Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Syndecan-2”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed1998

Syndecan-4 proteoglycan cytoplasmic domain and phosphatidylinositol 4,5-bisphosphate coordinately regulate protein kinase C activity.

Phosphatidylinositol 4,5-bisphosphate (PIP2) is involved in the organization of the actin cytoskeleton by regulating actin-associated proteins. The transmembrane heparan sulfate proteoglycan syndecan-4 also plays a critical role in protein kinase C (PKC) signaling in the formation of focal adhesions and actin stress fibers. The cytoplasmic domain of syndecan-4 core protein directly interacts with and potentiates PKCalpha activity, and it can directly interact with the phos- phoinositide PIP2. We, therefore, investigated whether the interaction of inositol phosphates and inositol phospholipids with syndecan-4 could regulate PKC activity. Data from in vitro kinase assays using purified PKCalpha beta gamma show that in the absence of phosphatidylserine and diolein, PIP2 increased the extent of autophosphorylation of PKCalpha beta gamma and partially activated it to phosphorylate both histone III-S and an epidermal growth factor receptor peptide. This activity was dose-dependent, and its calcium dependence varied with PKC isotype/source. Addition of the cytoplasmic syndecan-4 peptide, but not equivalent syndecan-1 or syndecan-2 peptides, potentiated the partial activation of PKCalpha beta gamma by PIP2, resulting in activity greater than that observed with phosphatidylserine, diolein, and calcium. This study indicates that syndecan-4 cytoplasmic domain may bind both PIP2 and PKCalpha, localize them to forming focal adhesions, and potentiate PKCalpha activity there.

Amino Acid Sequence↗
PubMed1998

Heparan sulfate proteoglycans as adhesive and anti-invasive molecules. Syndecans and glypican have distinct functions.

ARH-77 cells do not adhere to type I collagen and readily invade into collagen gels, but following expression of the transmembrane heparan sulfate proteoglycan syndecan-1, they bind collagen and fail to invade. We now show that cells transfected with syndecan-2 or syndecan-4 also bind collagen and are non-invasive. In contrast, cells transfected with the glycosylphosphatidylinositol-anchored proteoglycan glypican-1 do not bind to collagen and remain invasive, even though glypican- and syndecan-expressing cells have similar surface levels of heparan sulfate, and their proteoglycans have similar affinities for collagen. Analysis of cells expressing syndecan-1-glypican-1 chimeric proteoglycans reveals that inhibition of invasion requires the extracellular domain of syndecan but not its transmembrane or cytoplasmic domain. Surprisingly, cells bearing a chimera composed of the glypican extracellular domain fused to the syndecan transmembrane and cytoplasmic domains bind to collagen but remain invasive, implying that adhesion to collagen is not by itself sufficient to inhibit invasion. Apparently, the extracellular domain of syndecan-1, presumably by interacting with cell-surface signal transducing molecules, directly regulates complex cell behaviors such as motility and invasiveness. These results also show for the first time that syndecans and glypicans can have distinct functions, even when expressed by the same cell type.

Animals↗
PubMed2000

High molecular weight kininogen utilizes heparan sulfate proteoglycans for accumulation on endothelial cells.

