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PubMed2003

Variation of biomechanical, structural, and compositional properties along the tendon to bone insertion site.

The tendon to bone insertion site is a complex transitional region that links two very different materials. The insertion site must transfer a complex loading environment effectively to prevent injury and provide proper joint function. In order to accomplish this load transfer effectively, the properties of the insertion site were hypothesized to vary along its length. The quasilinear viscoelastic (QLV) Model was used to determine biomechanical properties, polarized light analysis was used to quantitate collagen orientation (structure), and in situ hybridization was used to determine the expression of extracellular matrix genes (composition). All assays were performed at two insertion site locations: the tendon end of the insertion and the bony end of the insertion. Biomechanically, the apparent properties of peak strain, the coefficients (A and B) that describe the elastic component of the QLV model, and one of the coefficients (tau(1)) of the viscous component of the model were significantly higher, while another of the coefficients (C) of the viscous component was significantly lower at the tendon insertion compared to the bony insertion. The collagen was significantly more oriented at the tendon insertion compared to the bony insertion. Finally, collagen types II, IX, and X, and aggrecan were localized only to the bony insertion, while decorin and biglycan were localized only to the tendon insertion. Thus, the tendon to bony insertion site varies dramatically along its length in terms of its viscoelastic properties, collagen structure, and extracellular matrix composition.

Aggrecans↗
PubMed1993

Regulation of extracellular matrix genes during fracture healing in mice.

The expression of several collagens, cartilage proteoglycan core protein (aggrecan), and osteonectin was investigated during healing of standardized fractures of the mouse tibia. Total RNA was extracted from fracture calluses and normal bone, and analyzed by Northern hybridization using specific cDNA probes. Based on the predominant fibrillar collagen type expressed, three phases of fracture healing were observed. Type III collagen expression characteristic for the inflammatory stage increased first, followed by Type II collagen expression indicative of the cartilaginous reparative phase, and by Type I collagen production, characteristic for the ossification and remodelling stages. Type IX collagen and aggrecan expression coincided with Type II collagen expression during the chondrogenesis. The mRNA for Type X collagen, a marker for hypertrophic chondrocytes during endochondral ossification, occurred somewhat later than that of other cartilage-specific genes. Osteonectin mRNA was present throughout the healing process and peaked during rapid new bone growth. This study confirms that the pattern of gene expression in the murine system is similar to, but somewhat faster than, other species analyzed (rat, rabbit, human).

Aggrecans↗
PubMed1990

The collagens and glycosaminoglycans of the extracellular matrices secreted by bone marrow stromal cells cultured in vivo in diffusion chambers.

When rabbit bone marrow cells are cultured in a diffusion chamber implanted into the peritoneal cavity of an athymic mouse, the stromal cells proliferate, differentiate, and produce tissues that have the morphological features of loose fibrous tissue, woven or chondroid bone, and cartilage. The collagens synthesized during the development of the tissues from 7 to 28 days after implantation were identified using specific antibodies to rabbit types I, II, III, and V and rat type IX collagens, while the glycosaminoglycans were characterized histochemically using the dye, Alcian blue. Fibrous tissue forms in the first week and it contains types I, III, and V collagens and hyaluronan. Bone and cartilage develop within the fibrous tissue from about 12 days onwards. The bone matrix contains types I and V collagens, and chondroitin and keratan sulphates. The cartilaginous matrix contains types II and IX collagens, and chondroitin and keratan sulphates. Small amounts of type III collagen are found in the bone, and types I, III, and V collagens in the cartilage. These are thought to be the remnants of the fibrous matrix and decrease as the matrices mature. It is concluded that the tissue in diffusion chambers, formed by a small number of early precursor cells present in the soft tissues of the endosteum and marrow of young rabbits, contains extracellular matrix macromolecules similar to those found in bone and cartilage.

Animals↗
PubMed1988

Changes in the expression of collagen genes show two stages in chondrocyte differentiation in vitro.

This report deals with the quantitation of both mRNA and transcription activity of type I collagen gene and of three cartilage-specific collagens (types II, IX, and X) during in vitro differentiation of chick chondrocytes. Differentiation was obtained by transferal to suspension culture of dedifferentiated cells passaged for 3 wk as adherent cells. The type I collagen mRNA, highly represented in the dedifferentiated cells, rapidly decreased during chondrocyte differentiation. On the contrary, types II and IX collagen mRNAs sharply increased within the first week of suspension culture, peaked in the second week, and thereafter began to decrease. This decrease was particularly significant for type IX collagen mRNA. The level of type X collagen mRNA progressively increased during the course of the culture, reached its maximal value after 3-4 wk, and decreased only at a later stage of cell differentiation. As determined by in vitro run-off transcription assays, all these changes in collagen mRNA levels could be attributed to parallel modifications in the relative rate of transcription of the corresponding collagen genes. We suggest that chicken chondrocyte differentiation proceeds through at least two different steps: (a) first, transition from a stage characterized by a high level of type I collagen mRNA to a stage characterized by predominance of types II and IX collagen mRNAs; (b) later, transition to a stage characterized by the highest level of type X collagen mRNA.

