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Bowers EV, Horvath JJ, Bond JE, Cianciolo GJ, Pizzo SV. Antigen delivery by alpha(2)-macroglobulin enhances the cytotoxic T lymphocyte response. J Leukoc Biol 2009; 86:1259-68. [PMID: 19652028 DOI: 10.1189/jlb.1008653] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
alpha(2)M* targets antigens to APCs for rapid internalization, processing, and presentation. When used as an antigen-delivery vehicle, alpha(2)M* amplifies MHC class II presentation, as demonstrated by increased antibody titers. Recent evidence, however, suggests that alpha(2)M* encapsulation may also enhance antigen-specific CTL immunity. In this study, we demonstrate that alpha(2)M*-delivered antigen (OVA) enhances the production of specific in vitro and in vivo CTL responses. Murine splenocytes expressing a transgenic TCR specific for CTL peptide OVA(257-264) (SIINFEKL) demonstrated up to 25-fold greater IFN-gamma and IL-2 secretion when treated in vitro with alpha(2)M*-OVA compared with soluble OVA. The frequency of IFN-gamma-producing cells was increased approximately 15-fold, as measured by ELISPOT. Expansion of the OVA-specific CD8+ T cell population, as assayed by tetramer binding and [3H]thymidine incorporation, and OVA-specific cell-mediated cytotoxicity, as determined by a flow cytometric assay, were also enhanced significantly by alpha(2)M*-OVA. Furthermore, significant CTL responses were observed at antigen doses tenfold lower than those required with OVA alone. Finally, we also observed enhanced humoral and CTL responses by naïve mice following intradermal immunization with alpha(2)M*-OVA. These alpha(2)M*-OVA-immunized mice demonstrated increased protection against a s.c.-implanted, OVA-expressing tumor, as demonstrated by delayed tumor growth and prolonged animal survival. The observation that alpha(2)M*-mediated antigen delivery elicits specific CTL responses suggests the cross-presentation of antigen onto MHC class I. These results support alpha(2)M* as an effective antigen-delivery system that may be particularly useful for vaccines based on weakly immunogenic subunits or requiring dose sparing.
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Affiliation(s)
- Edith V Bowers
- Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA
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2
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Tayade C, Esadeg S, Fang Y, Croy BA. Functions of alpha 2 macroglobulins in pregnancy. Mol Cell Endocrinol 2005; 245:60-6. [PMID: 16297527 DOI: 10.1016/j.mce.2005.10.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2005] [Revised: 10/12/2005] [Accepted: 10/12/2005] [Indexed: 10/25/2022]
Abstract
The alpha 2 macroglobulins (A2M) are a family of abundant plasma proteins produced predominantly by the mammalian liver. Pregnancy zone proteins (PZP) of humans and rats are A2M family members that bind a wide variety of macromolecules including the important pregnancy-associated molecules such as vascular endothelial growth factor, placenta growth factor and glycodelin (also called PP14). Recently, a mouse gene analogous to PZP (A2M of pregnancy or A2Mp) was cloned. A2Mp has a unique pattern of expression in reproductive and cardiovascular tissues and, unexpectedly, is not expressed by liver. Since changes in heart function and remodeling of renal and uterine vasculature are amongst the earliest maternal responses to pregnancy, the product of the A2Mp gene has been postulated to systemically regulate these changes. A2Ms with and without non-covalently bound ligands also down regulate immune cell activation but promote immune cell migration, additional features associated with gestational success. Here, we review the A2M gene families of mice and humans, the predicted structural relationships between A2M and its pregnancy induced forms and the postulated roles for this gene family in normal pregnancy.
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Affiliation(s)
- Chandrakant Tayade
- Department of Biomedical Sciences, University of Guelph, Guelph, Ont., Canada NIG 2W1.
