Regulation of defective mitochondrial DNA accumulation and transmission in C. elegans by the programmed cell death and aging pathways

• Published in: eLife Vol. 12
• Main Authors: Flowers, Sagen, Kothari, Rushali, Torres Cleuren, Yamila N, Alcorn, Melissa R, Ewe, Chee Kiang, Alok, Geneva, Fiallo, Samantha L, Joshi, Pradeep M, Rothman, Joel H
• Format: Journal Article
• Language: English
• Published: England eLife Science Publications, Ltd 02.10.2023; eLife Sciences Publications Ltd; eLife Sciences Publications, Ltd
• Subjects: Aging; Aging - genetics; Animals; Apoptosis; Apoptosis - genetics; Biochemistry; Caenorhabditis elegans - physiology; Caenorhabditis elegans Proteins - genetics; Caenorhabditis elegans Proteins - metabolism; Caspase; Caspases - genetics; Caspases - metabolism; Cell Biology; Cell death; DNA, Mitochondrial - genetics; DNA, Mitochondrial - metabolism; Gene deletion; Genetics and Genomics; Genomes; Genomics; Heteroplasmy; insulin signaling; Laboratories; Mitochondria; Mitochondrial DNA; Mutants; Mutation; programmed cell death; Proteins; purifying selection; Quality control; Transfer RNA; uaDf5; heteroplasmy; C. elegans; purifying selection; cell biology; genetics; insulin signaling; genomics; uaDf5; aging; programmed cell death
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/eLife.79725

The heteroplasmic state of eukaryotic cells allows for cryptic accumulation of defective mitochondrial genomes (mtDNA). 'Purifying selection' mechanisms operate to remove such dysfunctional mtDNAs. We found that activators of programmed cell death (PCD), including the CED-3 and CSP-1 caspases, the BH3-only protein CED-13, and PCD corpse engulfment factors, are required in to attenuate germline abundance of a 3.1-kb mtDNA deletion mutation, , which is normally stably maintained in heteroplasmy with wildtype mtDNA. In contrast, removal of CED-4/Apaf1 or a mutation in the CED-4-interacting prodomain of CED-3, do not increase accumulation of the defective mtDNA, suggesting induction of a non-canonical germline PCD mechanism or non-apoptotic action of the CED-13/caspase axis. We also found that the abundance of germline mtDNA reproducibly increases with age of the mothers. This effect is transmitted to the offspring of mothers, with only partial intergenerational removal of the defective mtDNA. In mutants with elevated mtDNA levels, this removal is enhanced in older mothers, suggesting an age-dependent mechanism of mtDNA quality control. Indeed, we found that both steady-state and age-dependent accumulation rates of are markedly decreased in long-lived, and increased in short-lived, mutants. These findings reveal that regulators of both PCD and the aging program are required for germline mtDNA quality control and its intergenerational transmission.