Mitochondrial Respiratory Thresholds Regulate Yeast Chronological Life Span and its Extension by Caloric Restriction

We have explored the role of mitochondrial function in aging by genetically and pharmacologically modifying yeast cellular respiration production during the exponential and/or stationary growth phases and determining how this affects chronological life span (CLS). Our results demonstrate that respiration is essential during both growth phases for standard CLS, but that yeast have a large respiratory capacity, and only deficiencies below a threshold (∼40% of wild-type) significantly curtail CLS. Extension of CLS by caloric restriction also required respiration above a similar threshold during exponential growth and completely alleviated the need for respiration in the stationary phase. Finally, we show that supplementation of media with 1% trehalose, a storage carbohydrate, restores wild-type CLS to respiratory-null cells. We conclude that mitochondrial respiratory thresholds regulate yeast CLS and its extension by caloric restriction by increasing stress resistance, an important component of which is the optimal accumulation and mobilization of nutrient stores. [Display omitted] ► Respiration below a 40% of WT threshold alters cell protection systems and limits CLS ► Trehalose supplementation of the culture media extends CLS of respiratory-null cells ► Respiration above a low threshold is required for efficient CR-induced CLS extension ► CR abolishes the requirement of respiration during the stationary phase