Kininogens, the high molecular weight precursor of vasoactive kinins, bind to a wide variety of cells in a specific, reversible, and saturable manner. The cell docking sites have been mapped to domains D3 and D5(H) of kininogens; however, the corresponding cellular acceptor sites are not fully established. To characterize the major cell binding sites for kininogens exposed by the endothelial cell line EA.hy926, we digested intact cells with trypsin and other proteases and found a time- and concentration-dependent loss of (125)I-labeled high molecular weight kininogen (H-kininogen) binding capacity (up to 82%), indicating that proteins are crucially involved in kininogen cell attachment. Cell surface digestion with heparinases similarly reduced kininogen binding capacity (up to 78%), and the combined action of heparinases and trypsin almost eliminated kininogen binding (up to 85%), suggesting that proteoglycans of the heparan sulfate type are intimately involved. Consistently, inhibitors such as p-nitrophenyl-beta-d-xylopyranoside and chlorate interfering with heparan sulfate proteoglycan biosynthesis reduced the total number of kininogen binding sites in a time- and concentration-dependent manner (up to 67%). In vitro binding studies demonstrated that biotinylated H-kininogen binds to heparan sulfate glycosaminoglycans via domains D3 and D5(H) and that the presence of Zn(2+) promotes this association. Cloning and over-expression of the major endothelial heparan sulfate-type proteoglycans syndecan-1, syndecan-2, syndecan-4, and glypican in HEK293t cells significantly increased total heparan sulfate at the cell surface and thus the number of kininogen binding sites (up to 3. 3-fold). This gain in kininogen binding capacity was completely abolished by treating transfected cells with heparinases. We conclude that heparan sulfate proteoglycans on the surface of endothelial cells provide a platform for the local accumulation of kininogens on the vascular lining. This accumulation may allow the circumscribed release of short-lived kinins from their precursor molecules in close proximity to their sites of action.

Amino Acid Sequence↗
PubMed1996

Stimulation of fibroblast growth factor receptor-1 occupancy and signaling by cell surface-associated syndecans and glypican.

The formation of distinctive basic FGF-heparan sulfate complexes is essential for the binding of bFGF to its cognate receptor. In previous experiments, cell-surface heparan sulfate proteoglycans extracted from human lung fibroblasts could not be shown to promote high affinity binding of bFGF when added to heparan sulfate-deficient cells that express FGF receptor-1 (FGFR1) (Aviezer, D., D. Hecht, M. Safran, M. Eisinger, G. David, and A. Yayon. 1994. Cell 79:1005-1013). In alternative tests to establish whether cell-surface proteoglycans can support the formation of the required complexes, K562 cells were first transfected with the IIIc splice variant of FGFR1 and then transfected with constructs coding for either syndecan-1, syndecan-2, syndecan-4 or glypican, or with an antisense syndecan-4 construct. Cells cotransfected with receptor and proteoglycan showed a two- to three- fold increase in neutral salt-resistant specific 125I-bFGF binding in comparison to cells transfected with only receptor or cells cotransfected with receptor and anti-syndecan-4. Exogenous heparin enhanced the specific binding and affinity cross-linking of 125I-bFGF to FGFR1 in receptor transfectants that were not cotransfected with proteoglycan, but had no effect on this binding and decreased the yield of bFGFR cross-links in cells that were cotransfected with proteoglycan. Receptor-transfectant cells showed a decrease in glycophorin A expression when exposed to bFGF. This suppression was dose-dependent and obtained at significantly lower concentrations of bFGF in proteoglycan-cotransfected cells. Finally, complementary cell-free binding assays indicated that the affinity of 125I-bFGF for an immobilized FGFR1 ectodomain was increased threefold when the syndecan-4 ectodomain was coimmobilized with receptor. Equimolar amounts of soluble syndecan-4 ectodomain, in contrast, had no effect on this binding. We conclude that, at least in K562 cells, syndecans and glypican can support bFGF-FGFR1 interactions and signaling, and that cell-surface association may augment their effectiveness.

Base Sequence↗
PubMed1997

Syndecan-4 is a primary-response gene induced by basic fibroblast growth factor and arterial injury in vascular smooth muscle cells.