Animals↗
PubMed1990

Homozygous achondroplasia: morphologic and biochemical study of cartilage.

We have performed histochemical, immunohistochemical, electron microscopic, and biochemical studies on the upper tibial cartilage from a case of homozygous achondroplasia. The growth zone was narrow and disorganized. Columnization was absent except for a few areas with short rows of cells. Hypertrophy was reduced to scattered clusters of cells. The provisional calcification was patchy and primary trabeculae were thick and irregularly arranged. Islands of fibrous or fibrocartilagineous tissue were found along the growth zone. The matrix did not stain with safranin O and lacked metachromasia, except for pericellular rims around the hypertrophic cell clusters. Staining with antibodies against the large proteoglycan monomers and chondroitin-4-sulfate was weakly positive. Electron microscopic examination showed that only a few cells had degenerative signs. In most areas of the matrix, proteoglycan granules were absent. Areas with dense collagen fibers were seen. In contrast to the growth zone, the cartilage of the remaining epiphyses had normal histochemical, immunohistochemical, and electron microscopic appearance. The large proteoglycan monomers had a normal composition and hydrodynamic size. Type II and XI collagen, pepsin fragments of type IX collagen, and several noncollagenous proteins extracted from cartilage had a normal electrophoretic migration. It is suggested that a mutation affecting a matrix component or a regulatory pathway present only or predominantly in the growth area of the chondroepiphysis might explain the findings.

Achondroplasia↗
PubMed1990

Etodolac: efficacy in osteoarthritis and effects on chondrocyte function.

Some nonsteroidal anti-inflammatory drugs (NSAIDs) used in the treatment of osteoarthritis (OA) may damage articular cartilage. This damage may be caused by suppression of proteoglycan synthesis or by altered collagen synthesis in the presence of prostaglandin E2 (PGE2) induced by interleukin-1 (IL-1). The clinical and biochemical effects of etodolac, a new NSAID, on the symptoms of OA and on cartilage metabolism are reviewed. Clinically, etodolac (200-600 mg/day) was more effective than placebo, and as effective as aspirin (3200-4800 mg/day), piroxicam (20 mg/day), naproxen (1000 mg/day), and diclofenac (150 mg/day) in relieving the symptoms of OA. In in vitro studies, proteoglycan synthesis was not affected by the presence of etodolac when human chondrocytes were grown in a three-dimensional culture. Etodolac preserved collagen phenotype in human chondrocytes cultured in a monolayer in the presence of IL-1. In contrast, the collagen phenotype of cells cultured in the presence of indomethacin and IL-1 changed. Under those conditions, less type II and type IX collagen were synthesized and more type I and type III collagen were synthesized. These findings suggest that etodolac, an effective agent in the treatment of OA, has the potential advantage of not damaging articular cartilage in vivo.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1993

Detection of a type IX collagen-related mRNA in an invertebrate, the marine annelid Nereis virens.

Fibrous and non-fibrous collagens have been described in both vertebrate and invertebrate animals. However, there has been limited characterization of non-fibrous collagens and their corresponding genes in invertebrate animals. In the present study we have used as a probe an avian cDNA clone which encompasses the COL3, NC3 and part of the COL2 domain of the collagen alpha 3(IX) subunit. This probe hybridized to mRNA obtained from the cuticle and body of the marine annelid, Nereis virens. Northern blot hybridization exhibited an mRNA of ca. 7.5-8 kilobases which in situ hybridization shows to be most abundant over cuticle-associated cells. Dot-blot hybridization, comparing cuticle mRNA and body mRNA, indicates that this collagen mRNA is five times more abundant in the cuticle. The composite data suggest evolutionary conservation, in both vertebrate and invertebrate animals, of a non-fibrillar collagen.

Animals↗
PubMed1989

Tissue-specific forms of type IX collagen-proteoglycan arise from the use of two widely separated promoters.

