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Horton MA, Whittington ID. A new species of Metabenedeniella (Monogenea: Capsalidae) from the dorsal fin of Diagramma pictum (Perciformes: Haemulidae) from the great barrier reef, Australia with a revision of the genus. J Parasitol 1994; 80:998-1007. [PMID: 7799172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Metabenedeniella parva n. sp. is described from the marine teleost Diagramma pictum from Heron Island, Queensland, Australia. The type species of the genus, Metabenedeniella hoplognathi, is redescribed and the generic diagnosis emended. Metabenedeniella parva differs from M. hoplognathi in many respects: M. parva is smaller; in M. parva the accessory sclerites and anterior hamuli are of similar length, but the posterior hamuli are smaller, whereas in M. hoplognathi the accessory sclerites are longer than the anterior hamuli and the anterior and posterior hamuli are of similar length; in M. parva the anterior hamuli span the distance between accessory sclerites and posterior hamuli and the anterior hamuli overlap the posterior hamuli considerably, but in M. hoplognathi the anterior hamuli partially overlap the posterior hamuli and do not extend anteriorly to reach the accessory sclerites; a sclerite close to the common genital aperture in M. parva is absent from M. hoplognathi. The 2 species differ also in some of their soft body parts. Specimens reported previously from the gills of Plectorhynchus chaetodonoides off Okinawa, Japan as M. hoplognathi are considered to be M. parva. The discovery of M. parva from only the dorsal fin of D. pictum at Heron Island enhances the notion that some benedeniine monogeneans from the body surfaces of fish exhibit strong site specificity.
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Horton MA, Whittington ID. A New Species of Metabenedeniella (Monogenea: Capsalidae) from the Dorsal Fin of Diagramma pictum (Perciformes: Haemulidae) from the Great Barrier Reef, Australia with a Revision of the Genus. J Parasitol 1994. [DOI: 10.2307/3283449] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Horton MA, Spragg JH, Bodary SC, Helfrich MH. Recognition of cryptic sites in human and mouse laminins by rat osteoclasts is mediated by beta 3 and beta 1 integrins. Bone 1994; 15:639-46. [PMID: 7532981 DOI: 10.1016/8756-3282(94)90312-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Laminins may be encountered by osteoclasts and their precursors in basement membranes when they migrate from periosteal vasculature during skeletal development and in pathological situations. We have examined the recognition by osteoclasts of intact laminins and their proteolytic derivatives, and analysed the mechanism of adhesion. Rat osteoclasts fail to bind intact mouse Engelbreth-Holm-Swarm (EHS) laminin (3% adhesion relative to adhesion to foetal calf serum proteins) and bind only weakly to native human placental laminin (13%) or human merosin (9%). Pepsin treatment of native mouse EHS and human laminins increased osteoclast adhesion. Rat osteoclasts adhered to mouse EHS laminin-derived P1 fragment (70%), but failed to bind the E8 fragment, which contains adhesion sites recognised by some integrins. Binding to human and mouse P1 laminins was abolished by treatment with RGD-containing peptides and required divalent cations, but not by YIGSR peptide. Combinations of monoclonal antibodies to rat beta 3 and alpha v integrins reduced binding to P1 fragment by 91% and to human laminin by 72%, demonstrating that the major integrin involved in rat osteoclast adhesion to proteolysed laminin is alpha v beta 3. Antiserum to beta 1 integrin inhibited adhesion to human laminin by 40%, but to P1 fragment by only 8%; this suggests that beta 1 integrins(s) contribute to osteoclast adhesion to human laminin but probably not to P1 fragment. The involvement of alpha v beta 3 integrin was confirmed using a recombinant human alpha v beta 3 solid phase binding assay, alpha v beta 3 bound to mouse P1 fragment and proteolytically digested human laminin, but not intact laminins.(ABSTRACT TRUNCATED AT 250 WORDS)
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Wu X, Helfrich MH, Horton MA, Feigen LP, Lefkowith JB. Fibrinogen mediates platelet-polymorphonuclear leukocyte cooperation during immune-complex glomerulonephritis in rats. J Clin Invest 1994; 94:928-36. [PMID: 8083378 PMCID: PMC295129 DOI: 10.1172/jci117459] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The metabolic and functional alterations which occur during the acute phase of nephrotoxic nephritis (NTN) in rats, a model of immune-mediated glomerulonephritis, result from a cooperative interaction between PMNs and platelets (PLTs). In consequence, we hypothesized that fibrinogen (Fg) might play a critical role in this process and, accordingly, we found that defibrination of animals decreased both the acute phase proteinuria in NTN (approximately 70%) as well as the influx of PLTs and PMNs into the glomerulus (approximately 40-50%). In contrast, blockade of the PLT Fg receptor, alpha IIb beta 3, with the RGD peptidomimetic SC-49992 decreased proteinuria (approximately 90%) without substantially altering the influx of PMNs or PLTs. Immunocytochemistry showed a marked increase in beta 3 integrin expression in inflamed glomeruli which was prevented either by PMN or PLT depletion before disease induction. FACS and immunocytochemical analysis of glomerular cell dissociates demonstrated that beta 3 integrin expression was predominantly on intraglomerular PLTs. In vitro, activated PLTs stimulated the PMN respiratory burst, an interaction which could be inhibited by Fg receptor blockade. In sum, acute NTN is accompanied by a marked increase in glomerular beta 3 integrin expression predominantly due to the influx of PLTs which localize to the glomerulus in a PMN-dependent fashion. Fg appears to serve a major role as a coactivating stimulus for PLT-PMNs in situ via alpha IIb beta 3, potentially mediating the PMN respiratory burst which contributes to proteinuria. Fg may also play a subsidiary role in PMN/PLT comigration.
