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M Jalkanen

Publications and source records attributed to M Jalkanen.

At least 91 records · Page 5Linked to original sources
PubMed1989

Syndecan and tenascin expression is induced by epithelial-mesenchymal interactions in embryonic tooth mesenchyme.

Morphogenesis of embryonic organs is regulated by epithelial-mesenchymal interactions associating with changes in the extracellular matrix (ECM). The response of the cells to the changes in the ECM must involve integral cell surface molecules that recognize their matrix ligand and initiate transmission of signal intracellularly. We have studied the expression of the cell surface proteoglycan, syndecan, which is a matrix receptor for epithelial cells (Saunders, S., M. Jalkanen, S. O'Farrell, and M. Bernfield. J. Cell Biol. In press.), and the matrix glycoprotein, tenascin, which has been proposed to be involved in epithelial-mesenchymal interactions (Chiquet-Ehrismann, R., E. J. Mackie, C. A. Pearson, and T. Sakakura. 1986. Cell. 47:131-139) in experimental tissue recombinations of dental epithelium and mesenchyme. Our earlier studies have shown that in mouse embryos both syndecan and tenascin are intensely expressed in the condensing dental mesenchyme surrounding the epithelial bud (Thesleff, I., M. Jalkanen, S. Vainio, and M. Bernfield. 1988. Dev. Biol. 129:565-572; Thesleff, I., E. Mackie, S. Vainio, and R. Chiquet-Ehrismann. 1987. Development. 101:289-296). Analysis of rat-mouse tissue recombinants by a monoclonal antibody against the murine syndecan showed that the presumptive dental epithelium induces the expression of syndecan in the underlying mesenchyme. The expression of tenascin was induced in the dental mesenchyme in the same area as syndecan. The syndecan and tenascin positive areas increased with time of epithelial-mesenchymal contact. Other ECM molecules, laminin, type III collagen, and fibronectin, did not show a staining pattern similar to that of syndecan and tenascin. Oral epithelium from older embryos had lost its ability to induce syndecan expression but the presumptive dental epithelium induced syndecan expression even in oral mesenchyme of older embryos. Our results indicate that the expression of syndecan and tenascin in the tooth mesenchyme is regulated by epithelial-mesenchymal interactions. Because of their early appearance, syndecan and tenascin may be used to study the molecular regulation of this interaction. The similar distribution patterns of syndecan and tenascin in vivo and in vitro and their early appearance as a result of epithelial-mesenchymal interaction suggest that these molecules may be involved in the condensation and differentiation of dental mesenchymal cells.

Animals↗
PubMed1989

Cell-matrix interactions in tooth development.

A chain of reciprocal interactions between the epithelial and mesenchymal tissues regulates both morphogenesis and cell differentiation in the developing tooth. The very early interactions lead to budding of the oral epithelium and to the characteristic condensation of the neural crest-derived mesenchymal cells around the epithelial bud. During the bell stage of morphogenesis, the mesenchymal cells which are in contact with the dental epithelium differentiate into odontoblasts. In this reveiw article we summarize the results of our descriptive and experimental studies, which indicate that differentiation of the dental mesenchymal cells into odontoblasts, as well the condensation of dental mesenchymal cells at the bud stage, are regulated by interactions between the cell surface and the extracellular matrix. Transfilter studies where the dental epithelium and mesenchyme were cultured on opposite sides of Nuclepore filters, led to the hypothesis that the differentiation of dental mesenchymal cells into odontoblasts is triggered by interactions between the cell surface and the epithelial basement membrane matrix. Immunohistochemical localization of various matrix molecules showed that the matrix glycoproteins fibronectin and tenascin are accumulated in the dental basement membrane at the time of odontoblast differentiation. Fibronectin and tenascin are known to interact with each other, with other matrix molecules as well as with the cell surface, and also to influence cell shape. We suggest that fibronectin and tenascin are involved in the cell-matrix interaction which leads to the polarization and differentiation of odontoblasts.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Biochemical properties of glycoproteins involved in lymphocyte recognition of high endothelial venules in man.