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3
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Tonganunt M, Phongdara A, Chotigeat W, Fujise K. Identification and characterization of syntenin binding protein in the black tiger shrimp Penaeus monodon. J Biotechnol 2005; 120:135-45. [PMID: 16055222 DOI: 10.1016/j.jbiotec.2005.06.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2005] [Revised: 05/17/2005] [Accepted: 06/01/2005] [Indexed: 11/23/2022]
Abstract
Shrimp exhibit a diverse response to viral infection that is manifested in drastic up- and down-regulations of a variety of genes. In our previous work, we identified syntenin of the shrimp Penaeus monodon (Pm) as a dynamic responder to white spot syndrome virus (WSSV) infection, its message being greatly upregulated in the acute phase of the infection. In order to further explore the link between Pm-syntenin and viral infection, we performed a yeast two-hybrid screening of a P. monodon cDNA library, using Pm-syntenin as bait. One of the molecules that specifically interacted with Pm-syntenin was the receptor-binding domain of alpha-2-macroglobulin (alpha2M). A GST pull-down assay showed that GST-alpha2M, but not GST alone, was capable of co-precipitating syntenin. Another GST pull-down assay showed that GST-syntenin, but not GST alone, was capable of co-precipitating alpha2M. In addition, mutant analyses showed that the N-terminal 131 amino acids of syntenin were both necessary and sufficient to bind the C-terminus receptor-binding domain of alpha2M. Furthermore, WSSV-infected Pm showed a significant upregulation of the alpha2M message, suggesting that both syntenin and its protein partner alpha2M are upregulated in the acute phase of a WSSV infection. Taken together with a previous report showing the co-localization of alpha2M and syntenin in the exosome of a dendritic cell line, it is likely that syntenin, through its interaction with alpha2M, plays an important role in the immune defense mechanisms of viral infections of shrimps.
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Affiliation(s)
- Moltira Tonganunt
- Department of Biochemistry, Faculty of Science, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand
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4
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Kurdowska A, Alden SM, Noble JM, Stevens MD, Carr FK. Involvement of alpha-2-macroglobulin receptor in clearance of interleukin 8-alpha-2-macroglobulin complexes by human alveolar macrophages. Cytokine 2000; 12:1046-53. [PMID: 10880251 DOI: 10.1006/cyto.1999.0640] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to determine if interleukin 8 (IL-8) in complex with alpha2-macroglobulin (alpha-2-M) can be taken up by human alveolar macrophages. First, we demonstrated that human alveolar macrophages have receptors for alpha-2-M but not IL-8. The binding of(125)I-labeled alpha-2-M to the cells was specific and saturable, whereas(125)I-labeled recombinant human IL-8 (rhIL-8) did not bind to macrophages. However,(125)I-rhIL-8-alpha-2-M complexes bound to macrophages, and unlabeled alpha-2-M competed for the binding. We then cultured the cells in the presence of(125)I-rhIL-8-alpha-2-M complexes,(125)I-rhIL-8 alone or buffer for 24 h. Macrophages were lysed, and the released radioactivity measured. IL-8 concentrations in supernatants and cells were also measured using an IL-8 ELISA. When the macrophages were incubated with(125)I-rhIL-8-alpha-2-M complexes there was a significant amount of IL-8 associated with the cells. However, this was not the case when the cells were incubated with(125)I- rhIL-8 alone suggesting that only these complexes were taken-up by human alveolar macrophages. Furthermore, the clearance of complexes was specifically inhibited by a monoclonal antibody against the 515-kDa subunit of the alpha-2-M receptor (alpha-2-MR) but not by an isotopic mouse IgG1. The study shows an important clearance mechanism for IL-8 in the lung.
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Affiliation(s)
- A Kurdowska
- Department of Biochemistry, University of Texas Health Center at Tyler, 75708, USA.
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5
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Huang W, Dolmer K, Liao X, Gettins PG. Localization of basic residues required for receptor binding to the single alpha-helix of the receptor binding domain of human alpha2-macroglobulin. Protein Sci 1998; 7:2602-12. [PMID: 9865955 PMCID: PMC2143881 DOI: 10.1002/pro.5560071214] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
To better understand the structural basis for the binding of proteinase-transformed human alpha2-macroglobulin (alpha2M) to its receptor, we have used three-dimensional multinuclear NMR spectroscopy to determine the secondary structure of the receptor binding domain (RBD) of human alpha2M. Assignment of the backbone NMR resonances of RBD was made using 13C/15-N and 15N-enriched RBD expressed in Escherichia coli. The secondary structure of RBD was determined using 1H and 13C chemical shift indices and inter- and intrachain nuclear Overhauser enhancements. The secondary structure consists of eight strands in beta-conformation and one alpha-helix, which together comprise 44% of the protein. The beta-strands form three regions of antiparallel beta-sheet. The two lysines previously identified as being critical for receptor binding are located in (Lys1374), and immediately adjacent to (Lys1370) the alpha-helix, which also contains an (Arg1378). Secondary structure predictions of other alpha-macroglobulins show the conservation of this alpha-helix and suggest an important role for this helix and for basic residues within it for receptor binding.
