@article{HollmannWieseDennstaedtetal.2019, author = {Hollmann, Claudia and Wiese, Teresa and Dennst{\"a}dt, Fabio and Fink, Julian and Schneider-Schaulies, J{\"u}rgen and Beyersdorf, Niklas}, title = {Translational approaches targeting ceramide generation from sphingomyelin in T cells to modulate immunity in humans}, series = {Frontiers in Immunology}, volume = {10}, journal = {Frontiers in Immunology}, number = {2363}, issn = {1664-3224}, doi = {10.3389/fimmu.2019.02363}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-198806}, year = {2019}, abstract = {In T cells, as in all other cells of the body, sphingolipids form important structural components of membranes. Due to metabolic modifications, sphingolipids additionally play an active part in the signaling of cell surface receptors of T cells like the T cell receptor or the co-stimulatory molecule CD28. Moreover, the sphingolipid composition of their membranes crucially affects the integrity and function of subcellular compartments such as the lysosome. Previously, studying sphingolipid metabolism has been severely hampered by the limited number of analytical methods/model systems available. Besides well-established high resolution mass spectrometry new tools are now available like novel minimally modified sphingolipid subspecies for click chemistry as well as recently generated mouse mutants with deficiencies/overexpression of sphingolipid-modifying enzymes. Making use of these tools we and others discovered that the sphingolipid sphingomyelin is metabolized to ceramide to different degrees in distinct T cell subpopulations of mice and humans. This knowledge has already been translated into novel immunomodulatory approaches in mice and will in the future hopefully also be applicable to humans. In this paper we are, thus, summarizing the most recent findings on the impact of sphingolipid metabolism on T cell activation, differentiation, and effector functions. Moreover, we are discussing the therapeutic concepts arising from these insights and drugs or drug candidates which are already in clinical use or could be developed for clinical use in patients with diseases as distant as major depression and chronic viral infection.}, language = {en} } @article{GrafenSchumacherChithelenetal.2019, author = {Grafen, Anika and Schumacher, Fabian and Chithelen, Janice and Kleuser, Burkhard and Beyersdorf, Niklas and Schneider-Schaulies, J{\"u}rgen}, title = {Use of acid ceramidase and sphingosine kinase inhibitors as antiviral compounds against measles virus infection of lymphocytes in vitro}, series = {Frontiers in Cell and Developmental Biology}, volume = {7}, journal = {Frontiers in Cell and Developmental Biology}, number = {218}, issn = {2296-634X}, doi = {10.3389/fcell.2019.00218}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-196099}, year = {2019}, abstract = {As structural membrane components and signaling effector molecules sphingolipids influence a plethora of host cell functions, and by doing so also the replication of viruses. Investigating the effects of various inhibitors of sphingolipid metabolism in primary human peripheral blood lymphocytes (PBL) and the human B cell line BJAB we found that not only the sphingosine kinase (SphK) inhibitor SKI-II, but also the acid ceramidase inhibitor ceranib-2 efficiently inhibited measles virus (MV) replication. Virus uptake into the target cells was not grossly altered by the two inhibitors, while titers of newly synthesized MV were reduced by approximately 1 log (90\%) in PBL and 70-80\% in BJAB cells. Lipidomic analyses revealed that in PBL SKI-II led to increased ceramide levels, whereas in BJAB cells ceranib-2 increased ceramides. SKI-II treatment decreased sphingosine-1-phosphate (S1P) levels in PBL and BJAB cells. Furthermore, we found that MV infection of lymphocytes induced a transient (0.5-6 h) increase in S1P, which was prevented by SKI-II. Investigating the effect of the inhibitors on the metabolic (mTORC1) activity we found that ceranib-2 reduced the phosphorylation of p70 S6K in PBL, and that both inhibitors, ceranib-2 and SKI-II, reduced the phosphorylation of p70 S6K in BJAB cells. As mTORC1 activity is required for efficient MV replication, this effect of the inhibitors is one possible antiviral mechanism. In addition, reduced intracellular S1P levels affect a number of signaling pathways and functions including Hsp90 activity, which was reported to be required for MV replication. Accordingly, we found that pharmacological inhibition of Hsp90 with the inhibitor 17-AAG strongly impaired MV replication in primary PBL. Thus, our data suggest that treatment of lymphocytes with both, acid ceramidase and SphK inhibitors, impair MV replication by affecting a number of cellular activities including mTORC1 and Hsp90, which alter the metabolic state of the cells causing a hostile environment for the virus.}, language = {en} } @article{TiwarekarFehrholzSchneiderSchaulies2019, author = {Tiwarekar, Vishakha and Fehrholz, Markus and Schneider-Schaulies, J{\"u}rgen}, title = {KDELR2 competes with measles virus envelope proteins for cellular chaperones reducing their chaperone-mediated cell surface transport}, series = {Viruses}, volume = {11}, journal = {Viruses}, number = {1}, issn = {1999-4915}, doi = {10.3390/v11010027}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-197468}, pages = {27}, year = {2019}, abstract = {Recently, we found that the cytidine deaminase APOBEC3G (A3G) inhibits measles (MV) replication. Using a microarray, we identified differential regulation of several host genes upon ectopic expression of A3G. One of the up-regulated genes, the endoplasmic reticulum (ER) protein retention receptor KDELR2, reduced MV replication ~5 fold when it was over-expressed individually in Vero and CEM-SS T cells. Silencing of KDELR2 in A3G-expressing Vero cells abrogated the antiviral activity induced by A3G, confirming its role as an A3G-regulated antiviral host factor. Recognition of the KDEL (Lys-Asp-Glu-Leu) motif by KDEL receptors initiates the retrograde transport of soluble proteins that have escaped the ER and play an important role in ER quality control. Although KDELR2 over-expression reduced MV titers in cell cultures, we observed no interaction between KDELR2 and the MV hemagglutinin (H) protein. Instead, KDELR2 retained chaperones in the ER, which are required for the correct folding and transport of the MV envelope glycoproteins H and fusion protein (F) to the cell surface. Our data indicate that KDELR2 competes with MV envelope proteins for binding to calnexin and GRP78/Bip, and that this interaction limits the availability of the chaperones for MV proteins, causing the reduction of virus spread and titers.}, language = {en} }