Lymphocyte interactions with high endothelial venules (HEV) are important to the in vivo migration of normal and neoplastic lymphocyte populations. We have previously described an 85- to 95-kDa lymphocyte surface glycoprotein(s) defined by mAb Hermes-1, that is involved in the recognition of HEV by human lymphocytes: antibodies against distinct epitopes of the Hermes-1 Ag differentially inhibit lymphocyte binding to lymph node, mucosal, or synovial HEV. Here we characterize further the Hermes-1-defined glycoproteins. No well defined differences were observed between the Hermes-1 Ag immunoprecipitated from PBL and from mucosa- vs lymph HEV-specific cell lines. The Ag is an acidic (isoelectric point = 4.2) sulfated molecule bearing both O-linked and (3,4) N-linked oligosaccharide side chains. A subset of the Hermes-1-immunoprecipitated species is modified by covalent linkage to chondroitin sulfate, yielding a Mr of approximately 180 to 200 kDa. Pulse-chase labeling reveals a major precursor of 76 kDa that appears to be processed either to the 85- to 95-kDa form or, by addition of chondroitin sulfate, to a 180- to 200-kDa form. The potential role of these structural modifications, and particularly of chondroitin sulfate, in the function of the putative adhesion molecules is discussed.

Animals↗
PubMed1988

Cell surface proteoglycan expression correlates with epithelial-mesenchymal interaction during tooth morphogenesis.

Tooth morphogenesis and differentiation of the dental cells are guided by interactions between epithelial and mesenchymal tissues. Because the extracellular matrix is involved in these interactions, the expression of matrix receptors located at the cell surface may change during this developmental sequence. We have examined the distribution of an epithelial cell surface proteoglycan antigen, known to behave as a receptor for interstitial matrix, during tooth morphogenesis. Intense staining was seen around the cells of the embryonic oral epithelium as well as the dental epithelium at the early bud stage. With development, expression was greatly reduced in the enamel organ. Differentiation of these cells into ameloblasts was associated with the loss of expression, while the epithelial cells remaining in the stratum intermedium and stellate reticulum regained intense staining. The PG antigen was weakly expressed in the loose neural crest-derived jaw mesenchyme but it became strongly reactive in the condensed dental papilla mesenchyme when extensive morphogenetic movements took place. With development, the PG antigen disappeared from the advanced dental papilla mesenchyme but persisted in the dental sac mesenchyme, which gives rise to periodontal tissues. The PG antigen was not expressed by odontoblasts. Hence, the expression of the PG antigen changes during the epithelial-mesenchymal interactions of tooth development and is lost during terminal cell differentiation. The expression follows morphogenetic rather than histologic boundaries. The acquisition and loss of expression in epithelial and mesenchymal tissues during tooth development suggest that this proteoglycan has specific functions in the epithelial-mesenchymal interactions that guide morphogenesis.

Animals↗
PubMed1988

Mouse mammary epithelial cells produce basement membrane and cell surface heparan sulfate proteoglycans containing distinct core proteins.

Cultured mouse mammary (NMuMG) cells produce heparan sulfate-rich proteoglycans that are found at the cell surface, in the culture medium, and beneath the monolayer. The cell surface proteoglycan consists of a lipophilic membrane-associated domain and an extracellular domain, or ectodomain, that contains both heparan and chondroitin sulfate chains. During culture, the cells release into the medium a soluble proteoglycan that is indistinguishable from the ectodomain released from the cells by trypsin treatment. This medium ectodomain was isolated, purified, and used as an antigen to prepare an affinity-purified serum antibody from rabbits. The antibody recognizes polypeptide determinants on the core protein of the ectodomain of the cell surface proteoglycan. The reactivity of this antibody was compared with that of a serum antibody (BM-1) directed against the low density basement membrane proteoglycan of the Englebarth-Holm-Swarm tumor (Hassell, J. R., W. C. Leyshon, S. R. Ledbetter, B. Tyree, S. Suzuki, M. Kato, K. Kimata, and H. Kleinman. 1985. J. Biol. Chem. 250:8098-8105). The BM-1 antibody recognized a large, low density heparan sulfate-rich proteoglycan in the cells and in the basal extracellular materials beneath the monolayer where it accumulated in patchy deposits. The affinity-purified anti-ectodomain antibody recognized the cell surface proteoglycan on the cells, where it is seen on apical cell surfaces in subconfluent cultures and in fine filamentous arrays at the basal cell surface in confluent cultures, but detected no proteoglycan in the basal extracellular materials beneath the monolayer. The amino acid composition of the purified medium ectodomain was substantially different from that reported for the basement membrane proteoglycan. Thus, NMuMG cells produce at least two heparan sulfate-rich proteoglycans that contain distinct core proteins, a cell surface proteoglycan, and a basement membrane proteoglycan. In newborn mouse skin, these proteoglycans localize to distinct sites; the basement membrane proteoglycan is seen solely at the dermal-epidermal boundary and the cell surface proteoglycan is seen solely at the surfaces of keratinocytes in the basal, spinous, and granular cell layers. These results suggest that although heparan sulfate-rich proteoglycans may have similar glycosaminoglycan chains, they are sorted by the epithelial cells to different sites on the basis of differences in their core proteins.

