TY - JOUR A1 - Neuschäfer-Rube, Frank A1 - Pathe-Neuschäfer-Rube, Andrea A1 - Püschel, Gerhard Paul T1 - Discrimination of the activity of low-affinity wild-type and high-affinity mutant recombinant BoNT/B by a SIMA cell-based reporter release assay JF - Toxins N2 - Botulinum neurotoxin (BoNT) is used for the treatment of a number of ailments. The activity of the toxin that is isolated from bacterial cultures is frequently tested in the mouse lethality assay. Apart from the ethical concerns inherent to this assay, species-specific differences in the affinity for different BoNT serotypes give rise to activity results that differ from the activity in humans. Thus, BoNT/B is more active in mice than in humans. The current study shows that the stimulus-dependent release of a luciferase from a differentiated human neuroblastoma–based reporter cell line (SIMA-hPOMC1-26-Gluc) was inhibited by clostridial and recombinant BoNT/A to the same extent, whereas both clostridial and recombinant BoNT/B inhibited the release to a lesser extent and only at much higher concentrations, reflecting the low activity of BoNT/B in humans. By contrast, the genetically modified BoNT/B-MY, which has increased affinity for human synaptotagmin, and the BoNT/B protein receptor inhibited luciferase release effectively and with an EC50 comparable to recombinant BoNT/A. This was due to an enhanced uptake into the reporter cells of BoNT/B-MY in comparison to the recombinant wild-type toxin. Thus, the SIMA-hPOMC1-26-Gluc cell assay is a versatile tool to determine the activity of different BoNT serotypes providing human-relevant dose-response data. KW - cell-based assay KW - genetically modified BoNT KW - BoNT/B uptake Y1 - 2022 U6 - https://doi.org/10.3390/toxins14010065 SN - 2072-6651 VL - 14 SP - 1 EP - 11 PB - MDPI CY - Basel, Schweiz ET - 1 ER - TY - JOUR A1 - Pathe-Neuschäfer-Rube, Andrea A1 - Neuschäfer-Rube, Frank A1 - Püschel, Gerhard Paul T1 - Cell-based reporter release assay to determine the activity of calcium-dependent neurotoxins and neuroactive pharmaceuticals JF - Toxins / Molecular Diversity Preservation International (MDPI) N2 - The suitability of a newly developed cell-based functional assay was tested for the detection of the activity of a range of neurotoxins and neuroactive pharmaceuticals which act by stimulation or inhibition of calcium-dependent neurotransmitter release. In this functional assay, a reporter enzyme is released concomitantly with the neurotransmitter from neurosecretory vesicles. The current study showed that the release of a luciferase from a differentiated human neuroblastoma-based reporter cell line (SIMA-hPOMC1-26-GLuc cells) can be stimulated by a carbachol-mediated activation of the Gq-coupled muscarinic-acetylcholine receptor and by the Ca2+-channel forming spider toxin α-latrotoxin. Carbachol-stimulated luciferase release was completely inhibited by the muscarinic acetylcholine receptor antagonist atropine and α-latrotoxin-mediated release by the Ca2+-chelator EGTA, demonstrating the specificity of luciferase-release stimulation. SIMA-hPOMC1-26-GLuc cells express mainly L- and N-type and to a lesser extent T-type VGCC on the mRNA and protein level. In accordance with the expression profile a depolarization-stimulated luciferase release by a high K+-buffer was effectively and dose-dependently inhibited by L-type VGCC inhibitors and to a lesser extent by N-type and T-type inhibitors. P/Q- and R-type inhibitors did not affect the K+-stimulated luciferase release. In summary, the newly established cell-based assay may represent a versatile tool to analyze the biological efficiency of a range of neurotoxins and neuroactive pharmaceuticals which mediate their activity by the modulation of calcium-dependent neurotransmitter release. KW - cell-based assay KW - neurotoxins KW - muscarinic acetylcholine receptor KW - voltage-dependent calcium channels KW - VGCC Y1 - 2021 U6 - https://doi.org/10.3390/toxins13040247 SN - 2072-6651 VL - 13 IS - 4 PB - MDPI CY - Basel ER -