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PubMed1994

Molecular cloning and genomic organization of chicken syndecan-4.

We have cloned and determined the genomic organization of the core protein of the chicken transmembrane proteoglycan, syndecan-4. Identification of the initial cDNA was accomplished using polyclonal antibodies directed against the cytoplasmic domain of murine syndecan-1 core protein. The cDNA for chicken syndecan-4 encodes a putative core protein of 197 amino acids which consists of a 19-amino acid signal peptide, a 125-amino acid ectodomain, a 25-amino acid transmembrane domain, and a 28-amino acid cytoplasmic domain. The predicted molecular mass of the mature core protein is 19,639 daltons. The ectodomain of chicken syndecan-4 core protein contains three potential sites for glycosaminoglycan attachment, two sites for N-glycosylation, and lacks a dibasic protease cleavage site proximal to the membrane-spanning region found in other syndecan family members. Comparison of the complete amino acid sequence with human syndecan-4 (amphlican (David, G., van der Schueren, B., Marynen, P., Cassiman, J. J., and van den Berghe, H. (1992) J. Cell Biol. 118, 961-969)) and rat syndecan-4 (ryudocan (Kojima, T., Shworak, N. W., and Rosenberg, R. D. (1992) J. Biol. Chem. 267, 4870-4877)) indicates an overall identity of 58 and 56%, respectively, with a 91 and 92% identity in the highly conserved transmembrane and cytoplasmic domains. The core protein of chicken syndecan-4 synthesized by chicken cells is modified with heparan sulfate side chains yielding a proteoglycan with a molecular mass of > 200 kDa in LMH cells (immortalized male leghorn LM strain hepatocytes) and primary skin fibroblasts. Syndecan-4 isolated from chondrocyte cultures runs as a diffuse band between 100 and 200 kDa. Northern analysis of chicken syndecan-4 indicates three messages with distinct sizes of 0.9, 1.3, and 2.9 kb and a wide mRNA tissue distribution. The chicken syndecan-4 gene is divided into 5 exons encoding distinct regions which contain the signal peptide, the glycosaminoglycan attachment sites, a small spacer of unknown function, the glycosylation sites and the transmembrane and cytoplasmic domains.

Amino Acid Sequence↗
PubMed1995

Protein kinase C regulates the recruitment of syndecan-4 into focal contacts.

Cell surface heparan sulfate proteoglycans have been implicated as co-receptors facilitating cell adhesion and growth factor binding. Recent studies on the role of a family of transmembrane heparan sulfate proteoglycans, syndecans, in cell adhesion has identified one member, syndecan-4, to be present within focal contacts. The current study investigates the mechanisms regulating the association of syndecan-4 with focal contacts based upon its immunolocalization with vinculin in quiescent, serum-stimulated, and 12-0-tetradecanoylphorbol 13-acetate (TPA)-induced cultures. In quiescent cells, syndecan-4 did not localize to focal contacts. However, activation of protein kinase C by TPA or serum induces the active recruitment of syndecan-4 into focal contacts. This induction preferentially localizes syndecan-4 to focal contacts behind the leading lamella, the subnuclear region, and along the trailing edge of migratory cells. Focal contacts in either freshly adhered cells or in the leading lamellae of migrating cells did not stain for syndecan-4. In addition to the observed subcellular distribution and recruitment, syndecan-4 was observed to co-localize with endogenously synthesized fibronectin fibrils within focal contacts as well as with fibrils present in the matrix. These findings suggest that protein kinase C activation results in syndecan-4 recruitment to focal contacts and its association with sites of matrix deposition.

Animals↗
PubMed1993

Membrane-anchored proteoglycans of mouse macrophages: P388D1 cells express a syndecan-4-like heparan sulfate proteoglycan and a distinct chondroitin sulfate form.

