TY  - JOUR
A1  - Eder, Sascha
A1  - Hollmann, Claudia
A1  - Mandasari, Putri
A1  - Wittmann, Pia
A1  - Schumacher, Fabian
A1  - Kleuser, Burkhard
A1  - Fink, Julian
A1  - Seibel, Jürgen
A1  - Schneider-Schaulies, Jürgen
A1  - Stigloher, Christian
A1  - Beyersdorf, Niklas
A1  - Dembski, Sofia
T1  - Synthesis and characterization of ceramide-containing liposomes as membrane models for different T cell subpopulations
JF  - Journal of Functional Biomaterials
N2  - A fine balance of regulatory (T\(_{reg}\)) and conventional CD4\(^+\) T cells (T\(_{conv}\)) is required to prevent harmful immune responses, while at the same time ensuring the development of protective immunity against pathogens. As for many cellular processes, sphingolipid metabolism also crucially modulates the T\(_{reg}\)/T\(_{conv}\) balance. However, our understanding of how sphingolipid metabolism is involved in T cell biology is still evolving and a better characterization of the tools at hand is required to advance the field. Therefore, we established a reductionist liposomal membrane model system to imitate the plasma membrane of mouse T\(_{reg}\) and T\(_{conv}\) with regards to their ceramide content. We found that the capacity of membranes to incorporate externally added azide-functionalized ceramide positively correlated with the ceramide content of the liposomes. Moreover, we studied the impact of the different liposomal preparations on primary mouse splenocytes in vitro. The addition of liposomes to resting, but not activated, splenocytes maintained viability with liposomes containing high amounts of C\(_{16}\)-ceramide being most efficient. Our data thus suggest that differences in ceramide post-incorporation into T\(_{reg}\) and T\(_{conv}\) reflect differences in the ceramide content of cellular membranes.
KW  - liposome
KW  - ceramide
KW  - cell membrane model
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-286130
SN  - 2079-4983
VL  - 13
IS  - 3
ER  - 
TY  - JOUR
A1  - Jarick, Marcel
A1  - Bertsche, Ute
A1  - Stahl, Mark
A1  - Schultz, Daniel
A1  - Methling, Karen
A1  - Lalk, Michael
A1  - Stigloher, Christian
A1  - Steger, Mirco
A1  - Schlosser, Andreas
A1  - Ohlsen, Knut
T1  - The serine/threonine kinase Stk and the phosphatase Stp regulate cell wall synthesis in Staphylococcus aureus
JF  - Scientific Reports
N2  - The cell wall synthesis pathway producing peptidoglycan is a highly coordinated and tightly regulated process. Although the major components of bacterial cell walls have been known for decades, the complex regulatory network controlling peptidoglycan synthesis and many details of the cell division machinery are not well understood. The eukaryotic-like serine/threonine kinase Stk and the cognate phosphatase Stp play an important role in cell wall biosynthesis and drug resistance in S. aureus. We show that stp deletion has a pronounced impact on cell wall synthesis. Deletion of stp leads to a thicker cell wall and decreases susceptibility to lysostaphin. Stationary phase Δstp cells accumulate peptidoglycan precursors and incorporate higher amounts of incomplete muropeptides with non-glycine, monoglycine and monoalanine interpeptide bridges into the cell wall. In line with this cell wall phenotype, we demonstrate that the lipid II:glycine glycyltransferase FemX can be phosphorylated by the Ser/Thr kinase Stk in vitro. Mass spectrometric analyses identify Thr32, Thr36 and Ser415 as phosphoacceptors. The cognate phosphatase Stp dephosphorylates these phosphorylation sites. Moreover, Stk interacts with FemA and FemB, but is unable to phosphorylate them. Our data indicate that Stk and Stp modulate cell wall synthesis and cell division at several levels.
KW  - bacterial transcription
KW  - pathogens
KW  - cell wall synthesis
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177333
VL  - 8
IS  - 13693
ER  - 
TY  - JOUR
A1  - Lichter, Katharina
A1  - Paul, Mila Marie
A1  - Pauli, Martin
A1  - Schoch, Susanne
A1  - Kollmannsberger, Philip
A1  - Stigloher, Christian
A1  - Heckmann, Manfred
A1  - Sirén, Anna-Leena
T1  - Ultrastructural analysis of wild-type and RIM1α knockout active zones in a large cortical synapse
JF  - Cell Reports
N2  - Rab3A-interacting molecule (RIM) is crucial for fast Ca\(^{2+}\)-triggered synaptic vesicle (SV) release in presynaptic active zones (AZs). We investigated hippocampal giant mossy fiber bouton (MFB) AZ architecture in 3D using electron tomography of rapid cryo-immobilized acute brain slices in RIM1α\(^{−/−}\) and wild-type mice. In RIM1α\(^{−/−}\), AZs are larger with increased synaptic cleft widths and a 3-fold reduced number of tightly docked SVs (0–2 nm). The distance of tightly docked SVs to the AZ center is increased from 110 to 195 nm, and the width of their electron-dense material between outer SV membrane and AZ membrane is reduced. Furthermore, the SV pool in RIM1α\(^{−/−}\) is more heterogeneous. Thus, RIM1α, besides its role in tight SV docking, is crucial for synaptic architecture and vesicle pool organization in MFBs.
KW  - active zone
KW  - acute brain slices
KW  - CA3
KW  - electron tomography
KW  - high-pressure freezing
KW  - hippocampal mossy fiber bouton
KW  - RIM1α
KW  - SV pool
KW  - synaptic ultrastructure
KW  - presynaptic
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-300913
VL  - 40
IS  - 12
ER  -