Syndecans are a family of transmembrane proteoglycans that have been implicated in cell-extracellular matrix adhesion and growth factor binding. We reported previously that syndecan-1 expression by cultured rate vascular smooth muscle cells (VSMCs) is induced by serum- or platelet-derived growth factor (PDGF). We now report that syndecan-4 mRNA is rapidly induced in cultured VSMCs in response to basic fibroblast growth factor (bFGF) or serum stimulation. In the presence of cycloheximide, induction of syndecan-4 mRNA was enhanced. These characteristics identified syndecan-4 as a primary-response gene product in VSMCs. In contrast, syndecan-1 mRNA expression in response to serum was completely blocked in the presence of cycloheximide. We also examined the expression of syndecan mRNAs in VSMCs in response to balloon catheter injury in vivo. A reverse transcriptase-polymerase chain reaction technique was developed that enabled us to amplify all four syndecan mRNAs in a single reaction tube and determine relative changes in their expression. All four syndecan mRNAs were detected in uninjured rat carotid arteries. In endothelium-denuded arteries, the medial layer (presumably VSMCs) accounted for 70% to 90% of the syndecan mRNAs in the vessel wall. The levels of syndecan-2 and syndecan-3 mRNAs were not altered significantly after balloon injury. In contrast, syndecan-4 mRNA was increased at early times after injury but then decreased to control level by 7 days. Syndecan-1 mRNA levels showed a slower but prolonged increase that reached a maximum at 7 days after injury. Immunostaining with anti-syndecan-4 antibodies demonstrated a rapid increase in syndecan-4 proteoglycan expression in the injured carotid artery.

Animals↗
PubMed1994

Differential expression of multiple cell-surface heparan sulfate proteoglycans during embryonic tooth development.

Heparan sulfate accumulates on cell surfaces and at cell-matrix interfaces, and functionally modulates several of the effector molecules that support the interactions, growth, and differentiation of developing tissues. Using heparin sulfate-specific monoclonal antibodies MAb, we obtained evidence that extracts from rodent embryos contain multiple forms of cell surface-associated heparan sulfate proteoglycan (PG). Taking tooth development in the mouse embryo as a model to further investigate the relevance of this PG redundancy and using MAb against heparan sulfate, antibodies specific for syndecan (syndecan-1) and fibroglycan (syndecan-2) (two distinct members of a larger family of cell-surface heparan sulfate PGs), and specific cDNA probes for these two cell-surface PGs, we obtained in situ evidence for regulated and differential expression of multiple cell-surface heparan sulfate PGs. The unique, distinctive, and coordinated changes in the expressions of these PGs during morphogenesis and differentiation of dental tissues suggest that the various cell-surface PGs are not truly redundant but play important, specific, and potentially complementary roles during embryonic development.

Animals↗
PubMed2000

Participation of syndecan 2 in the induction of stress fiber formation in cooperation with integrin alpha5beta1: structural characteristics of heparan sulfate chains with avidity to COOH-terminal heparin-binding domain of fibronectin.

The present study provides direct evidence that syndecan 2 participates selectively in the induction of stress fiber formation in cooperation with integrin alpha5beta1 through specific binding of its heparan sulfate side chains to the fibronectin substrate. Our previous study with Lewis lung carcinoma-derived P29 cells demonstrated that the cell surface heparan sulfate proteoglycan, which binds to fibronectin, is syndecan 2 (N. Itano et al., 1996, Biochem. J. 315, 925-930). We here report that in vitro treatment of the cells by antisense oligonucleotide for syndecan 2 resulted in a failure to form stress fibers on fibronectin substrate in association with specific suppression of its cell surface expression. Instead, localization of actin filaments in the cytoplasmic cortex occurred. A similar response of the cells was observed when the cells were treated to eliminate functions of cell surface heparan sulfates, including exogenous addition of heparin and pretreatment with anti-heparan sulfate antibody, F58-10E4, and with proteinase-free heparitinase I. Size- and structure-defined oligosaccharides prepared from heparin and chemically modified heparins were utilized as competitive inhibitors to examine the structural characteristics of the cell surface heparan sulfates involved in organization of the actin cytoskeleton. Their affinity chromatography on a column linked with a recombinant H-271 peptide containing a C-terminal heparin-binding domain of fibronectin demonstrated that 2-O-sulfated iduronates were essential for the binding. Inhibition studies revealed that a heparin-derived dodecasaccharide sample enriched with an IdoA(2OS)-GlcNS(6OS) disaccharide completely blocked binding of the syndecan 2 ectodomain to immobilized H-271 peptide. Finally, the dodecasaccharide sample was shown to inhibit stress fiber formation, triggered by adhesion of P29 cells to a CH-271 polypeptide consisting of both the RGD cell-binding and the C-terminal heparin-binding domains of fibronectin in a fused form. All these results consistently suggest that syndecan 2 proteoglycan interacts with the C-terminal heparin-binding domain of fibronectin at the highly sulfated cluster(s), such as [IdoA(2OS)-GlcNS(6OS)](6) present in its heparan sulfate chains, to result in the induction of stress fiber formation in cooperation with integrin alpha5beta1.