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Affiliation(s)
- W Huang
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Illinois at Chicago 60612-4316, USA
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6
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Douglas GC, Moreira-Cali P, King BF, Lonnerdal B. Uptake of125I-labelled α2-macroglobulin and albumin by human placental syncytiotrophoblast in vitro. J Cell Biochem 1998. [DOI: 10.1002/(sici)1097-4644(19980315)68:4<427::aid-jcb3>3.0.co;2-s] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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7
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Paresce DM, Chung H, Maxfield FR. Slow degradation of aggregates of the Alzheimer's disease amyloid beta-protein by microglial cells. J Biol Chem 1997; 272:29390-7. [PMID: 9361021 DOI: 10.1074/jbc.272.46.29390] [Citation(s) in RCA: 197] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Microglia are immune system cells associated with senile plaques containing beta-amyloid (Abeta) in Alzheimer's disease. Although microglia are an integral part of senile plaques, their role in the development of Alzheimer's disease is not known. Because microglia are phagocytic cells, it has been suggested that microglia may function as plaque-attacking scavenger cells. Microglia bind and internalize microaggregates of Abeta that resemble those present in dense Alzheimer's disease plaques. In this study, we compared the degradation by microglia of Abeta microaggregates with the degradation of two other proteins, acetylated low density lipoprotein and alpha2-macroglobulin. We found that the majority of the internalized Abeta in microaggregates was undegraded 72 h after uptake, whereas 70-80% of internalized acetylated low density lipoprotein or alpha2-macroglobulin was degraded and released from cells in trichloroacetic acid-soluble form after 4 h. In the continued presence of fluorescent Abeta microaggregates for 4 days, microglia took up huge amounts of Abeta and became engorged with undigested material. These data suggest that microglia can slowly degrade limited amounts of Abeta plaque material, but the degradation mechanisms can be overwhelmed by larger amounts of Abeta.
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Affiliation(s)
- D M Paresce
- Biochemistry Department, Cornell University Medical College, New York, New York 10021, USA
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Brown MD, Banker GA, Hussaini IM, Gonias SL, VandenBerg SR. Low density lipoprotein receptor-related protein is expressed early and becomes restricted to a somatodendritic domain during neuronal differentiation in culture. Brain Res 1997; 747:313-7. [PMID: 9046007 DOI: 10.1016/s0006-8993(96)01321-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Low density lipoprotein receptor-related protein (LRP) is a multi-functional receptor which mediates the endocytotic uptake of several ligands implicated in neuronal pathophysiology. In this study, LRP expression and localization, in cultured hippocampal neurons from 18-day-old rats, were examined by immunofluorescence microscopy. LRP was restricted to the cell bodies and dendrites of mature neurons, where it was uniformly distributed on both dendritic shafts and spines. Immunoreactive protein was detected within the first 24 h of culture and acquired a polarized distribution by the end of the first week. Expression of LRP mRNA by the cultured neurons was demonstrated by Northern blot analysis. Binding studies with the LRP ligand, activated alpha2-macroglobulin, confirmed that LRP was present and functional on the hippocampal neuron cell surface. These studies demonstrate that neuronal LRP undergoes selective compartmentation during neuronal maturation and suggest that LRP-mediated endocytosis is largely restricted to the somatodendritic compartment.
