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B R Olsen

Publications and source records attributed to B R Olsen.

At least 145 records · Page 8Linked to original sources
PubMed1992

Type X collagen is transcriptionally activated and specifically localized during sternal cartilage maturation.

Type X collagen is an extracellular matrix protein which is synthesized by chondrocytes when they undergo hypertrophy. We present evidence here that the expression of type X collagen in the developing chick sternum is controlled primarily by transcriptional mechanisms. Using chondrocyte nuclei isolated from 15-, 16-, 17- and 18-day chick embryonic sterna, nuclear run-off assays demonstrate that type X collagen gene transcription begins at day 16 in chondrocytes isolated from the cephalic portion. This occurs two days prior to mineralization of this tissue as observed by alizarin red staining. The rate of type X transcription increases dramatically through days 17 and 18. Western blot analyses of extracts of freshly isolated sternal chondrocytes from the same stages show that intracellular levels of the type X protein follow the same time course. Immunostaining with a monoclonal antibody specific for type X collagen demonstrates that the initial appearances of hypertrophic cells and pericellular type X collagen occur at embryonic day 16 in the cephalic portion of sterna. Observation of immunostained cephalic sternal sections from day 18 embryos by confocal microscopy reveals that type X collagen is localized in a capsule-like configuration around each hypertrophic chondrocyte.

Animals↗
PubMed1992

Tissue-specific expression of type XIV collagen--a member of the FACIT class of collagens.

The collagens represent a highly diverse superfamily of extracellular matrix proteins that can be divided into several distinct families. One of the families, called FACIT (fibril-associated collagens with interrupted triple-helices) family, contains molecules that appear to be associated with cross-striated fibrils composed of members of the fibrillar collagen family. We have determined a portion of the primary structure of a recently discovered member of the FACIT family, chicken alpha 1(XIV) collagen, based on cloning and sequencing cDNAs. A synthetic oligopeptide from within the carboxy-terminal non-triple-helical domain of the alpha 1(XIV) chain has been used for generating specific polyclonal antibodies. The antiserum, PS1, recognizes a 220 kDa polypeptide in immunoblots of extracts of chicken skin, tendons, and cartilage. Sequencing of a tryptic peptide generated from purified, immunoreactive material, gives a sequence identical to that derived from cDNA sequencing, providing strong support for the type XIV-specificity of PS1. We have examined the expression of type XIV collagen in developing chick embryos by immunostaining of sections from 12-day-old embryos with PS1 and by Northern blot analysis of RNA from several tissues from both 12- and 17-day-old embryos. The results show that type XIV collagen is prevalent within relatively dense connective tissues such as dermis, tendons, perichondrium, perimysium, the stroma of lungs and liver, and blood vessels.

Amino Acid Sequence↗
PubMed1991

Cloning of a cDNA for a new member of the class of fibril-associated collagens with interrupted triple helices.

cDNA from embryonic chick skin has been isolated and characterized which encodes a novel member of the FACIT (fibril-associated collagen with interrupted triple helices) group whose other known members are collagen types IX and XII. Nucleotide sequence analysis of the cDNA, combined with characterization of a pepsin-resistant fragment of the protein from embryonic chick skin, demonstrates that the collagen chain is more closely related to the chain of type XII collagen than to those of type IX. It is most similar to a collagen, type XIV, recently identified in bovine skin. It is possible, therefore, that the cDNA codes for a chain of chicken type XIV collagen. From the additional data on molecular structure obtained by sequencing the cDNA, the FACIT family appears to consist of at least two classes of molecules: one of which contains the three chains of type IX collagen, and a second which includes the chains of collagen types XII and XIV.

Amino Acid Sequence↗
PubMed1991

The complete primary structure of the human alpha 1 (VIII) chain and assignment of its gene (COL8A1) to chromosome 3.

Type VIII collagen molecules, expressed by corneal and vascular endothelial cells, appear to be heterotrimers composed of two genetically distinct polypeptides, alpha 1 (VIII) and alpha 2(VIII), in the ratio of 2:1. Characterization of the rabbit alpha 1(VIII) gene has demonstrated that it consists of only four exons, one of which is large and encodes the entire triple-helical and carboxyl non-triple-helical domains. A similar exon organization has been found for the chicken alpha 1(X) and the mouse and human alpha 2(VIII) collagen genes. The genes encoding alpha 1(VIII), alpha 2(VIII), and alpha 1(X) collagen chains are therefore homologous members of a unique class of genes within the collagen superfamily. In the present paper we describe for the first time the primary structure of the human alpha 1(VIII) collagen chain, based on isolation and sequencing of a genomic DNA fragment. The results indicate that the human alpha 1(VIII) chain has the same domain structure as the rabbit protein. We also demonstrate that the gene is localized on the long arm of the human chromosome 3. The availability of genomic DNA encoding the human alpha 1(VIII) collagen chain and information about its chromosomal location should make it possible to examine whether hereditary diseases are linked to abnormalities in the structure or expression of the alpha 1(VIII) gene.

Amino Acid Sequence↗
PubMed1991

Cloning of human alpha 1(X) collagen DNA and localization of the COL10A1 gene to the q21-q22 region of human chromosome 6.