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Bates RC, Buret A, van Helden DF, Horton MA, Burns GF. Apoptosis induced by inhibition of intercellular contact. J Cell Biol 1994; 125:403-15. [PMID: 8163556 PMCID: PMC2120042 DOI: 10.1083/jcb.125.2.403] [Citation(s) in RCA: 194] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The LIM 1863 colon carcinoma cell line grows as structural organoids of goblet and columnar cells around a central lumen and provides a model for the development of stem cells in the normal colon. The organoid structure can be disrupted by removal of calcium from the medium, resulting in a suspension of single cells. Upon readdition of calcium, the cells reform the organoid structure over a period of 24 h, and ultrastructural examination of the reforming cells reveals that this involves a complex process that we have termed clutching. To determine the adhesion molecules involved in organoid formation we attempted to block this process by single cell suspensions of LIM 1863 reseeded in the presence of monoclonal antibodies. An anti-integrin antibody directed against a conformational epitope on the alpha v subunit totally inhibited organoid reformation. As a consequence of this inhibition of cell contact the colon carcinoma cells rapidly underwent apoptosis. Investigations of the apoptotic pathway involved suggested an induction mechanism since the onset of apoptosis in the contact-inhibited cells showed specific increased synthesis of 68- and 72-kD proteins. In addition, immunoblotting of cytosolic and nuclear extracts of the cells revealed the rapid translocation of the tumor suppressor gene product, p53 to the cell nucleus upon induction of apoptosis. These results suggest that cell-cell adhesion may be a vital regulator of colon development overcome in tumor cells by loss of adhesion molecules or of functional p53 protein.
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Davison I, Shankar G, Horton MA, Mason WT. Integrin-dependent mobilization of intracellular calcium ions in osteoclasts. A possible role in the regulation of the secretion of protons and lysosomal enzymes. Ann N Y Acad Sci 1994; 710:287-300. [PMID: 8154755 DOI: 10.1111/j.1749-6632.1994.tb26636.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Shankar G, Davison I, Helfrich MH, Mason WT, Horton MA. Integrin receptor-mediated mobilisation of intranuclear calcium in rat osteoclasts. J Cell Sci 1993; 105 ( Pt 1):61-8. [PMID: 7689577 DOI: 10.1242/jcs.105.1.61] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cell-matrix interactions have been shown to play an important role in regulating cell function and behaviour. In bone, where calcified matrix formation and resorption events are required to be in dynamic equilibrium, regulation of adhesive interactions between bone cells and their matrix is critical. The present study focuses on the osteoclast, the bone resorbing cell, as well as integrins, which are cell surface adhesion receptors that mediate osteoclast attachment to bone matrix. In osteoclasts, the most abundant integrin receptor is the vitronectin receptor (VNR, alpha v beta 3). The objective of the study was to investigate changes in intracellular calcium, a regulator of osteoclast function, following addition of peptides that bind integrins, in particular the alpha v beta 3 form of the vitronectin receptor (VNR), which is highly expressed in osteoclasts. The study demonstrated a unique spatial localisation of the calcium signal in response to cell membrane receptor occupancy by integrin ligands in rat osteoclasts. Addition of peptides with the Arg-Gly-Asp (RGD) sequence such as BSP-IIA, GRGDSP and GRGDS to rat osteoclasts evoked an immediate increase in free calcium ion concentration [Ca2+]i, localised to the nuclei and to the thin cytoplasmic skirt. These responses were inhibited by F11, a monoclonal antibody to the rat integrin beta 3 chain, as well as echistatin, a snake venom shown to colocalise with the alpha v chain in osteoclasts, suggesting that the calcium signal is mediated by the alpha v beta 3 form of VNR.(ABSTRACT TRUNCATED AT 250 WORDS)
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Lakkakorpi PT, Helfrich MH, Horton MA, Väänänen HK. Spatial organization of microfilaments and vitronectin receptor, alpha v beta 3, in osteoclasts. A study using confocal laser scanning microscopy. J Cell Sci 1993; 104 ( Pt 3):663-70. [PMID: 7686168 DOI: 10.1242/jcs.104.3.663] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The primary function of the osteoclast is that of the major cell mediating bone resorption. They are actively migrating cells but during resorption they polarize to form a specialized tight attachment structure, the sealing zone, adjacent to the mineralized bone matrix. The processes of adhesion to, and migration on, bone involves cell adhesion molecules, integrins, interacting with their ligands in bone. We have used confocal