Journal
BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH
Volume 1867, Issue 1, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.bbamcr.2019.118573
Keywords
Cytochrome c; Apoptosome; Caspase activation; Tumorigenesis; Mitochondria; Nucleotides
Categories
Funding
- National Cancer Institute of the National Institutes of Health (NIH) [R01CA160685, K01CA123142]
- American Cancer Society [RSG-12-214-01 - CCG]
- National Cancer Institute Center Support Grant [P30 CA016056]
- NIH [P30 GM 103450]
- National Science Foundation (NSF) [IOS-0842937]
- Department of Energy (DOE) [DE-02-01ER15161]
- Arkansas Bioscience Institute
- Bioinformatics Shared Resources
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Cytochrome c (Cyt c) released from mitochondria interacts with Apaf-1 to form the heptameric apoptosome, which initiates the caspase cascade to execute apoptosis. Although lysine residue at 72 (K72) of Cyt c plays an important role in the Cyt c-Apaf-1 interaction, the underlying mechanism of interaction between Cyt c and Apaf-1 is still not clearly defined. Here we identified multiple lysine residues including K72, which are also known to interact with ATP, to play a key role in Cyt c-Apaf-1 interaction. Mutation of these lysine residues abrogates the apoptosome formation causing inhibition of caspase activation. Using in-silico molecular docking, we have identified Cyt c-binding interface on Apaf-1. Although mutant Cyt c shows higher affinity for Apaf-1, the presence of Cyt c-WT restores the apoptosome activity. ATP addition modulates only mutant Cyt c binding to Apaf-1 but not WT Cyt c binding to Apaf-1. Using TCGA and cBioPortal, we identified multiple mutations in both Apaf-1 and Cyt c that are predicted to interfere with apoptosome assembly. We also demonstrate that transcript levels of various enzymes involved with dATP or ATP synthesis are increased in various cancers. Silencing of nucleotide metabolizing enzymes such as ribonucleotide reductase subunit M1 (RRM1) and ATP-producing glycolytic enzymes PKM2 attenuated ATP production and enhanced caspase activation. These findings suggest important role for lysine residues of Cyt c and nucleotides in the regulation of apoptosome-dependent apoptotic cell death as well as demonstrate how these mutations and nucleotides may have a pivotal role in human diseases such as cancer.
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