1,721,163 research outputs found
Expression and Androgen Regulation of C-Cam Cell Adhesion Molecule Isoforms in Rat Dorsal and Ventral Prostate
No full textC-CAM is an epithelial cell adhesion molecule with two major splice variants that differ in the length of the cytoplasmic domain. C-CAM1 (long (L)-form) strongly suppresses the tumorigenicity of human prostate carcinoma cells. In contrast, C-CAM2 (short (S)-form) does not exhibit tumor-suppressive activity. In the present study we have investigated the functional significance of L-form and S- form C-CAM in rat prostate by examining their expression and distribution in different prostate lobes and their response to androgen deprivation. RNase protection assays with a probe for both C-CAM isoforms detected high levels of C-CAM messages in the rat dorso-lateral prostate (DLP). L- and S- form proteins, localized by indirect immunofluorescence using isoform-specific antipeptide antibodies, were co- expressed on the apical surface of prostate epithelial cells in normal DLP. Androgen depletion did not significantly change the steady state levels of C-CAM message and protein expression in the DLP, although there was a change in the pattern of protein expression in these lobes. In contrast, C -CAM isoform messages and proteins were undetectable in normal ventral prostate (VP) but increased markedly in this lobe in response to castration, producing isoform ratios similar to those in DLP. These results demonstrate that coordinate expression of C- CAM isoforms is maintained in the VP following androgen depletion and suggest that androgen suppresses C-CAM expression in VP but not in DLP. These results suggest that balanced expression of L- and S-form C- CAM is important for normal prostate growth and differentiation
C-CAM (cell-CAM 105) is an adhesive cell surface glycoprotein with homophilic binding properties
No full textC-CAM (Cell-CAM 105) is a cell surface glycoprotein that is involved in cell-cell adhesion of rat hepatocytes in vitro. To elucidate the adhesion mechanism the binding properties of purified C-CAM were investigated. Using proteins immobilized on nitrocellulose it was found that radiolabeled C-CAM bound to C-CAM but not to a variety of other proteins. Partitioning in Triton X-114 showed that C-CAM has hydrophobic properties. In accordance with this, C-CAM was effectively incorporated into phosphatidylcholine liposomes by dialysis from octylglucoside-containing solutions. The C-CAM-containing liposomes bound specifically to isolated hepatocytes. This binding was blocked by Fab fragments of anti-C-CAM antibodies. Furthermore, preincubation of hepatocytes with anti-C-CAM antibodies followed by washing of the cells blocked binding of C-CAM-containing liposomes. At increasing C-CAM contents in the reconstituted liposomes a marked self-aggregation of the liposomes occurred. This aggregation was blocked by Fab fragments of anti-C-CAM antibodies and by alkaline pH. After neutralization a rapid reaggregation occurred. Neither C-CAM binding to C-CAM immobilized on nitrocellulose nor C-CAM-liposome aggregation required calcium ions. Liposomes reconstituted with C-CAM-depleted membrane glycoproteins did not self-aggregate or bind to hepatocytes. Thus, it is concluded that C-CAM can bind specifically to C-CAM in a homophilic binding reaction that does not require calcium. Accordingly, C-CAM has the potential of directly mediating cell-cell adhesion via C-CAM-C-CAM binding between adjacent cells
Spatiotemporal Expression of C-CAM in the Rat Placenta
No full textWe investigated the expression of the immunoglobulin superfamily cell adhesion molecule, C-CAM, in developing and mature rat placenta. By immunohistochemical staining at the light microscopic level, no C-CAM-expression was seen before Day 9 of gestation, when it appeared in the trophoblasts of ectoplacental cones. On Day 10.5, spongiotrophoblasts and invasive trophoblasts around the maternal vessels of the decidua basalis were stained positively. On Day 12.5, C-CAM was detected in the spongiotrophoblasts of the junctional layer, but labyrinth trophoblasts and secondary giant trophoblasts were not stained. On Day 17.5, C-CAM was found only in the labyrinth and lacunae of the junctional layer. At this stage, both the labyrinth cytotrophoblasts of the maternal blood vessels and the endothelial cells of the embryonic capillaries were strongly stained. Placental tissues from gestational Days 12.5 and 17.5 were analyzed by immunoelectron microscopy to determine the location of C-CAM at the subcellular level. On Day 12.5, positive staining of the spongiotrophoblasts was observed, mainly on surface membranes and microvilli between loosely associated cells. On Day 17.5, staining was found primarily on the microvilli of the maternal luminal surfaces of the labyrinth cytotrophoblasts, and both on the luminal surface and in the cytoplasm of endothelial cells of the embryonic vessels. RT-PCR analysis and Southern blotting of the PCR products revealed expression of mRNA species for both of the major isoforms, C-CAM1 and C-CAM2. Immunoblotting analysis of C-CAM isolated from 12.5-day and 14.5-day placentae showed that it appeared as a broad band with an apparent molecular mass of 110–170 kD. In summary, C-CAM was strongly expressed in a specific spatiotemporal pattern in trophoblasts actively involved in formation of the placental tissue, suggesting an important role in placental development. In the mature placenta, C-CAM expression was confined to the trophoblastic and endothelial cells lining the maternal and embryonic vessels, respectively, suggesting important functions in placental physiology.</jats:p
C-CAM (Cell-CAM 105) is a calmodulin binding protein
