The gene structure and organization of mouse PG-Lb, a small chondroitin/dermatan sulphate proteoglycan

PG-Lb was originally characterized as a small chondroitin/dermatan sulphate proteoglycan expressed preferentially in the zones of flattened chondrocytes in developing chick limb cartilage. The occurrence of this proteoglycan in mammalian cartilage has been shown by the isolation of a cDNA clone from mouse cartilage cDNA library [Kurita, Shinomura,Ujita, Zako, Kida, Iwata and Kimata (1996) Biochem. J. 318, 909-914]. To understand the regulation mechanisms for such a unique expression, we have investigated a genomic DNA structure of the PG-Lb gene. The gene is composed of seven exons and six introns spanning more than 50 kb. The leucine-rich repeats are encoded from exon V to exon VII. The transcription initiation site has been determined by rapid amplification of the cDNA ends ('5'-RACE'). The possible TATA box was detected about 90 bp upstream of the adenosine residue that was numbered as position +1. Further analyses of 1.5 kb of the 5' flanking region and 2.2 kb of the first intron have revealed several potential binding motifs for transcription factors such as Sox 5 and 9. The presence of those sequences in the PG-Lb gene was discussed in relation to the unique expression of this proteoglycan. The chromosomal localization of the murine PG-Lb gene was determined to be on the mouse chromosome 10 by the fluorescence-in-situ-hybridization ('FISH') method.

Molecular characterization and expression of heparan-sulfate 6-sulfotransferase. Complete cDNA cloning in human and partial cloning in Chinese hamster ovary cells

Heparan-sulfate 6-sulfotransferase (HS6ST) catalyzes the transfer of sulfate from 3'-phosphoadenosine 5'-phosphosulfate to position 6 of the N-sulfoglucosamine residue of heparan sulfate. The enzyme was purified to apparent homogeneity from the serum-free culture medium of Chinese hamster ovary (CHO) cells (Habuchi, H., Habuchi, O., and Kimata, K. (1995) J. Biol Chem. 270, 4172-4179). From the amino acid sequence data of the purified enzyme, degenerate oligonucleotides were designed and used as primers for the reverse transcriptase-polymerase chain reaction using poly(A)+ RNA from CHO cells as a template. The amplified cDNA fragment was then used as a probe to screen a cDNA library of CHO cells. The cDNA clone thus obtained encoded a partial peptide sequence composed of 236 amino acid residues that included the sequences of six peptides obtained after endoproteinase digestion of the purified enzyme. This cDNA clone was applied to the screening of a human fetal brain cDNA library by cross-hybridization. The isolated cDNA clones contained a whole open reading frame that predicts a type II transmembrane protein composed of 401 amino acid residues. No significant amino acid sequence identity to any other proteins, including heparan-sulfate 2-sulfotransferases, was observed. When the cDNA for the entire coding sequence of the protein was inserted into a eukaryotic expression vector and transfected into COS-7 cells, the HS6ST activity increased 7-fold over the control. The FLAG fusion protein purified by anti-FLAG affinity chromatography showed the HS6ST activity alone. Northern blot analysis revealed the occurrence of a single transcript of 3.9 kilobases in both human fetal brain and CHO cells. The results, together with the ones from our recent cDNA analysis of heparan-sulfate 2-sulfotransferase (Kobayashi, M., Habuchi, H., Yoneda, M., Habuchi, O., and Kimata, K. (1997) J. Biol. Chem. 272, 13980-13985), suggest that at least two different gene products are responsible for 6- and 2-O-sulfations of heparan sulfate.