Aggrecans↗
PubMed1987

Cell surface proteoglycan of mouse mammary epithelial cells is shed by cleavage of its matrix-binding ectodomain from its membrane-associated domain.

The cell surface proteoglycan on normal murine mammary gland (NMuMG) epithelial cells consists of a lipophilic domain, presumably intercalated into the plasma membrane, and an ectodomain that binds via its glycosaminoglycan chains to matrix components, is released intact by proteases and is detected by monoclonal antibody 281-2. The antibody 281-2 also detects a proteoglycan in the culture medium conditioned by NMuMG cells. This immunoactive proteoglycan was purified to homogeneity using DEAE-cellulose chromatography, isopycnic centrifugation, and 281-2 affinity chromatography. Comparison of the immunoreactive medium proteoglycan with the trypsin-released ectodomain revealed that these proteoglycans are indistinguishable by several criteria as both: (a) contain heparan sulfate and chondroitin sulfate chains; and (b) are similar in hydrodynamic size and buoyant density; (c) have the same size core protein (Mr approximately 53 kD); (d) are nonlipophilic as studied by liposomal intercalation and transfer to silicone-treated paper. Kinetic studies of the release of proteoglycan from the surface of suspended NMuMG cells are interpreted to indicate that the immunoreactive medium proteoglycan is derived directly from the cell surface proteoglycan. Suspension of the cells both augments the release and inhibits the replacement of cell surface proteoglycan. These results indicate that the cell surface proteoglycan of NMuMG cells can be shed by cleavage of its matrix-binding ectodomain from its membrane-associated domain, providing a mechanism by which the epithelial cells can loosen their proteoglycan-mediated attachment to the matrix.

Animals↗
PubMed1987

Immunocytochemistry of cell surface heparan sulfate proteoglycan in mouse tissues. A light and electron microscopic study.

The core protein of the proteoglycan at the cell surface of NMuMG mouse mammary epithelial cells bears both heparan and chondroitin sulfate chains and is recognized by the monoclonal antibody 281-2. Using this antibody and the peroxidase-antiperoxidase staining technique in adult mouse tissues, we found that the antibody recognizes the antigen in a highly restricted distribution, staining a variety of epithelial cells but no cells derived from embryonic mesoderm or neural crest. The antibody fails to stain any stromal (mesenchymal) or neuronal cells, with the exception of plasma cells and Leydig cells. Squamous and transitional epithelia stain intensely over their entire surfaces, whereas cuboidal and columnar epithelia stain moderately and only at the lateral surface of the basal cells. Within squamous and transitional epithelial tissues that undergo physiological regeneration (e.g., epidermis), the most superficial and differentiated cell types fail to stain. Within glandular and branched epithelia (e.g., pancreas), the secretory alveolar cells fail to stain. When evaluated by electron microscopy, granular deposits of stain are seen on the plasma membrane, especially on lateral surfaces, but none are noted within the cells or the basement membrane. These results indicate that in adult tissues the core protein of this heparan sulfate-rich proteoglycan is expressed almost exclusively at epithelial cell surfaces. Expression appears to be lost as the cells become either mature or highly differentiated.

Animals↗
PubMed1987

Biology of cell surface heparan sulfate proteoglycans.

The central question in cell biology is how cells detect, interact and respond to extracellular matrix. The cell surface molecules, which mediate this recognition, consist of a lipophilic membrane domain and an ectodomain binding matrix materials. One group of this kind of molecules is the cell surface heparan sulfate proteoglycans (HSPG). This review summarizes recent information obtained on the cell surface PG of mouse mammary epithelial cells. The glycosaminoglycan containing ectodomain of this PG binds with high affinity Type I, III and V collagen fibrils and the C-terminal heparin binding domain of fibronectin. The PG is mobile on the cell surface, but can be immobilised by ligand binding. At the same time the PG associates with cytoskeleton and links the epithelial cytoskeleton to extracellular matrix. Thus the PG can mediate the changes in the matrix into changes in cellular behaviour, often seen during the regulation of cell shape, proliferation and differentiation. The cell surface PG is also released from the cell surface by cleaving the matrix-binding ectodomain from the membrane domain. Because of the binding properties of the ectodomain, this shedding may provide a means by which epithelial cells loosen their association with the matrix and with other cells, e.g., during normal epithelial development and the invasion of carcinomas.