No full textAbstractC-CAM (Cell-CAM 105) is a transmembrane cell adhesion molecule belonging to the immunoglobulin superfamily. It mediates intercellular adhesion of rat hepatocytes and occurs in various isoforms in several epithelia, vessel endothelia and leukocytes. We now report that purified liver C-CAM interacts specifically with calmodulin. Binding was observed both when 125I-labeled C-CAM was used in a dot-blot assay and when 125I-labeled calmodulin was used in a gel overlay assay. Experiments with protease-generated peptides indicated that calmodulin bound to the cytoplasmic domain of C-CAM. Analyses of whole liver membranes demonstrated that C-CAM is one of five major proteins that bind calimodulin in a calcium-dependent manner
C-CAM (cell-CAM 105) is an adhesive cell surface glycoprotein with homophilic binding properties [Elektronisk resurs]
No full textC-CAM (Cell-CAM 105) is a cell surface glycoprotein that is involved in cell-cell adhesion of rat hepatocytes in vitro. To elucidate the adhesion mechanism the binding properties of purified C-CAM were investigated. Using proteins immobilized on nitrocellulose it was found that radiolabeled C-CAM bound to C-CAM but not to a variety of other proteins. Partitioning in Triton X-114 showed that C-CAM has hydrophobic properties. In accordance with this, C-CAM was effectively incorporated into phosphatidylcholine liposomes by dialysis from octylglucoside-containing solutions. The C-CAM-containing liposomes bound specifically to isolated hepatocytes. This binding was blocked by Fab fragments of anti-C-CAM antibodies. Furthermore, preincubation of hepatocytes with anti-C-CAM antibodies followed by washing of the cells blocked binding of C-CAM-containing liposomes. At increasing C-CAM contents in the reconstituted liposomes a marked self-aggregation of the liposomes occurred. This aggregation was blocked by Fab fragments of anti-C-CAM antibodies and by alkaline pH. After neutralization a rapid reaggregation occurred. Neither C-CAM binding to C-CAM immobilized on nitrocellulose nor C-CAM-liposome aggregation required calcium ions. Liposomes reconstituted with C-CAM-depleted membrane glycoproteins did not self-aggregate or bind to hepatocytes. Thus, it is concluded that C-CAM can bind specifically to C-CAM in a homophilic binding reaction that does not require calcium. Accordingly, C-CAM has the potential of directly mediating cell-cell adhesion via C-CAM-C-CAM binding between adjacent cells
The cell adhesion molecule C-CAM is a substrate for tissue transglutaminase
No full textAbstractC-CAM, a ubiquitously expressed cell adhesion molecule belonging to the carcinoembryonic antigen family, appears as two co-expressed isoforms, C-CAM-L and C-CAM-S, with different cytoplasmic domains, that can form homo-dimers in epithelial cells. In addition, C-CAM-L has been found in large molecular weight forms suggesting posttranslational, covalent modification. Here we have investigated the possibility that the cytoplasmic domain of C-CAM-L can act as a transglutaminase substrate. Glutathione S-transferase fusion proteins of the cytoplasmic domains of rat and mouse C-CAM-L as well as free cytoplasmic domains, released by thrombin cleavage from the fusion proteins, were converted into covalent dimers by tissue transglutaminase. These results demonstrate that the cytoplasmic domains of rat and mouse C-CAM-L are substrates for tissue transglutaminase, and lend support to the notion that higher molecular weight forms of C-CAM-L are formed by transglutaminase modification
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Characterization of protein kinase C-mediated phosphorylation of the short cytoplasmic domain isoform of C-CAM
No full textAbstractC-CAM is a ubiquitously expressed cell adhesion molecule belonging to the carcinoembryonic antigen family. Two co-expressed isoforms, C-CAM-L and C-CAM-S, are known, having different cytoplasmic domains both of which can be phosphorylated in vivo. Here we have characterized the PKC-mediated phosphorylation of the short cytoplasmic domain isoform, C-CAM-S. Phorbol myristyl acetate induced phosphorylation of C-CAM-S in transfected CHO cells. Using synthetic peptides and Edman degradation we identified Ser449 as the PKC-phosphorylated amino acid residue. Binding experiments with modified peptides indicated that this phosphorylation decreases the ability of the cytoplasmic domain of C-CAM-S to bind calmodulin
Differential Expression of C-Cam Cell Adhesion Molecule in Prostate Carcinogenesis in a Transgenic Mouse Model
No full textPurpose: The transgenic adenocarcinoma of mouse prostate ( TRAMP) model, in which various grades of prostate intraepithelial neoplasia (PIN) and prostate cancer with metastases can be reproducibly generated, is a paradigm for prostate disease progression. We have previously shown that C -CAM, an adhesion molecule, can suppress the growth of prostate cancer. In this report, we describe immunohistochemical characterization of differential expression of C-CAM at various stages of prostate tumorigenesis in the TRAMP model. Materials and Methods: We sampled prostate specimens and periaortic lymph nodes from TRAMP mice. Indirect immunohistochemical staining with a polyclonal anti-C-CAM antibody was performed on the formalin -fixed, paraffin-embedded specimens. After castration at 12 weeks of age, the TRAMP mice developed androgen- independent prostate cancer (AIPC) and lymph node metastasis at 18 to 24 weeks of age. Samples from these castrated mice were also analyzed. Results: C-CAM protein was expressed in the normal prostate epithelia of non-transgenic and TRAMP mice as well as in low-grade PINs in TRAMP mice. Expression was uniform on the luminal surfaces of these epithelia. C-CAM expression was noticeably reduced and the staining pattern heterogeneous in some high-grade PINs. C-CAM staining was generally absent in prostate cancer and metastatic lymph nodes. Androgen independent prostate cancer and its metastatic tumors generated in castrated TRAMP mice were also C- CAM negative. Conclusions: C-CAM expression correlates with the differentiation states of prostate epithelia and is down regulated early in prostate tumorigenesis in the TRAMP model
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