Heparan/chondroitin/dermatan sulfate primer 2-(6-hydroxynaphthyl)-O-beta-D-xylopyranoside preferentially inhibits growth of transformed cells

Xylose forms the direct carbohydrate-protein link in extra- or pericellular proteoglycans (PGs) that are substituted with either chondroitin sulfate (CS)/dermatan sulfate (DS) and/or heparan sulfate (HS). Cell surface PGs carrying HS are important regulators of cell growth. Xylose coupled to an aromatic compound can enter cells and initiate either CS/DS synthesis or both HS and CS/DS synthesis, depending on the nature of the aromatic adduct. Here, we show that 2-(6-hydroxynaphthyl)-O-beta-D-xylopyranoside, which can prime both types of glycan chains, inhibits growth of a set of normal and transformed cells. Transformed cells are preferentially inhibited, and at a concentration of 0.15-0.20 mM xyloside, transformed cells are totally growth arrested, whereas normal cells are only < or = 50% inhibited. No inhibition of growth is observed with the stereoisomeric 2-(6-hydroxynaphthyl)-O-beta-L-xylopyranoside, which does not prime glycosaminoglycan synthesis at all; with the nonhydroxylated 2-naphthyl-O-beta-D-xylopyranoside, which only primes CS/DS synthesis under these conditions; or with p-nitrophenyl-O-beta-D-xylopyranoside, which is known to prime only CS/DS synthesis. We conclude that growth inhibition is due to priming of HS and/or CS/DS synthesis, which may either lead to the formation of specific antiproliferative glycans or glycan fragments or to interference with endogenous PG synthesis and turnover.

The gene structure and promoter sequence of mouse hyaluronan synthase 1

The structure and organization of mouse hyaluronan synthase 1 gene, HAS1 were determined by direct sequencing of lambda phage clones carrying the entire gene and by application of the long and accurate (LA)-PCR method to amplify regions encompassing the exon-intron boundaries and all of the exons. This gene spans about 11kb of genomic DNA and consists of 5 exons and 4 introns. A similarity in the exon-intron organization was found between the genes of mouse HAS1 and Xenopus laevis DG42 which was recently identified as Xenopus hyaluronan synthase. The transcription initiation site was determined by rapid amplification of the cDNA ends (5'-RACE). Position +1 is located 55 nucleotides upstream of the ATG initiation codon. The promoter region of the HAS1 gene has no typical TATA box, but contains a CCAAT box located 190 nucleotides upstream of the transcription initiation site. Further analysis of 1.4 kb of the 5' flanking region revealed several potential binding motifs for transcription factors. This information about the gene structure may be useful for further studies on the promoter activity.

Modulation of cytokine function by heparan sulfate proteoglycans: sophisticated models for the regulation of cellular responses to cytokines

Cytokines are diffusible, soluble factors with pleiotropic actions. The ability of some cytokines to blind to and be immobilized by heparan sulfate proteoglycan (HS-PG) on either the surface of cells or within the extracellular matrix accentuates their action by 1) promoting the accumulation of cytokines at high concentrations in the appropriate location to encounter their target cells; 2) activating cytokines by inducing conformational changes in the bound cytokine; 3) promoting conformation-dependent association or polymerization of cytokines and their cell-surface receptors and facilitating the assembly of the appropriate molecular complex to initiate signal transduction; and 4) protecting cytokines from both chemical and physiological degradation. Furthermore, many interactions between HS-PG and cytokines are highly specific. Thus, variations in the HS-PG, core protein, or carbohydrate sequences that are seen at different sites or that occur with inflammation will determine which cytokines bind to a particular HS-PG, providing multiple options for cytokine binding and regulation. HS-PG therefore plays a pivotal role in regulating the function of the large number of heparin-binding cytokines. The involvement of HS-PG in promoting paracrine, autocrine, juxtacrine, and matricrine functions provides a powerful and sophisticated model for regulating cytokine-mediated cellular interactions. These functions of HS-PG have direct relevance for the control of cell growth as well as for the pathogenesis of leukocyte trafficking and inflammation, cell infiltration, and tumor metastasis. Therapies aimed at modulating HS-PG/cytokine binding may provide powerful tools for inhibiting unwanted cytokine effects in several disease processes.

