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  - 
TY  - JOUR
A1  - Krones, David
A1  - Rühling, Marcel
A1  - Becker, Katrin Anne
A1  - Kunz, Tobias C.
A1  - Sehl, Carolin
A1  - Paprotka, Kerstin
A1  - Gulbins, Erich
A1  - Fraunholz, Martin
T1  - Staphylococcus aureus α-Toxin Induces Acid Sphingomyelinase Release From a Human Endothelial Cell Line
JF  - Frontiers in Microbiology
N2  - Staphylococcus aureus (S. aureus) is well known to express a plethora of toxins of which the pore-forming hemolysin A (α-toxin) is the best-studied cytolysin. Pore-forming toxins (PFT) permeabilize host membranes during infection thereby causing concentration-dependent effects in host cell membranes ranging from disordered ion fluxes to cytolysis. Host cells possess defense mechanisms against PFT attack, resulting in endocytosis of the breached membrane area and delivery of repair vesicles to the insulted plasma membrane as well as a concurrent release of membrane repair enzymes. Since PFTs from several pathogens have been shown to recruit membrane repair components, we here investigated whether staphylococcal α-toxin is able to induce these mechanisms in endothelial cells. We show that S. aureus α-toxin induced increase in cytosolic Ca2+ in endothelial cells, which was accompanied by p38 MAPK phosphorylation. Toxin challenge led to increased endocytosis of an extracellular fluid phase marker as well as increased externalization of LAMP1-positive membranes suggesting that peripheral lysosomes are recruited to the insulted plasma membrane. We further observed that thereby the lysosomal protein acid sphingomyelinase (ASM) was released into the cell culture medium. Thus, our results show that staphylococcal α-toxin triggers mechanisms in endothelial cells, which have been implicated in membrane repair after damage of other cell types by different toxins.
KW  - acid sphingomyelinase
KW  - staphylococcal alpha-toxin
KW  - sphingomyelinase release
KW  - lysosomal recruitment
KW  - Staphylococcus aureus
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-244843
SN  - 1664-302X
VL  - 12
ER  -