Nicotinamide riboside (NR), a NAD+-booster molecule, fails to increase lifespan and improve metabolism in Caenorhabditis elegans

Author(s)

Guilherme Tonon da Silva

• Document type: Master's Dissertation
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2020-02-28

Examining board members

Murilo Vieira Geraldo; Fernanda Marques da Cunha

• Advisor: Marcelo Alves da Silva Mori

Abstract

The world¿s population is increasingly aging, leading to an increase in the prevalence of age-related diseases. Caloric restriction (CR) is an evolutionarily conserved intervention shown to extend lifespan and delay the onset of age-related diseases across species. However, due to some undesirable effects in humans, and because CR consists of a strict diet, the search for CR mimetics and the understanding of their molecular effects becomes necessary. It has been shown that some beneficial effects of CR depend on an increase in NAD+ levels. In fact, interventions aiming to raise NAD+ levels, such as supplementation with nicotinamide riboside (NR), a vitamin B3 analogue, have been shown to prevent age-associated metabolic decline, increase oxidative metabolism and promote longevity in mice and worms, which made this compound very promising to target age-related diseases. Unexpectedly though, we observed no increase in C. elegans lifespan using NR at the standard conditions found in the literature. We performed the experiments altering multiple experimental conditions, like using live or dead bacteria, adding FUdR (a mitosis inhibitor) or not, passing worms to new plates or keeping them in the same plate throughout their lifespan, changing the timing of the treatment, testing worms of different genetic backgrounds, adding NR in the plate or to the bacteria and even changing the NR supplier. In none of these conditions could we see a consistent increase in worms¿ lifespan. In fact, in some replicates we even saw a decrease in worm lifespan. Similarly, neither hsp-6::GFP nor sod-3::GFP reporters were activated upon NR treatment, opposite to what has been shown. Finally, in our hands NR at 500 µM could neither prevent age-related mobility decline nor increase genes coding for enzymes controlling key metabolic pathways (TCA cycle (cts-1), glycolysis (hxk-1), gluconeogenesis (pyc-1)), as assessed by RT-qPCR. Together, these data suggest that NR effects in worm lifespan and metabolism might be less robust than previously anticipated (AU)

• FAPESP's process: 17/08829-5 - Investigation of the interaction between Dicer and the NAD+ signalling pathway in C. elegans metabolism and aging
• Grantee: Guilherme Tonon da Silva
• Support Opportunities: Scholarships in Brazil - Master