Assembly of basement membrane in vitro by cooperation between alveolar epithelial cells and pulmonary fibroblasts

To investigate basement membrane formation by cooperation between pneumocytes and pulmonary fibroblasts, we cultured type II alveolar epithelial cells obtained from rats transfected with SV40-large T antigen gene (SV40-T2 cells) on type I collagen matrices. On fibroblasts-embedded gel (T2-Fgel), SV40-T2 cells ultrastructurally formed a continuous and thin layer of lamina densa, while on collagen gel without fibroblasts (T2-gel) SV40-T2 cells produced only discontinuous and diffuse deposits. Stripping SV40-T2 cells off the tissues by H2O2 treatment revealed a continuous and plane surface of lamina densa assembled on the T2-Fgel tissue, whereas only amorphous deposits appeared on the T2-gel tissue. Immunolocalization of major basement membrane components showed that type IV collagen, laminin, perlecan and entactin (nidogen) were continuously integrated on the lamina densa in T2-Fgel. In T2-gel, all these components were discontinuously distributed beneath SV40-T2 cells. The contribution of pulmonary fibroblasts to the assembly of basement membrane through reorganization of collagen matrix and/or soluble factors was examined by the cultured of SV40-T2 cells on the freeze-thawed fibroblast-tissue and/or with the fibroblast-conditioned medium. Both SV40-T2 cells on the freeze-thawed fibroblast-tissue and SV40-T2 cells in T2-gel in the fibroblast-conditioned medium failed to produce a lamina densa. SV40-T2 cells could assemble a lamina densa only on the freeze-thawed fibroblast-tissue in the fibroblast-conditioned medium. These results show that the basement membrane components are assembled to a lamina densa by combination of the reorganization of collagen matrix and the supply of soluble factors by pulmonary fibroblasts.

cAMP receptor protein-cAMP plays a crucial role in glucose-lactose diauxie by activating the major glucose transporter gene in Escherichia coli

The inhibition of beta-galactosidase expression in a medium containing both glucose and lactose is a typical example of the glucose effect in Escherichia coli. We studied the glucose effect in the lacL8UV5 promoter mutant, which is independent of cAMP and cAMP receptor protein (CRP). A strong inhibition of beta-galactosidase expression by glucose and a diauxic growth were observed when the lacL8UV5 cells were grown on a glucose-lactose medium. The addition of isopropyl beta-D-thiogalactoside to the culture medium eliminated the glucose effect. Disruption of the crr gene or overproduction of LacY also eliminated the glucose effect. These results are fully consistent with our previous finding that the glucose effect in wild-type cells growing in a glucose-lactose medium is not due to the reduction of CRP-cAMP levels but is due to the inducer exclusion. We found that the glucose effect in the lacL8UV5 cells was no longer observed when either the crp or the cya gene was disrupted. Evidence suggested that CRP-cAMP may not enhance directly the lac repressor action in vivo. Northern blot analysis revealed that the mRNA for ptsG, a major glucose transporter gene, was markedly reduced in a delta crp or delta cya background. The constitutive expression of the ptsG gene by the introduction of a multicopy plasmid restored the glucose effect in delta cya or delta crp cells. We conclude that CRP-cAMP plays a crucial role in inducer exclusion, which is responsible for the glucose-lactose diauxie, by activating the expression of the ptsG gene.

Transient expression of PG-M/versican, a large chondroitin sulfate proteoglycan in developing chicken retina

We previously showed the expression of PG-M/versican in embryonic chicken retina. In this study, we characterized the alternatively spliced forms of PG-M/versican and their developmental regulation to investigate the implication of PG-M/versican in neurite outgrowth from retinal cells during development. On day 5, the immunolocalization of PG-M was first observed at the inner surface of neural retina. On day 7, the pronounced staining was observed in the nerve fiber layer and inner plexiform layer where neural networks of ganglion cells were being formed. As the development proceeded, more intensive staining was observed in these layers. The staining peaked on day 14 and then decreased. Northern analysis and western blotting revealed the presence of a single-sized transcript (13 kb) and the PG-M/versican core protein (550 kDa) on day 14, but the absence of any transcripts or protein bands on day 20, indicating a transient expression of PG-M+ (VO), the alternatively spliced form with the most abundant sites for the chondroitin sulfate attachment. Taken together, it is likely that PG-M/versican is involved in neurite outgrowth from ganglion cells during retinal development, and antiadhesion activity of its chondroitin sulfate chains may be important for regulation.

