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- Surmann-Schmitt, C, et al.
(författare)
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UCMA, a novel secreted cartilage-specific protein with implications in osteogenesis
- 2008
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 283:11, s. 7082-7093
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Tidskriftsartikel (refereegranskat)abstract
- Here we report on the structure, expression and function of a novel cartilage-specific gene coding for a 17 kDa small, highly charged and secreted protein that we termed Ucma (Unique Cartilage Matrix Associated protein). The protein is processed by a furin-like protease into an N-terminal peptide of 37 amino acids and a C-terminal fragment (Ucma-C) of 74 amino acids. Ucma is highly conserved between mouse, rat, human, dog, clawed frog, and zebrafish, but has no homology to other known proteins. Remarkable are 1-2 tyrosine sulphate residues per molecule and dense clusters of acidic and basic residues in the C-terminal part. In the developing mouse skeleton Ucma-mRNA is expressed in resting chondrocytes in the distal and peripheral zones of epiphyseal and vertebral cartilage. Ucma is secreted into the extracellular matrix as uncleaved precursor and shows the same restricted distribution pattern in cartilage as Ucma mRNA. In contrast, antibodies prepared against the processed C-terminal fragment located Ucma-C in the entire cartilage matrix, indicating that it either diffuses or is retained until chondrocytes reach hypertrophy. During differentiation of an MC615 chondrocyte subclone in vitro, Ucma expression parallels largely the expression of collagen II, and decreases with maturation towards hypertrophic cells. Recombinant Ucma-C does not affect expression of chondrocyte-specific genes or proliferation of chondrocytes, but interferes with osteogenic differentiation of osteoblast precursors. These findings suggest that Ucma may be involved in the negative control of osteogenic differentiation of osteo-chondrogenic precursor cells in peripheral zones of fetal cartilage and at the cartilage-bone interface.
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| 3. |
- Brachvogel, B, et al.
(författare)
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Perivascular cells expressing annexin A5 define a novel mesenchymal stem cell-like population with the capacity to differentiate into multiple mesenchymal lineages
- 2005
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Ingår i: Development: For advances in developmental biology and stem cells. - : The Company of Biologists. - 1477-9129. ; 132:11, s. 2657-2668
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Tidskriftsartikel (refereegranskat)abstract
- The annexin A5 gene (Anxa5) was recently found to be expressed in the developing and adult vascular system as well as the skeletal system. In this paper, the expression of an Anxa5-lacZ fusion gene was used to define the onset of expression in the vasculature and to characterize these Anxa5-lacZ-expressing vasculature-associated cells. After blastocyst implantation, Anxa5-lacZ-positive cells were first detected in extra-embryonic tissues and in angioblast progenitors forming the primary vascular plexus. Later, expression is highly restricted to perivascular cells in most blood vessels resembling pericytes or vascular smooth muscle cells. Viable Anxa5-lacZ(+) perivascular cells were isolated from embryos as well as adult brain meninges by specific staining with fluorescent X-gal substrates and cell-sorting. These purified lacZ(+) cells specifically express known markers of pericytes, but also markers characteristic for stem cell populations. In vitro and in vivo differentiation experiments show that this cell pool expresses early markers of chondrogenesis, is capable of forming a calcified matrix and differentiates into adipocytes. Hence, Anxa5 expression in perivascular cells from mouse defines a novel population of cells with a distinct developmental potential.
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| 4. |
- Herzog, C, et al.
(författare)
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Dystroglycan in skin and cutaneous cells: beta-subunit is shed from the cell surface
- 2004
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Ingår i: Journal of Investigative Dermatology. - 1523-1747. ; 122:6, s. 1372-1380
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Tidskriftsartikel (refereegranskat)abstract
- In skin, hemidesmosomal protein complexes attach the epidermis to the dermis and are critical for stable connection of the basal epithelial cell cytoskeleton with the basement membrane (BM). In muscle, a similar supramolecular aggregate, the dystrophin glycoprotein complex links the inside of muscle cells with the BM. A component of the muscle complex, dystroglycan (DG), also occurs in epithelia. In this study, we characterized the expression and biochemical properties of authentic and recombinant DG in human skin and cutaneous cells in vitro. We show that DG is present at the epidermal BM zone, and it is produced by both keratinocytes and fibroblasts in vitro. The biosynthetic precursor is efficiently processed to the alpha- and beta-DG subunits; and, in addition, a distinct extracellular segment of the transmembranous beta-subunit is shed from the cell surface by metalloproteinases. Shedding of the beta-subunit releases the alpha-subunit from the DG complex on the cell surface into the extracellular space. The shedding is enhanced by IL-1beta and phorbol esters, and inhibited by metalloproteinase inhibitors. Deficiency of perlecan, a major ligand of alpha-DG, enhanced shedding suggesting that lack of a binding partner destabilizes the epithelial DG complex and makes it accessible to proteolytic processing.
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