We demonstrate that the gene encoding an extracellular matrix component contains two widely separated promoters controlling the generation of different transcripts in a tissue-specific fashion. Two transcription start sites, about 20 kilobase pairs apart, in the alpha 1(IX) collagen gene are utilized to generate different forms of a collagen-proteoglycan (collagen IX) in chicken cartilage and cornea. Transcripts from the upstream site encode a large (266 amino acid residues) globular domain at the amino terminus of alpha 1(IX) chains, whereas the transcripts from the downstream site encode chains that lack this globular domain and contain a short alternative sequence. Transcripts from the upstream site are predominantly present in cartilage, and transcripts from the downstream site are predominantly used in cornea. The structural differences in collagen IX molecules that are synthesized as a consequence of the use of these two alternative transcription start sites in the alpha 1(IX) gene are likely to contribute to the differences in the macromolecular organization of the extracellular matrix in cartilage and cornea. Our finding provides a novel clue to answering the general question of what mechanisms are used to generate unique fibrillar patterns in different tissues.

Amino Acid Sequence↗
PubMed1993

Molecular cloning of the human alpha 2(IX) collagen cDNA and assignment of the human COL9A2 gene to chromosome 1.

Type IX collagen, a heterotrimer of alpha 1(IX), alpha 2(IX) and alpha 3(IX) chains, is a cartilage-specific fibril-associated collagen. In the process of characterizing genomic clones for the mouse alpha 2(IX) collagen gene four pairs of oligonucleotide primers designed for amplification of murine exon sequences were also utilized to construct cDNA clones for human alpha 2(IX) collagen spanning > 90% of the coding region. The amino acid and nucleotide sequence identities between human and chick are 78% and 71%, respectively. Localization of the COL9A2 gene to human chromosome 1 was subsequently performed using a panel of DNAs from human/rodent somatic cell hybrids.

Amino Acid Sequence↗
PubMed1998

Development and roles of collagenous matrices in the embryonic avian cornea.

Corneal development requires the production, assembly and sometimes replacement of a number of collagenous matrices. The embryonic chick cornea is well-characterized and offers certain advantages for studying the assembly and roles of these matrices. We will first describe the matrices to be examined. These include the corneal stroma proper, first formed as the primary stroma and subsequently as the secondary (mature) stroma; Bowman's Membrane; Descemet's Membrane; and the hemidesmosome of the epithelial cell attachment complex. We will then describe the characteristics of the collagen types involved, including: the fibrillar collagens (types I, II and V), the fibril-associated collagens (types IX, XII and XIV), and the transmembrane collagen of the hemidesmosome (type XVII). Then, in each subsequent section we will examine in detail the structure, assembly and development of each collagenous matrix, and how each specific collagen and/or combination of collagens are thought to provide the matrices with their unique properties. The work and views presented here are largely from our own laboratories. Thus, this article is not meant to be a comprehensive review of the literature. For pertinent references by others, when possible, we will cite recent reviews.

Animals↗
PubMed1991

Type XIV collagen, a new homotrimeric molecule extracted from fetal bovine skin and tendon, with a triple helical disulfide-bonded domain homologous to type IX and type XII collagens.

Previously undescribed disulfide-bonded collagenous pepsin-derived fragments have been isolated from fetal calf tendon and skin. One fragment, 10.5 kDa after reduction, was shown to be similar but distinct to the COL1 domain of the recently characterized type XII collagen (64% primary structure identity). The similarity includes important features such as size, location of the cysteine residues, and nature and position of an imperfection of the triple helix. From fetal calf skin, two approximately 34-kDa disulfide-bonded trimeric fragments were isolated in the unreduced form. Amino acid sequencing showed that one fragment contained solely the COL1 domain of type XII collagen while the other one only contained the COL1 domain of the new chain. Like type XII collagen, the new chain is therefore part of a homotrimeric molecule and should thus be considered as a distinct collagen type. We propose to call the molecule from which this fragment is derived, type XIV collagen, with a chain composition (alpha 1 (XIV]3. The presence of a domain similar to the COL1 domain of collagens types IX and XII suggests that type XIV collagen belongs to the group of fibril-associated collagens with interrupted triple helices (FACIT). Two other fragments, 13.5 and 17 kDa after reduction, were also purified. They were shown to contain the same triple helical domain with different pepsin cleavage sites at the amino terminus. Several tryptic peptides were sequenced, and the derived sequences could be aligned with the COL2 domain of type XII collagen or with flanking sequences in the NC2 and NC3 domains (61% sequence identity). These fragments are very likely to be also derived from type XIV collagen.

Amino Acid Sequence↗
PubMed1997

Developmental regulation of mRNA species for types II, IX and XI collagens during mouse embryogenesis.