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Affiliation(s)
- M D Brown
- Department of Pathology (Neuropathology), University of Virginia Health Sciences Center, Charlottesville 22908, USA
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9
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Misra UK, Gawdi G, Pizzo SV. Binding of rat alpha 1-inhibitor-3-methylamine to the alpha 2-macroglobulin signaling receptor induces second messengers. J Cell Biochem 1996; 61:61-71. [PMID: 8726356 DOI: 10.1002/(sici)1097-4644(19960401)61:1%3c61::aid-jcb8%3e3.0.co;2-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Binding of receptor-recognized forms of tetrameric human alpha 2-macroglobulin (alpha 2M*) to a macrophage signaling receptor induces cAMP synthesis, increases in inositol 1,4,5-triphosphate (IP3) synthesis, and a concomitant rise in cytosolic free calcium ([Ca2+]i). The alpha 2M* signaling receptor is coupled to a pertussis-toxin insensitive G protein. Binding of alpha 2M* also occurs to the low density lipoprotein receptor-related protein/alpha 2M receptor (LRP/alpha 2MR), but this binding does not induce signal transduction. Rat alpha 1-inhibitor-3 (alpha 1I3) is a monomeric member of the alpha-macroglobulin/complement superfamily. Like alpha 2M, it can react with proteinases or methylamine which induces a conformational change causing activated alpha 1I3 to bind to LRP/alpha 2MR. We now report that alpha 1I3-methylamine binds to the macrophage alpha 2M* signaling receptor inducing a rapid rise in the synthesis of IP3 with a subsequent 1.5- to 3-fold rise in [Ca2+]i. alpha 1I3-methylamine binding to macrophages also caused a statistically significant elevation in cAMP. Native alpha 1I3, like alpha 2M, was unable to induce signal transduction. alpha 1I3 forms a complex with alpha 1-microglobulin, which has a distinct conformation from alpha 1I3 and is recognized by LRP/alpha 2MR. This complex also induces an increase in [Ca2+]i comparable to the effect of alpha 1I3-methylamine on macrophages. It is concluded that activation of alpha 1I3 by methylamine or binding of alpha 1-microglobulin causes similar conformational changes in the inhibitor, exposing the receptor recognition site for the alpha 2M* signaling receptor, as well as for LRP/alpha 2MR.
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Affiliation(s)
- U K Misra
- Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710, USA
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10
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Misra UK, Gawdi G, Pizzo SV. Binding of rat α1-inhibitor-3-methylamine to the α2-macroglobulin signaling receptor induces second messengers. J Cell Biochem 1996. [DOI: 10.1002/(sici)1097-4644(19960401)61:1<61::aid-jcb8>3.0.co;2-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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11
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Affiliation(s)
- C T Chu
- Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710
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12
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Moestrup SK. The alpha 2-macroglobulin receptor and epithelial glycoprotein-330: two giant receptors mediating endocytosis of multiple ligands. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1197:197-213. [PMID: 7518253 DOI: 10.1016/0304-4157(94)90005-1] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- S K Moestrup
- Department of Medical Biochemistry, University of Aarhus, Denmark
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13
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Williams S, Ashcom J, Argraves W, Strickland D. A novel mechanism for controlling the activity of alpha 2-macroglobulin receptor/low density lipoprotein receptor-related protein. Multiple regulatory sites for 39-kDa receptor-associated protein. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50384-2] [Citation(s) in RCA: 272] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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14
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Hussaini IM, Srikumar K, Quesenberry PJ, Gonias SL. Colony-stimulating factor-1 modulates alpha 2-macroglobulin receptor expression in murine bone marrow macrophages. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)45392-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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15
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Sequence identity between the alpha 2-macroglobulin receptor and low density lipoprotein receptor-related protein suggests that this molecule is a multifunctional receptor. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)38172-9] [Citation(s) in RCA: 507] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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16
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Ashcom JD, Tiller SE, Dickerson K, Cravens JL, Argraves WS, Strickland DK. The human alpha 2-macroglobulin receptor: identification of a 420-kD cell surface glycoprotein specific for the activated conformation of alpha 2-macroglobulin. J Biophys Biochem Cytol 1990; 110:1041-8. [PMID: 1691187 PMCID: PMC2116111 DOI: 10.1083/jcb.110.4.1041] [Citation(s) in RCA: 234] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Ligand affinity chromatography was used to purify a cell surface alpha 2-macroglobulin (alpha 2M) receptor. Detergent extracts of human placenta were applied to an affinity matrix consisting of alpha 2M, previously reacted with methylamine, coupled to Sepharose. Elution with EDTA specifically released polypeptides with apparent molecular masses of 420 and 39 kD. In some preparations, small amounts of a 90-kD polypeptide were observed. The 420- and 39-kD polypeptides appear specific for the forms of alpha 2M activated by reaction with proteinases or methylamine and do not bind to an affinity matrix consisting of native alpha 2M coupled to Sepharose. Separation of these two polypeptides was accomplished by anion exchange chromatography, and binding activity was exclusively associated with the 420-kD polypeptide. The purified 420-kD protein binds to the conformationally altered forms of alpha 2M that are known to specifically interact with alpha 2M receptors and does not bind to native alpha 2M. Binding of the 420-kD polypeptide to immobilized wheat germ agglutinin indicates that this polypeptide is a glycoprotein. The cell surface localization of the 420-kD glycoprotein was confirmed by affinity chromatography of extracts from surface radioiodinated fibroblasts. These properties suggest that the 420-kD polypeptide is a cell surface receptor for the activated forms of alpha 2M.