Proteoglycan accumulation by thioglycollate-elicited mouse peritoneal macrophages and a panel of murine monocyte-macrophage cell lines has been examined to determine whether these cells express plasma membrane-anchored heparan sulfate proteoglycans. Initially, cells were screened for heparan sulfate and chondroitin sulfate glycosaminoglycans after metabolic labeling with radiosulfate. Chondroitin sulfate is secreted to a variable extent by every cell type examined. In contrast, heparan sulfate is all but absent from immature pre-monocytes and is associated predominantly with the cell layer of mature macrophage-like cells. In the P388D1 cell line, the cell-associated chondroitin sulfate is largely present as a plasma membrane-anchored proteoglycan containing a 55 kD core protein moiety, which appears to be unique. In contrast, the cell-associated heparan sulfate is composed of a proteoglycan fraction and protein-free glycosaminoglycan chains, which accumulate intracellularly. A fraction of the heparan sulfate proteoglycan contains a lipophilic domain and can be released from cells following mild treatment with trypsin, suggesting that it is anchored in the plasma membrane. Isolation of this proteoglycan indicates that it is likely syndecan-4: it is expressed as a heparan sulfate proteoglycan at the cell surface, it is cleaved from the plasma membrane by low concentrations of trypsin, and it consists of a single 37 kD core protein moiety that co-migrates with syndecan-4 isolated from NMuMG mouse mammary epithelial cells. Northern analysis reveals that a panel of macrophage-like cell lines accumulate similar amounts of syndecan-4 mRNA, demonstrating that this proteoglycan is expressed by a variety of mature macrophage-like cells. Syndecan-1 mRNA is present only in a subset of these cells, suggesting that the expression of this heparan sulfate proteoglycan may be more highly regulated by these cells.

Animals↗
PubMed1995

Heparan sulfate-mediated cell aggregation. Syndecans-1 and -4 mediate intercellular adhesion following their transfection into human B lymphoid cells.

Because syndecans are present at sites of cell-cell contact in vivo it has been hypothesized that they play a role in mediating cell-cell adhesion. However, there has been no direct evidence to support this notion. To address this question, B lymphoid (ARH-77) cells were transfected with the cDNA for murine syndecan-1. Unlike the parental cells, the transfectants form large multicellular aggregates in suspension cultures and stain intensely for syndecan-1 at sites of cell-cell contact. Using rotation-mediated aggregation assays, we find that aggregation of syndecan-1-transfected cells is dependent on divalent cations and is inhibited by the following: (i) addition of heparin and heparin-like glycosaminoglycans, (ii) removal of heparan sulfate from the cell surface, or (iii) addition of exogenous purified syndecan-1. Mixing of syndecan-1-transfected and control-transfected cells results in aggregates containing both cell types indicating that aggregation occurs through a heterophilic adhesion mechanism in which heparan sulfate chains bind to a counter-receptor present on these cells. Importantly, syndecan-4-transfected cells also aggregate in a heparan sulfate-dependent manner, while in contrast, betaglycan-transfected cells aggregate poorly. Thus, syndecans may be important mediators of cell-cell adhesion, but this function may not be common to all transmembrane heparan sulfate-bearing proteoglycans.

Animals↗
PubMed1994

Mapping of the syndecan genes in the mouse: linkage with members of the myc gene family.

The syndecans are a family of four cell surface heparan sulfate proteoglycans in vertebrates that mediate a variety of cell behaviors, including cell adhesion and the action of growth factors. Their core proteins contain conserved transmembrane and cytoplasmic domains but divergent extracellular regions in which only the glycosaminoglycan attachment sites are conserved. By extensive PCR analyses based on the conserved sequences, we find only four syndecan-related sequences in the mouse. These correspond to the previously described core proteins of syndecan proteoglycans from other vertebrates. We have mapped the genes for syndecan-2 to chromosome 15, syndecan-3 to chromosome 4, and syndecan-4 to chromosome 2 in the mouse. Together with the previous localization of the gene for syndecan-1 to chromosome 12, these data establish that the four syndecan genes are dispersed on different chromosomes and that each syndecan gene is located near a member of the myc gene family. Synd1 is next to Nmyc, Synd2 close to myc, Synd3 near Lmyc, and Synd4 on the same chromosome as Bmyc. The physical relationship between the members of these two gene families appears to be ancient and conserved after the two genome duplications thought to have occurred during vertebrate evolution.

Animals↗
PubMed1993

Post-transcriptional regulation of syndecan-1 expression by cAMP in peritoneal macrophages.

