Literaturberichte

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Bemerkungen über volksthümliche Pflanzennamen

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B7/CD28 costimulation of T cells induces a distinct proteome pattern

Effective immune strategies for the eradication of human tumors require a detailed understanding of the interaction of tumor cells with the immune system, which might lead to an optimization of T cell responses. To understand the impact of B7-mediated costimulation on T cell activation comprehensive proteome analysis of B7-primed T cell populations were performed. Using this approach we identified different classes of proteins in T cells whose expression is either elevated or reduced upon B7-1- or B7-2-mediated CD28 costimulation. The altered proteins include regulators of the cell cycle and cell proliferation, signal transducers, components of the antigen processing machinery, transporters, cytoskeletal proteins, and metabolic enzymes. A number of differentially expressed proteins are further modified by phosphorylation. Our results provide novel insights into the complexity of the CD28 costimulatory pathway of T cells and will help to identify potential targets of therapeutic interventions for modulating anti-tumor T cell activation.     

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Die Maria-Theresia-Palme

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Staurosporine Induces Astrocytic Phenotypes and Differential Expression of Specific PKC Isoforms in C6 Glial Cells

Abstract: In this study we examined the effects of staurosporine, a potent inhibitor of protein kinase C (PKC), on the differentiation of C6 glial cells and on the expression and cellular distribution of specific PKC isoforms. Staurosporine reduced cell proliferation and induced distinctive changes in the morphological appearance of the cells to that characteristic of cells exhibiting astrocytic phenotypes. The differentiative effect of staurosporine was further indicated by the increased expression of two proteins related to astrocytic phenotypes, glial fibrillary acidic protein (GFAP) and glutamine synthetase. Thus, staurosporine induced a dose-dependent increase both in GFAP immunoreactivity and in the activity and protein levels of glutamine synthetase. Staurosporine also induced a decrease in the expression of PKC-β₂ and an increase in that of PKC-γ. In addition, it induced translocation of PKC-ε from the membrane to the cytosol, whereas no differences were observed in the distribution of the other PKC isoforms. The results of our study indicate that staurosporine induced astrocytic phenotypes in glial cells and that changes in the expression and cellular distribution of these PKC isoforms may be related to astrocytic differentiation.