Characterization and functional studies on epiphycan and osteoglycin, two small leucine-rich proteoglycans /
Endochondral ossification is a process by which mesenchymal precursor cells begin a differentiation process where cells become committed chondrocytes and change their biosynthesis program and end when the chondrocytes become hypertrophic and are eventually removed and replaced by bone. We have disco...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1999.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=730298041&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Endochondral ossification is a process by which mesenchymal precursor cells begin a differentiation process where cells become committed chondrocytes and change their biosynthesis program and end when the chondrocytes become hypertrophic and are eventually removed and replaced by bone. We have discovered a molecule which we name epiphycan that has been isolated from fetal epiphyseal cartilage. Epiphycan is a member of the small leucine-rich repeat proteoglycan (SLRP) family of extracellular matrix proteins. We have isolated and characterized this proteoglycan from fetal bovine epiphyseal cartilage. We found that the amino acid sequence had sequence similarity to chick PG-Lb, a small fermatas sulfate proteoglycan previously isolated from chick epiphyseal cartilage. The intact proteoglycan had a median size of ~133kDa as determined by gel permeation chromatography. The core protein was 46kDa as determined by gel electrophoresis. The glycosaminoglycan chains ranged in size from 23 to 34 kDa as determined by gel permeation chromatography. The coding region for epiphycan was determined, and the primary amino acid sequence was deduced. To determine the expression pattern and protein localization, in situ hybridization and immunolocalization using sections taken from developing mouse embryos were performed. The onset of epiphycan/PG-Lb expression was determined to occur at 12.5dpc in the developing mouse embryo and is restricted to the resting and proliferating chondrocytes in growth plate cartilage. By comparison with other cartilage-specific markers, epiphycan/PG-Lb was determined to be an intermediate marker for chondrogenesis. Using an antibody to epiphycan, we see that the epiphycan/tab protein is localized throughout the growth plate cartilage including the hypertrophic zone where there is no expression. Using gene targeting technology, we have generated heterozygotes for a null mutation in the epiphycan/Lb gene. These mice are being used to produce the homozygote null mutant animals for analysis of gene function. We have now characterized the mouse gene encoding osteoglycin, a related molecule. The Ogn gene has seven ebons that are spaced similarly to mouse Pglb. We have also localized this gene to both mouse and human chromosomes, 9q22 and 13, respectively. Finally, we have determined the expression pattern of the Ogn gene during fetal mouse development. |
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| Item Description: | Vita. "Major Subject: Biochemistry". |
| Physical Description: | xiii, 167 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 143-157). |