Actins↗
PubMed1996

Embryonic expression patterns of Xenopus syndecans.

Syndecans are a family of heparan sulfate proteoglycans implicated in cell-cell and cell-matrix interactions. To investigate the roles of syndecans in early development, we identified three syndecan family members in Xenopus laevis: Xsyn-1, Xsyn-2, and Xsyn-3. Xsyn-1 and Xsyn-2 are maternal mRNAs localized to the animal pole in blastulae, and are expressed in the ectoderm of gastrulae. In neurulae, Xsyn-1 is restricted to non-neural ectoderm and Xsyn-2 is restricted to neural ectoderm. In tailbud embryos, the three syndecans are expressed in adjacent, non-overlapping patterns. Xsyn-2 is expressed in the heart while Xsyn-1 is expressed in the underlying anterior endoderm. Xsyn-3 is expressed in the hindbrain, midbrain, and forebrain, while Xsyn-2 is expressed in the intervening regions. These results suggest that different members of the syndecan family have distinct developmental roles, perhaps acting as barriers to define tissue boundaries.

Amino Acid Sequence↗
PubMed1999

A role for a PDZ protein in the early secretory pathway for the targeting of proTGF-alpha to the cell surface.

In general, plasma membrane integral proteins, such as the membrane-anchored growth factor proTGF-alpha, are assumed to be transported to the cell surface via a nonregulated, constitutive pathway. proTGF-alpha C-terminal mutants are retained in an early secretory compartment. Here, using a two-hybrid screen, we identify two TACIPs (proTGF-alpha cytoplasmic domain-interacting proteins) that contain PDZ domains and do not interact with proTGF-alpha C-terminal mutants. The binding specificity of one of them, TACIP18 (previously identified and named Syntenin or mda-9), coincides with that of the component that possibly mediates the normal trafficking of proTGF-alpha. TACIP18 colocalizes and interacts specifically with immature, intracellular forms of proTGF-alpha. Therefore, it appears that the interaction of TACIP18 with proTGF-alpha in the early secretory pathway is necessary for the targeting of the latter to the cell surface.

Amino Acid Sequence↗
PubMed1998

Syndecan-1 is up-regulated in ras-transformed intestinal epithelial cells.

The syndecans, a family of cell-surface heparan sulphate proteoglycans, have been proposed to mediate cellular interactions with extracellular effector molecules, such as growth factors and components of the extracellular matrix, during critical phases of development. Transcripts of all four syndecans are expressed at varying levels in the developing rat intestine and in a series of immature rat intestinal epithelial cell lines. In addition, we report the novel finding that, in the intestinal epithelial cell lines, expression of syndecan-1 transcript is up-regulated by transformation with activated H-ras. This is in contrast to other cell lines in which ras transformation is associated with a decrease in syndecan-1 levels. The observed increase in the syndecan-1 occurs as a result of increased transcription and can be correlated with the degree of transformation of the IEC-18 cells. Transformation is also associated with a decrease in apparent molecular weight and increased shedding of the proteoglycan into the culture medium. Increased shedding of syndecan-1 into the culture medium after transformation with H-ras may contribute to the disruption of proteoglycan interactions with the extracellular matrix, leading to alterations in cell adhesion and organization.

Aging↗
PubMed1995

Expression of a Xenopus counterpart of mammalian syndecan 2 during embryogenesis.