Selectivity of electron-donor- and electron-acceptor-bonded silica packing materials for hydrophobic environmental contaminants in polar and non-polar eluents

Electron-acceptor-bonded stationary phases, 2-(nitrophenyl)ethylsilyl (NPE) and 3-(p-nitrophenoxy)propylsilyl (NPO), and electron-donor-bonded phases, 3-(N-carbazolyl)propylsilyl (CZP), 2-(1-pyrenyl)ethylsilyl (PYE), and 5-coronenylpentylsilyl (COP), were prepared from silica particles and their selectivities were examined in both polar and non-polar solvents for specific isomers of polychlorodibenzo-p-dioxins (PCDDs), hexachloronaphthalenes (HxCNs) and planar and non-planar polychlorobiphenyl (PCB) congeners. Although no single stationary phase was able to separate all the isomer pairs that are coproduced during the synthesis of the PCDDs and HxCNs, pairs can be separated by selecting a suitable stationary phase and solvent. The separation of mixtures of PCDD isomers were found to be most successful with PYE and NPO phases, which yielded the opposite elution orders for each isomer pair that is produced as a mixture. Similar results were obtained for the HxCN isomers that were separated on PYE and CZP phases. The COP phase provided easier separation of non-ortho-substituted and mono-ortho-substituted PCBs from the other PCBs based on the planarity than PYE phase.

Identification of hyaluronan-binding domains of aggrecan

Aggrecan, a large cartilage proteoglycan, interacts with hyaluronan (HA), to form aggregates which function to resist compression in joints. The N-terminal region of aggrecan contains two structurally related globular domains, G1 and G2 separated by IGD domain. The G1 domain consists of three subdomains, A, B, and B', structural features characteristic to many other HA-binding proteoglycans. Here, we studied the interaction of aggrecan domains with HA using recombinant proteins expressed in 293 cells, an embryonal kidney cell line. Deglycosylation of the recombinant aggrecan fragment reduced the HA binding activity. We found that both the B and B' subdomains were required for HA binding and that a single module of A, B, or B' was unable to bind HA. The A subdomain increased the HA binding activity of the B-B' region. The G2 domain had no HA binding activity confirming previous reports. Studies of HA-binding properties using a BIAcoreTM biosensor system revealed that the KD of recombinant aggrecan fragment (AgW) consisting of G1, IGD, and G2 was 0.226 microM, whereas the KD of another HA-binding protein, native bovine link protein, is 0.089 microM. In contrast, AgMut11 which lacked subdomain A showed little HA binding activity. AgMut12 consisting of only B-B' had a 3.4-fold lower affinity and AgMut13 containing A-B-B' was 1.5-fold lower than AgW. These results suggest that carbohydrates are essential for high level aggrecan binding to HA and that the A subdomain of aggrecan functions in a cooperative manner with subdomains B and B'.

