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  - Geiger, Nina
A1  - Kersting, Louise
A1  - Schlegel, Jan
A1  - Stelz, Linda
A1  - Fähr, Sofie
A1  - Diesendorf, Viktoria
A1  - Roll, Valeria
A1  - Sostmann, Marie
A1  - König, Eva-Maria
A1  - Reinhard, Sebastian
A1  - Brenner, Daniela
A1  - Schneider-Schaulies, Sibylle
A1  - Sauer, Markus
A1  - Seibel, Jürgen
A1  - Bodem, Jochen
T1  - The acid ceramidase is a SARS-CoV-2 host factor
JF  - Cells
N2  - SARS-CoV-2 variants such as the delta or omicron variants, with higher transmission rates, accelerated the global COVID-19 pandemic. Thus, novel therapeutic strategies need to be deployed. The inhibition of acid sphingomyelinase (ASM), interfering with viral entry by fluoxetine was reported. Here, we described the acid ceramidase as an additional target of fluoxetine. To discover these effects, we synthesized an ASM-independent fluoxetine derivative, AKS466. High-resolution SARS-CoV-2–RNA FISH and RTqPCR analyses demonstrate that AKS466 down-regulates viral gene expression. It is shown that SARS-CoV-2 deacidifies the lysosomal pH using the ORF3 protein. However, treatment with AKS488 or fluoxetine lowers the lysosomal pH. Our biochemical results show that AKS466 localizes to the endo-lysosomal replication compartments of infected cells, and demonstrate the enrichment of the viral genomic, minus-stranded RNA and mRNAs there. Both fluoxetine and AKS466 inhibit the acid ceramidase activity, cause endo-lysosomal ceramide elevation, and interfere with viral replication. Furthermore, Ceranib-2, a specific acid ceramidase inhibitor, reduces SARS-CoV-2 replication and, most importantly, the exogenous supplementation of C6-ceramide interferes with viral replication. These results support the hypotheses that the acid ceramidase is a SARS-CoV-2 host factor.
KW  - SARS-CoV-2
KW  - ceramides
KW  - ceramidase
KW  - fluoxetine
KW  - acid sphingomyelinase
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-286105
SN  - 2073-4409
VL  - 11
IS  - 16
ER  -