We have identified a Xenopus cDNA, XS-2, by screening a Xenopus embryonic stage-22-24 cDNA library with a DNA probe encoding the transmembrane and cytoplasmic domains of mouse syndecan 1. The 1.4 kb cDNA consists of an open reading frame of 642 nucleotides encoding a protein of 191 amino acids. The predicted protein of 20869 Da contains a 25-amino acid putative transmembrane domain and a 32-amino acid putative cytoplasmic domain, both of which are highly similar to the corresponding regions of rat syndecan 2 (92% identity) and to a lesser degree those of rat syndecans 1, 3 and 4 (62, 64 and 78% respectively). The putative N-terminal ectodomain contains a possible attachment site for heparan sulphate, identical with the comparable glycosaminoglycan-attachment sequence of rat syndecan 2. Polyclonal antisera raised against recombinant ectodomain of XS-2, expressed as a fusion protein, recognized a heparan sulphate proteoglycan in XTC cell-culture medium. This proteoglycan bound to DEAE-Sephacel and was eluted with 1 M NaCl; digestion with heparitinase but not chondroitinase ABC resulted in the identification of a 46 kDa protein by these antisera. Northern-blot analysis indicated that XS-2 identifies two Xenopus mRNA species approx. 4 and 2 kb in size in embryos ranging in maturation from the 64-cell stage to stage 54. These results demonstrate that a heparan sulphate proteoglycan, similar to syndecan 2, is expressed during Xenopus embryogenesis.

Amino Acid Sequence↗
PubMed2001

Cell surface heparan sulfate proteoglycans control the response of renal interstitial fibroblasts to fibroblast growth factor-2.

BACKGROUND: While the progression of renal disease to end stage is strongly correlated with tubulointerstitial changes, the control of the fibrotic process within the interstitium is poorly understood. Basic fibroblast growth factor (FGF-2) has been implicated as a major growth factor involved in fibroblast activation and extracellular matrix synthesis. Furthermore, in many cells, the activity of FGF-2 is controlled by a low-affinity but high-capacity interaction with heparan sulfate (HS) proteoglycans (PGs), such as members of the syndecan family. These molecules are likely to be central to the control of interstitial fibrosis, but as yet, there has been no characterization of their synthesis by interstitial cells. METHODS: The expression of HSPG on the surface of NRK 49F fibroblasts was demonstrated by immunohistochemistry and by metabolic labeling with [(35)S]-sulfate. HSs were characterized by specific enzymatic digestion, size exclusion chromatography, and anion exchange chromatography. The mRNA for syndecan 1 through syndecan 4 in the fibroblasts was detected by semiquantitative reverse transcription-polymerase chain reaction. Fibroblast proliferation was measured by the MTT assay. RESULTS: Immunohistochemistry and [(35)S]-sulfate-labeling demonstrated that renal fibroblasts expressed HSPGs on their surface. Furthermore, enzymatic removal of these HS (but not chondroitin sulfate) glycosaminoglycan (GAG) chains, or inhibition of GAG sulfation, abolished the proliferative response of both NRK cells and primary human cortical fibroblasts to FGF-2 but not to platelet-derived growth factor. The addition of conditioned medium, containing HS-GAG fragments, restored the proliferative response to FGF-2, confirming the specificity of the interaction. Finally, the mRNA for all four syndecans was detected in the fibroblasts, and that for syndecan 1 in particular was up-regulated by FGF-2. CONCLUSIONS: The present study demonstrates that the expression of cell surface HSPG was essential for the proliferation of renal fibroblasts in response to FGF-2, and therefore may play a major role in the development and persistence of a proliferating phenotype during interstitial nephritis.

Animals↗
PubMed1997

Syntenin, a PDZ protein that binds syndecan cytoplasmic domains.

