex to endosomes and phagosomes. As a result, SNX10 deficiency decreased the bacterial killing ability of macrophages, and SNX10-deficient mice showed increased susceptibility to L. monocytogenes infection in vivo. Thus, this study revealed an essential role of SNX10 in controlling bacterial infection.

| S-EPMC5589552 | biostudies-literature

Antigen-presenting genes and genomic copy number variations in the Tasmanian devil MHC.

Project description:BACKGROUND:The Tasmanian devil (Sarcophilus harrisii) is currently under threat of extinction due to an unusual fatal contagious cancer called Devil Facial Tumour Disease (DFTD). DFTD is caused by a clonal tumour cell line that is transmitted between unrelated individuals as an allograft without triggering immune rejection due to low levels of Major Histocompatibility Complex (MHC) diversity in Tasmanian devils. RESULTS:Here we report the characterization of the genomic regions encompassing MHC Class I and Class II genes in the Tasmanian devil. Four genomic regions approximately 960 kb in length were assembled and annotated using BAC contigs and physically mapped to devil Chromosome 4q. 34 genes and pseudogenes were identified, including five Class I and four Class II loci. Interestingly, when two haplotypes from two individuals were compared, three genomic copy number variants with sizes ranging from 1.6 to 17 kb were observed within the classical Class I gene region. One deletion is particularly important as it turns a Class Ia gene into a pseudogene in one of the haplotypes. This deletion explains the previously observed variation in the Class I allelic number between individuals. The frequency of this deletion is highest in the northwestern devil population and lowest in southeastern areas. CONCLUSIONS:The third sequenced marsupial MHC provides insights into the evolution of this dynamic genomic region among the diverse marsupial species. The two sequenced devil MHC haplotypes revealed three copy number variations that are likely to significantly affect immune response and suggest that future work should focus on the role of copy number variations in disease susceptibility in this species.

| S-EPMC3414760 | biostudies-literature

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