- Alternative oxidase dependent respiration leads to an increased mitochondrial content in two long-lived mutants of the aging model Podospora anserina (2011)
- The retrograde response constitutes an important signalling pathway from mitochondria to the nucleus which induces several genes to allow compensation of mitochondrial impairments. In the filamentous ascomycete Podospora anserina, an example for such a response is the induction of a nuclear-encoded and iron-dependent alternative oxidase (AOX) occurring when cytochrome-c oxidase (COX) dependent respiration is affected. Several long-lived mutants are known which predominantly or exclusively respire via AOX. Here we show that two AOX-utilising mutants, grisea and PaCox17::ble, are able to compensate partially for lowered OXPHOS efficiency resulting from AOX-dependent respiration by increasing mitochondrial content. At the physiological level this is demonstrated by an elevated oxygen consumption and increased heat production. However, in the two mutants, ATP levels do not reach WT levels. Interestingly, mutant PaCox17::ble is characterized by a highly increased release of the reactive oxygen species (ROS) hydrogen peroxide. Both grisea and PaCox17::ble contain elevated levels of mitochondrial proteins involved in quality control, i. e. LON protease and the molecular chaperone HSP60. Taken together, our work demonstrates that AOX-dependent respiration in two mutants of the ageing model P. anserina is linked to a novel mechanism involved in the retrograde response pathway, mitochondrial biogenesis, which might also play an important role for cellular maintenance in other organisms.
- A Genome-Wide Longitudinal Transcriptome Analysis of the Aging Model Podospora anserine (2013)
- Aging of biological systems is controlled by various processes which have a potential impact on gene expression. Here we report a genome-wide transcriptome analysis of the fungal aging model Podospora anserina. Total RNA of three individuals of defined age were pooled and analyzed by SuperSAGE (serial analysis of gene expression). A bioinformatics analysis identified different molecular pathways to be affected during aging. While the abundance of transcripts linked to ribosomes and to the proteasome quality control system were found to decrease during aging, those associated with autophagy increase, suggesting that autophagy may act as a compensatory quality control pathway. Transcript profiles associated with the energy metabolism including mitochondrial functions were identified to fluctuate during aging. Comparison of wild-type transcripts, which are continuously down-regulated during aging, with those down-regulated in the long-lived, copper-uptake mutant grisea, validated the relevance of age-related changes in cellular copper metabolism. Overall, we (i) present a unique age-related data set of a longitudinal study of the experimental aging model P. anserina which represents a reference resource for future investigations in a variety of organisms, (ii) suggest autophagy to be a key quality control pathway that becomes active once other pathways fail, and (iii) present testable predictions for subsequent experimental investigations.