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Affiliation(s)
- J D Ashcom
- Biochemistry Department, Holland Laboratory, American Red Cross, Rockville, Maryland 20855
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17
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Affiliation(s)
- F R Maxfield
- Department of Pathology and Physiology, College of Physicians & Surgeons, Columbia University, New York, New York 10032
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18
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Plasminogen activation and regulation of pericellular proteolysis. BIOCHIMICA ET BIOPHYSICA ACTA 1985; 823:35-65. [PMID: 2413894 DOI: 10.1016/0304-419x(85)90014-9] [Citation(s) in RCA: 95] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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19
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Abstract
Anion-exchange chromatography is shown to permit resolution and separation of subforms of the serum glycoprotein alpha 2-macroglobulin. The subforms differ dramatically in their stability as judged by differential scanning calorimetry, undergoing thermally induced unfolding at temperatures of 61 and 69 degrees C respectively. In addition, the proteinase-binding stoichiometry of the subforms differs by a factor of 2, with the more- and less-stable forms binding 2 and 1 mol of proteinase per mol of tetramer respectively. The calorimetric stability of the two forms is differentially affected on treatment with neuraminidase, suggesting that the nature of glycosylation may in part account for the observed differences in physical and functional properties.
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20
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Chapter 9 Receptors as Models for the Mechanisms of Membrane Protein Turnover and Dynamics. CURRENT TOPICS IN MEMBRANES AND TRANSPORT 1985. [DOI: 10.1016/s0070-2161(08)60331-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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21
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Osterberg R, Malmensten B. Methylamine-induced conformational change of alpha 2-macroglobulin and its zinc (II) binding capacity. An X-ray scattering study. EUROPEAN JOURNAL OF BIOCHEMISTRY 1984; 143:541-4. [PMID: 6207020 DOI: 10.1111/j.1432-1033.1984.tb08403.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Methylamine induces a conformational change of alpha 2-macroglobulin which is very similar to that obtained by proteinase reaction and binding. This was shown by small-angle X-ray scattering at 21 degrees C in 0.03 M Hepes buffer of pH 8.0 containing 0.15 M NaCl and 0.3 mM EDTA. When alpha 2-macroglobulin reacts with methylamine the side maximum virtually disappears from the X-ray scattering curve and the radius of gyration decreases from 7.8 nm to 7.2 nm. The X-ray data of alpha 2-macroglobulin are consistent with an open shape model similar to that deduced via electron micrographs [Schramm, H. J. and Schramm, W. (1982) Hoppe-Seyler's Z. Physiol. Chem. 363, 803-812]; one projection of the model resembles the letter H; the four subunits are mainly represented as elliptical cylinders which are connected via a central, quite flat cylinder. Zinc(II) ions cause aggregation of alpha 2-macroglobulin even at such a low total zinc concentration as 12.5 microM; for 25 microM zinc(II) concentration, the average molecular mass indicates that the aggregation goes beyond the dimeric stage. Monomeric species of alpha 2-macroglobulin appear to have the capacity specifically to bind 8.0 zinc(II) ions per molecule, which corresponds to two zinc(II) ions per subunit.
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22
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Smit S, Huijskes-Heins MI, Leijnse B. Iron uptake by Chinese hamster fibroblasts from human transferrin. Exp Cell Res 1984; 153:73-80. [PMID: 6734743 DOI: 10.1016/0014-4827(84)90449-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The manner of uptake or iron by Chinese hamster fibroblasts, type DON, from human transferrin was investigated by means of replacement studies, in which the cells that were incubated with 125I-labelled human transferrin were chased with non-radioactive transferrin for only a few minutes. The results did not support the reversible endocytosis hypothesis for the uptake of iron from transferrin. The uptake of iron measured as 59Fe during several cell divisions was found to be a function of time and cell number. It was found that the total uptake of iron in the harvests was directly proportional to the incubation, and that the uptake per 10(6) cells levelled off in the course of time.