Syndecan-1 is a cell surface heparan sulfate proteoglycan that is proposed to serve in cell-cell adhesion, cell-matrix anchorage, and growth factor signaling. Its expression is temporally and spatially regulated during epithelial-mesenchymal interactions in many developing tissues. In some cases, this regulation appears to be achieved at the level of transcription. However, induction of syndecan-1 expression in the embryonic kidney mesenchyme is suggested to occur at the level of mRNA translation (Vainio, S., M. Jalkanen, M. Bernfield, and L. Saxén. 1992. Dev. Biol. 152:221-232). To identify a system in which the regulatory mechanisms controlling syndecan-1 expression can be studied, cells of the monocyte-macrophage lineage, which regulate the expression of many cell surface receptors, were screened for syndecan-1 expression. The syndecan-1 gene is active in blood monocytes as well as resident and thioglycollate-elicited mouse peritoneal macrophages, but expression of the proteoglycan is regulated at two levels. First, elicited macrophages accumulate nine-fold more syndecan-1 mRNA than do resident macrophages or circulating blood monocytes. Another member of the syndecan family of proteoglycans, syndecan-4, shows a distinct pattern of expression, suggesting that this regulation is specific for syndecan-1. Second, utilization of the mRNA for syndecan-1 production encounters a post-transcriptional block in the elicited macrophages that can be overcome by triggering agents such as E-type prostaglandins or dibutyryl cAMP, which raise intracellular cAMP levels. Dibutyryl cAMP does not induce syndecan-1 expression in resident peritoneal macrophages, which lack a pool of stored mRNA. This suggests that this agent promotes the post-transcriptional utilization of stored syndecan-1 mRNA. The induced proteoglycan appears at the cell surface as a integral of 100-kD heparan sulfate-rich isoform of syndecan-1. This suggests that a cAMP-dependent post-transcriptional control mechanism may be present in a variety of tissues when syndecan-1 expression is regulated.

Animals↗
PubMed1993

Human ryudocan core protein: molecular cloning and characterization of the cDNA, and chromosomal localization of the gene.

We have isolated a series of overlapping cDNA clones encoding a 2,628 bp transcript, which potentially codes for a 198 amino acid protein with predicted molecular mass of 21,641 daltons, for the human ryudocan core protein. The deduced core proteins of the human and the rat ryudocan have high structural conservation, particularly in the NH2 and COOH terminus regions of the putative mature core protein, including the combined transmembrane/cytoplasmic domains with conserved positions of all 4 tyrosine groups and 3 conserved glycosaminoglycan chain attachment regions, which might serve important roles for biological function of ryudocan. A major 2.7 kb transcript was detected in all tissues tested, with relatively high levels of expression observed in mRNA from lung, liver, skeletal muscle and kidney. A minor 1.9 kb transcript was also observed in some of tissues, which would be caused by alternative polyadenylation. Human ryudocan gene has been localized on the chromosome 20q12 by fluorescence in situ hybridization.

Amino Acid Sequence↗
PubMed1995

Molecular cloning of the human ryudocan promoter.

The promoter region of human ryudocan was isolated from a human lambda dash genomic library and cloned into pBluescript. The 5'flanking region contained a classical TATA box and GC rich regions that are commonly found in constitutively expressed genes. Two fusion gene constructs, one of 898 bp and the other of 480 bp of the 5' flanking DNA coupled to the luciferase gene, were transiently expressed in a mouse endothelioma cell line and in human umbilical endothelial cell cultures. Both constructs were capable of driving luciferase expression; the 898 bp construct produced greater levels of luciferase activity than the 480 bp construct in both cell types examined. Analysis of the sequence revealed the presence of several potential sites for nuclear transcription factor binding; the relevance of these sites is presently unknown.

Base Sequence↗
PubMed1994

Syndecans, cell surface heparan sulfate proteoglycans, are induced by a proline-rich antimicrobial peptide from wounds.

Cell surface heparan sulfate proteoglycans, such as the syndecans, are required for cellular responses to heparin-binding growth factors and extracellular matrix components. Expression of syndecan-1 and -4 is induced in mesenchymal cells during wound repair in the mouse, consistent with a role for syndecans in regulating cell proliferation and migration in response to these effectors. Here we show that wound fluid contains inductive activity that mimics the in vivo induction in time of appearance, specificity for mesenchymal cells, and selectivity for syndecan-1 and -4. We have purified and synthesized a 4.8-kDa proline-rich protein from wound fluid that reproduces this induction of syndecan-1 and -4 in cultured cells. This peptide, identical to the antibacterial peptide PR-39, is released into the wound by the cellular infiltrate and induces syndecan expression at the same peptide concentrations that lyse bacteria. These results indicate that wounds contain a multifunctional protein that induces mammalian cells to express cell surface heparan sulfate proteoglycans as part of the wound repair process and that kills bacteria as part of a nonimmune defense mechanism.

3T3 Cells↗
PubMed1992

Molecular cloning of amphiglycan, a novel integral membrane heparan sulfate proteoglycan expressed by epithelial and fibroblastic cells.