Widespread expression of chondroitin sulfate-type serglycins with CD44 binding ability in hematopoietic cells

Serglycin is a family of small proteoglycans with Ser-Gly dipeptide repeats and is modified with various types of glycosaminoglycan side chains. We previously demonstrated that chondroitin sulfate-modified serglycin is a novel ligand for CD44 involved in the adherence and activation of lymphoid cells. In this study, we investigated the production and distribution of CD44 binding serglycins in various hematopoietic cells and characterized their carbohydrate side chains. Immunoprecipitation analysis using CD44-IgG and polyclonal antibody against the serglycin core peptide demonstrated that various serglycin species capable of binding CD44 are produced by a variety of hematopoietic cells including lymphoid cells, myeloid cells, and a few tumor cell lines. Glycosaminoglycans on these serglycins, which are essential for CD44 binding, are composed of chondroitin 4-sulfate or a mixture of chondroitin 4-sulfate and chondroitin 6-sulfate, but no heparin or heparan sulfate side chain was detected. The serglycins are also secreted by normal splenocytes, lymph node lymphocytes, and bone marrow cells, whereas they are secreted in very small amounts by normal thymocytes. Secretion of serglycins is greatly enhanced by mitogenic stimulation with concanavalin A or lipopolysaccharide. Our results showed that serglycin, unlike hyaluronate, is produced and secreted in a functional (CD44 binding) form by many members of the hematopoietic system including various lymphocyte subsets. Our data suggest that serglycin may serve as a major ligand for CD44 in various events in the lymphohematopoietic system.

Localization of perlecan (or a perlecan-related macromolecule) to isolated microglia in vitro and to microglia/macrophages following infusion of beta-amyloid protein into rodent hippocampus

The origin of the heparan sulfate proteoglycan (PG), perlecan, in beta-amyloid protein (A beta)-containing amyloid deposits in Alzheimer's disease (AD) brain is not known. In the present investigation we used indirect immunofluorescence, SDS-PAGE, and Western blotting with a specific perlecan core protein antibody to identify possible cell candidates of perlecan production in both primary cell cultures and in a rat infusion model. Double and triple-labeled indirect immunofluorescence was performed on dissociated primary rat septal cultures using antibodies for specific identification of cell types and for perlecan core protein. In mixed cultures of both embryonic day 18 (containing neurons and glia) and postnatal day 2-3 (devoid of neurons), microglia identified by labeling with OX-42 or anti-ED1 were the only cell type also double labeled with an affinity-purified polyclonal antibody against perlecan core protein. Similar immunolabeling of microglia with the anti-perlecan antibody was also observed in purified cultures of post-natal rat microglia. Analyses of PGs from cultured postnatal rat microglia by Western blotting using a polyclonal antibody against perlecan core protein revealed an approximately 400 kDa band in cell layer, which was intensified following heparitinase/heparinase digestion, suggestive of perlecan core protein. Other lower Mr bands were also found implicating either degradation of the 400 kDa core protein or the presence of separate and distinct gene products immunologically related to perlecan. Reverse transcription followed by polymerase chain reaction using human perlecan domain I specific primers demonstrated perlecan mRNA in cultured human microglia derived from postmortem normal aged and AD brain. Following a 1-week continuous infusion of A beta (1-40) into rodent hippocampus, immunoperoxidase immunocytochemistry and double-labeled immunofluorescent studies revealed perlecan accumulation primarily localized to microglia/macrophages within the A beta infusion site. These studies have identified microglia/macrophages as one potential source of perlecan (or a perlecan-related macromolecule) which may be important for the ongoing accumulation of both perlecan and A beta in the amyloid deposits of AD.