microscopy to analyse, in rat osteoclasts cultured on bone and glass substrata, the distribution of vitronectin receptor, the major integrin of osteoclasts, and cytoskeletal proteins that it may be linked to. Double staining for F-actin and vinculin, and for vinculin with talin, revealed that cytoskeletal organization differs at various activation states of osteoclasts. Microfilament structures were flat, of 1.5 microns size, and concentrated near the bone surface. The vitronectin receptor was localized both in the basolateral membrane (away from the bone surface) and in the ruffled border (adjacent to bone) in osteoclasts cultured on bone, but was detected mainly in the basolateral membrane when cultured on glass. The vitronectin receptor appeared to be condensed on small microvilli-like projections on the basolateral membrane of osteoclasts on either bone or glass and may provide a route for alternative signalling pathways to modify osteoclast behaviour, other than by influencing cell adhesion directly. The leading edges of migrating osteoclasts, and the attachment structure, a broad vinculin band, which forms before bone resorption, also expressed vitronectin receptor, particularly when the antibody against the alpha v subunit was used.(ABSTRACT TRUNCATED AT 250 WORDS)
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Horton MA, Dorey EL, Nesbitt SA, Samanen J, Ali FE, Stadel JM, Nichols A, Greig R, Helfrich MH. Modulation of vitronectin receptor-mediated osteoclast adhesion by Arg-Gly-Asp peptide analogs: a structure-function analysis. J Bone Miner Res 1993; 8:239-47. [PMID: 7680185 DOI: 10.1002/jbmr.5650080215] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
This study details the investigation of induction of retractile shape change in the osteoclast through inhibition of adhesion between osteoclasts and matrix with (1) peptide analogs bearing an Arg-Gly-Asp (RGD) sequence, (2) antibodies to the integrin alpha V beta 3 vitronectin receptor, and (3) the RGD-containing snake venom peptide echistatin. Osteoclast retraction on dentin has been demonstrated for GRGDSP peptide, in contrast to the inactivity of the analog containing the conservative RGE sequence modification. An osteoclast adhesion assay employing rat or chick bone cells and serum-coated glass coverslips as substrate was developed for routine evaluation of inhibition of adhesion. Antibodies F4 and F11 to the beta 3 chain of rat vitronectin receptor were effective at submicromolar concentrations in rat osteoclasts (IC50 0.29 and 0.05 microM, respectively), whereas MAb 23C6 to human/chick vitronectin receptor was somewhat less effective against chick osteoclasts (IC50 1.6 microM). A rank order of RGD analog activity (mean IC50, microM) in the serum-coated glass adhesion assay was derived for the linear peptides GRGDSP (201 microM), GRGDTP (180 microM), Ac-RGDS-NH2 (84 microM), Ac-RGDV-NH2 (68 microM), RGDV (43 microM), GRGDS (38 microM), and RGDS (26 microM). The two most potent short peptides were the cyclic analog SK&F 106760 Ac-S,S-cyclo-(Cys-(N alpha Me)Arg-Gly-Asp-Pen)-NH2 (IC50 7.0 microM), and the Telios peptide H-Gly-S,S-cyclo-(Pen-Gly-Arg-Gly-Asp-Ser-Pro-Cys)-Ala-OH (IC50 6.6 microM). The snake venom peptide echistatin was the most potent substance evaluated in the serum-coated glass assay (IC50 0.78 nM) employing either rat or chick osteoclasts.(ABSTRACT TRUNCATED AT 250 WORDS)
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Helfrich MH, Horton MA. Antigens of Osteoclasts Phenotypic Definition of a Specialized Hemopoietic Cell Lineage. ACTA ACUST UNITED AC 1993. [DOI: 10.1007/978-1-4757-9534-9_7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
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Nesbitt SA, Horton MA. A nonradioactive biochemical characterization of membrane proteins using enhanced chemiluminescence. Anal Biochem 1992; 206:267-72. [PMID: 1443597 DOI: 10.1016/0003-2697(92)90365-e] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Here we demonstrate a nonradioactive immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) technique which replaces the standard practice of isotopic protein labeling by iodination or metabolic tagging in the analysis of membrane proteins. The technique has proved extremely valuable in the biochemical analysis of small quantities of frozen, pathological tissue. Membranes were prepared from Dx3 (a human melanoma cell line), C6 (a rat glial cell line), and osteoclastoma (a human giant cell tumor of bone). The membranes were labeled with biotin and immunoprecipitated with a variety of antibodies to the vitronectin receptor (VNR). The VNR proteins were resolved by SDS-PAGE and immunoblotted onto nitrocellulose paper. The biotinylated protein was visualized using streptavidin horseradish peroxidase and enhanced chemiluminescence (ECL). Film exposures ranged from 15 min to 16 h. Good visualization of the VNR, yielding the typical heterodimeric receptor of 90 and 150 kDa, was given. Signals generated were high and background noise low with a 30-min film exposure. An overnight exposure increased the detection of weaker bands. In conclusion, biotinylation of membrane proteins proved a satisfactory label for immunoprecipitation and SDS-PAGE analysis. The ECL development stage was extremely flexible with visualization of strong and weak signals. The method has several advantages over a conventional radioactive immunoprecipitation in that it is relatively inexpensive, simple, quick and nonhazardous.
