Pharmacologic targeting of sirtuin and PPAR signaling improves longevity and mitochondrial physiology in respiratory chain complex I mutant Caenorhabditis elegans

Abstract

Mitochondrial respiratory chain (RC) diseases are highly morbid multi-systemic conditions for which few effective therapies exist. Given the essential role of sirtuin and PPAR signaling in mediating both mitochondrial physiology and the cellular response to metabolic stress in RC complex I (CI) disease, we postulated that drugs that alter these signaling pathways either directly (resveratrol for sirtuin, rosiglitazone for PPARγ, fenofibrate for PPARα), or indirectly by increasing NAD+ availability (nicotinic acid), might offer effective treatment strategies for primary RC disease. Integrated effects of targeting these cellular signaling pathways on animal lifespan and multi-dimensional in vivo parameters were studied in gas-1(fc21) relative to wild-type (N2 Bristol) worms. Specifically, animal lifespan, transcriptome profiles, mitochondrial oxidant burden, mitochondrial membrane potential, mitochondrial content, amino acid profiles, stable isotope-based intermediary metabolic flux, and total nematode NADH and NAD+ concentrations were compared. Shortened gas-1(fc21) mutant lifespan was rescued with either resveratrol or nicotinic acid, regardless of whether treatments were begun at the early larval stage or in young adulthood. Rosiglitazone administration beginning in young adult stage animals also rescued lifespan. All drug treatments reversed the most significant transcriptome alterations at the biochemical pathway level relative to untreated gas-1(fc21) animals. Interestingly, increased mitochondrial oxidant burden in gas-1(fc21) was reduced with nicotinic acid but exacerbated significantly by resveratrol and modestly by fenofibrate, with little change by rosiglitazone treatment. In contrast, the reduced mitochondrial membrane potential of mutant worms was further decreased by nicotinic acid but restored by either resveratrol, rosiglitazone, or fenofibrate. Using a novel HPLC assay, we discovered that gas-1(fc21) worms have significant deficiencies of NAD+ and NADH. Whereas resveratrol restored concentrations of both metabolites, nicotinic acid only restored NADH. Characteristic branched chain amino acid elevations in gas-1(fc21) animals were normalized completely by nicotinic acid and largely by resveratrol, but not by either rosiglitazone or fenofibrate. We developed a visualization system to enable objective integration of these multi-faceted physiologic endpoints, an approach that will likely be useful to apply in future drug treatment studies in human patients with mitochondrial disease. Overall, these data demonstrate that direct or indirect pharmacologic restoration of altered sirtuin and PPAR signaling can yield significant health and longevity benefits, although by divergent bioenergetic mechanism(s), in a nematode model of mitochondrial RC complex I disease. Thus, these animal model studies introduce important, integrated insights that may ultimately yield rational treatment strategies for human RC disease.

Regulation of nuclear epigenome by mitochondrial DNA heteroplasmy

“…After filtration, samples were loaded onto a HPLC system, using an YMC-Pack ODS-A column (5 μm, 4.6 × 250 mm) preceded by a guard column. NAD + and NADH peak areas were integrated by the Shimadzu Lab Solution software with standard curves normalized to protein (31).…”

Mitochondrial dysfunction in cardiac aging

“…With this idea, more NAD + /NADH therapies are being created. In a study of gas-1 mutant worms, nicotinic acid (NA) and resveratrol both improved survival of the worms [221]. NA helped decrease the amount of ROS in the worms system and it was suggested that the NA increased NAD + pools which can help maintain Sirt3 acetylation patterns.…”

Flunarizine rescues reduced lifespan in CLN3 triple knock‐out Caenorhabditis elegans model of batten disease

“…20,21 Briefly, worms were treated with either 1 μM flunarizine or 0.1% DMSO buffer control from the early development L1-larval stage. Upon reaching the first day of egg-laying, synchronous populations of young adults were moved to 3.5 cm NGM plates spread with OP50 E. coli , either 1 μM flunarizine or 0.1% DMSO buffer control, and 10 μM MitoTracker Green FM (to evaluate relative mitochondrial mass) for 24 hours.…”