We have synthesized an antisense oligonucleotide primer that matches a supposedly conserved sequence in messages for heparan sulfate proteoglycans with transmembrane orientations. With the aid of this primer we have amplified partial and selected full-length copies of a message from human lung fibroblasts that codes for a novel integral membrane heparan sulfate proteoglycan. The encoded protein is 198 amino-acids long, with discrete cytoplasmic, transmembrane, and amino-terminal extracellular domains. Except for the sequences that represent putative heparan sulfate chain attachment sites, the extracellular domain of this protein has a unique structure. The transmembrane and cytoplasmic domains, in contrast, are highly similar to the corresponding domains of fibroglycan and syndecan, the two cell surface proteoglycans that figured as models for the design of the antisense primer. This similarity includes the conservation of four tyrosine residues, one immediately in front of the stop transfer sequence and three in the cytoplasmic segment, and of the most proximal and most distal cytoplasmic sequences. The cDNA detects a single 2.6-kb message in cultured human lung fibroblasts and in a variety of human epithelial and fibroblastic cell lines. Polyclonal and monoclonal antibodies raised against the encoded peptide after expression as a beta-galactosidase fusion protein react with the 35-kD coreprotein of a cell surface heparan sulfate proteoglycan of human lung fibroblasts and decorate the surface of many cell types. We propose to name this proteoglycan "amphiglycan" (from the Greek words amphi, "around, on both sides of" and amphoo, "both") referring to its domain structure which extends on both sides of the plasmamembrane, and to its localization around cells of both epithelial and fibroblastic origin.

Amino Acid Sequence↗
PubMed1994

Syndecan 4 heparan sulfate proteoglycan is a selectively enriched and widespread focal adhesion component.

Focal adhesion formation in fibroblasts results from complex transmembrane signaling processes initiated by extracellular matrix molecules. Although a role for integrins with attendant tyrosine kinases has been established, there is evidence that cell surface heparan sulfate proteoglycans (HSPGs) are also involved with an associated role of protein kinase C. The identity of the proteoglycan has remained elusive, but we now report that syndecan 4 (ryudocan/amphiglycan) is present in focal adhesions of a number of cell types. Affinity-purified antibodies raised against a unique portion of the cytoplasmic domain of syndecan 4 core protein recognized an HSPG of similar characteristics to those of syndecan 4. These antibodies stained focal adhesions only after cell permeabilization and recognized differing mammalian species. Syndecan 4 was associated with focal adhesions that contained either beta 1 or beta 3 integrin subunits and those that formed on substrates of fibronectin, laminin, vitronectin, or type I collagen. No focal adhesions were found that were vinculin-containing but lacked syndecan 4. In contrast, syndecan 2, whose cytoplasmic domain is closely homologous to syndecan 4, does not appear to be a focal adhesion component. Thus, syndecan 4 represents a new transmembrane focal adhesion component, probably involved in their assembly.

Amino Acid Sequence↗
PubMed1993

Isolation and characterization of ryudocan and syndecan heparan sulfate proteoglycans, core proteins, and cDNAs from a rat endothelial cell line.

We have isolated heparan sulfate proteoglycans (HSPGs) from cloned rat microvascular endothelial cells using a combination of ion-exchange chromatography, affinity fractionation with antithrombin III (AT III), and gel filtration in denaturing solvents. The anticoagulantly active heparan sulfate proteoglycans (HSPGact) which bind tightly to AT III bear mainly anticoagulantly active heparan sulfate (HSact) whereas the anticoagulantly inactive heparan sulfate proteoglycans (HSPGinact) possess mainly anticoagulantly inactive heparan sulfate (HSinact). The core proteins of HSPGact and HSPGinact were isolated by treatment with Flavobacterium heparitinase and purification by ion-exchange chromatography. SDS-PAGE showed that both sets of core proteins exhibited three major components with M(r) of 25-, 30-, and 50-kD, respectively. Peptide mapping revealed that HSPGact and HSPGinact possess extremely similar core proteins. The primary sequences of internal peptides obtained from HSPGinact core proteins and the NH2-terminal sequence analyses of the 25-kD component from the HSPGinact core proteins demonstrate that the 30-kD component is a previously unidentified species--designated as ryudocan--with the 25-kD component representing a proteolytic degradation product; while the 50-kD component is the rat homolog of syndecan [Saunders S, Jalkanen M, O'Farrell S, Bernfield M: J Cell Biol 1989; 108:1547-1556]. Specific oligonucleotide probes were obtained for ryudocan and syndecan by PCR, and the corresponding cDNAs were isolated from a RFP-EC library. The cDNAs encode type I integral membrane proteins of 202 and 313 amino acids, respectively, which have homologous transmembrane and intracellular domains but very distinct extracellular regions. In particular, ryudocan exhibits only 3 potential glycosaminoglycan (GAG) attachment sites within the extracellular region while syndecan has 5 GAG attachment sites within the same domain. The levels of ryudocan and syndecan mRNA were measured by quantitative PCR in primary microvascular endothelial cells and associated non-endothelial cells isolated by cell sorting. Ryudocan and syndecan mRNAs were abundantly expressed in both populations representing about 0.1-0.5% of mRNA.

