Mitochondrial E3 ubiquitin ligase MARCHF5 controls BAK apoptotic activity independently of BH3-only proteins

• Published in: Cell death and differentiation Vol. 30; no. 3; pp. 632 - 646
• Main Authors: Huang, Allan Shuai, Chin, Hui San, Reljic, Boris, Djajawi, Tirta M., Tan, Iris K. L., Gong, Jia-Nan, Stroud, David A., Huang, David C. S., van Delft, Mark F., Dewson, Grant
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-03-2023; Nature Publishing Group
• Subjects: 13/106; 631/67; 631/80; 64; 82; 82/29; 82/58; 96; 96/2; Apoptosis; Apoptosis - physiology; bcl-2 Homologous Antagonist-Killer Protein - metabolism; Bcl-2 protein; Bcl-x protein; bcl-X Protein - metabolism; Biochemistry; Biomedical and Life Sciences; Cell Biology; Cell Cycle Analysis; Cell death; Conformation; CRISPR; Drug resistance; Genomes; Life Sciences; Mcl-1 protein; Mitochondria; Myeloid Cell Leukemia Sequence 1 Protein - metabolism; Proteins; Proto-Oncogene Proteins c-bcl-2 - metabolism; Stem Cells; Ubiquitin; Ubiquitin-protein ligase; Ubiquitin-Protein Ligases
• ISSN: 1350-9047; 1476-5403
• DOI: 10.1038/s41418-022-01067-z

Intrinsic apoptosis is principally governed by the BCL-2 family of proteins, but some non-BCL-2 proteins are also critical to control this process. To identify novel apoptosis regulators, we performed a genome-wide CRISPR-Cas9 library screen, and it identified the mitochondrial E3 ubiquitin ligase MARCHF5/MITOL/RNF153 as an important regulator of BAK apoptotic function. Deleting MARCHF5 in diverse cell lines dependent on BAK conferred profound resistance to BH3-mimetic drugs. The loss of MARCHF5 or its E3 ubiquitin ligase activity surprisingly drove BAK to adopt an activated conformation, with resistance to BH3-mimetics afforded by the formation of inhibitory complexes with pro-survival proteins MCL-1 and BCL-XL. Importantly, these changes to BAK conformation and pro-survival association occurred independently of BH3-only proteins and influence on pro-survival proteins. This study identifies a new mechanism by which MARCHF5 regulates apoptotic cell death by restraining BAK activating conformation change and provides new insight into how cancer cells respond to BH3-mimetic drugs. These data also highlight the emerging role of ubiquitin signalling in apoptosis that may be exploited therapeutically.