Simultaneous Ablation of the Catalytic AMPK α-Subunit SNF1 and Mitochondrial Matrix Protease CLPP Results in Pronounced Lifespan Extension

Abstract

Organismic aging is known to be controlled by genetic and environmental traits. Pathways involved in the control of cellular metabolism play a crucial role. Previously, we identified a role of PaCLPP, a mitochondrial matrix protease, in the control of the mitochondrial energy metabolism, aging, and lifespan of the fungal aging model Podospora anserina. Most surprisingly, we made the counterintuitive observation that the ablation of this component of the mitochondrial quality control network leads to lifespan extension. In the current study, we investigated the role of energy metabolism of P. anserina. An age-dependent metabolome analysis of the wild type and a PaClpP deletion strain verified differences and changes of various metabolites in cultures of the PaClpP mutant and the wild type. Based on these data, we generated and analyzed a PaSnf1 deletion mutant and a ΔPaSnf1/ΔPaClpP double mutant. In both mutants PaSNF1, the catalytic α-subunit of AMP-activated protein kinase (AMPK) is ablated. PaSNF1 was found to be required for the development of fruiting bodies and ascospores and the progeny of sexual reproduction of this ascomycete and impact mitochondrial dynamics and autophagy. Most interestingly, while the single PaSnf1 deletion mutant is characterized by a slight lifespan increase, simultaneous deletion of PaSnf1 and PaClpP leads to a pronounced lifespan extension. This synergistic effect is strongly reinforced in the presence of the mating-type “minus”-linked allele of the rmp1 gene. Compared to the wild type, culture temperature of 35°C instead of the standard laboratory temperature of 27°C leads to a short-lived phenotype of the ΔPaSnf1/ΔPaClpP double mutant. Overall, our study provides novel evidence for complex interactions of different molecular pathways involved in mitochondrial quality control, gene expression, and energy metabolism in the control of organismic aging.

Inactivity of Peptidase ClpP Causes Primary Accumulation of Mitochondrial Disaggregase ClpX with Its Interacting Nucleoid Proteins, and of mtDNA

“…The observation of normal levels for valine, arginine/proline, glutamate/glutamine, and, in particular, ornithine in our ClpP-null MEFs suggests normal enzymatic activity remains for OAT even though it is accumulated and although the OAT hexamer might be misassembled. Additionally, a previous study of Podospora anserina ClpP deletion mutants also observed increased leucine/isoleucine, as opposed to decreased histidine levels [ 81 ]. The previously reported metabolome data in PRLTS3 patient 58955, where urinary excretion contained excess amounts of fumarate and oxo-glutarate [ 37 ], suggest that carbon flux in the TCA cycle occurs at high levels, possibly at the expense of specific amino acids as well as glucose.…”

Disruption of the MICOS complex leads to an aberrant cristae structure and an unexpected, pronounced lifespan extension in Podospora anserina

“…RNA isolation and cDNA synthesis was performed as previously described 53 . For each strain three biological replicates were analyzed three times each (technical replicates).…”

Inactivity of Peptidase ClpP Causes Primary Accumulation of Mitochondrial Disaggregase ClpX With Its Interactors at the Nucleoid and RNA Granule

“…OAT may be misassembled but normal enzymatic activity remains. Also a previous study of Podospora anserina ClpP deletion mutants observed increased leucine/isoleucine, as opposed to decreased histidine levels [59]. The previously reported metabolome data in PRLTS3 patient 58955 where urinary excretion contained excess amounts of fumarate and oxo-glutarate [36] suggest that carbon flux in the TCA cycle occurs at high levels, possibly at the expense of specific amino acids as well as glucose.…”