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Watt SM, Thomas JA, Edwards AJ, Murdoch SJ, Horton MA. Adhesion receptors are differentially expressed on developing thymocytes and epithelium in human thymus. Exp Hematol 1992; 20:1101-11. [PMID: 1361454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
Abstract
The thymic microenvironment consists of a network of interrelated cells of epithelial, fibroblastic, endothelial, and hemopoietic origin. Within this environment, the development of specific T-lymphocyte subpopulations partially depends on the selective interaction of T-cell precursors with such cells. Human thymic epithelial cell strains, generated with a defective retroviral vector containing simian virus 40 (SV40) large T antigen and the neomycin resistance gene or by transfection with an SV40 plasmid defective in the origin of replication, provide useful tools for understanding the mechanisms contributing to the control of T-cell maturation. Because interepithelial, epithelial-macrophage, and lymphocyte-epithelial cell interactions are important for thymocyte differentiation, the distribution of integrin and nonintegrin adhesion receptors on these cells and on developing thymocytes in vivo and in vitro has been examined in detail. Our results indicate that the transformed human thymic epithelial cell strains express the common very late antigen (VLA)-beta 1 receptor and unique alpha chains VLA-2, VLA-3, and VLA-6. The cells are also positive for LFA-3 and ICAM-1 and weakly express beta 3, beta 4, and VNR alpha. They do not express the Leu-cellular adhesion molecules (CAM). This phenotypic profile on cultured thymic epithelium generally corresponds to the distribution of integrin and other receptor molecules on thymic epithelial cells in tissue sections. The majority of thymocytes also express the integrin VLA-beta 1 and -beta 2 chains as well as VLA-4, VLA-6, and LFA-1 alpha(L). Three-color flow cytometric analyses show differential levels of expression of these adhesion receptors on human thymocyte subsets. Taken together with the immunohistochemical localization of extracellular matrix molecules, these studies suggest that both the distribution of receptor-ligand pairs and the level of expression of adhesion molecules may influence T-cell development within the thymus.
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Flanagan AM, Horton MA, Dorey EL, Collins DA, Evely RS, Moseley JM, Firkin FC, Chambers TJ, Helfrich MH, Martin TJ. An assessment of the ability of human bone marrow cultures to generate osteoclasts. Int J Exp Pathol 1992; 73:387-401. [PMID: 1320395 PMCID: PMC2002338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Several groups have successfully generated osteoclasts in cultures of murine haemopoietic cells. This approach would clearly be useful in the analysis of mechanisms of regulation of human osteoclast formation if analogous results could be obtained in cultures of human bone marrow. This communication describes independent attempts by three groups to generate unequivocally defined osteoclasts from bone marrow obtained from human iliac crest, femoral neck, rib, and from foetuses. The haemopoietic tissue was incubated using techniques described by others for production of osteoclast-like cells, and with variants of this technique using strategies based on our experiences with murine osteoclastogenesis. Haemopoietic cells were incubated with calcium regulating hormones, cytokines, osteoblastic supernatants, and osteoblastic or bone marrow stromal cell layers. Formation of cells capable of excavation of bone slices was rarely seen. Despite the paucity of bone resorbing cells, multinucleate cells (MNCs) developed with similar characteristics to the MNCs that have been interpreted as osteoclast-like in human bone marrow cultures. The MNCs were, however, calcitonin-receptor (CTR) negative, and did not show the typical pattern of reactivity with osteoclast-specific antibodies. They possessed instead an antigenic profile characteristic of macrophage polykaryons. We conclude that the MNCs which consistently generate in human bone marrow cultures do not possess phenotypic characteristics specific for osteoclasts and appear to be macrophage polykaryons. The conditions required for osteoclast generation in cultures of human haemopoietic cells remain to be defined.