With consensus primers based upon the nucleotide sequence of the chicken alpha 1(X) collagen gene, we have used PCR with human genomic DNA as template to isolate a 289 bp fragment coding for part of the carboxyl non-triple helical domain of the human alpha 1(X) gene. We have demonstrated the presence of the sequence of the PCR clone within the human genome by partial sequence analysis of a 1 kb HindIII genomic DNA fragment that hybridized with the PCR clone. Furthermore, using the PCR clone as a probe for in situ hybridization of human metaphase chromosome spreads, and for Southern analysis of a panel of human-hamster somatic cell hybrid DNAs, we have assigned the locus for the alpha 1(X) gene to the q21-q22 region of human chromosome 6.

Amino Acid Sequence↗
PubMed1991

The alpha 2(VIII) collagen gene. A novel member of the short chain collagen family located on the human chromosome 1.

Type VIII collagen is a major component of Descemet's membrane, the specialized basement membrane of corneal endothelial cells. Sequence analysis of a cDNA isolated from a library made with mRNA from rabbit corneal endothelial cells has indicated that type VIII molecules contain a polypeptide chain, alpha 1(VIII), consisting of a short triple-helical domain of 454 amino acid residues flanked by non-triple-helical domains of 117 and 173 amino acid residues at the amino and carboxyl ends, respectively (Yamaguchi, N., Benya, P. D., van der Rest, M., and Ninomiya, Y. (1989) J. Biol. Chem. 264, 16022-16029). The sequence of alpha 1(VIII) is strikingly similar to that of alpha 1(X) collagen, a product of hypertrophic chondrocytes. Also, characterization of the alpha 1(VIII) and alpha 1(X) collagen genes has shown that they are quite similar in their exon organization. It has been concluded, therefore, that they are homologous members of a distinct subclass of collagen genes (Yamaguchi, N., Mayne, R., and Ninomiya, Y. (1991) J. Biol. Chem. 266, 4508-4513). We have given this subclass the name short chain collagens because of the relatively small size of the triple-helical domain. In the present study, we report on the identification and characterization of a collagen gene encoding a polypeptide which is co-expressed with the alpha 1(VIII) chain in corneal endothelial cells. This collagen chain contains a triple-helical and a carboxyl non-triple-helical domain encoded by a single, large exon both in mice and humans. We conclude, therefore, that the genes encodes a novel member of the short chain collagen family, and we have given this chain the designation alpha 2(VIII) collagen. By in situ hybridization we demonstrate that the alpha 2(VIII) gene is located in the p32.3-p34.3 region of the short arm of chromosome 1.

Amino Acid Sequence↗
PubMed1991

Spatiotemporal pattern of type X collagen gene expression and collagen deposition in embryonic chick vertebrae undergoing endochondral ossification.

We examined the spatio-temporal pattern of type X collagen mRNA and its protein in the embryonic chick vertebrae undergoing ossification by in situ hybridization and immunohistochemistry. Hypertrophic chondrocytes, producing type X collagen, were developed as islands of cells in a few vertebral body segments of stage 36 embryos. These cells were increased in number at stages 37 and 38 and they expressed high levels of type X collagen mRNA and deposited its protein in the matrix. Blood vessels entered from the perichondrium at stage 37 and invaded deeply into hypertrophic cartilage at stage 38. As the vertebrae grew further at stage 40, the leading front of active hypertrophic chondrocytes with high levels of type X mRNA shifted from the midvertebral perivascular area towards intervertebral borders, while the perivascular area retained a number of inactive hypertrophic chondrocytes with low levels of type X mRNA. Type X collagen was found in large amounts throughout the matrix areas containing both active and inactive hypertrophic chondrocytes. Calcium was detected by von Kossa's technique in hypertrophic cartilage matrix in a small amount at stage 37, in parts of the matrix with type X collagen deposition in succeeding stages, and finally in almost the entire area of type X collagen deposition at stage 45. The vertebral segments of stage 45 embryos also showed a clearly reversed pattern of expression between type X collagen mRNA and types II and IX collagen mRNAs. The results demonstrate that the production of type X collagen by hypertrophic chondrocytes precedes both vascular invasion and mineralization of the matrix, suggesting that hypertrophic chondrocytes have an important role in regulating these events.

Animals↗
PubMed1991

FACIT collagens: diverse molecular bridges in extracellular matrices.

The collagens form a large family of proteins. Collagen fibrils, composed of staggered arrays of fibrillar collagen molecules (types I, II, III, V and XI), provide a supporting scaffold for extracellular matrices of connective tissues. The non-fibrillar collagens are less abundant than the fibrillar collagens, but it is becoming clear that they have important functions in the matrix. Recently, a group with unique structural characteristics has been defined and named the FACIT (Fibril-Associated Collagens with Interrupted Triple-helices) group. There is evidence that these collagens may serve as molecular bridges that are important for the organization and stability of extracellular matrices.

Animals↗
PubMed1990

The complete primary structure of two distinct forms of human alpha 1 (IX) collagen chains.

