PubMed Health⌕ Search

Biomedical subjects

C Ocklind

Publications and source records attributed to C Ocklind.

10 recordsLinked to original sources
PubMed1985

Comparison of two cell-adhesion molecules, uvomorulin and cell-CAM 105.

Two cell adhesion molecules, cell-CAM 105 and uvomorulin (UM), were compared by analysing their antigenic structures, their activity in cell aggregation assays and their expression in various tissues. Cell-CAM 105 is a membrane glycoprotein which mediates the intercellular adhesion of reaggregating rat hepatocytes, and UM was first described to be involved in the compaction of preimplantation mouse embryos and embryonal carcinoma cells. UM is not only expressed during embryonic development but also in various adult tissues including liver, epithelia of lung, gut, kidney and uterus. A similar distribution for UM was found in rat tissues on cell types where cell-CAM 105 is known to be present. Our studies show that (i) cell-CAM 105 and UM are distinct and different proteins; (ii) uvomorulin is involved in the compaction of rat preimplantation embryos but Fab anti-UM has no effect on reaggregating rat hepatocytes, where Fab anti-cell CAM is effective; (iii) distribution studies show that UM is expressed on a broader range of epithelial cells while cell-CAM 105 is more restricted to hepatocytes and simple epithelia. In cases where both cell adhesion molecules are expressed on the same cell types they can be localized to different parts of the cell surface.

Adenosine Triphosphatases↗
PubMed1984

Two different cell adhesion molecules--cell-CAM 105 and a calcium-dependent protein--occur on the surface of rat hepatocytes.

We have recently identified a 105000 D plasma membrane glycoprotein, denoted cell-CAM 105 (CAM, cell adhesion molecule), that is involved in intercellular adhesion of reaggregating rat hepatocytes (Ocklind & Obrink, J biol chem 257 (1982) 6788 [11]). In this communication we identify another cell surface protein that is also involved in hepatocyte cell-cell adhesion. This protein has an apparent molecular weight (MW) of 70000 and can be released from the surface membrane by chelation of calcium with EGTA. Results are presented indicating that it is identical with a previously discovered protein, CDP-1 (CDP, calcium-dependent protein) (Obrink, Lindström & Svennung, FEBS lett 70 (1976) 28 [28]). Antisera produced against either cell-CAM 105 or CDP-1 inhibit hepatocyte aggregation, but not attachment to collagen. Cell-CAM 105 and CDP-1 are present on the cell surface as separate components, as judged by the fact that both EGTA treatment and trypsin treatment of hepatocytes selectively make the cells insensitive to blocking of aggregation by antibodies against CDP-1 but not by antibodies against cell-CAM 105. However, although much less efficiently, the antibodies against CDP-1 can recognize a 105000 D protein which is also bound by the antibodies against cell-CAM 105, and under certain conditions the antibodies against cell-CAM 105 seem to recognize a 70000 D protein. CDP-1 may thus be derived from cell-CAM 105, or the two proteins might have a common precursor.

Adenosine Triphosphatases↗
PubMed1983

Ligand-dependent regulation of intracellular protein transport: effect of vitamin a on the secretion of the retinol-binding protein.

As a model of ligand-dependent protein secretion the biosynthesis, intracellular transport, and release of the retinol-binding protein (RBP) were studied in primary cultures of rat hepatocytes pulse-labeled with [35S]methionine. After various periods of chase RBP was isolated by immunoprecipitation and identified by SDS PAGE. Both normal and vitamin A-deficient hepatocytes synthesized RBP. The normal cells secreted the pulse-labeled RBP within 2 h. RBP synthesized by deficient cells was not secreted, and intracellular degradation of the protein appeared to be slow. Deficient cells could be induced to secrete RBP on the addition of retinol to the culture medium. This occurred also after protein synthesis had been blocked by cycloheximide. Since retinol induces the secretion of RBP, accumulated in the endoplasmic reticulum (ER), it seems reasonable to conclude that the transport of RBP from the ER to the Golgi complex is regulated by retinol.

Animals↗
PubMed1983

Cell surface localization and tissue distribution of a hepatocyte cell-cell adhesion glycoprotein (cell-CAM 105).