Turnover of heparan sulfate depends on 2-O-sulfation of uronic acids

To study how the pattern of sulfation along a heparan sulfate chain affects its turnover, we examined heparan sulfate catabolism in wild-type Chinese hamster ovary cells and mutant pgsF-17, defective in 2-O-sulfation of uronic acid residues (Bai, X., and Esko, J. D. (1996) J. Biol. Chem. 271, 17711-17717). Heparan sulfate from the mutant contains normal amounts of 6-O-sulfated glucosamine residues and iduronic acid and somewhat higher levels of N-sulfated glucosamine residues but lacks any 2-O-sulfated iduronic or glucuronic acid residues. Pulse-chase experiments showed that both mutant and wild-type cells transport newly synthesized heparan sulfate proteoglycans to the plasma membrane, where they shed into the medium or move into the cell through endocytosis. Internalization of the cell-associated molecules leads to sequential endoglycosidase (heparanase) fragmentation of the chains and eventual lysosomal degradation. In wild-type cells, the chains begin to degrade within 1 h, leading to the accumulation of intermediate (10-20-kDa) and small (4-7-kDa) oligosaccharides. Mutant cells did not generate these intermediates, although internalization and intracellular trafficking of the heparan sulfate chains appeared normal, and the chains degraded with normal kinetics. This difference was not due to defective heparanase activities in the mutant, since cytoplasmic extracts from mutant cells cleaved wild-type heparan sulfate chains in vitro. Instead, the heparan sulfate chains from the mutant were relatively resistant to degradation by cellular heparanases. These findings suggest that 2-O-sulfated iduronic acid residues in heparan sulfate are important for cleavage by endogenous heparanases but not for the overall catabolism of the chains.

Dwarfism and age-associated spinal degeneration of heterozygote cmd mice defective in aggrecan

Mouse cartilage matrix deficiency (cmd) is an autosomal recessive disorder caused by a genetic defect of aggrecan, a large chondroitin sulfate proteoglycan in cartilage. The homozygotes (-/-) are characterized by cleft palate and short limbs, tail, and snout. They die just after birth because of respiratory failure, and the heterozygotes (+/-) appear normal at birth. Here we report that the heterozygotes show dwarfism and develop spinal misalignment with age. Within 19 months of age, they exhibit spastic gait caused by misalignment of the cervical spine and die because of starvation. Histological examination revealed a high incidence of herniation and degeneration of vertebral discs. Electron microscopy showed a degeneration of disc chondrocytes in the heterozygotes. These findings may facilitate the identification of mutations in humans predisposed to spinal degeneration.

Molecular cloning and expression of Chinese hamster ovary cell heparan-sulfate 2-sulfotransferase

Heparan-sulfate 2-sulfotransferase (HS2ST), which catalyzes the transfer of sulfate from 3'-phosphoadenosine 5'-phosphosulfate to L-iduronic acid at position 2 in heparan sulfate, was purified from cultured Chinese hamster ovary (CHO) cells to apparent homogeneity (Kobayashi, M., Habuchi, H., Habuchi, O., Saito, M., and Kimata, K. (1996) J. Biol. Chem. 271, 7645-7653). The internal amino acid sequences were obtained from the peptides after digestion of the purified protein with a combination of endoproteinases. Mixed oligonucleotides based on the peptide sequences were used as primers to obtain a probe fragment by reverse transcriptase-polymerase chain reaction using CHO cell poly(A)+ RNA as template. The clone obtained from a CHO cDNA library by screening with the probe is 2.2 kilobases in size and contains an open reading frame of 1068 bases encoding a new protein composed of 356 amino acid residues. The protein predicts a type II transmembrane topology similar to other Golgi membrane proteins. Messages of 5.0 and 3.0 kilobases were observed in Northern analysis. Evidence that the cDNA clone corresponds to the purified HS2ST protein is as follows. (a) The predicted amino acid sequence contains all five peptides obtained after endoproteinase digestion of the purified protein; (b) the characteristics of the predicted protein fit those of the purified protein in terms of molecular mass, membrane localization, and N-glycosylation; and (c) when the cDNA containing the entire coding sequence of the enzyme in a eukaryotic expression vector was transfected into COS-7 cells, the HS2ST activity increased 2.6-fold over controls, and the FLAG-HS2ST fusion protein purified by affinity chromatography showed the HS2ST activity alone.

