Alterations in the protein composition of maturing phagosomes.

Pitt, Alan; Mayorga, Luis S.; Stahl, Philip D.; Schwartz, A.

doi:10.1172/jci116077

Cited by 189 publications

(163 citation statements)

References 27 publications

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“…However, we also observed that many proteins, including LAMP-1, heterotrimeric G proteins from the plasma membrane, and some cathepsins, display a biphasic profile with a smaller peak earlier in the time course. Although not explicitly defining a biphasic profile, different studies have found LAMP-1 on phagosomes very early after phagocytosis (15) or at later times (4). Many of the other proteins we measured also display a similar pattern ( Fig.…”

Section: Resultssupporting

confidence: 59%

The dynamic phagosomal proteome and the contribution of the endoplasmic reticulum

Rogers

Foster²

2007

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

108

155

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Macrophages use phagocytosis to control the spread of pathogens in the body, to clear apoptotic cells, and to aid in tissue remodeling. The phagosomal membrane is traditionally thought to originate from the plasmalemma and then go through a series of maturation steps involving sequential fusion with endosomal compartments, leading to the formation of a phagolysosome. A recent model suggests that the endoplasmic reticulum (ER) is involved in the maturation as well. Here we use stable isotope labeling and multiple quantitative proteomic approaches to follow the dynamic composition of the maturing phagosome in RAW 264.7 macrophage cells to a greater depth and higher temporal resolution than was previously possible. Analysis of the results suggests that the traditional model of a linear sequence of fusion events with different compartments is more complex or variable than previously thought. By concomitantly measuring the degree to which each component is enriched on phagosomes, our data argue that the amount of ER involved in phagocytosis is much less than predicted by the model of ER-mediated phagocytosis.innate immunity ͉ organelle ͉ phagocytosis ͉ stable isotope labeling ͉ latex bead vacuoles

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Section: Resultssupporting

confidence: 59%

The dynamic phagosomal proteome and the contribution of the endoplasmic reticulum

Rogers

Foster²

2007

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

108

155

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“…The existence of such vesicles in D. discoideum has already been suggested by the study of Rab7 mutants (48,49). Given the similarity between D. discoideum and professional phagocytes, it is likely that syntaxin 7 plays similar roles in the endo-phagosomes of mammalian phagocytes, organelles where homotypic as well as heterotypic fusions take place (50,51).…”

Section: Discussionmentioning

confidence: 89%

A Syntaxin 7 Homologue Is Present in Dictyostelium discoideum Endosomes and Controls Their Homotypic Fusion

Bogdanovic¹,

Brückert²,

Morio³

et al. 2000

Journal of Biological Chemistry

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Endo-phagocytic activity is prominent in Dictyostelium discoideum and makes it a good model organism to study the molecular organization of membrane traffic in this pathway. We have identified a syntaxin 7 homologue (26% identity and 54% similarity to human syntaxin 7) in Dictyostelium cDNA and genomic data banks. In addition to the Habc and H3 helices and the C-terminal transmembrane domain characteristic of syntaxins, this protein contains a repetitive N-terminal extension of 68 amino acids. We first showed that Dictyostelium syntaxin 7 was able to form a complex with N-ethylmaleimide-sensitive fusion protein and ␣-and ␥-soluble Nethylmaleimide-sensitive fusion protein attachment protein. Its intracellular localization was then studied by cell fractionation techniques and magnetic purification of the endocytic compartments. Most of D. discoideum syntaxin 7 is contained in endosomes. Finally, an in vitro endosome homotypic fusion assay (Laurent, O., Bruckert, F., Adessi, C., and Satre, M. (1998) J. Biol. Chem. 273, 793-799) was used to study a possible role for syntaxin 7 in this process. Purified anti-syntaxin 7 antibodies and a recombinant soluble fragment of syntaxin 7 both strongly inhibited fusion activity, indicating that this protein was necessary for endosome-endosome fusion. These results demonstrate the importance of this syntaxin 7 homologue in the early phases of Dictyostelium endo-phagocytic pathway.Intracellular membrane fusion is a complex and multistage process that requires pairing of specialized membrane proteins called SNAREs, 1 carried by both partners of the fusion reaction (1, 2). Three SNARE subfamilies, syntaxin, vesicle-associated membrane protein (VAMP)/synaptobrevin, and SNAP-25, are conserved from yeast to man (3). The structural basis of SNARE pairing is due to the characteristic presence in each SNARE of at least one ␣-helix able to adopt a coiled-coil conformation in association with other SNAREs (4, 5). In neurons, a tripartite SNARE complex is formed from four parallel ␣-helices, one contributed by the syntaxin, one by the synaptobrevin, and two by SNAP-25 (6, 7).The most diverse and currently best known SNARE family is the syntaxin family. Specific syntaxins are present in almost every compartment undergoing membrane fusion, including endocytic compartments. Yeast syntaxins are organized in a sequential manner along the endocytic pathway, with Tlg1p and Tlg2p in early endosomes (8, 9), Pep12p in the pre-vacuolar compartment (10) and Vam3p in the vacuole (11,12). A similar spatial organization is also found in Arabidopsis thaliana, where the yeast syntaxin homologues AtPep12p and AtVam3p are present on the prevacuolar and vacuolar compartments, respectively (13,14). In mammalian cells that recycle plasma membrane receptors by endocytosis, syntaxin 7 is present in early (15, 16) and late endosomes, and its activity is required for efficient transport of internalized fluid-phase marker from early to late endosomes (17). In addition, syntaxin 7 is involved in the heterotypic fusion...