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Helfrich MH, Nesbitt SA, Horton MA. Integrins on rat osteoclasts: characterization of two monoclonal antibodies (F4 and F11) to rat beta 3. J Bone Miner Res 1992; 7:345-51. [PMID: 1585837 DOI: 10.1002/jbmr.5650070315] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Two monoclonal antibodies, F4 and F11, were raised to newborn rat bone cell suspensions. These antibodies are shown by immunocytochemistry on tissue sections to recognize an antigen shared between osteoclasts, megakaryocytes, and platelets. Immunoprecipitation analysis of the antigen from C6 rat glial cells followed by SDS-PAGE showed a heterodimeric molecule with a characteristic integrin-like shift in apparent molecular mass upon reduction (137/78 kD nonreduced; 118/100 kD reduced); the low-molecular-mass band comigrates with the beta 3 subunit precipitated with polyclonal antihuman vitronectin receptor antiserum, and the high-molecular-mass band comigrates with the alpha v subunit precipitated with a polyclonal antiserum to a C-terminal amino acid sequence of human alpha v. Antibody F4 strongly cross-reacts with human cells and is shown in cross-blocking experiments and immunoprecipitation analysis with a human melanoma cell line DX3 to recognize a seemingly identical molecule as identified by anti-alpha v beta 3 monoclonal antibody 23C6. Expression of F4 and F11 is reduced in platelets from a patient heterozygous for Glanzmann's thrombasthenia. Taken together, these results indicate that F4 and F11 recognize rat CD61, the integrin beta 3 chain, which, as was confirmed with polyclonal anti CD61 antisera, is highly expressed in rat osteoclasts. These antibodies may be useful tools in investigating the biochemical nature and biologic function of beta 3 integrins in rat osteoclasts. Additionally, because high expression of beta 3 in vivo is restricted to osteoclasts, megakaryocytes, and platelets, these antibodies may be used to help identify osteoclasts in tissue sections and bone cell suspensions.(ABSTRACT TRUNCATED AT 250 WORDS)
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Helfrich MH, Nesbitt SA, Dorey EL, Horton MA. Rat osteoclasts adhere to a wide range of RGD (Arg-Gly-Asp) peptide-containing proteins, including the bone sialoproteins and fibronectin, via a beta 3 integrin. J Bone Miner Res 1992; 7:335-43. [PMID: 1585836 DOI: 10.1002/jbmr.5650070314] [Citation(s) in RCA: 155] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The ligand binding ability of rat osteoclast adhesion receptors was investigated in an attachment assay using osteoclasts disaggregated from bone. Osteoclasts adhered well to the Arg-Gly-Asp (RGD)-containing proteins osteopontin (bone sialoprotein I) and BSP (bone sialoprotein II), vitronectin, fibrinogen, von Willebrand factor, and fibronectin. Osteoclasts also adhered, but less strongly, to type I collagen. No attachment of osteoclasts was observed to thrombospondin, tenascin, laminin, or a range of non-RGD-containing bone proteins and proteins from other sources. The attachment of osteoclasts to all ligands was abolished in the presence of GRGDSP peptide, indicating the involvement of the RGD cell binding sequence in ligand binding. Attachment of osteoclasts to all substrates, with the exception of type I collagen, was also strongly inhibited by the addition of monoclonal antibody F11 to the beta 3 integrin subunit, indicating that a beta 3 integrin, probably the vitronectin receptor, was involved. Attachment to type I collagen was blocked by EDTA chelation of divalent cations and was not significantly affected by anti-beta 3 or anti-beta 1 antibodies; when taken with the inhibition by RGD peptide, this suggests the involvement of various receptors, possibly including nonintegrin collagen receptors, in the binding of osteoclasts to this protein. These results define the wide range of ligands for extracellular matrix receptors in osteoclasts in vitro. It remains to be established which of these proteins are important in osteoclast adhesion and osteoclastic bone resorption in vivo.