The syndecans are transmembrane proteoglycans that place structurally heterogeneous heparan sulfate chains at the cell surface and a highly conserved polypeptide in the cytoplasm. Their versatile heparan sulfate moieties support various processes of molecular recognition, signaling, and trafficking. Here we report the identification of a protein that binds to the cytoplasmic domains of the syndecans in yeast two-hybrid screens, surface plasmon resonance experiments, and ligand-overlay assays. This protein, syntenin, contains a tandem repeat of PDZ domains that reacts with the FYA C-terminal amino acid sequence of the syndecans. Recombinant enhanced green fluorescent protein (eGFP)-syntenin fusion proteins decorate the plasmamembrane and intracellular vesicles, where they colocalize and cosegregate with syndecans. Cells that overexpress eGFP-syntenin show numerous cell surface extensions, suggesting effects of syntenin on cytoskeleton-membrane organization. We propose that syntenin may function as an adaptor that couples syndecans to cytoskeletal proteins or cytosolic downstream signal-effectors.

Amino Acid Sequence↗
PubMed1998

Tyrosine phosphorylation of syndecan-1 and -4 cytoplasmic domains in adherent B82 fibroblasts.

The syndecans, a family of cell surface proteoglycans, have highly conserved cytoplasmic domains that bind proteins containing PDZ domains and co-localize with the actin cytoskeleton. The syndecan cytoplasmic domains contain four conserved tyrosine residues, two of which are located within favorable sequences for phosphorylation. Endogenous tyrosine phosphorylation of syndecans-1 and -4 is detected in adherent B82 fibroblasts. Approximately 1.5% of total syndecan is endogenously phosphorylated, while most, if not all, cell surface syndecan is phosphorylated following treatment with the tyrosine phosphatase inhibitor pervanadate. Syndecan phosphorylation is also detected in Raji-S1 and NMuMG cells, but only following treatment with vanadate or pervanadate, suggesting that endogenous phosphorylation is maintained in an "off" state in these cells. Endogenous syndecan phosphorylation in B82 cells is rapidly blocked by genistein (IC50 < 10 microM) confirming the presence of a constitutively active kinase and a corresponding tyrosine phosphatase. Phosphorylation is also inhibited by herbimycin A (IC50 < 1.0 microM) and staurosporine (IC50 < 1.0 nM), suggesting a role for Src family kinases in regulating syndecan phosphorylation. Together, these data suggest an important role for tyrosine phosphorylation of the syndecan cytoplasmic domains in regulating downstream signaling events in response to cell adhesion and/or growth factor activity.

Amino Acid Sequence↗
PubMedDate not supplied

Time-dependent increases in syndecan-1 and fibroglycan messenger RNA expression in the infarct zone after experimentally induced myocardial infarction in rats.

BACKGROUND: Syndecan-1 and fibroglycan, heparan sulphate proteoglycans, play important roles in extracellular matrix formation via their biological functions. OBJECTIVE: To examine experimentally the sequential changes in syndecan-1 and fibroglycan messenger RNA (mRNA) expression after acute myocardial infarction. MATERIALS AND METHODS: The left coronary arteries of male Sprague-Dawley rats were ligated and the hearts were excised on days 1-14, 28 and 42. Syndecan-1 and fibroglycan mRNA expression in the infarct and non-infarct zones and in sham-operated hearts was determined by reverse transcriptase-polymerase chain reaction. Amplified products were quantified by densitometry of the electrophoresed bands stained with ethidium bromide and standardized relative to the glyceraldehyde 3-phosphate dehydrogenase or beta-actin mRNA expression. Northern hybridization was also performed in the infarct and non-infarct zones on day 3. RESULTS: Expression both of syndecan-1 and of fibroglycan mRNA began to increase on day 2. The expression attained maximum levels on day 3. The maximum levels of syndecan-1 and fibroglycan expression were, respectively, sevenfold and fivefold the preligation level and the level in the sham-operated hearts. The levels remained elevated until day 14, whereupon they declined gradually, returning to the control levels by around day 42. Northern blotting also demonstrated that there was an increased expression both of syndecan-1 and of fibroglycan mRNA in the infarct compared with that in the non-infarct zone on day 3. CONCLUSION: Our results demonstrated that there are sequential increases in the expression both of syndecan-1 and of fibroglycan mRNA in the infarct zone after experimentally induced myocardial infarction in rats, suggesting that these proteoglycans play some role in the pathological course of infarction.