Several techniques were used to study the co-ordination of mRNA levels for five constituent chains of cartilage collagen fibrils during mouse development. Short cDNA clones were first constructed for mouse and human alpha3(IX) and for mouse proalpha1(XI) collagen mRNA species. Northern analysis of developing mouse embryos revealed that the mRNA species for alpha1, alpha2 and alpha3 chains of type IX collagen peaked earlier than those for proalpha1(II) and proalpha1(XI) collagen chains. Quantification of these mRNA species by slot-blot hybridization confirmed this developmental regulation: the mRNA ratios for type II/type IX/type XI collagens changed from 5.7:1:0.6 (at embryonic day 12.5) to 10.6:1:0.9 (in newborn mice). However, the genes coding for the three chains of type IX collagen seemed to be under more co-ordinated regulation during mouse development. In addition to high mRNA levels in cartilages and the eye, low levels of type IX collagen transcripts were identified in brain and skin of newborn mouse using RNase protection and reverse transcriptase-PCR assays. Finally, hybridization in situ revealed identical tissue distributions of the three type IX collagen mRNA species during early chondrogenesis but somewhat more widespread expression of the alpha1(IX) and alpha3(IX) mRNA species during endochondral ossification at day 16.5 of embryonic development. These results suggest a relatively tight co-ordination of the alpha1(IX), alpha2(IX), and alpha3(IX) collagen mRNA species in chondrocytes, but a lack of co-ordination in several non-cartilaginous tissues.

Amino Acid Sequence↗
PubMed1993

Amplification of cDNAs for human cartilage-specific types II, IX and XI collagens from chondrocytes and Epstein-Barr virus-transformed lymphocytes.

The identification of mutations in cartilage-specific collagen genes in inherited forms of osteoarthritis (OA) and other heritable cartilage diseases has been hampered by the difficulty in obtaining sufficient tissue to isolate RNA and by the loss of the cartilage phenotype during in vitro chondrocyte culture. To overcome these limitations we employed RNA Polymerase Chain Reaction (PCR) to amplify cDNAs for the cartilage-specific collagens types II, IX and XI from mRNA obtained from small numbers of chondrocytes. We also amplified cDNAs for these collagens from "illegitimate transcripts" from Epstein-Barr virus (EBV)-transformed lymphocytes. Total RNA was obtained from freshly isolated human fetal and adult chondrocytes and from long-term (90 days) chondrocyte cultures. The RNA was reverse transcribed to cDNA and the cDNA amplified in the same tube with oligonucleotide primers specific for types II, IX and XI collagens. The amplified double-stranded products were cloned and sequenced. Successful amplification of the entire 4.4 kb of the type II procollagen cDNA was obtained from as little as 6 ng of RNA from freshly isolated fetal human chondrocytes. Seven hundred and eighty base pairs of the alpha 1 (IX) collagen cDNA and the entire published sequence of alpha 2 (XI) collagen cDNA, were also amplified from these cells. We were also able to amplify cDNAs for the three cartilage-specific collagens from "illegitimate transcripts" from EBV-transformed lymphocytes. Thus, these methods will allow the identification of mutations in cartilage-specific collagen genes in patients with inherited OA and other heritable cartilage diseases from small amounts of cartilage or chondrocyte RNA or from non-cartilaginous sources.

Base Sequence↗
PubMed1993

Composition and organization of the collagen network produced by fetal bovine chondrocytes cultured at high density.

Fetal bovine chondrocytes isolated from the resting zone of epiphyseal cartilage were maintained in high-density culture for 4 weeks. From Day 2 in culture, the chondrocytes deposited an extracellular matrix composed of Types II, IX, and XI collagen. Types IX and XI collagen were restricted to the pericellular domain from Day 5. By 2 weeks the entire cell layer stained for antibodies to Type II and IX collagens. Type XI could be demonstrated throughout the cell layer by pepsinization of the sections. Results from both rotary shadowing and immunochemistry showed that the fibrils formed in culture were heterotypic, with Type IX collagen arranged along the surface and with Type XI collagen buried in Type II fibrils. Nonspecific Type VI collagen and the glycoproteins tenascin and fibrillin, previously described in cartilaginous tissue, were identified by their ultrastructural characteristics in the cell layer homogenate. Although the cells presented morphological characteristics of chondrocytes and still expressed cartilage-specific collagens, the appearance of Type I collagen in the culture cell layer after 4 weeks of culture demonstrates a partial dedifferentiation of the chondrocytes. The culture system described in this report provides an interesting tool for maintaining chondrocytes in a cartilage-like matrix to study the influence of different physical and chemical factors on the expression and differentiation of the cells.