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Marshall JF, Nesbitt SA, Helfrich MH, Horton MA, Polakova K, Hart IR. Integrin expression in human melanoma cell lines: heterogeneity of vitronectin receptor composition and function. Int J Cancer 1991; 49:924-31. [PMID: 1720426 DOI: 10.1002/ijc.2910490621] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Ten human melanoma cell lines were examined for integrin-receptor expression using a panel of antibodies directed against different integrin subunits. Considerable heterogeneity was detected for levels of expression of 7 integrins, including the alpha v beta 3 vitronectin receptor where a correlation between tumorigenic capacity in athymic nude mice and alpha v beta 3 levels was found. Detailed analysis of the vitronectin receptor on these lines revealed heterogeneity of composition. In one cell line, VUP, an alpha v beta 1 association was detected and, by antibody-inhibition studies, this receptor was shown to bind vitronectin as its ligand. In another line, DX3, evidence was obtained which indicated that apart from the alpha v beta 3 receptor the alpha v was able to associate with another beta subunit which was not beta 3. The existence of these alternative forms of the vitronectin receptor in this small sample of tumours of common origin might explain why the capacity to bind to fibrinogen and vitronectin substrates by these cells did not necessarily correlate with alpha v beta 3 levels.
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Anstey A, Lowe DG, Kirby JD, Horton MA. Familial mastocytosis: a clinical, immunophenotypic, light and electron microscopic study. Br J Dermatol 1991; 125:583-7. [PMID: 1836952 DOI: 10.1111/j.1365-2133.1991.tb14800.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A women and her daughter both developed diffuse cutaneous mastocytosis in early infancy. The immunophenotypes of the cutaneous mast cells in the two cases were shown to be identical: leucocyte common antigen (CD45) and macrophage/monocyte marker EBM11 were both strongly positive, HLA-DR was positive and CD25 was weakly positive. The peripheral lymphocytes of the patients were analysed by flow cytometry and this revealed that there was no increase in the activation markers HLA-DR and CD25, contrary to recent claims that lymphocytes have a contributory role in driving mast-cell proliferation. Mast-cell granules in both cases were found on electron microscopy to have an abnormal ultrastructure. The close similarity between the two cases at clinical, immunophenotypic and ultrastructural levels strongly suggests that genetic factors are important in the development of this type of mastocytosis.
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Lakkakorpi PT, Horton MA, Helfrich MH, Karhukorpi EK, Väänänen HK. Vitronectin receptor has a role in bone resorption but does not mediate tight sealing zone attachment of osteoclasts to the bone surface. J Cell Biol 1991; 115:1179-86. [PMID: 1720122 PMCID: PMC2289948 DOI: 10.1083/jcb.115.4.1179] [Citation(s) in RCA: 134] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
During bone resorption, osteoclasts form a tight attachment, the sealing zone, around resorption lacunae. Vitronectin receptor has previously been shown to be expressed in osteoclasts and it has been suggested that it mediates the tight attachment at the sealing zone. In this study we have shown that glycine-arginine-glycine-aspartic acid-serine pentapeptide inhibits bone resorption by isolated osteoclasts and drastically changes the morphology of the osteoclasts. When the vitronectin receptor was localized by immunofluorescence in rat and chicken osteoclasts cultured on bone slices, it was found to be distributed throughout the osteoclast cell membrane except in the sealing zone areas. Immunoperoxidase staining of rat bone sections at the light microscopical level also revealed intense staining of the cell membrane with occasional small unstained areas, probably corresponding to the sealing zones. Immunoelectron microscopy confirmed the results obtained by light microscopy showing specific labeling only at the ruffled borders and basolateral membranes (0.82 and 2.43 gold particles/microns of membrane, respectively), but not at the sealing zone areas (0.06 gold particles/microns of membrane). Both alpha v and beta 3 subunits of the vitronectin receptor were similarly localized. These results strongly suggest that, although the vitronectin receptor is important in the function of osteoclasts, it is not mediating the final sealing zone attachment of the osteoclasts to the mineralized bone surface.