Type IX collagen molecules contain three genetically distinct subunits. One of the subunits, alpha 2(IX), contains a covalently attached glycosaminoglycan side chain. A second subunit, alpha 1 (IX), has been found to be synthesized in two forms. The two forms are generated by the alternative use of two transcription start sites and splice patterns. The two forms have been found in chicken, mouse and human but cDNAs encoding both forms have only been reported for chicken. In the present report we describe the isolation of cDNA clones encoding the complete translated portion of both forms of human alpha 1(IX) collagen chains. Nucleotide sequence analysis has permitted the determination of the primary structure of both forms. These probes and sequences should prove useful in future studies of chondrodysplasias involving type IX collagen.

Amino Acid Sequence↗
PubMed1990

Temporal and spatial distribution of type XII collagen in high cell density culture of periosteal-derived cells.

Periosteal-derived cells of young chicks have been reported to possess the potential to undergo terminal differentiation into osteogenic or chondrogenic phenotypes under high cell density culture conditions. In this culture, the temporal and spatial distribution of type XII collagen was immunocytochemically assessed using a monoclonal antibody. These high-density plated cells first formed a multilayer of fibroblast-like cells, in which type I and XII collagen were evenly distributed throughout the full thickness of the culture. With time, the top portion of the culture differentiated into bone tissue, while cells below this top layer differentiated into hypertrophic chondrocytes. In this transition, type XII collagen was temporally and spatially colocalized primarily with type I collagen: the top portion of bone layer was positive for both type I and XII collagens, whereas their staining intensity in the bottom portion decreased with time in culture. Using this antibody, type XII collagen was also found in developing embryonic chick tibiotarsus. These observations, taken together, suggest that type XII collagen production is a characteristic property of bone-forming cells.

Animals↗
PubMed1990

The alpha 1 (IX) collagen gene gives rise to two different transcripts in both mouse embryonic and human fetal RNA.

We have isolated and characterized portions of the alpha 1 (IX) collagen gene from mouse and human DNA. Nucleotide sequence analysis and comparison with the chicken gene suggest that the mammalian genes contain an alternative exon that is located within the intron between exons 6 and 7. Using oligonucleotide primers specific for exons 4, 8, and the alternative exon (exon 1*), we demonstrated by the polymerase chain reaction that embryonic mouse and fetal human RNAs contain two types of alpha 1(IX) collagen transcripts. One type of transcript does not contain the sequence encoded by exon 1*; the second type of transcript contains this exon. Both mouse and human alpha 1(IX) collagen genes give rise, therefore, to (at least) two mRNA transcripts.

Amino Acid Sequence↗
PubMed1990

Non-fibrillar collagenous proteins synthesized by rat mesangial cells.

Recent studies have shown that nonrenal extracellular matrices are composed of collagenous proteins with properties that are different from those of fibrillar collagens and type IV collagen. The structures of these newly described collagens suggest that they may provide connections between specific matrix molecules and, in so doing, partially determine the three-dimensional structure of the matrix. The molecular composition and organization of normal and diseased mesangial matrix are incompletely understood. As a means to further understand the structure of the mesangial matrix, we have further defined the collagenous proteins synthesized by rat mesangial cells. By using monospecific antibodies, we have shown that these cells secrete types III and IV collagen. Metabolic labeling and electrophoretic analysis of proteins isolated from the culture medium revealed that mesangial cells also synthesize and secrete short-chain collagenous proteins of 80, 75, and 69 kDa which differ in their binding to concanavalin A. Cell-free translation of mesangial mRNA demonstrated the presence of two additional collagenase sensitive proteins, 40 and 35 kDa in size, which were not detected in the culture medium. These results demonstrate that mesangial cells synthesize several short-chain collagenous proteins which may be similar to short-chain collagens isolated from nonrenal tissues. Further definition of these proteins will lead to a greater understanding of the extracellular matrix elaborated by mesangial cells.

Animals↗
PubMed1989

Type XII collagen. A large multidomain molecule with partial homology to type IX collagen.

Three overlapping cDNAs encoding alpha 1 (XII) collagen have been isolated and sequenced. The DNAs define five sequence domains within the chain. Three domains are nontriple-helical; two are relatively short triple-helical regions. The amino acid sequences of tryptic peptides derived from 16- and 10-kDa pepsin-resistant fragments isolated from tendon extracts are in full agreement with the deduced sequences of the triple-helical regions. Two of the five sequence domains in alpha 1 (XII), one triple-helical and one nontriple-helical, show a high degree of similarity to regions in type IX collagen chains. In addition, examination of seven exons in the alpha 1 (XII) gene shows that the gene is, in part, similar to the structure of type IX collagen genes. Therefore, collagen types IX and XII are partially homologous. The alpha 1 (XII) sequence data predict an asymmetric structure for type XII collagen molecules, fully consistent with the rotary shadowing images. These images show a triple-helical 75-nm tail attached through a central globule to three finger-like structures, each 60 nm long (Dublet, B., Oh, S., Sugrue, S. P., Gordon, M. K., Gerecke, D. R., Olsen, B. R., and van der Rest, M. (1989) J. Biol. Chem. 264, 13150-13156).

Amino Acid Sequence↗
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↗