Sirtuin 1 is a member of the sirtuin family of proteins, homologs of the Sir2 gene in S. cerevisiae. Members of the sirtuin family are characterized by a sirtuin core domain and grouped into four classes. The functions of human sirtuins have not yet been determined; however, yeast sirtuin proteins are known to regulate epigenetic gene silencing and suppress recombination of rDNA. Studies suggest that the human sirtuins may function as intracellular regulatory proteins with mono-ADP-ribosyltransferase activity. The protein encoded by this gene is included in class I of the sirtuin family.^[6]

Sirtuin 1 is downregulated in cells that have high insulin resistance and inducing its expression increases insulin sensitivity, suggesting the molecule is associated with improving insulin sensitivity.^[9]Furthermore, SIRT1 was shown to de-acetylate and affect the activity of both members of the PGC1-alpha/ERR-alpha complex, which are essential metabolic regulatory transcription factors.^{[10][11][12][13][14][15]}

In mammals, SIRT1 has been shown to deacetylate and thereby deactivate the p53 protein.^[16] SIRT1 also stimulates autophagy by preventing acetylation of proteins (via deacetylation) required for autophagy as demonstrated in cultured cells and embryonic and neonatal tissues. This function provides a link between sirtuin expression and the cellular response to limited nutrients due to caloric restriction.^[17] Furthermore, SIRT1 was shown to de-acetylate and affect the activity of both members of the PGC1-alpha/ERR-alpha complex, which are essential metabolic regulatory transcription factors.^{[10][11][12][13][14][15]}

Human aging is characterized by a chronic, low-grade inflammation level^[18] and NF-κB is the main transcriptional regulator of genes related to inflammation.^[19] SIRT1 inhibits NF-κB-regulated gene expression by deacetylating the RelA/p65 subunit of NF-κB at lysine 310.^[20][21]

^{Increased expression of SIRT1 protein extended both the mean and maximal lifespan of mice.[53] In these mice health was also improved as well as bone and muscle mass. Another SIRT1 activator (SRT1720) also extended lifespan and improved the health of mice.[54]}