Inhibition of vacuolar ATPase attenuates the TRAIL‐induced activation of caspase‐8 and modulates the trafficking of TRAIL receptosomes

• Published in: The FEBS journal Vol. 280; no. 14; pp. 3436 - 3450
• Main Authors: Horova, Vladimira, Hradilova, Nada, Jelinkova, Iva, Koc, Michal, Svadlenka, Jan, Brazina, Jan, Klima, Martin, Slavik, Josef, Hyrslova Vaculova, Alena, Andera, Ladislav
• Format: Journal Article
• Language: English
• Published: England Blackwell 01-07-2013; Blackwell Publishing Ltd
• Subjects: acidification; Antineoplastic Agents - pharmacology; Apoptosis; CASP8 and FADD-Like Apoptosis Regulating Protein - metabolism; Caspase 8 - metabolism; caspase-10; caspase-8; Cell Line, Tumor; cells; Cellular biology; Death Domain Receptor Signaling Adaptor Proteins - metabolism; death domain receptors; Down-Regulation; Endosomes - metabolism; Enzyme Activation; Enzymes; fluorescence microscopy; H-transporting ATP synthase; Humans; Hydrogen-Ion Concentration; Ligands; Macrolides - pharmacology; neoplasm cells; Protein Transport; Proteins; receptors; Receptors, TNF-Related Apoptosis-Inducing Ligand - metabolism; Signal Transduction - drug effects; Sphingolipids - physiology; Sphingomyelin Phosphodiesterase - metabolism; TNF-Related Apoptosis-Inducing Ligand - pharmacology; TRAIL; transcription factor NF-kappa B; tumor necrosis factors; tumour necrosis factor; Vacuolar Proton-Translocating ATPases - antagonists & inhibitors; Vacuolar Proton-Translocating ATPases - metabolism; V‐ATPase; apoptosis; caspase-8; TRAIL; V-ATPase; acidification
• ISSN: 1742-464X; 1742-4658
• DOI: 10.1111/febs.12347

Tumour necrosis factor (TNF) related apoptosis inducing ligand (TRAIL), a membrane‐bound ligand from the TNF family, has attracted significant attention due to its rather specific and effective ability to induce apoptotic death in various types of cancer cells via binding to and activating its pro‐apoptotic death receptors. However, a significant number of primary cancer cells often develop resistance to TRAIL treatment, and the signalling platform behind this phenomenon is not fully understood. Upon blocking endosomal acidification by the vacuolar ATPase (V‐ATPase) inhibitors bafilomycin A1 (BafA1) or concanamycin A, we observed a significantly reduced initial sensitivity of several, mainly colorectal, tumour cell lines to TRAIL‐induced apoptosis. In cells pretreated with these inhibitors, the TRAIL‐induced processing of caspase‐8 and the aggregation and trafficking of the TRAIL receptor complexes were temporarily attenuated. Nuclear factor κB or mitogen activated protein/stress kinase signalling from the activated TRAIL receptors remained unchanged, and neither possible lysosomal permeabilization nor acid sphingomyelinase was involved in this process. The cell surface expression of TRAIL receptors and their TRAIL‐induced internalization were not affected by V‐ATPase inhibitors. The inhibitory effect of BafA1, however, was blunted by knockdown of the caspase‐8 inhibitor cFLIP. Altogether, the data obtained provide the first evidence that endosomal acidification could represent an important regulatory node in the proximal part of TRAIL‐induced pro‐apoptotic signalling. STRUCTURED DIGITAL ABSTRACT: TRAIL and Caspase-8 colocalize by fluorescence microscopy (View interaction) TRAIL physically interacts with DR-5, Caspase-10, Caspase-8, cFLIP and FADD by pull down (View interaction)