| 2. |
- Terracio, Louis, et al.
(författare)
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Induction of platelet-derived growth factor receptor expression in smooth muscle cells and fibroblasts upon tissue culturing
- 1988
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Ingår i: Journal of Cell Biology. - 0021-9525. ; 107:5, s. 1947-1957
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Tidskriftsartikel (refereegranskat)abstract
- The expression of platelet-derived growth factor (PDGF) receptors in porcine uterus and human skin in situ, was compared with that of cultured primary cells isolated from the same tissues. PDGF receptor expression was examined by monoclonal antibodies specific for the B type PDGF receptor and by RNA/RNA in situ hybridization with a probe constructed from a cDNA clone encoding the B type PDGF receptor. In porcine uterus tissue both mRNA and the protein product for the PDGF receptor were detected in the endometrium; the myometrium, in contrast, contained much lower amounts. Moreover, freshly isolated myometrial cells were devoid of PDGF receptors. However, after 1 d in culture receptors appeared, and after 2 wk of culturing essentially all of the myometrial cells stained positively with the anti-PDGF receptor antibodies and contained PDGF receptor mRNA. Similarly, B type PDGF receptors were not detected in normal human skin, but fibroblast-like cells from explant cultures of human skin possessed PDGF receptors. When determined by immunoblotting, porcine uterus myometrial membranes contained approximately 20% of the PDGF receptor antigen compared with the amount found in endometrial membranes. In addition, PDGF stimulated the phosphorylation of a 175-kD component, most likely representing autophosphorylation of the B type PDGF receptor in endometrial membranes, whereas only a marginal phosphorylation was seen in myometrial membranes. Taken together, these results demonstrate that PDGF receptor expression varies in normal tissues and that fibroblasts and smooth muscle cells do not uniformly express the receptor in situ. Furthermore, fibroblasts and smooth muscle cells that are released from tissues are induced to express PDGF receptors in response to cell culturing. The data suggest that, in addition to the availability of the ligand, PDGF-mediated cell growth in vivo is dependent on factors regulating expression of the receptor.
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| 3. |
- Tingström, Anders, et al.
(författare)
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Distribution and dynamics of cell surface-associated cellCAM 105 in cultured rat hepatocytes
- 1989
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Ingår i: Experimental Cell Research. - : Elsevier BV. - 1090-2422 .- 0014-4827. ; 185:1, s. 132-142
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Tidskriftsartikel (refereegranskat)abstract
- The cellular location of cellCAM 105 was studied by indirect immunofluorescence microscopy of primary rat hepatocytes grown in monolayer culture. Staining corresponding to cellCAM 105 was seen both in cell-cell contact areas and on the upper surfaces of the cells. In the cell-cell contact areas the antigen was not accessible to the antibodies unless the cells were either permeabilized with detergent or incubated in a calcium-free medium. Removal of calcium from the medium caused the cells to separate from each other. Within a few minutes wide intercellular clefts were formed, and upon further incubation the cells became stellate-shaped and finally remained in contact with each other only via thin cellular processes. These processes were cellCAM 105-positive and at sites where they attached to the bodies of the contracted cells a granular fluorescence pattern appeared. After 24-48 h of culture, intercellular channels resembling bile canaliculi were sometimes formed in the hepatocyte monolayers. The membranes of these intercellular channels were stained for cellCAM 105. After culture for several days the hepatocytes lost their polygonal shape and gradually acquired a more fibroblast-like morphology. This morphological change was accompanied by a decrease in cellCAM 105-specific fluorescence, both in the cell-cell contact areas and on the free cell surfaces.
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