Redefined nomenclature for members of the carcinoembryonic antigen family.
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Alternative Splicing↗
Biomedical subjects
P Draber
Publications and source records attributed to P Draber.
Comparison of the expression of specific cell surface epitopes on in vitro fertilized and parthenogenetic bovine embryos.
Parthenogenetic embryos, which are produced by the spontaneous or artificial stimulation of the oocyte, partially develop in the complete absence of the male gamete but fail to produce live young in many mammalian species. The identification of developmentally regulated molecules on the cell surface of embryos has implicated their possible role in cell interactions during embryogenesis and differentiation. In this study the expression patterns of four stage-specific cell surface antigenic determinants (TEC-1, -2, -3, and -4) were investigated in both parthenogenetic and in vitro fertilized bovine embryos. When compared to embryos produced using in vitro fertilization methods the parthenogenotes, although appearing morphologically normal, differed markedly in their TEC epitope pattern of presentation. TEC-1, -2, -3, and -4 epitope presentation on in vitro fertilized embryos occurred during specific stages of preimplantation development. TEC-1 and -2 presentation was detected on oocytes and blastocysts only, TEC-3 on morulae and blastocysts, and TEC-4 on oocytes through to 8-cell embryos, with all subsequent stages negative. Parthenogenetic embryos did not show TEC-1, -2, or -3 epitope presentation whereas the TEC-4 epitope was present throughout the developmental period examined. Enzymatic cleavage of sialic acid residues on in vitro fertilized and parthenogenetic embryos resulted in presentation of the TEC epitopes during all the embryonic stages. Western blot analysis of the embryos showed the TEC epitopes to be present on all the embryonic stages examined. This study suggests the mechanisms responsible for control and presentation of each of the TEC epitopes may not be functioning the same in parthenogenetic embryos that undergo changed glycosylation or deglycosylation resulting in altered patterns of sialylation. The study also shows TEC epitope presentation may prove to be a useful indicator of parthenogenetically activated bovine embryos. J. Exp. Zool. 284:392-400, 1999.
Animals↗
Requirement for a negative charge at threonine 60 of the FcRgamma for complete activation of Syk.
Aggregation of FcepsilonRI on mast cells results in the phosphorylation of the FcepsilonRIgamma chain on tyrosine and threonine residues within the immunoreceptor tyrosine-based activation motif. In the present study we sought to identify the site of threonine phosphorylation in FcepsilonRIgamma and investigate its functional importance. We found that threonine 60 was phosphorylated in vitro and in vivo. Expression of a mutated FcepsilonRIgamma (T60A), in either FcepsilonRIgamma-deficient or gamma-null mast cells, resulted in a delay of FcepsilonRI endocytosis, inhibition of TNF-alpha mRNA production, and inhibition of degranulation but did not affect FcepsilonRI-induced cell adhesion. Tyrosine phosphorylation of the T60A mutant gamma chain was normal, but Syk phosphorylation was dramatically reduced in these transfectants. This correlated with reduced co-immunoprecipitation of FcepsilonRIgamma with Syk. Substitution of an aspartic residue for threonine 60 of the FcepsilonRIgamma reconstituted complete activation of Syk and co-immunoprecipitation of FcepsilonRIgamma with Syk. We conclude that the negative charge provided by phosphorylation of threonine 60 of the FcepsilonRIgamma is required for the appropriate interaction and activation of Syk. This is a likely requirement for immunoreceptor tyrosine-based activation motifs involved in Syk activation.
Amino Acid Sequence↗
The stage-specific expression of TEC-1, -2, -3, and -4 antigens on bovine preimplantation embryos.
