Specialization of the macrophage plasma membrane at sites of interaction with opsonized erythrocytes.

Montesano, Roberto; Mossaz, A; Vassalli, Pierre; Orci, Lelio

doi:10.1083/jcb.96.5.1227

Cited by 32 publications

(17 citation statements)

References 38 publications

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“…Several electron microscopy studies on macrophages have reported the enrichment of nascent phagosomal membranes with large flat clathrin patches, which disappear after 30 min (Aggeler and Werb, 1982;Montesano et al, 1983;Clerc and Sansonetti, 1989). Clathrin-coated pits have been also observed on phagosomes upon engagement of Fc receptors in phagocytic RBL-2H3 cells (Castellano et al, 2000).…”

Section: Ap-1 Is Required For Efficient Phagocytosismentioning

confidence: 99%

“…The presence of clathrin on membranes of forming phagosomes (Aggeler and Werb, 1982;Montesano et al, 1983;Clerc and Sansonetti, 1989;Castellano et al, 2000;Tse et al, 2003) suggested that clathrin-associated adaptor complexes could associate with phagosomes. To test this hypothesis, mouse peritoneal macrophages were incubated with zymosan particles and stained with anti-␥-adaptin (AP-1) or anti-␣-adaptin (AP-2).…”

Section: 〈P-1 Localizes To Nascent Phagosomesmentioning

confidence: 99%

“…One of the best-characterized coat proteins is clathrin, which participates in multiple transport steps (Hirst and Robinson, 1998;Smith and Pearse, 1999). There is some evidence that clathrin associates with the phagocytic cup in mammalian cells, although its precise role remains unclear (Aggeler and Werb, 1982;Montesano et al, 1983;Clerc and Sansonetti, 1989). Because adaptor protein complexes (APs) are the main components of clathrin-coated vesicles, a specific AP complex is likely to be associated to clathrin on phagosomes.…”

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Involvement of the AP-1 Adaptor Complex in Early Steps of Phagocytosis and Macropinocytosis

Lefkir

Malbouyres

Gotthardt

et al. 2004

MBoC

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The best described function of the adaptor complex-1 (AP-1) is to participate in the budding of clathrin-coated vesicles from the trans-Golgi network and endosomes. Here, we show that AP-1 is also localized to phagocytic cups in murine macrophages as well as in Dictyostelium amoebae. AP-1 is recruited to phagosomal membranes at this early stage of phagosome formation and rapidly dissociates from maturing phagosomes. To establish the role of AP-1 in phagocytosis, we made used of Dictyostelium mutant cells (apm1 ؊ cells) disrupted for AP-1 medium chain. In this mutant, phagocytosis drops by 60%, indicating that AP-1 is necessary for efficient phagocytosis. Furthermore, phagocytosis in apm1 ؊ cells is more affected for large rather than small particles, and cells exhibiting incomplete engulfment are then often observed. This suggests that AP-1 could participate in the extension of the phagocytic cup. Interestingly, macropinocytosis, a process dedicated to fluid-phase endocytosis and related to phagocytosis, is also impaired in apm1 ؊ cells. In summary, our data suggest a new role of AP-1 at an early stage of phagosome and macropinosome formation. INTRODUCTIONPhagocytosis involves the uptake of large particles (typically 1 m in diameter) by phagocytic cells. In the human organism, phagocytic cells are responsible for the elimination of invasive microorganisms and thus participate in the immune defense. Phagocytosis is triggered by the recognition of particles by cell surface phagocyte receptors. This event results in the activation of signaling pathways, mainly depending on phosphatidyl inositol 3-kinase (Cox et al., 1999;Vieira et al., 2001) and syk tyrosine kinase (Durden and Liu, 1994;Greenberg et al., 1994;Cox et al., 1996) and leading to actin polymerization underneath the contact zone, pseudopodia extension, and particles sequestration in membranebound organelles called phagosomes. Phagosomes undergo a maturation process, which involves extensive recycling of proteins back to the cell surface and fusion with endocytic compartments. Whereas the fusion of endosomes with maturing phagosomes has been investigated in detail (for review, see Vieira et al., 2002), the mechanisms responsible for the transport of components into and out of phagosomes are still poorly understood.Transport of proteins in the endocytic and biosynthetic pathways occurs via vesicles coated with specific proteins (Mellman, 1996;Rothman and Wieland, 1996). One of the best-characterized coat proteins is clathrin, which participates in multiple transport steps (Hirst and Robinson, 1998;Smith and Pearse, 1999). There is some evidence that clathrin associates with the phagocytic cup in mammalian cells, although its precise role remains unclear (Aggeler and Werb, 1982;Montesano et al., 1983;Clerc and Sansonetti, 1989). Because adaptor protein complexes (APs) are the main components of clathrin-coated vesicles, a specific AP complex is likely to be associated to clathrin on phagosomes. One early study on APs has reported that AP-2 adaptor complexes...

