Biology subjects

Kurz, T.

Publications and source records attributed to Kurz, T..

6 recordsLinked to original sources

bioRxiv2026

3-Hydroxypropanamidines: from antiplasmodial leads to a novel antibacterial scaffold

Arylamino alcohols constitute an established class of antimalarial agents. While this class is best known for its potent antiplasmodial activity, selected members, most notably mefloquine, have also been reported to exhibit antibacterial activity. Structurally related 3-hydroxypropanamidines were developed as highly potent antimalarial agents. Here, we explored the antibacterial activity of three 3-hydroxypropanamidines (4 (BLK278), 5 (BLK280), and 6 (TKK088)) against clinically relevant Gram-positive and Gram-negative bacteria and investigated their cytotoxicity, in vitro pharmacokinetic properties, and proteome-based bacterial response to treatment. We observed good antibacterial activity against Staphylococcus aureus, with 6 (TKK088) displaying the highest activity against multidrug-resistant MRSA and VISA strains. 5 (BLK280) demonstrated the greatest spectrum of activity acting also against clinically relevant Gram-negative strains of Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, Klebsiella aerogenes, and Shigella sonnei. In cytotoxicity assays with HUVEC and HAOSMC cells, 4 (BLK278) and the previously reported 7 (TKK129) showed the most favourable overall profiles among the investigated 3-hydroxypropanamidines. The selectivity indices for S. aureus were below 2.5 with clear cell-type-dependent differences for all compounds including mefloquine, suggesting that improving antibacterial selectivity is an important objective for further optimization. In vitro pharmacokinetics showed high plasma protein binding and good human microsomal and plasma stability for all three 3-hydroxypropanamidines. Gel-based proteomic responses revealed a strong impact on the bacterial cell envelope. The observed acute proteomic responses reflect pleiotropic effects and are consistent with earlier reports implicating F0F1-ATPase as a potential molecular target of mefloquine in Streptococcus pneumoniae.

microbiology↗

bioRxiv2024

Small-molecule inhibitor of C-terminal HSP90 dimerization modulates autophagy and functions synergistically with mTOR inhibition to kill cisplatin-resistant cancer cells

BackgroundA major obstacle for the successful treatment of cancer is the primary presence or development of resistance mechanisms toward therapeutic intervention. In urothelial cancer, cisplatin-based regimens are still routinely employed, and multiple cellular pathways contribute to chemoresistance. Since the identification of heat shock protein 90 (HSP90) as potential cancer target, various HSP90 inhibitors (HSP90i) have been developed and evaluated in clinical trials. However, limited efficacy has been observed, mainly caused by dose-limiting toxicity and the concomitant induction of a cytoprotective heat shock response (HSR). To avoid this effect, inhibitors targeting the C-terminal domain (CTD) of HSP90 that do not elicit an HSR have been put forward. Additionally, the crosstalk between autophagy and HSP90 is currently being explored, since both processes work together in proteostasis, and the modulation of autophagic responses might be helpful in order to improve the efficacy of HSP90 inhibitors. MethodsThe second-generation small-molecule inhibitor VWK147 targeting HSP90 CTD dimerization was synthesized and characterized in detail by biochemical cell-free and cellular assays and molecular modeling. Specifically, HSP90 inhibition, cell viability, and autophagy were monitored in mono- and combined treatments. ResultsWe demonstrate that VWK147 induces cell death in both cisplatin-sensitive and cisplatin-resistant urothelial carcinoma cells. The treatment with VWK147 in these cells led to the destabilization of classical HSP90 client proteins without triggering an HSR. Additionally, we observe that VWK147 re-sensitizes resistant urothelial carcinoma cells to cisplatin and--in combination with mTOR inhibition--synergistically kills cisplatin-sensitive and -resistant cells, in contrast to what is observed upon treatment with the N-terminal domain-targeting HSP90 inhibitor 17-AAG. This synergy may be explained by VWK147-mediated inhibition of late autophagy events, and thus a blockade of autophagic flux. Finally, we also observed that VWK147 induces non-canonical LC3 lipidation, indicating that this compound possibly exerts a broader effect on ion balance or pH of the endolysosomal system. ConclusionVWK147 is a promising inhibitor that targets the C-terminal dimerization of HSP90 and simultaneously exhibits autophagy-modulating effects. This compound could potentially be an effective option for improving anti-cancer therapies and/or overcoming treatment resistance.

cell biology↗

bioRxiv2024

α-Aminooxyacetic acid derivatives acting as pro-drugs against Mycobacterium tuberculosis