The preimplantation developmental period is associated with constant changes within the embryo, and some of these changes are apparent on the embryo cell surface. For example, during transition from maternal to embryonic genome control and the compaction and differentiation of embryonic cells, the cell surface undergoes morphologic alterations that reflect changes in gene control. In order to gain insight into the events occurring during embryonic development and cellular differentiation, monoclonal antibodies specific for cell surface antigens (TEC antigens) of embryonic cells have been generated previously and shown to recognise either the carbohydrate moiety of embryoglycan or a developmentally regulated protein epitope. The TEC antigens have been identified on mouse preimplantation embryos, and their expression is specific to particular developmental stages. To determine whether these antigens are conserved in higher mammals, we examined the expression of four TEC antigens (TEC-1 to TEC-4) on in vitro-derived bovine and murine embryos during the preimplantation stage of development. It was found that bovine oocytes and embryos derived from in vitro maturation (IVM) and in vitro fertilisation (IVF) showed stage-specific expression of each of the TEC antigens investigated, with the pattern of expression overlapping but not identical to that seen in the mouse. Immunoprecipitation together with Western blot analysis showed that the TEC monoclonal antibodies recognised a single glycoprotein band with an apparent molecular weight of 70 kDa. Confocal microscopy of immunofluorescence staining of the bovine cells showed this protein to be located on the cell surface. The apparent negative expression of these TEC antigens by immunohistochemistry and immunoprecipitation at particular stages of development appears to be due to the epitopes being inaccessible to the TEC antibodies, since Western blotting revealed the TEC antigens to be present at all stages of development examined. Antibodies identifying stage-specific antigens will provide useful markers to characterise early embryonic cells, monitor normal embryonic development in vitro, and identify cell surface structures having a function in cell-cell interactions during embryogenesis and differentiation.
Animals↗
Treatment of Vicia faba root tip cells with specific inhibitors to cyclin-dependent kinases leads to abnormal spindle formation.
Many events during cell division are triggered by an evolutionary conserved regulator, the cyclin-dependent kinase (Cdk). Here we used two novel drugs, the purine analogues bohemine and roscovitine, to study the role of Cdks in cell cycle progression and microtubule organisation in Vicia faba root tip cells. Both drugs inhibited the activity of immunopurified Vicia faba and alfalfa Cdc2-kinase. The transcript levels of an A- and B-type cyclin, as well as of the cdc2 genes, declined in treated root tips, while the mRNA level of a D-type cyclin gene was not affected. An observed transient arrest at the G1/S and G2/M regulatory points indicated that inhibition of the Cdc2-kinase had an effect on both transitions. In contrast to the regular bipolar spindle in untreated cell, in drug-treated metaphase cells abnormally short and dense kinetochore microtubule fibres were observed. These microtubules were randomly arranged in the vicinity of the kinetochores and connected the chromosomes. Thus, the chromosomes were not aligned on the metaphase plate but were arranged in a circle, with kinetochores pointing inwards and chromosome arms pointing outwards. gamma-Tubulin, which plays a role in microtubule nucleation, also localised to the centre of the monopolar spindle. The observed abnormalities in mitosis, after inhibition of Cdc2-kinase by specific drugs, suggest a role for this enzyme in regulating some of the steps leading to a bipolar spindle structure.
CDC2 Protein Kinase↗
Cell-surface levels of human carcinoembryonic antigen are inversely correlated with colonocyte differentiation in colon carcinogenesis.
