TY  - JOUR
A1  - Bartel, Karin
A1  - Pein, Helmut
A1  - Popper, Bastian
A1  - Schmitt, Sabine
A1  - Janaki-Raman, Sudha
A1  - Schulze, Almut
A1  - Lengauer, Florian
A1  - Koeberle, Andreas
A1  - Werz, Oliver
A1  - Zischka, Hans
A1  - Müller, Rolf
A1  - Vollmar, Angelika M.
A1  - Schwarzenberg, Karin von
T1  - Connecting lysosomes and mitochondria – a novel role for lipid metabolism in cancer cell death
JF  - Cell Communication and Signaling
N2  - Background
The understanding of lysosomes has been expanded in recent research way beyond their view as cellular trash can. Lysosomes are pivotal in regulating metabolism, endocytosis and autophagy and are implicated in cancer. Recently it was discovered that the lysosomal V-ATPase, which is known to induce apoptosis, interferes with lipid metabolism in cancer, yet the interplay between these organelles is poorly understood.

Methods
LC-MS/MS analysis was performed to investigate lipid distribution in cells. Cell survival and signaling pathways were analyzed by means of cell biological methods (qPCR, Western Blot, flow cytometry, CellTiter-Blue). Mitochondrial structure was analyzed by confocal imaging and electron microscopy, their function was determined by flow cytometry and seahorse measurements.

Results
Our data reveal that interfering with lysosomal function changes composition and subcellular localization of triacylglycerids accompanied by an upregulation of PGC1α and PPARα expression, master regulators of energy and lipid metabolism. Furthermore, cardiolipin content is reduced driving mitochondria into fission, accompanied by a loss of membrane potential and reduction in oxidative capacity, which leads to a deregulation in cellular ROS and induction of mitochondria-driven apoptosis. Additionally, cells undergo a metabolic shift to glutamine dependency, correlated with the fission phenotype and sensitivity to lysosomal inhibition, most prominent in Ras mutated cells.

Conclusion
This study sheds mechanistic light on a largely uninvestigated triangle between lysosomes, lipid metabolism and mitochondrial function. Insight into this organelle crosstalk increases our understanding of mitochondria-driven cell death. Our findings furthermore provide a first hint on a connection of Ras pathway mutations and sensitivity towards lysosomal inhibitors.
KW  - lysosome
KW  - V-ATPase
KW  - mitochondria
KW  - fission
KW  - apoptosis
KW  - lipid metabolism
KW  - cardiolipin
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-221524
VL  - 17
ER  - 
TY  - JOUR
A1  - Hennessen, Fabienne
A1  - Miethke, Marcus
A1  - Zaburannyi, Nestor
A1  - Loose, Maria
A1  - Lukežič, Tadeja
A1  - Bernecker, Steffen
A1  - Hüttel, Stephan
A1  - Jansen, Rolf
A1  - Schmiedel, Judith
A1  - Fritzenwanker, Moritz
A1  - Imirzalioglu, Can
A1  - Vogel, Jörg
A1  - Westermann, Alexander J.
A1  - Hesterkamp, Thomas
A1  - Stadler, Marc
A1  - Wagenlehner, Florian
A1  - Petković, Hrvoje
A1  - Herrmann, Jennifer
A1  - Müller, Rolf
T1  - Amidochelocardin overcomes resistance mechanisms exerted on tetracyclines and natural chelocardin
JF  - Antibiotics
N2  - The reassessment of known but neglected natural compounds is a vital strategy for providing novel lead structures urgently needed to overcome antimicrobial resistance. Scaffolds with resistance-breaking properties represent the most promising candidates for a successful translation into future therapeutics. Our study focuses on chelocardin, a member of the atypical tetracyclines, and its bioengineered derivative amidochelocardin, both showing broad-spectrum antibacterial activity within the ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) panel. Further lead development of chelocardins requires extensive biological and chemical profiling to achieve favorable pharmaceutical properties and efficacy. This study shows that both molecules possess resistance-breaking properties enabling the escape from most common tetracycline resistance mechanisms. Further, we show that these compounds are potent candidates for treatment of urinary tract infections due to their in vitro activity against a large panel of multidrug-resistant uropathogenic clinical isolates. In addition, the mechanism of resistance to natural chelocardin was identified as relying on efflux processes, both in the chelocardin producer Amycolatopsis sulphurea and in the pathogen Klebsiella pneumoniae. Resistance development in Klebsiella led primarily to mutations in ramR, causing increased expression of the acrAB-tolC efflux pump. Most importantly, amidochelocardin overcomes this resistance mechanism, revealing not only the improved activity profile but also superior resistance-breaking properties of this novel antibacterial compound.
KW  - chelocardins
KW  - atypical tetracyclines
KW  - broad-spectrum antibiotics
KW  - clinical isolates
KW  - uropathogens
KW  - urinary tract infection (UTI)
KW  - resistance-breaking properties
KW  - mechanism of resistance
KW  - AcrAB-TolC efflux pump
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-213149
SN  - 2079-6382
VL  - 9
IS  - 9
ER  -