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D'Ardenne AJ, Richman PI, Horton MA, Mcaulay AE, Jordan S. Co-ordinate expression of the alpha-6 integrin laminin receptor sub-unit and laminin in breast cancer. J Pathol 1991; 165:213-20. [PMID: 1662264 DOI: 10.1002/path.1711650304] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Interactions between cells and extracellular matrices are mediated in part by a family of heterodimeric molecules known as integrins. We have investigated, using immunohistology, the distribution of six integrin alpha sub-units in normal breast tissue and 26 breast carcinomas. Alpha-1 integrin (collagen/laminin receptor sub-unit) was detected in myoepithelium, but not in luminal epithelium nor in most (20/26) carcinomas. Its expression on fibroblasts was enhanced in desmoplastic stroma. Both benign and malignant epithelium showed uniform positive staining for alpha-2 (collagen receptor sub-unit) and for alpha-3 (collagen/fibronectin/laminin receptor sub-unit). All epithelium was negative for alpha-4 (sub-unit of a fibronectin receptor). Epithelial staining for alpha-5 (fibronectin receptor sub-unit) was weak in all samples. Alpha-6 (sub-unit of two integrin laminin receptors) showed conspicuous changes in all invasive carcinomas. In normal tissues, there was weak staining of epithelial cytoplasm with alpha-6 antibody and moderate cell membrane staining. Strongest staining was present in a basement membrane distribution. In carcinomas, loss of cytoplasmic and cell membrane staining was variable, but basal membrane staining was diminished or absent in all tumours. Loss of basal membrane staining for alpha-6 integrin corresponded closely to loss of immunoreactivity for its ligand laminin in invasive breast cancer.
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Moseley JM, Danks JA, Grill V, Lister TA, Horton MA. Immunocytochemical demonstration of PTHrP protein in neoplastic tissue of HTLV-1 positive human adult T cell leukaemia/lymphoma: implications for the mechanism of hypercalcaemia. Br J Cancer 1991; 64:745-8. [PMID: 1911223 PMCID: PMC1977688 DOI: 10.1038/bjc.1991.391] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The infiltrated tissues from seven West Indian patients with HTLV-1 positive adult T cell lymphoma/leukaemia (ATLL) have been analysed by immunocytochemical techniques for the presence of immunoreactive parathyroid hormone-related protein (PTHrP), a hormonal mediator of humoral hypercalcaemia of malignancy. Six of the seven were hypercalcaemic at some stage of the course of their disease. Four of the six evaluable patients showed evidence of specific cellular and extracellular expression of PTHrP protein in neoplastic tissues. This finding suggests that PTHrP may be involved in the production of hypercalcaemia in at least some cases of T cell lymphoma - proof of a causal relationship however must await the demonstration of tissue release of PTHrP resulting in raised circulating hormone levels.
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Hall PA, Coates P, Lemoine NR, Horton MA. Characterization of integrin chains in normal and neoplastic human pancreas. J Pathol 1991; 165:33-41. [PMID: 1720170 DOI: 10.1002/path.1711650107] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Integrins are a complex family of non-covalently linked heterodimeric glycoproteins which function as cell adhesion molecules, interacting with extracellular matrix molecules such as laminin, fibronectin, vitronectin, and collagen, and also having a role in intercellular adhesion. Each integrin subfamily is characterized by a common beta chain associated with variable alpha chains. We have examined, using immunohistological methods, the expression of the VLA (very late activation) family comprising beta 1 in association with alpha 1-6, and also alpha 6 in association with beta 4, the LFA beta chain beta 2, and the vitronectin receptor, in association with beta 1 or beta 5 and as the complex alpha v beta 3. Cryostat sections of normal pancreas, pancreatic adenocarcinomas, and ampullary tumours were studied together with six pancreatic carcinoma cell lines. Normal pancreas showed expression of beta 1 in all parenchyma. alpha 2 and alpha 6 had a similar distribution whereas alpha 3 expression was confined to ducts, including the very smallest radicles. Staining along the basement membranes of ducts was seen with beta 4 and the anti-vitronectin alpha v chain receptor antibody 13C2. Islet cells failed to stain with any antibody. No staining of epithelial components was seen with antibodies to alpha 1, alpha 4, alpha 5, or to the alpha v beta 3 form of the vitronectin receptor (beta 3 and alpha v beta 3 using the antibody 23C6). Pancreatic adenocarcinomas and ampullary tumours showed expression of alpha 2, alpha 3, alpha 6, beta 1, beta 4, and the vitronectin receptor (alpha v associated with beta 1 or beta 5).(ABSTRACT TRUNCATED AT 250 WORDS)
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Moseley JM, Hayman JA, Danks JA, Alcorn D, Grill V, Southby J, Horton MA. Immunohistochemical detection of parathyroid hormone-related protein in human fetal epithelia. J Clin Endocrinol Metab 1991; 73:478-84. [PMID: 1874927 DOI: 10.1210/jcem-73-3-478] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
PTH-related protein (PTHrP) is commonly produced by squamous cell carcinomata and is the mediator of the PTH-like features of humoral hypercalcemia of malignancy. It has also been implicated in calcium regulation during fetal development. In this study immunohistochemical techniques, using rabbit polyclonal antibodies to synthetic PTHrP peptides, have been used to localize PTHrP in human fetal tissues from one fetus of 7 weeks and two of approximately 18 and 20 weeks gestation, respectively, in order to identify sites of potential functional significance. PTHrP immunoreactivity was identified in epithelia from many sources, including skin, bronchus, pancreas, pharynx, gut, stomach, and renal pelvis. Thyroid and parathyroid glands, which develop from epithelial origins, also stained positive for PTHrP, as did kidney collecting tubules, adrenal tissue, and skeletal and smooth muscle. PTHrP immunoreactivity was also located in developing long bones and calvaria, where it may have relevance in bone turnover during fetal development. The role of PTHrP at these locations remains to be elucidated, but the identification of specific PTHrP immunoreactivity in fetal epithelia is consistent with PTHrP production by cancers of epithelial origin and supports the hypothesis that PTHrP may have a role in epithelial growth and differentiation.