Animals↗
PubMed1986

Cell surface proteoglycan associates with the cytoskeleton at the basolateral cell surface of mouse mammary epithelial cells.

The cell surface proteoglycan on normal murine mammary gland mouse mammary epithelial cells consists of an ectodomain bearing heparan and chondroitin sulfate chains and a lipophilic domain that is presumed to be intercalated into the plasma membrane. Because the ectodomain binds to matrix components produced by stromal cells with specificity and high affinity, we have proposed that the cell surface proteoglycan is a matrix receptor that binds epithelial cells to their underlying basement membrane. We now show that the proteoglycan surrounds cells grown in subconfluent or newly confluent monolayers, but becomes restricted to the basolateral surface of cells that have been confluent for a week or more; Triton X-100 extraction distinguishes three fractions of cell surface proteoglycan: a fraction released by detergent and presumed to be free in the membrane, a fraction bound via a salt-labile linkage, and a nonextractable fraction; the latter two fractions co-localize with actin filament bundles at the basal cell surface; and when proteoglycans at the apical cell surface are cross-linked by antibodies, they initially assimilate into detergent-resistant, immobile clusters that are subsequently aggregated by the cytoskeleton. These findings suggest that the proteoglycan, initially present on the entire surface and free in the plane of the membrane, becomes sequestered at the basolateral cell surface and bound to the actin-rich cytoskeleton as the cells become polarized in vitro. Binding of matrix components may cross-link proteoglycans at the basal cell surface and cause them to associate with the actin cytoskeleton, providing a mechanism by which the cell surface proteoglycan acts as a matrix receptor to stabilize the morphology of epithelial sheets.

Actins↗
PubMed1986

Urinary kallikrein excretion in normal and hypertensive pregnancy at term.

To study the urinary kallikrein excretion before the delivery of term pregnancy we measured its excretion preterm (between 32-36 gestational week) in 13 patients with normotensive pregnancy and 17 patients with pregnancy-induced hypertension and one to five days before the delivery at term in 18 and 22 patients, respectively. In normotensive pregnancy urinary kallikrein excretion remained unchanged during the late third trimester until delivery (12.6 +/- 1.7 ncat in 24 hours in preterm, 10.8 +/- 1.2 before delivery). In pregnancy-induced hypertension and particularly in pre-eclampsia urinary kallikrein excretion was lower than in normotensive pregnancy and the decrease became more marked as the time of delivery approached (respective values: in pregnancy induced hypertension 9.2 +/- 1.2 and 7.0 +/- 0.7; in pre-eclampsia 7.6 +/- 1.3 and 7.3 +/- 0.9). The decrease in urinary kallikrein excretion suggests progressive disturbances in the interactions of renal vasoactive systems (the kallikrein-kinin system, the renin-angiotensin system and prostaglandins) with resultant changes in renal hemodynamics.

Adult↗
PubMed1985

The cell surface proteoglycan from mouse mammary epithelial cells bears chondroitin sulfate and heparan sulfate glycosaminoglycans.

The cell surface proteoglycan fraction isolated by mild trypsin treatment of NMuMG mouse mammary epithelial cells contains largely heparan sulfate, but also 15-24% chondroitin sulfate glycosaminoglycans. We conclude that this fraction contains a unique hybrid proteoglycan bearing both heparan sulfate and chondroitin sulfate glycosaminoglycans because (i) the proteoglycan behaves as a single species by sizing, ion exchange and collagen affinity chromatography, and by isopycnic centrifugation, even in the presence of 8 M urea or 4 M guanidine hydrochloride, (ii) the behavior of the chondroitin sulfate in these separation techniques is affected by heparan sulfate-specific probes and vice versa, and (iii) proteoglycan core protein bearing both heparan sulfate and chondroitin sulfate is recognized by a single monoclonal antibody. Removal of both types of glycosaminoglycan reduces the proteoglycan to a core protein of approximately 53 kDa. The proteoglycan fraction is heterogeneous in size, largely due to a variable number and/or length of the glycosaminoglycan chains. We estimate that one or two chondroitin sulfate chains (modal Mr of 17,000) exist on the proteoglycan for every four heparan sulfate chains (modal Mr of 36,000). Synthesis of these chains is reportedly initiated on an identical trisaccharide that links the chains to the same amino acid residues on the core protein. Therefore, some regulatory information, perhaps residing in the amino acid sequence of the core protein, must determine the type of chain synthesized at any given linkage site. Post-translational addition of these glycosaminoglycans to the protein may provide information affecting its ultimate localization. It is likely that the protein is directed to specific sites on the cell surface because of the ability of the glycosaminoglycans to recognize and bind extracellular components.

