Related Experiment Video
Updated: Jun 20, 2026

A Suppressor Screen for the Characterization of Genetic Links Regulating Chronological Lifespan in Saccharomyces cerevisiae
Published on: September 17, 2020
SIRT1 markedly extends replicative lifespan if the NAD+ salvage pathway is enhanced
Cynthia Ho1, Eric van der Veer, Oula Akawi
1Robarts Research Institute, London Health Sciences Centre, Department of Medicine (Cardiology), University of Western Ontario, London, Canada N6A 5K8.
Abstract:
Sir2 mediates lifespan extension in lower eukaryotes but whether its mammalian homolog, sirtuin 1, silent mating type information regulation 2 homolog (SIRT1), is a longevity protein is controversial. We stably introduced the SIRT1 gene into human vascular smooth muscle cells (SMCs) and observed minimal extension of replicative lifespan. However, SIRT1 activity was found to be exquisitely dependent on nicotinamide phosphoribosyltransferase (Nampt) activity. Moreover, overexpression of Nampt converted SIRT1-overexpressing SMCs to senescence-resistant cells together with heightened SIRT1 activity, suppressed p21, and strikingly lengthened replicative lifespan. Thus, SIRT1 can markedly postpone SMC senescence, but this requires overcoming an otherwise vulnerable nicotinamide adenine dinucleotide salvage reaction in aging SMCs.
Related Concept Videos
Replicative Cell Senescence
Replicative Cell Senescence
Replication in Eukaryotes
Many Proteins Orchestrate Replication at the Origin
Eukaryotic replication follows many of the same...
Replication in Eukaryotes
Telomeres and Telomerase
DNA Damage can Stall the Cell Cycle

