DRP-1 is required for BH3 mimetic-mediated mitochondrial fragmentation and apoptosis

Milani, Mateus, Byrne, Dominic P, Greaves, Georgia, Butterworth, Michael, Cohen, Gerald M, Eyers, Patrick A ORCID: 0000-0002-9220-2966 and Varadarajan, Shankar ORCID: 0000-0002-8827-6567
(2018) DRP-1 is required for BH3 mimetic-mediated mitochondrial fragmentation and apoptosis. Cell Death and Disease, 8.

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The concept of using BH3 mimetics as anticancer agents has been substantiated by the efficacy of selective drugs, such as Navitoclax and Venetoclax, in treating BCL-2-dependent haematological malignancies. However, most solid tumours depend on MCL-1 for survival, which is highly amplified in multiple cancers and a major factor determining chemoresistance. Most MCL-1 inhibitors that have been generated so far, while demonstrating early promise in vitro, fail to exhibit specificity and potency in a cellular context. To address the lack of standardised assays for benchmarking the in vitro binding of putative inhibitors before analysis of their cellular effects, we developed a rapid differential scanning fluorimetry (DSF)-based assay, and used it to screen a panel of BH3 mimetics. We next contrasted their binding signatures with their ability to induce apoptosis in a MCL-1 dependent cell line. Of all the MCL-1 inhibitors tested, only A-1210477 induced rapid, concentration-dependent apoptosis, which strongly correlated with a thermal protective effect on MCL-1 in the DSF assay. In cells that depend on both MCL-1 and BCL-XL, A-1210477 exhibited marked synergy with A-1331852, a BCL-XL specific inhibitor, to induce cell death. Despite this selectivity and potency, A-1210477 induced profound structural changes in the mitochondrial network in several cell lines that were not phenocopied following MCL-1 RNA interference or transcriptional repression, suggesting that A-1210477 induces mitochondrial fragmentation in an MCL-1-independent manner. However, A-1210477-induced mitochondrial fragmentation was dependent upon DRP-1, and silencing expression levels of DRP-1 diminished not just mitochondrial fragmentation but also BH3 mimetic-mediated apoptosis. These findings provide new insights into MCL-1 ligands, and the interplay between DRP-1 and the anti-apoptotic BCL-2 family members in the regulation of apoptosis.

Item Type: Article
Depositing User: Symplectic Admin
Date Deposited: 25 Jan 2017 08:47
Last Modified: 04 Mar 2021 15:10
DOI: 10.1038/cddis.2016.485
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3005379