Animals↗
PubMed1985

Characterization of the perivascular reticulin network in a case of primary brain lymphoma. Immunohistochemical demonstration of collagen types I, III, IV, and V; laminin; and fibronectin.

The character of the silver positive reticulin network was analyzed with immunofluorescence and immunoperoxidase methods in an intra vitam diagnosed case of primary brain lymphoma. The network was shown to contain connective tissue proteins rich in hexose-sugars, such as type III collagen (classical "reticulin"), basal lamina constituents type IV collagen and laminin, pericellular type V collagen, as well as fibronectin (protein involved in cell adhesion). On the other hand, very little of the fibrous type I collagen was discernible. Similarly as the silver positive network, the immunohistochemically demonstrable reticulum seemed to hold the cells in the perivascular location, and once it was broken diffuse spread into the tissue occurred. Since malignant cells of B-lymphocyte origin are not known to synthesize so-called reticulin, it is suggested that the network in primary brain lymphomas is produced by cells in the brain parenchyma (possibly pericytes or astrocytes) as a protective attempt to restrict the spread of foreign cells into the brain.

Brain↗
PubMed1985

Heparan sulfate proteoglycans from mouse mammary epithelial cells: localization on the cell surface with a monoclonal antibody.

Mouse mammary epithelial cells, of the normal murine mammary gland (NMuMG) cell line, bear a heparan sulfate-rich proteoglycan (HSPG) on their surfaces. A hybridoma (281-2) secreting a monoclonal antibody that recognizes this HSPG was produced by fusion of SP-2/0 myeloma cells with spleen cells from rats immunized with NMuMG cells. The 281-2 monoclonal antibody is directed against the core protein of the cell surface HSPG, as demonstrated by (a) recognition of the isolated proteoglycan but not its glycosaminoglycan chains, (b) co-localization of 281-2-specific antigen and radioactive cell surface HSPG on gradient polyacrylamide gel electrophoresis and on isopycnic centrifugation, and (c) abolition of immunofluorescent staining of the NMuMG cell surface by the intact, but not the protease-digested ectodomain of the cell surface HSPG. The antibody is specific for cell surface HSPG and does not recognize the HSPG that accumulates extracellularly beneath the basal cell surface. Therefore, the 281-2 antibody may be used to isolate the cell surface HSPG and to explore its distribution in tissues.

Aggrecans↗
PubMed1984

Collagen types and fibronectin in the uterine muscle of normal and hypertensive pregnant patients.

Specimens from the uterine wall were obtained from 16 patients at 31 to 40 weeks of pregnancy: 10 underwent surgical procedures for a hypertensive disorder and six for abnormality of the birth canal or faulty presentation. Collagen types I, III, and V and fibronectin antibodies were used for immunohistologic studies. Collagen types I and V were located mainly around single cells, but type III and fibronectin were found mainly around cell bundles. Collagenous structures in the uterine muscle of patients with hypertensive disorder in pregnancy were torn. Abundant fibronectin fluorescence was detected in the lobuli within the disrupted tissue. Disruption of the uterine structure correlated with the amount of urinary protein excreted.

Adult↗
PubMed1984

Antigenicity of proteins from cultured synovial fibroblasts.

We were able to characterize about 25 antigenic proteins of cultured synovial fibroblasts with apparent molecular weights of 15-230 kd by SDS-electrophoresis and immunoblotting using guinea pig antiserum. Some of these proteins were bovine-serum-derived, adsorbed onto fibroblasts from culture medium. Both rheumatoid and normal sera contained natural antibodies reacting with synovial fibroblast as well as bovine serum antigens when studied with immunoblotting. The amounts of antibodies were quantitated with enzyme immunoassay, measuring IgG and IgA class antibodies against plasma membrane preparations of rheumatoid and normal synovial fibroblasts. No rheumatoid arthritis-related changes were detected in synovial fibroblast protein antigens or antibodies against them in rheumatoid patient specimens.

Antibodies↗