We recently identified a 105,000-dalton plasma membrane glycoprotein, denoted cell-CAM 105 (CAM, cell adhesion molecule), that is involved in intercellular adhesion of reaggregating rat hepatocytes (Ocklind, C., and B. Obrink, 1982, J. Biol. Chem., 257:6788-6795). In this communication we used a monospecific rabbit antiserum against cell-CAM 105 to localize the antigen by indirect immunofluorescence on isolated rat cells and on frozen rat tissue sections. This antiserum stained the surface of freshly isolated hepatocytes. In liver sections, however, the fluorescence seemed to be located exclusively along the bile canaliculi. In addition, cell-CAM 105 showed a very specific tissue distribution. Thus a specific fluorescence was seen only in the epithelia of the stomach, the small intestine, the large intestine, the glandular epithelium of the parotid gland, and the tubules of the kidney. No specific fluorescence was found in variety of other tissues, including cartilage, interstitial connective tissue, smooth muscle, skeletal muscle, heart muscle, eye, brain, skin, the epithelia of oesophagus, bladder, uterin mucosa, thyroid follicles, prostate gland, or collecting ducts of the kidney. In the simple epithelia of the intestine and the kidney tubules the fluorescence was confined to the apical, luminal portion. Thus, both in these epithelia and in liver, cell-CAM 105 was confined to the apical, luminal portion. Thus, both in these epithelia and in liver, cell-CAM 105 was located where the typical junctional complexes between cells are found. These findings taken together with the fact that cell-CAM 105 is involved in intercellular adhesion between hepatocytes suggest with the fac that cell-CAM 105 is involved in intercellular adhesion between hepatocytes suggest that cell-CAM 105 is a member of the junctional complexes of hepatocytes and some simple epithelia.

Adenosine Triphosphatases↗
PubMed1983

Cell-cell recognition: relation to cell adhesion with special reference to adhesion of hepatocytes.

Cell recognition is defined as an active process giving rise to a specific response. Cell adhesion is a good example of cell recognition when it can be demonstrated that the adhesion is mediated by molecules having specific binding properties. Such cell adhesion molecules have now been identified in several cellular systems. We have demonstrated that cell-cell adhesion between rat hepatocytes involves a 105,000 dalton cell surface glycoprotein (cell-CAM 105) and that other high molecular weight glycoproteins participate in the attachment of these cells to collagen. Using immunofluorescence we found cell-CAM 105 in the liver, the simple epithelia of the gastrointestinal tract, the kidney tubules and in the glandular epithelium of the parotid gland. In these tissues it was specifically located at the places of the junctional complexes. We have thus demonstrated that adhesion of adult rat hepatocytes is characterized by specificity both at the molecular and the cellular levels. However, the specificity at the cellular level was not complete, since the same cell-cell adhesion molecule was also present in some simple epithelia in addition to the liver.

Adenosine Triphosphatases↗
PubMed1982

Intercellular adhesion of rat hepatocytes. Identification of a cell surface glycoprotein involved in the initial adhesion process.

A cell surface molecule involved in intercellular adhesion between rat hepatocytes in vitro has been identified. Papain-solubilized plasma membrane components were fractionated; the ability of the solubilized components to neutralize the inhibition of cell aggregation, caused by multispecific antibodies directed against the cell surface, was used to follow the purification. The purified components were used to immunize rabbits. The resulting antibodies effectively inhibited hepatocyte aggregation, and this inhibitory effect could be neutralized by detergent-solubilized plasma membrane components having an apparent molecular weight of 105,000 in polyacrylamide gel electrophoresis. Also by immunoprecipitation, immunoblotting, and immunosorbent techniques it was demonstrated that the antibodies specifically reacted with a plasma membrane component having an apparent molecular weight of 105,000. This component was susceptible to digestion with papain and showed specific binding to the carbohydrate-binding lectin Lens culinaris hemagglutinin. It was thus concluded that a glycoprotein with a mass of about 105,000 daltons is involved in rat hepatocyte intercellular adhesion.

Animals↗