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Horton MA, Taylor ML, Arnett TR, Helfrich MH. Arg-Gly-Asp (RGD) peptides and the anti-vitronectin receptor antibody 23C6 inhibit dentine resorption and cell spreading by osteoclasts. Exp Cell Res 1991; 195:368-75. [PMID: 1712731 DOI: 10.1016/0014-4827(91)90386-9] [Citation(s) in RCA: 204] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Studies with a range of monoclonal and polyclonal antisera to components of the human, rat, and chick vitronectin receptor, alpha V beta 3, and the VLA beta 1 chain show that chick and rat osteoclasts express similar integrin receptors to those described in man. Biochemical analysis with monoclonal antibody 23C6 confirmed the presence on chick osteoclasts of a vitronectin receptor heterodimer of similar size (110/95 kDa reduced) to that immunoprecipitated from human osteoclastoma giant cells. The synthetic peptide GRGDSP, corresponding to the cell adhesion sequence in fibronectin, but not GRGESP peptide, induced significant (P less than 0.005) osteoclast retraction in chick and rat osteoclasts at IC50s (+/- SEM) of 210.0 +/- 14.4 and 191.4 +/- 13.7 microM, respectively; monoclonal anti-vitronectin receptor alpha V beta 3 complex antibody, 23C6, produced similar changes in chick osteoclasts (IC50 = 1.45 +/- 0.22 microM). Antibody 23C6 inhibited the number of pits resorbed in dentine by chick osteoclasts over a concentration range of 4.4 to 88 micrograms/ml; a significant 76% reduction (P = 0.03) was observed at a final concentration of 88 micrograms/ml (6 microM). The effect of peptides upon dentine resorption was less dramatic. No consistent inhibition was seen using chick osteoclasts. Inhibitory effects on resorption by rat osteoclasts were, however, observed; significant reduction in resorption occurred with both GRGDSP (78%; P less than 0.01) and GRGESP (67%; P = 0.02) peptides at 400 microM peptide concentration. These data demonstrate that osteoclast function can be disrupted by low concentrations of the anti-vitronectin receptor antibody, 23C6. The inhibitory effects of the peptides used in this study produced effects on dentine resorption which were generally weaker and variable, although osteoclast cell adhesion was consistently inhibited in an Arg-Gly-Asp (RGD)-dependent manner. We conclude that the vitronectin receptor may play an important role in effecting resorption of mineralized tissues by osteoclasts.
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MacDonald TT, Horton MA, Choy MY, Richman PI. Increased expression of laminin/collagen receptor (VLA-1) on epithelium of inflamed human intestine. J Clin Pathol 1990; 43:313-5. [PMID: 2341567 PMCID: PMC502365 DOI: 10.1136/jcp.43.4.313] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Immunohistochemical techniques were used to investigate the epithelial expression of VLA-1 in inflammatory bowel disease in six patients with Crohn's disease, in four patients with ulcerative colitis, and in one patient with indeterminate colitis, and compared with that in the small intestine and colons of 10 normal controls. In normal small bowel VLA-1 was expressed on crypt epithelial cells and only weakly or not at all on surface epithelium. VLA-1 was again expressed weakly in normal colon, except in one case, a 1 year old child with diarrhoea but no histological abnormalities. In small and large intestine affected with Crohn's disease, ulcerative colitis, or indeterminate colitis, there was increased expression of VLA-1 on the basolateral aspects of crypt cells and de novo expression on surface epithelium. It is suggested that this is an adaptive response to prevent epithelial cell loss as a result of inflammation in the underlying lamina propria.
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