Tuberculosis (TB), a significant cause of mortality globally, continues to claim 1.5 million lives each year. Despite recent advances in TB management, the emergence of multidrug-resistant strains of TB is exacerbating the treatment of TB. Therefore, there is an immediate necessity to uncover new anti-TB compounds with unprecedented targets. This study introduces novel antimycobacterial molecules that are based on -aminooxyacetic acid core structures. The lead compounds KSK-104 and KSK-106 displayed potent sub-micromolar antibacterial activity against Mycobacterium tuberculosis H37Rv and XDR clinical isolates, while exhibiting virtually no cytotoxicity against various human cells. Complementation experiments following whole genome sequencing of spontaneously resistant mutants generated against these bactericidal compounds suggested that they are pro-drugs that are intracellularly hydrolyzed by one or both of two specific amidohydrolases, Rv0552 and AmiC. Furthermore, proteomic and transcriptomic analyses of stressed cells and genetic interaction mapping employing transposon insertion sequencing suggest a "dirty drug" mechanism that involves the simultaneous attack of the various drug cleavage products on multiple intracellular targets. Our results suggest a primary role of the pyridoxal 5-phosphate (PLP) synthesis and salvage pathway and/or PLP-dependent enzymes, the oxidative stress network, and the largely uncharacterized Rv3092c-Rv3095 gene cluster in the mode of action.

microbiology↗

bioRxiv2024

Development of a Bipyrimidineamide based α-Helix Mimetic Lead Compound for efficient Targeting of MDM2 in Triple-Negative Breast Cancer

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=155 SRC="FIGDIR/small/582899v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@89ffd0org.highwire.dtl.DTLVardef@1f9cba2org.highwire.dtl.DTLVardef@a821b3org.highwire.dtl.DTLVardef@3c7b6a_HPS_FORMAT_FIGEXP M_FIG C_FIG Triple-negative breast cancer (TNBC) represents the most aggressive form among breast carcinoma subtypes. Due to limited therapy options, identification of novel active pharmacological compounds is an urgent medical need. A promising approach in cancer treatment is the pharmacological inhibition of murine double minutes 2 (MDM2)-p53/p73 interactions inducing apoptosis in tumors. We here describe a novel bipyrimidineamide based -helix mimetic 9 (VWK603) which was designed as a lead candidate to target MDM2. 9 (VWK603) potently induced cell death in the TNBC cell lines MDA-MB-231, MDA-MB-436 and MDA-MB-468 with IC50 values ranging between 3.7 {micro}M and 6.6 {micro}M. The anti-tumor activity was about four more potent higher than determined for the MDM2-specific inhibitor Nutlin-3a. Mechanistic analysis revealed induction of cellular apoptosis as the underlying mode of action of 9 (VWK603) anti-tumor activity. Since toxicity was observed to be reduced in non-cancerous breast cells, these studies make 9 (VWK603) a promising candidate for further preclinical MDM2 inhibitor development.

cancer biology↗

bioRxiv2020

In vivo identification of apoptotic and extracellular vesicle-bound live cells using image-based deep learning

The in vivo detection of dead cells remains a major challenge due to technical hurdles. Here we present a novel method, where injection of fluorescent Milk fat globule-EGF factor 8 protein (MFG-E8) in vivo combined with imaging flow cytometry and deep learning allows the identification of dead cells based on their surface exposure of phosphatidylserine (PS) and other image parameters. A convolutional autoencoder (CAE) was trained on defined pictures and successfully used to identify apoptotic cells in vivo. However, unexpectedly, these analyses also revealed that the great majority of PS+ cells were not apoptotic, but rather live cells associated with PS+ extracellular vesicles (EVs). During acute viral infection apoptotic cells increased slightly, while up to 30% of lymphocytes were decorated with PS+ EVs of Dendritic cell exosomal origin. The combination of recombinant fluorescent MFG-E8 and the CAE-method will greatly facilitate analyses of cell death and EVs in vivo.

cell biology↗

bioRxiv2020

Global proteomics of Ubqln2-based murine models of ALS

Familial forms of neurodegenerative diseases commonly involve mutation of aggregation-prone proteins or components of the protein degradation machinery that act on aberrant proteins. Ubqln2 encodes a member of the UBL/UBA family of proteasome shuttle factors that is thought to facilitate proteasomal degradation of substrates, and mutation of this gene results in a familial form of ALS/FTD in humans. How Ubqln2 dysfunction leads to neurodegeneration, however, remains uncertain. We undertook a comprehensive study to identify proteomic changes upon Ubqln2 perturbation in multiple murine models of Ubqln2-mediated neurodegenerative disease. By performing quantitative multiplexed proteomics on neural tissues of affected animals, we identified a small group of proteins whose abundance is tightly linked to UBQLN2 function: the ubiquitin ligase TRIM32 and two retroelement-derived proteins, PEG10 and CXX1B. Further studies using cultured cells of human origin, including induced neurons, found similar changes in protein abundance upon Ubqln2 loss, and pulse-chase studies suggested that PEG10 and TRIM32 are direct clients of UBQLN2. In conclusion, our study provides a deep understanding of the proteomic landscape of ALS-related Ubqln2 mutants and identifies candidate client proteins that are altered in vivo in disease models and whose degradation is promoted by UBQLN2.

cell biology↗