Chromosomal localization of the human and mouse hyaluronan synthase genes

We have recently identified a new vertebrate gene family encoding putative hyaluronan (HA) synthases. Three highly conserved related genes have been identified, designated HAS1, HAS2, and HAS3 in humans and Has1, Has2, and Has3 in the mouse. All three genes encode predicted plasma membrane proteins with multiple transmembrane domains and approximately 25% amino acid sequence identity to the Streptococcus pyogenes HA synthase, HasA. Furthermore, expression of any one HAS gene in transfected mammalian cells leads to high levels of HA biosynthesis. We now report the chromosomal localization of the three HAS genes in human and in mouse. The genes localized to three different positions within both the human and the mouse genomes. HAS1 was localized to the human chromosome 19q13.3-q13.4 boundary and Has1 to mouse Chr 17.HAS2 was localized to human chromosome 8q24.12 and Has2 to mouse Chr 15. HAS3 was localized to human chromosome 16q22.1 and Has3 to mouse Chr 8. The map position for HAS1 reinforces the recently reported relationship between a small region of human chromosome 19q and proximal mouse chromosome 17. HAS2 mapped outside the predicted critical region delineated for the Langer-Giedion syndrome and can thus be excluded as a candidate gene for this genetic syndrome.

Alternative splicing of the unique "PLUS" domain of chicken PG-M/versican is developmentally regulated

We investigated the occurrence of alternatively spliced forms (V0, V1, V2, and V3) of PG-M/versican, a large chondroitin sulfate proteoglycan in developing chicken retinas, using the reverse transcription-polymerase chain reaction. We characterized the PLUS domain, which is apparently unique to the chicken molecule and is regulated by alternative splicing. PG-M in chicken retinas consisted of four forms with (V0, V1, V2, and V3) and two forms without (V1 and V3) the PLUS domain (PG-M+ and PG-M-, respectively). The four forms of PG-M+ were found in all samples examined, but the occurrence of the two PG-M- forms was regulated developmentally. Genomic analysis has revealed that the PLUS and CS-alpha domains are encoded by a single exon, and this exon has an internal alternative 5'-splice donor site, allowing alternative spliced forms that do not include the 3'-end of the exon. Sequences corresponding to the chicken PLUS domain (plus) were not found in mouse and human and may have disappeared during evolution. Sequence similarity suggests that the PLUS domain corresponds to the keratan sulfate attachment domain of aggrecan and that it has a distinct function in the chicken eye.

Inhibition of experimental metastasis and cell adhesion of murine melanoma cells by chondroitin sulfate-derivatized lipid, a neoproteoglycan with anti-cell adhesion activity

Chondroitin sulfate dipalmitoylphosphatidylethanolamine (CS-PE), when immobilized onto substratum, inhibited the adhesion of B16F10 mouse melanoma cells to fibronectin-coated dishes (anti-adhesion activity). CS-PE showed the most potent anti-adhesion activity for the melanoma cells among various GAG-PEs. CS-PE also inhibited the adhesion of B16F10 cells to Matrigel and the invasion of the cells into Matrigel. In the in vivo system of experimental metastasis, administration of B16F10 cells with CS-PE into C57BL/6 mice significantly inhibited lung metastasis. The inhibition degree of CS or hyaluronic acid-PE was lower than CS-PE. CS-PE administered intravenously into mice before the injection of B16F10 cells also inhibited metastasis. Pretreatment of B16F10 cells with CS-PE caused some but a lower degree of inhibition. When CS-PE was injected intravenously into mice, more binding in the lung was found than when CS was injected. CS-PE but not CS inhibited the retention in the lung of fluorochrome-labeled B16F10 cells when injected intravenously into mice. Since there was no significant effect of CS-PE on the viability and growth of B16F10 cells, the results suggest that CS-PE immobilized onto the subendothelial matrix may prevent melanoma cells from adhering to the subendothelial substrata of lung capillaries and inhibit subsequent invasion processes of metastasis.