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Section: Ap-1 Is Required For Efficient Phagocytosismentioning

confidence: 99%

Section: 〈P-1 Localizes To Nascent Phagosomesmentioning

confidence: 99%

mentioning

confidence: 99%

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Involvement of the AP-1 Adaptor Complex in Early Steps of Phagocytosis and Macropinocytosis

Lefkir

Malbouyres

Gotthardt

et al. 2004

MBoC

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“…Sheep erythrocytes (SRBCs) (BioMerieux, Charbonnier les Bains, France) were opsonized with a rabbit antiserum (20). Resealed ghosts were prepared as described (21) tTo whom reprint requests should be addressed.…”

Section: Methodsmentioning

confidence: 99%

Erythrophagocytosis induces heat shock protein synthesis by human monocytes-macrophages.

Clerget

Polla

1990

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

103

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Exposure of cells to elevated temperatures and other environmental stresses results in the expression of specific genes encoding the so-called heat shock proteins (HSPs). Since exogenous H202 induces in human monocytes the synthesis of HSPs, and previous induction of HSPs protects these cells from oxidative hnjury, we investigated whether HSP synthesis was also induced during generation ofreactive oxygen species by the phagocyte itself during phagocytosis. As a model system, we analyzed the effects of erythrophagocytosis on protein synthesis by the human premonocytic line U937, in which phagocytosis is induced during differentiation with 1,25-dihydroxyvitamin D3. Exposure to whole erythrocytes, but not to erythrocyte ghosts, induced in the phagocytic cells only the synthesis of the 70-and 83-to 90-kDa HSPs and a 32-kDa oxidation-related stress protein identical by partial peptide mapping to heme oxygenase. The radioprotective aminothiol N-(2'-mercaptoethyl)-1,3-propanediamine (WR-1065), which can substitute for glutathione as hydrogen donor, prevented this induction. These results suggest that oxygen free radicals generated in the presence of hemoglobin-derived iron and consecutive glutathione depletion are involved in induction of stress protein synthesis during erythrophagocytosis. HSPs synthesized during phagocytosis may play a role in the phagocyte's defense mechanisms and in protective immunity.As a model system, we used the human premonocytic line U937 and phagocytosis of erythrocytes. (4), that preexposure to temperatures inducing the synthesis of HSPs partially protects monocytic cells from H202-induced cell death (5), and that in human neutrophils induction of a heat shock response by heat or cadmium is associated with an inhibition of superoxide production (6). These observations suggested potential implications of HSPs in the phagocytes' biology (7). We therefore asked the question whether HSP synthesis was also induced in association with the generation of reactive oxygen species by the phagocyte itself during phagocytosis. The analysis of the stress response in phagocytes is of particular relevance since it has been shown that several immunodominant antigens of intracellular microorganisms such as mycobacteria or plasmodia are indeed, by sequence homology, HSPs, and the potential role ofHSPs in protective immunity and/or immunopathology is an area of intense interest (8-11). Mycoplasma-free U937 cells were grown in RPMI 1640 medium (GIBCO) with 10% fetal calf serum/1% glutamine, with or without 1,25-(OH)2D3 (10 ng/ml) for 72 hr, then counted, centrifuged, and resuspended at 0.8 x 106 cells per ml in RPMI 1640 medium without methionine and incubated with or without SRBCs for 3 hr at 37°C. Peripheral blood monocytes from normal volunteers were isolated by gradient centrifugation and purified by adherence (4), and human alveolar macrophages were obtained as described (22) from bronchoalveolar lavage of lungs excised during surgery for carcinoma, then isolated by adherence, cultured, and stimul...