Animals↗
PubMed1999

Heparan sulfate proteoglycan expression is induced during early erythroid differentiation of multipotent hematopoietic stem cells.

Heparan sulfate (HS) proteoglycans of bone marrow (BM) stromal cells and their extracellular matrix are important components of the microenvironment of hematopoietic tissues and are involved in the interaction of hematopoietic stem and stromal cells. Although previous studies have emphasized the role of HS proteoglycan synthesis by BM stromal cells, we have recently shown that the human hematopoietic progenitor cell line TF-1 also expressed an HS proteoglycan. Immunochemical, reverse transcriptase-polymerase chain reaction (RT-PCR), and Northern blot analysis of this HS proteoglycan showed that it was not related to the syndecan family of HS proteoglycans or to glypican. To answer the question of whether the expression of HS proteoglycans is associated with the differentiation state of hematopoietic progenitor cells, we have analyzed the proteoglycan synthesis of several murine and human hematopoietic progenitor cell lines. Proteoglycans were isolated from metabolically labeled cells and purified by several chromatographic steps. Isolation and characterization of proteoglycans from the cell lines HEL and ELM-D, which like TF-1 cells have an immature erythroid phenotype, showed that these cells synthesize the same HS proteoglycan, previously detected in TF-1 cells, as a major proteoglycan. In contrast, cell lines of the myeloid lineage, like the myeloblastic/promyelocytic cell lines B1 and B2, do not express HS proteoglycans. Taken together, our data strongly suggest that expression of this HS proteoglycan in hematopoietic progenitor cell lines is associated with the erythroid lineage. To prove this association we have analyzed the proteoglycan expression in the nonleukemic multipotent stem cell line FDCP-Mix-A4 after induction of erythroid or granulocytic differentiation. Our data show that HS proteoglycan expression is induced during early erythroid differentiation of multipotent hematopoietic stem cells. In contrast, during granulocytic differentiation, no expression of HS proteoglycans was observed.

Cell Differentiation↗
PubMed1993

Differential expression of transmembrane proteoglycans in vascular smooth muscle cells.

Rat aortic vascular smooth muscle (VSM) cells synthesize the transmembrane proteoglycan syndecan (Cizmeci-Smith, G., Asundi, V., Stahl, R. C., Teichman, L. J., Chernousov, M., Cowan, K., and Carey, D. J. (1992) J. Biol. Chem. 267, 15729-15736). The present work demonstrated that VSM cells synthesize the related transmembrane proteoglycan fibroglycan and that increased expression of these two proteoglycans is stimulated under different conditions. Fibroglycan synthesis by cultured rat aortic VSM cells was demonstrated by Northern blot analysis with a rat fibroglycan cDNA probe and immunoblot analysis with anti-rat fibroglycan antibodies. Effects of growth factors and vasoactive substances on syndecan and fibroglycan expression were examined by Northern blot analysis. Syndecan mRNA levels increased in response to stimulation of VSM cells with serum, platelet-derived growth factor, or angiotensin II. VSM cells stimulated with platelet-derived growth factor contained more syndecan core protein and processed syndecan than control cells. Fibroglycan mRNA levels either decreased or remained unchanged in response to these agents. Fibroglycan mRNA levels increased following transforming growth factor-beta stimulation, while syndecan mRNA levels decreased. Other agents, including basic fibroblast growth factor, endothelin, and carbacyclin did not alter the expression of either proteoglycan. Syndecan and fibroglycan mRNA levels also varied as a function of cell density. These data demonstrate that syndecan and fibroglycan expression are regulated differently in VSM cells and lend support to the hypothesis that these proteoglycans carry out distinct physiological functions.

Angiotensin II↗