Hyaluronic acid of wound fluid in adult and fetal rabbits

Fetal wound healing proceeds without fibrosis or scar formation in contrast to adult wound healing. The mechanisms responsible for this remarkable process are mediated in part through a fetal wound extracellular matrix rich in hyaluronic acid (HA). Polyvinylalcohol sponge (PVA) wound implants were placed pervertebrally at 24 days' gestation in fetal (N = 118) rabbits and in adult (N = 44) rabbits, and then harvested at 1, 2, 3, 4, 5, and 7 days postwounding. To analyze the fetal and adult wound matrix, the HA concentration of wound fluid within the PVA sponge was quantitated using a newly developed assay. A significantly increased (P < .05) HA deposition on days 1 through 7 in the fetal wounds was found compared with the adult wound. These observations may suggest an important physiologic role in fetal wound healing by providing a more fluid and malleable matrix. These results, coupled with earlier findings of the lack of an acute inflammatory response in the fetus, further support the hypothesis that fetal response to injury is significantly different from adult response in this prescience of an implanted PVA sponge.

Establishment of a novel chondrocyte-like cell line derived from transgenic mice harboring the temperature-sensitive simian virus 40 large T-antigen gene

We established a clonal chondrocyte-like cell line (TC6, TC stands for large T immortalized chondrocyte-like cell line) derived from articular cartilage of transgenic mice harboring a temperature-sensitive simian virus 40 large T-antigen gene. TC6 cells exhibited spindle-like or polygonal morphology and grew well at 33 degrees C in alpha-minimal essential medium supplemented with 0.5% fetal bovine serum. After confluence, these cells formed nodules that were positive for staining with alcian blue. Northern blot analysis demonstrated that these cells expressed messenger RNAs (mRNA) of the genes encoding cartilage-specific proteins such as type II procollagen, link protein, and aggrecan. Furthermore, the expression of type II procollagen and link protein genes in TC6 cells was regulated by parathyroid hormone and basic fibroblast growth factor, suggesting the presence of the receptors for the hormone and cytokine. The expression of link protein mRNA in TC6 cells was regulated in a time-dependent manner and was enhanced in culture within a week and increased continuously up to 10-fold by the end of 4 weeks. Expression of mRNAs encoding type II procollagen and versican/PG-M also increased moderately during the culture period. TC6 cells expressed type I procollagen mRNA, however, its level declined along with time in culture in contrast to the enhancement of the genes encoding cartilage-specific molecules in these cells. Interestingly, alkaline phosphatase mRNA expression was barely detectable in the TC6 cells in their growing phase while it was enhanced dramatically more than 7-fold by day 14 in culture. These results indicate that the TC6 cells could serve as an excellent model for the studies on chondrocyte physiology.

Heparan sulfate proteoglycan on leukemic cells is primarily involved in integrin triggering and its mediated adhesion to endothelial cells

Leukocyte migration from circulation into tissue depends on leukocyte integrin-mediated adhesion to endothelium, but integrins cannot function until activated. However, it remains to be understood how tumor cells adhere to endothelium and infiltrate into underlying tissue. We studied mechanisms of extravasation of leukemic cells using adult T cell leukemia (ATL) cells and report the following novel features of cell surface heparan sulfate proteoglycan on ATL cells in ATL cell adhesion to endothelium: ATL cells adhere to endothelial cells through already activated integrins without exogenous stimulation; different from any other hematopoietic cells, ATL cells express a characteristic heparan sulfate capable of immobilizing heparin-binding chemokine macrophage inflammatory protein (MIP)-1 beta, a potent T cell integrin trigger, produced by the cells themselves; competitive interruption of endogenous heparan sulfate proteoglycan synthesis reduces cell surface MIP-1 beta and prevents ATL cells from integrin-mediated adhesion to endothelial cells or intercellular adhesion molecule-1 triggered through G-protein. We propose that leukemic cells adhere to endothelial cells through the adhesion cascade, similar to normal leukocyte, and that the cell surface heparan sulfate, particularly on ATL cells, is pivotally involved in chemokine-dependent autocrine stimulation of integrin triggering by immobilizing the chemokine on them.