0000000000218922
AUTHOR
T. Knittel
showing 7 related works from this author
Expression of the gene of the alpha-smooth muscle-actin isoform in rat liver and in rat fat-storing (ITO) cells.
1990
Fat storing cells (FSCs) in the liver represent the main site of vitamin A deposition in the body. These cells are considered to play an important role during scar formation and fibrogenesis in the liver. The putative descent of FSCs from the fibroblastic or from the myofibroblastic system have not been determined yet by morphological or immunohistochemical studies. To further define the origin of these liver cells, we analysed the pattern of expression of three structural proteins: vimentin, desmin and the α-smooth muscle (SM)-actin isoform in FSCs of the rat liver, in smooth muscle cells (SMCs) from the aorta and in rat skin fibroblasts. FSCs were studied by immunohistochemical methods im…
Cultured Ito cells of rat liver express the alpha 2-macroglobulin gene.
1987
Ito cells were isolated from rat liver and kept in culture for up to 13 days. The capability of the Ito cells to synthesize a2-macroglobulin was analyzed at different times after isolation and by pulse-chase experiments. Newly synthesized a2-macroglobulin was determined by immunoprecipitation followed by sodium dodecyl sulfate/ polyacrylamide gel electrophoresis and fluorography. a2-Macroglobulin synthesis was hardly detectable in Ito cells and their media 3 days after plating. However, 5 - 11 days after the isolation of the cells, increasing amounts of a2-macroglobulin were synthesized. The results of pulse-chase experiments performed on day 7 showed that radioactively labeled a2-macroglob…
Dexamethasone modulates α2-macroglobulin and apolipoprotein E gene expression in cultured rat liver fat-storing (Ito) cells
1991
Fat-storing (Ito) cells are perisinusoidal liver cells thought to play a central role in vitamin A metabolism and fibrogenesis. Glucocorticoids have been shown to be beneficial in the treatment of certain types of liver diseases by delaying the development of cirrhosis. To study the regulatory effects of dexamethasone on Ito cell gene expression, Ito cells were isolated from normal rat liver and primary cultures were established. The effect of dexamethasone on the synthesis of α2-macroglobulin, apolipoprotein E, fibronectin and actin was examined. Protein synthesis was studied both at the protein level and at the RNA level by means of biosynthetic labeling, immunoprecipitation followed by s…
Synthesis of undulin by rat liver fat-storing cells: Comparison with fibronectin and tenascin
1992
Abstract Fat-storing cells (FSCs) are known to synthesize various components of the hepatic extracellular matrix and thereby play an important role during liver fibrogenesis. The aim of our study was to investigate the synthesis of undulin, a recently described connective tissue protein belonging to the fibronectin—tenascin superfamily of glycoproteins, by fat-storing cells in primary culture. SDS-PAGE analysis of immunoprecipitates from cell layer lysates or media pulse-labeled with radioactive methionine revealed undulin-specific bands A (270 kDa), B1 (190 kDa), and B2 (180 kDa) after reduction. A single undulin-specific transcript was detected at about 7 kb. Undulin synthesized by cell-f…
Fat-storing cells of the rat liver synthesize and secrete C1-esterase inhibitor; modulation by cytokines.
1992
During liver fibrogenesis, fat-storing cells transform into myofibroblast-like cells and produce increasing amounts of extracellular matrix proteins. Because fat-storing cells produce α2-macroglobulin, an important serine protease inhibitor (serpin), we investigated whether fat-storing cells also synthesize C1-esterase inhibitor, another important serpin. C1-esterase inhibitor synthesis was studied in rat fatstoring cells at day 0, 3 and 7 after isolation by biosynthetic labeling, immunoprecipitation and sodium dodecyl sulfate–polyacrylamide gel electrophoresis. Messenger RNA was examined by Northern-blot analysis. C1-esterase inhibitor gene expression and synthesis were detectable in fresh…
The gene of hepatocyte growth factor is expressed in fat-storing cells of rat liver and is downregulated during cell growth and by transforming growt…
1992
Hepatocyte growth factor (HGF) has been detected in non-parenchymal cells but not in hepatocytes. We performed Northern blot analysis of total RNA extracted from rat hepatocytes, Kupffer cells, endothelial cells and fat-storing (Ito-) cells. Total RNA was extracted from fat-storing cells at different times after isolation and from cells treated with different amounts of transforming growth factor beta. The RNA was hybridized with HGF, fibronectin-, and alpha-actin-specific cDNA probes, consecutively. We found an abundant amount of HGF mRNA in freshly isolated fat-storing cells, but not in other liver cells. The amount of the HGF transcripts decreases significantly in FSC during the time of …
Differential expression of collagen types I, III, and IV by fat-storing (Ito) cells in vitro
1992
It has been observed that Ito cells in vitro undergo phenotypical changes ("activation") similar to those noted in vivo during the development of liver fibrosis. Because conflicting data have been published on the amount and different types of collagens synthesized by Ito cells in vitro, collagen biosynthesis was studied at different "activation" stages on both the protein and RNA levels. Immunoprecipitation of endogenously labeled collagen showed that freshly isolated ("resting") Ito cells synthesize mainly collagen type IV. Collagen type I was hardly detectable in the earlier stage of primary culture, but it clearly increased starting 5 days after isolation. Compared with the basal rates …