Amino Acid Sequence↗
PubMed1992

Molecular cloning and expression of two distinct cDNA-encoding heparan sulfate proteoglycan core proteins from a rat endothelial cell line.

The cloned rat fat pad endothelial cell (RFP-EC) line synthesizes anticoagulantly active heparan sulfate proteoglycans (HSPGact) and anticoagulantly inactive heparan sulfate proteoglycans (HSPGinact), both of which exhibit 25-, 30-, and 50-kDa core proteins of extremely similar structure. The primary sequences of internal peptides obtained from HSPGinact core proteins and the NH2-terminal sequence analyses of the 25-kDa component from the HSPGinact core proteins demonstrate that the 30-kDa component is a previously unidentified species, designated as ryudocan, with the 25-kDa component representing a proteolytic degradation product, while the 50-kDa component is the rat homolog of syndecan (Saunders, S. Jalkanen, M., O'Farrell, S., and Bernfield, M. (1989) J. Cell Biol. 108, 1547-1556). Specific oligonucleotide probes were obtained for ryudocan and syndecan by polymerase chain reaction, and the corresponding cDNAs were isolated from a RFP-EC library. The cDNAs encode type I integral membrane proteins of 202 and 313 amino acids, respectively, which have homologous transmembrane and intracellular domains but very distinct extracellular regions. In particular, ryudocan exhibits only three potential glycosaminoglycan attachment sites within the extracellular region while syndecan has five glycosaminoglycan attachment sites within the same domain. Both species are expressed in RFP-EC lines, primary rat aortic smooth muscle cells and primary rat skin fibroblast cells. The levels of ryudocan and syndecan mRNA were measured by quantitative polymerase chain reaction in primary microvascular endothelial cells and closely associated non-endothelial cells isolated by cell sorting. Ryudocan and syndecan mRNAs were abundantly expressed in both populations representing about 0.1-0.5% of mRNA.

Amino Acid Sequence↗
PubMed1994

Characterization of ryudocan glycosaminoglycan acceptor sites.

The specificity of the glycosaminoglycan (GAG) acceptor sites of ryudocan was examined by stably expressing epitope-tagged ryudocan cDNA constructs in mouse L cells, which normally produce this proteoglycan. Immunopurified ryudocan was glycanated with both heparan sulfate (HS) and chondroitin sulfate (CS). The attachment of GAGs to ryudocan was prevented by creating Ser-->Thr mutations in all possible combinations at positions 44, 65, and 67. The resulting ryudocan of exogenous origin was immunopurified and evaluated with regard to attached GAG chains. The data reveal that ryudocan possesses three functional GAG attachment sites, that the sites are always occupied with GAG chains, and that each site is capable of bearing either HS or CS. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis patterns of GAG lyase digests of intact ryudocan reveal the production of the following multiple isoforms: pure HS-ryudocan, various HS/CS-hybrids, and pure CS-ryudocan. The data suggest that the occupancy bias of each site for HS or CS is slight and that each site functions in a relatively independent fashion. The GAG lyase analysis of partially purified L cell proteoglycans shows two pure CS-homoglycans with core proteins of M(r) = 130,000 and 52,000, respectively. A similar analysis of immunopurified L cell glypican demonstrates that this species only exists as a pure HS-homoglycan. The production of pure homoglycans by this clonal cell line strongly suggests that the functional promiscuity of GAG attachment sites of ryudocan must be encoded in the core protein structure. This property of ryudocan is not peculiar to L cells, as ryudocan synthesized by early passage human endothelial cells also bears both HS and CS. The production of multiple isoforms of ryudocan may serve to expand the functional versatility of this cell surface component and allow it to participate in many different biologic processes.

Amino Acid Sequence↗
PubMed1994

Pathway-specific regulation of the synthesis of anticoagulantly active heparan sulfate.