Human carcinoembryonic antigen (CEA) is overexpressed in a wide variety of epithelial malignancies including colon cancer. CEA can function in vitro as a homotypic intercellular adhesion molecule and can block the terminal differentiation of rodent myoblasts, thus raising the possibility that deregulated expression of CEA might directly contribute to malignant progression. To address this question, the expression pattern and cell-surface levels of CEA were studied during malignant transformation of the colonic epithelium in sporadic and familial adenomatous polyposis-related neoplasms. The level of immunohistochemically detected CEA was higher in 30% to 62% of microadenomas and small adenomas from familial adenomatous polyposis patients compared with adjacent normal mucosa, and this proportion was positively correlated with lesion size and degree of dysplasia. Cytofluorometric analysis of highly purified single epithelial cell suspensions from freshly excised carcinomas versus adjacent normal tissue demonstrated up to a 20-fold increase of mean cell-surface CEA in a group of colon carcinomas representative of the overall majority of such tumors--from Dukes' stages A to D and ranging mainly from well to moderately differentiated, the degree of overproduction was inversely correlated with tumor differentiation and directly correlated with stage. A marked tendency toward nonpolarized versus apical cell-surface expression with progression was also noted. Nonspecific cross-reacting antigen (NCA), a CEA family member, is also a homotypic adhesion molecule and blocks terminal myogenic differentiation, whereas biliary glycoprotein is a CEA family adhesion molecule that does not. Cell-surface NCA showed even greater overexpression (up to 70-told) in dedifferentiated tumors, whereas total-cell biliary glycoprotein showed approximately 2-fold lower levels than was normal in more differentiated tumors and approximately 2-fold higher levels than in further progressed tumors. These results therefore support the suggestion that CEA and NCA can directly contribute to colon carcinogenesis by inhibiting colonocyte differentiation.
Adenoma↗
Changes of MAP2 phosphorylation during brain development.
The microtubule-associated protein MAP2 is essential for development of early neuronal morphology and maintenance of adult neuronal morphology. Several splice variants exist, MAP2a-d, with a lack of MAP2a in cat brain. MAP2 is widely used as a neuronal marker. In this study we compared five monoclonal antibodies (MAbs) against MAP2. They show differences in the immunocytochemical distribution of MAP2 isoforms during development of the visual cortex and cerebellum of the cat. Local and temporal differences were seen with MAb AP18, an antibody directed against a phosphorylation-dependent epitope near the N-terminal end. In large pyramidal dendrites in visual cortex, the AP18 epitope remained in parts immunoreactive after treatment with alkaline phosphatase. Three MAbs, AP14, MT-01, and MT-02, recognized the central region of the MAP2b molecule, which is not present in MAP2c and 2d, and reacted with phosphorylation-independent epitopes. During the first postnatal week the immunostaining in cerebellum differed between antibodies in that some cellular elements in external and internal granular layers and Purkinje cells were stained to various degrees, whereas at later stages staining patterns were similar. At early stages, antibody MT-02 stained cell bodies and dendrites in cerebral cortex and cerebellum. With progressing maturation, immunoreactivity became restricted to distal parts of apical dendrites of pyramidal cells and was absent from perikarya and finer proximal dendrites in cortex. MT-02 did not stain MAP2 in cerebellum of adult animals. This study demonstrates that the immunocytochemical detection of MAP2 depends on modifications such as phosphorylation and conformational changes of the molecule, and that MAP2 staining patterns differ between MAbs. Phosphorylation and specific conformations in the molecule may be essential for modulating function and molecular stability of MAP2, and monoclonal antibodies against such sites may provide tools for studying the functional role of modifications.
Animals↗
[Microinjections of antibodies against microtubule proteins: the effect on distribution and movement of melanosomes in melanophores].
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Animals↗
Autoimmune damage to spermatogenesis in rodents immunized with mouse F9 embryonic carcinoma cells.
Significant inhibition of spermatogenesis and appearance of antibodies against spermatogenic cells identified by cytotoxicity and immunofluorescence reactions were observed in mice of inbred strains 129/Sv and BALB/c and in albino guinea pigs after syngeneic, allogeneic, and xenogeneic immunization with mouse F9 embryonic carcinoma cells and Freund's complete adjuvant. A similar syngeneic immunization with PYS-2 cells was ineffective. Appropriate absorption experiments confirmed the similarity between the antigens of F9 and spermatogenic cells and the absence of such a similarity with antigens of PYS-2 cells. These results support the hypothesis that the oncofetal F9 antigens represent spermatogenic differentiation antigens and thus play an essential role in spermatogenic cell differentiation.
Animals↗