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“…The total exudate population (TEP) consisting mostly of macrophages (26) was lysed directly by Nonidet P-40 for isolation of nuclei as previously described (11) or cultured in petri dishes with supplemented Dulbecco modified Eagle medium for 18 h. The adherent macrophage population, resting or stimulated, was washed with phosphate-buffered saline (PBS), detached with a rubber policeman in Hanks medium containing powdered nonfat milk (5 mg/ml) and 1 mM dithiothreitol and supplemented with a cocktail of protease inhibitors (50 ,ug each of pepstatin A, leupeptin, chymostatin, and antipain per ml, 0.5 mM phenylmethylsulfonyl fluoride, 200 kallikrein inactivator units of aprotinin per ml, 78 ,ug of benzamidine per ml), and centrifuged for 10 min at 300 x g and 4°C; the cell pellet was lysed with Nonidet P-40 for isolation of nuclei. To prevent adherence, the TEP was incubated in Teflon beakers for 18 h and washed three times with PBS by centrifugation at 300 x g and 4°C, and the cell pellet was lysed by Nonidet P-40. Sheep erythrocytes (Behring AG, Marburg, Germany) were opsonized with a heat-inactivated (30 min at 56°C) rabbit antiserum (30), and 1 ml (50% packed cell volume) was added to 10 ml of medium per 100-mm petri dish. Cycloheximide (Sigma), cholera toxin (Sigma), N6,02-dibu-tyryladenosine-3',5'-cyclic monophosphate (dbcAMP) (Sigma), and 3-isobutyl-1-methylxanthine (IBMX) (Sigma) were added to the cultures at the concentrations indicated in the figure legends.…”

Section: Methodsmentioning

confidence: 99%

c-fos gene transcription in murine macrophages is modulated by a calcium-dependent block to elongation in intron 1.

Collart¹,

N²,

Belin³

et al. 1991

Mol. Cell. Biol.

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Cultured mouse thioglycolate-elicited peritoneal macrophages exhibit a strong block to transcriptional elongation beyond the end of the c-fos gene first exon. This block is absent in freshly isolated peritoneal cells, appears slowly during culture, and does not require adherence of the cells. The extent of this block is largely responsible for the levels of c-fos mRNA in cultured macrophages, even after modulation by agents such as the tumor promoter phorbol myristate acetate and increased intracellular cyclic AMP, which also increase the activity of the c-fos promoter. When macrophages are cultured in the absence of mobilizable calcium, the block can no longer be relieved by any inducing agent. Conversely, upon calcium influxes, there is little alteration in the level of transcriptional initiation, but transcription proceeds efficiently through the entire c-fos locus. These results suggest the presence of an intragenic calcium-responsive element in the c-fos gene and illustrate its key role in the control of c-fos gene transcription.The c-fos gene appears to constitute a master switch which is central for cell proliferation and differentiation in a wide variety of cell types. Regulation of its expression is very complex and involves both transcriptional and posttranscriptional mechanisms (for reviews, see references 18, 32, 35, 42, 46, and 47). Transcriptional control itself occurs at the levels of both initiation (13, 17, 19-21, 24, 33, 45) and elongation (5,6,16,43,44).In cultured macrophages, transcription of the c-fos gene can be induced by the stimulation of several potentially different second messenger pathways which control the functional activity of the cells (8,10,11,23,36). For instance, in a number of cell types, including macrophages, transcription of c-fos is strongly induced by the calcium ionophore A23187 (7, 8, 13, 36, 40). Recently, we have shown that mobilization of calcium from intracellular sources is required for induction of c-fos gene transcription in mouse thioglycolate-elicited (TG) peritoneal macrophages by a number of different inducing agents (10). This observation was surprising, considering that different upstream promoter elements respond, for instance, to phorbol 12-myristate 13-acetate (PMA) or increased intracellular cyclic AMP (cAMP) (4,13,14,17,38,40,41) and that induction of transcription by glucocorticoids is not known to require calcium. Macrophage activation thus seems an interesting model with which to study relationships between external signals, second messengers, and the complex regulation of c-fos expression.In this report, we show that cultured mouse inflammatory peritoneal macrophages display a strong block to transcriptional elongation beyond the end of the c-fos first exon. Induction of c-fos transcription by a number of different * Corresponding author. agents is in all cases accompanied by a relief of the elongation block with or without an additional increase in promoter activity. Furthermore, our previous observation that mobilizable intracellular calcium ...

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Specialization of the macrophage plasma membrane at sites of interaction with opsonized erythrocytes.

Cited by 32 publications

References 38 publications

Involvement of the AP-1 Adaptor Complex in Early Steps of Phagocytosis and Macropinocytosis

Involvement of the AP-1 Adaptor Complex in Early Steps of Phagocytosis and Macropinocytosis

Erythrophagocytosis induces heat shock protein synthesis by human monocytes-macrophages.

c-fos gene transcription in murine macrophages is modulated by a calcium-dependent block to elongation in intron 1.

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