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23
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Davies PJ, Murtaugh MP. Transglutaminase and receptor-mediated endocytosis in macrophages and cultured fibroblasts. Mol Cell Biochem 1984; 58:69-77. [PMID: 6200758 DOI: 10.1007/bf00240606] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The function of intracellular transglutaminases remains to be clarified. In fibroblasts the links between the activity of this enzyme and receptor-mediated endocytosis are complex and open to interpretation. However, the issue cannot be firmly laid to rest until the structural specificity of the alkylamine inhibitors of endocytosis is explained. In macrophages, there is substantial evidence that the enzyme plays some role in receptor-mediated phagocytosis, but what this role is and how it might relate to endocytosis in other types of cells is at present an unresolved issue.
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24
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Szego CM, Pietras RJ. Lysosomal functions in cellular activation: propagation of the actions of hormones and other effectors. INTERNATIONAL REVIEW OF CYTOLOGY 1984; 88:1-302. [PMID: 6145684 DOI: 10.1016/s0074-7696(08)62759-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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25
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Borth W. Alpha 2-macroglobulin in connective tissue matrix metabolism. COLLAGEN AND RELATED RESEARCH 1984; 4:83-94. [PMID: 6202458 DOI: 10.1016/s0174-173x(84)80031-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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26
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Willingham MC, Pastan I. Endocytosis and exocytosis: current concepts of vesicle traffic in animal cells. INTERNATIONAL REVIEW OF CYTOLOGY 1984; 92:51-92. [PMID: 6150907 DOI: 10.1016/s0074-7696(08)61324-8] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Animal cells have specific pathways to transport macromolecules from their surrounding environment to their interior, and from internal compartments to the cell surface or other intracellular locations. Many of these movements appear to be receptor-dependent processes in which specific membrane receptors bind macromolecules, segregate them into discrete membrane-limited compartments, and move the molecules to new locations. Such processes include the clustering and internalization of receptor-bound ligands at the cell surface in clathrin-coated pits, the formation of endocytic vesicles (receptosomes) from coated pits, the movement of receptosomes by saltatory motion to the Golgi system, the concentration of materials in the coated pits of the Golgi system that are destined for delivery to lysosomes, and the directed traffic of materials destined for exocytosis out of the Golgi to the cell surface. This review describes some of the experiments which have led to our current understanding of the various organelles involved in this traffic and some of the biochemical mechanisms involved.
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27
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Tycko B, DiPaola M, Yamashiro DJ, Fluss S, Maxfield FR. Acidification of endocytic vesicles and the intracellular pathways of ligands and receptors. Ann N Y Acad Sci 1983; 421:424-33. [PMID: 6202216 DOI: 10.1111/j.1749-6632.1983.tb18136.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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28
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Gliemann J, Larsen TR, Sottrup-Jensen L. Cell association and degradation of alpha 2-macroglobulin-trypsin complexes in hepatocytes and adipocytes. BIOCHIMICA ET BIOPHYSICA ACTA 1983; 756:230-7. [PMID: 6187372 DOI: 10.1016/0304-4165(83)90096-x] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
125I-Labelled alpha 2-macroglobulin-trypsin complex (125I-labelled alpha 2-macroglobulin X trypsin) was associated to isolated rat adipocytes and hepatocytes with a half-time of about 60 min at 37 degrees C. The association of 0.5 micrograms/ml 125I-labelled alpha 2-macroglobulin X trypsin was inhibited by unlabelled alpha 2-macroglobulin X trypsin with a half-inhibition constant of about 8 micrograms/ml (11 nM). 125I-Labelled alpha 2-macroglobulin became cell-associated to a smaller extent (10-40% of that of alpha 2-macroglobulin X trypsin) and the half-inhibition constant was about 35 micrograms/ml in adipocytes. The cell association of 125I-labelled alpha 2-macroglobulin X trypsin was markedly inhibited by dansylcadaverine, bacitracin, omission of Ca2+ from the medium or pretreatment of the cells with trypsin. After incubation for 180 min more than 60% of the cell-associated 125I-labelled alpha 2-macroglobulin X trypsin was not removed by treatment of the cells with trypsin-EDTA and represented probably internalized material. 125I-Labelled alpha 2-macroglobulin X trypsin was degraded to trichloroacetic acid-soluble fragments by suspensions of both cell types but only to a negligible extent by incubation media preincubated with these cells. The rate of degradation of 0.5 micrograms/ml 125I-labelled alpha 2-macroglobulin was approx. 40% of that of 125I-labelled alpha 2-macroglobulin X trypsin. Degradation of 125I-labelled alpha 2-macroglobulin X trypsin was abolished by a high concentration (0.5 mg/ml) of alpha 2-macroglobulin X trypsin. It is concluded that alpha 2-macroglobulin X trypsin by a specific and saturable mechanism is bound to, internalized and degraded by isolated rat adipocytes and hepatocytes.