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“…However, the residence time of TfR in the phagosome is limited, as they are removed by vesicular budding within 10 -20 min of phagosome closure (6,25,56,67). The possible role of COPI in such budding was analyzed by immunofluorescence.…”

Section: Fig 2 ⑀-Cop Is Degraded In Fcr-ldl Cells At the Restrictivmentioning

confidence: 99%

“…One of the protein complexes inserted into the phagosomal membrane through fusion with endomembranes, the vacuolar-type ATPase, mediates the acidification of the phagosomal lumen (22)(23)(24). Conversely, surface proteins that were internalized during the invagination of the plasma membrane are gradually removed from the phagosome as it matures (9,25). At least some of these proteins appear to be recycled back to the plasma membrane (6,10,26,27).…”

mentioning

confidence: 99%

“…In other organelles, such as the Golgi complex, several fission systems have been characterized, including the clathrin, COPI, and COPII complexes. Clathrin has been found to associate with the nascent phagosome, although its precise role in maturation remains unclear (9,29). Amorphous coats, distinct from those generated by clathrin, have also been found on phagosomes (6).…”

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confidence: 99%

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Role of COPI in Phagosome Maturation

Botelho¹,

Hackam²,

Schreiber³

et al. 2000

Journal of Biological Chemistry

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Phagosomes mature by sequentially fusing with endosomes and lysosomes. Vesicle budding is presumed to occur concomitantly, mediating the retrieval of plasmalemmal components and the regulation of phagosomal size. We analyzed whether fission of vesicles from phagosomes requires COPI, a multimeric complex known to be involved in budding from the Golgi and endosomes. The role of COPI was studied using ldlF cells, that harbor a temperature-sensitive mutation in ⑀-COP, a subunit of the coatomer complex. These cells were made phagocytic toward IgG-opsonized particles by heterologous expression of human Fc␥RIIA receptors. Following incubation at the restrictive temperature, ⑀-COP was degraded in these cells and their Golgi complex dispersed. Nevertheless, phagocytosis persisted for hours in cells devoid of ⑀-COP. Retrieval of transferrin receptors from phagosomes became inefficient in the absence of ⑀-COP, while clearance of the Fc␥RIIA receptors was unaffected. This indicates that fission of vesicles from the phagosomal membrane involves at least two mechanisms, one of which requires intact COPI. Traffic of fluid-phase markers and aggregated IgG-receptor complexes along the endocytic pathway was abnormal in ⑀-COP-deficient cells. In contrast, phagosome fusion with endosomes and lysosomes was unimpaired. Moreover, the resulting phagolysosomes were highly acidic. Similar results were obtained in RAW264.7 macrophages treated with brefeldin A, which precludes COPI assembly by interfering with the activation of adenosine ribosylation factor. These data indicate that neither phagosome formation nor maturation are absolutely dependent on COPI. Our findings imply that phagosomal maturation differs from endosomal progression, which appears to be more dependent on COPI-mediated formation of carrier vesicles.

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Alterations in the protein composition of maturing phagosomes.

Cited by 189 publications

References 27 publications

The dynamic phagosomal proteome and the contribution of the endoplasmic reticulum

The dynamic phagosomal proteome and the contribution of the endoplasmic reticulum

A Syntaxin 7 Homologue Is Present in Dictyostelium discoideum Endosomes and Controls Their Homotypic Fusion

Role of COPI in Phagosome Maturation

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