Members of the P 4 subfamily of P-type ATPases catalyze phospholipid transport and create membrane lipid asymmetry in late secretory and endocytic compartments. P-type ATPases usually pump small cations and the transport mechanism involved appears conserved throughout the family. How this mechanism is adapted to flip phospholipids remains to be es-

MOG antibodies are strongly skewed towards ADS children that present with an ADEM-like disease onset. The presence of such antibodies pleads against a future diagnosis of MS.

Tumor necrosis factor (TNF) exists both as a membrane-integrated type II precursor protein and a soluble cytokine that have different bioactivities on TNFR2 (CD120b) but not on TNFR1 (CD120a). To identify the molecular basis of this disparity, we have investigated receptor chimeras comprising the cytoplasmic part of Fas (CD95) and the extracellular domains of the two TNF receptors. The membrane form of TNF, but not its soluble form, was capable of inducing apoptosis as well as activation of c-Jun N-terminal kinase and NF-B via the TNFR2-derived chimera. In contrast, the TNFR1-Fas chimera displayed strong responsiveness to both TNF forms. This pattern of responsiveness is identical to that of wild type TNF receptors, demonstrating that the underlying mechanisms are independent of the particular type of the intracellular signaling machinery and rather are controlled upstream of the intracellular domain. We further demonstrate that the signaling strength induced by a given ligand/receptor interaction is regulated at the level of adaptor protein recruitment, as shown for FADD, caspase-8, and TRAF2. Since both incidents, strong signaling and robust adapter protein recruitment, are paralleled by a high stability of individual ligand-receptor complexes, we propose that half-lives of individual ligand-receptor complexes control signaling at the level of adaptor protein recruitment.

Since the first discovery of ATP-dependent translocation of lipids in the human erythrocyte membrane in 1984, there has been much evidence of the existence of various ATPases translocating lipids in eukaryotic cell membranes. They include Ptype ATPases involved in inwards lipid transport from the exoplasmic leaflet to the cytosolic leaflet and ABC proteins involved in outwards transport. There are also ATP-independent proteins that catalyze the passage of lipids in both directions. Five Ptype ATPase involved in lipid transport have been genetically characterized in yeast cells, suggesting a pool of several proteins with partially redundant activities responsible for the regulation of lipid asymmetry. However, expression and purification of individual yeast proteins is still insufficient to allow reconstitution experiments in liposomes. In this review, we want to give an overview over current investigation efforts about the identification and purification of proteins that may be involved in lipid translocation.

Most members of the tumor necrosis factor (TNF) ligand family occur in both a membrane-bound and a soluble form, which can possess differential bioactivities. The aim of this work was the construction of a synthetic-biological hybrid system consisting of chemically nanostructured core-shell particles with a diameter of 100 nm, 1 microm, or 10 microm and the cytokine TNF to obtain a tool that mimics the bioactivity of naturally occurring membrane-bound TNF. Synthetic core-shell nanoparticles consisting of an inorganic silica core and an ultrathin organic shell bearing a maleimide group at the shell surface which allowed for a covalent and site-directed coupling of CysHisTNF mutants were prepared. The TNF mutants were modified at the N-terminus by PCR cloning by introducing a His-Tag for purification and a free cysteine group for reaction with the particle-attached maleimide group. The resulting nanostructured hybrid particles initiated strong TNF receptor type 2 specific responses, otherwise only seen for the membrane-bound form of TNF, but not the soluble cytokine, thus clearly demonstrating new and membrane TNF-like properties of the bioconjugated soluble TNF.

Platinum-based anticancer agents have been widely used in the clinic to successfully treat many different types of cancer. However, the therapeutic efficacy of platinum drugs is limited by serious side effects and the occurrence of inherent or acquired resistance of tumor cells. Nanoparticulate drug-delivery systems have the potential to reduce side effects and circumvent drug resistance. Among these, cisplatin nanocapsules represent a unique lipid formulation of cisplatin with an unsurpassed encapsulation efficiency, which dramatically increases the cytotoxicity of cisplatin in several cell lines in vitro. The mechanism responsible for the strongly enhanced cytotoxicity of the nanocapsules and the remarkable cell-line dependence will be reviewed. The requirements and possibilities for future successful therapeutic use of nanocapsules will be discussed, based on the mechanisms of cellular uptake of cisplatin nanocapsules and the first in vivo tests in a mouse model.

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