Animals↗
PubMed1992

Antibodies against a 30 kilodalton cochlear protein and type II and IX collagens in the serum of patients with inner ear diseases.

Collagen molecules are major extracellular matrix proteins involved in the development and support of delicate auditory sensory organs. Type II collagen is widely distributed within inner ear tissues, while type IX is found only within the labyrinthine membrane and dense fibers of the tectorial membrane. Antibody specific for type II collagen has been shown to be elevated in some patients with hearing loss due to several presumably autoimmune illnesses (including Meniere's disease, otosclerosis, chronic progressive sensorineural hearing loss, and relapsing polychondritis). Purified human type II and IX collagens and an extract of human cochlear tissue were subjected to isolation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and transferred to nitrocellulose. The sera of 21 patients with inner ear disease were examined for the presence of anticollagen and anticochlear antibodies; the sera were used to probe Western blots of purified human collagens II, IX, and XI, and cochlear protein extract with peroxidase-conjugated goat anti human polyvalent immunoglobulin as the second antibody. Anti-type II collagen antibodies were seen in 12 of 21 (57%) patients, while 13 of 21 (62%) had anti-type IX antibodies detectable by Western blot. A previously unreported 30 kd (probably noncollagen) protein was 21 (62%) had anti-type IX antibodies detectable by Western blot. A previously unreported 30 kd (probably noncollagen) protein was found by SDS-PAGE of human cochlear tissue extracts, with 3 patients, all with Meniere's disease, having antibody activity to this protein detected by Western blot.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Western↗
PubMed1997

Deer antler does not represent a typical endochondral growth system: immunoidentification of collagen type X but little collagen type II in growing antler tissue.

The collagen isotypes present at early (6 week) and late (5 month) stages of growing deer antler were isolated and identified. Pepsin-digested collagens were separated by differential salt fractionation, SDS-PAGE and Western blotting and subsequently identified by immunostaining. Cyanogen bromide digestion of antler tissue was used to establish a collagen type-specific pattern of peptides, and these were also identified by immunoblotting. Collagen type I was found to be the major collagen in both early- and late-stage antler. Collagen type II was present in the young antler in small amounts but was not confined to the soft "cartilaginous" tip of the antler. Collagen type XI was found in the pepsin digest of the young antler, but collagen type IX was not present at either stage of antler growth. Collagen type X was found in the young antler in all fractions studied. Microscopic study showed that the deer antler did not possess a discrete growth plate as found in endochondral bone growth. Unequivocal immunolocalization of the different collagen types in the antler were unsuccessful. These results show that, despite the presence in the antler of many cartilage collagens, growth does not occur through a simple endochondral process.

Animals↗
PubMed2002

Cloning and expression of a type IX-like collagen in tissues of the ascidian Ciona intestinalis.

Collagens are highly preserved proteins in invertebrates and vertebrates. To identify the collagens in urochordates, the total RNA extracted from the pharynx of the ascidian Ciona intestinalis was hybridized with a heterologous probe specific for the echinoderm Paracentrotus lividus fibrillar type I-like larval collagen. Using this probe, two main bands (i.e. 6 and 2.8 kb mRNA) were observed on Northern blot hybridization. The cDNA library prepared from poly(A)+RNA extracted from pharyngeal tissue was screened and a cDNA that specifies a type IX-like collagen was identified. This molecule presents a conceptual open reading frame for a protein containing 734 amino acids. In particular, we showed a 1 alpha chain type IX-like collagen characterized by three short triple-helical domains interspersed with four non-triple-helical sequences, with structural features of fibril-associated collagens with interrupted triple-helices (FACIT) collagens. Northern blot hybridizations indicate a 2.8 kb transcript size. Sequence comparison indicated homology (47.64%, 48.95%) between the type IX-like collagen of C. intestinalis and mouse and human type IX collagen. In situ hybridization of tunic and pharynx tissues shows the presence of transcripts in connective tissue cells.

Amino Acid Sequence↗
PubMed1990

Collagen-platelet interaction: type XI collagen-induced platelet aggregation.

Type XI collagen in its native fibrillar but not in soluble monomeric form mediates human platelet aggregation and release of adenosine triphosphate in a dose-dependent manner. Its action is inhibited by aspirin. Type XI collagen also increased radiolabelled phosphate incorporation into protein bands with molecular weights of 42 KDa and 22 KDa, respectively. In contract, these events were not observed in platelets incubated with type IX collagen. These results suggest that the fibrillar type XI collagen has the same ability as other types of collagen to induce human platelet aggregation.

Adenosine Triphosphate↗