L cells and endothelial cells synthesize a heparan sulfate (HS) subpopulation, HSact, that exhibits anticoagulant activity due to a specific monosaccharide sequence; the remaining heparan sulfate, HSinact, lacks this region of defined structure and is anticoagulantly inactive. HSact biosynthesis was examined in these two cell types by stably expressing epitope-tagged rat ryudocan (ryudocan12CA5), which possesses three glycosaminoglycan (GAG) acceptor sites. Both HSact and HSinact were present on ryudocan12CA5 isolated from L cells and endothelial cells; thus, a core protein with a unique primary sequence initiates the synthesis of both GAGs. The expression in L cells of ryudocan12CA5 variants containing a single functional GAG acceptor site demonstrated that each of the three acceptor regions initiates the synthesis of both types of GAGs to a similar extent. Most importantly, in both cell types total HSact generation declined as a function of ryudocan12CA5 overexpression even though HSinact production increased linearly as a function of this variable. This discordant relationship is a general property of the biosynthetic machinery since in both cell types HSact production was reduced to an equal extent on protein cores of either exogenous or endogenous origins. The suppression of HSact generation was also observed with a secreted form of core protein lacking transmembrane and cytoplasmic domains or by a GAG acceptor site mutated form of core protein incapable of augmenting GAG synthesis. These results suggest that elevated intracellular levels of core protein saturate the capacity of a critical component of the HSact biosynthetic machinery. This critical component is not a member of the common set of biosynthetic enzymes involved in the production of HSact and HSinact since no structural changes were observed in either GAG during overexpression of core protein. Based upon the above data, we conclude that increased intracellular levels of ryudocan probably act by saturating the capacity of components which regulate HSact production by coordinating the function of biosynthetic enzymes.

Amino Acid Sequence↗
PubMed1994

Characterization of a cell mutant specifically defective in the synthesis of anticoagulantly active heparan sulfate.

We have investigated the characteristics of clonal L cell mutant VI-7 that has previously been demonstrated to exhibit reduced levels of cell surface proteoglycans containing heparan sulfate (HS) with regions of defined monosaccharide sequence that interact with antithrombin (HSact) (de Agostini, A. L., Lau, H. K., Leone, C., Youssoufian, H., and Rosenberg, R. D. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 9784-9788). Pulse labeling revealed that the synthesis of HSact in mutant cells, as compared to wild-type cells, was reduced by 5-7-fold, which is identical to the previously observed reduction in cell surface-bound antithrombin. This alteration is independent of growth state since production of HSact by mutant cells, as compared to wild-type cells, is decreased to a similar extent in exponentially growing and post-confluent cultures. The synthetic defect was specific for HSact since production of total HS and chondroitin sulfate by mutant cells, as compared to wild-type cells, was identical in magnitude. The synthetic abnormality is not due to an alteration in core protein since complementation was not observed when mutant cells were stably transfected with the epitope-tagged ryudocan cDNA which can initiate HSact production. Structural analyses revealed that HS from mutant cells, as compared to wild-type cells, exhibited normal molecular weight, extent and distribution of sulfate, and disaccharide composition, which indicate that the mutation did not affect HS biosynthetic enzymes. Together, the data suggest that mutant VI-7 is defective in a regulatory component which directly or indirectly coordinates HS biosynthetic enzymes to specifically generate the defined monosaccharide sequence of HSact.

Animals↗
PubMed1994

Smooth muscle cell expression of extracellular matrix genes after arterial injury.

Accumulation of extracellular matrix (ECM) after arterial injury is an important event in the development of intimal thickening and is modulated by heparin. To investigate the regulation of matrix protein expression, we have analyzed messenger RNA levels by Northern blotting for various ECM proteins in the rat carotid artery balloon injury model. RNA was extracted from normal arteries and from intima-medial preparations at 2 days, 1 week, 2 weeks, and 4 weeks after balloon injury of arteries in animals receiving either saline or heparin infusion. Transcripts for the heparan sulfate proteoglycans perlecan, syndecan, and ryudocan; the chondroitin sulfate proteoglycan versican; the dermatan sulfate proteoglycan biglycan; type I procollagen; and tropoelastin all were increased on Northern blots beginning at 1 week after injury. By in situ hybridization, the transcripts for elastin nd biglycan were primarily localized to smooth muscle cells in the intima and were diminished by heparin in proportion to the decrease in intimal mass. Other matrix genes (perlecan, ryudocan) were expressed in the intima and media and were not affected by heparin. The results support the conclusion that ECM gene expression is a relatively late event in the response of the carotid artery, and that some of the genes are expressed only in the intima whereas others are expressed in both the intima and media.

Animals↗