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Stauber W, Fritz V, Esnard F, Gauthier F. Immunofluorescent localization of four serum proteinase inhibitors in normal rat liver. THE HISTOCHEMICAL JOURNAL 1983; 15:161-6. [PMID: 6189806 DOI: 10.1007/bf01042284] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Four serum proteinase inhibitors, alpha 1-macroglobulin, alpha 1-proteinase inhibitor, alpha 1-inhibitor3 and alpha 2-acute phase macroglobulin, were localized in rat liver by immunofluorescent techniques. alpha 1-Macroglobulin was observed predominantly in the sinusoids and alpha 1-inhibitor3 in hepatocytes. In contrast, alpha 1-proteinase inhibitor was localized in two sites, sinusoids and parenchymal cells. The fourth inhibitor tested, alpha 2-acute phase macroglobulin, was barely detectable in normal liver. However, some appeared to be present in the extrahepatocyte space.
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Dickson RB, Schlegel R, Willingham MC, Pastan IH. Involvement of Na+ and HCO-3 in receptor-mediated endocytosis of alpha 2-macroglobulin, epidermal growth factor, and vesicular stomatitis virus. J Cell Physiol 1982; 113:353-8. [PMID: 6184377 DOI: 10.1002/jcp.1041130302] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
alpha 2-Macroglobulin (alpha 2M), epidermal growth factor (EGF), and vesicular stomatitis virus (VSV) each enter cultured fibroblasts by receptor-mediated endocytosis. The present study defines some basic ionic requirements in the cell culture medium which are necessary for the maximal rate of endocytosis of these three ligands. Na+ and HCO-3 were both necessary for maximal endocytosis of 125I-alpha 2M, 125I-EGF, and 35S-VSV at 37 degrees C. The ion specificities for both the anion and cation requirements were established. The binding of 125I-alpha 2M to its cellular receptors at 4 degrees C was unaffected by the absence of Na+ and HCO-3 in the culture medium. In addition, the absence of Na+ and HCO-3 in the culture medium did not reduce cellular uptake of horseradish peroxidase by fluid phase endocytosis. Na+ and HCO-3 may be general requirements in receptor-mediated endocytosis.
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Maxfield FR. Weak bases and ionophores rapidly and reversibly raise the pH of endocytic vesicles in cultured mouse fibroblasts. J Cell Biol 1982; 95:676-81. [PMID: 6183281 PMCID: PMC2112942 DOI: 10.1083/jcb.95.2.676] [Citation(s) in RCA: 451] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
It has been shown that endocytic vesicles in BALB/c 3T3 cells have a pH of 5.0 (Tycko and Maxfield, Cell, 28:643-651). In this paper, a method for measuring the effect of various agents, including weak bases and ionophores, on the pH of endocytic vesicles is presented. The method is based on the increase in fluorescein fluorescence with 490-nm excitation as the pH is raised above 5.0. Intensities of cells were measured using a microscope spectrofluorometer after internalization of fluorescein-labeled alpha 2-macroglobulin by receptor-mediated endocytosis. The increase in endocytic vesicle pH was determined from the increase in fluorescence after addition of various concentrations of the test agents. The following agents increased endocytic vesicle pH above 6.0 at the indicated concentrations: monensin (6 microM), FCCP (10 microM), chloroquine (140 microM), ammonia (5 mM), methylamine (10 mM). The ability of many of these agents to raise endocytic vesicle pH may account for many of their effects on receptor-mediated endocytosis. Dansylcadaverine caused no effect on vesicle pH at 1 mM. The observed increases in vesicle pH were rapid (1-2 min) and could be reversed by removal of the perturbant. This reversibility indicates that the vesicles themselves contain a mechanism for acidification. The increase in vesicle pH due to these treatments can be observed visually using an SIT video camera. Using this method, it is shown that endocytic vesicles become acidic at very early times (i.e., within 5-7 min of continuous uptake at 37 degrees C).
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