SIRT6 Overexpression Improves Various Aspects of Mouse Healthspan

The extension in human lifespan in the last century results in a significant increase in incidence of age related diseases. It is therefore crucial to identify key factors that control elderly healthspan. Similar to dietary restriction, mice overexpressing the NAD+ dependent protein deacylase SIRT6 (MOSES) live longer and have reduced IGF-1 levels. However, it is as yet unknown whether SIRT6 also affects various healthspan parameters. Here, a range of age related phenotypes was evaluated in MOSES mice. In comparison to their wild-type (WT) littermates, old MOSES mice showed amelioration of a variety of age-related disorders, including: improved glucose tolerance, younger hormonal profile, reduced age-related adipose inflammation and increased physical activity. The increased activity was accompanied with increased muscle AMP-activated protein kinase (AMPK) activity. Altogether, these results indicate that overexpression of SIRT6 in mice retards important aspects of the aging process and suggest SIRT6 to be a potential therapeutic target for the treatment of a set of age-related disorders.

Reciprocal Regulation between SIRT6 and miR-122 Controls Liver Metabolism and Predicts Hepatocarcinoma Prognosis

Mice overexpressing the longevity protein SIRT6 or deficient for the liver's most prevalent microRNA miR-122 display a similar set of phenotypes, including improved lipid profile and protection against damage linked to obesity. Here, we show that miR-122 and SIRT6 negatively regulate each other's expression. SIRT6 downregulates miR-122 by deacetylating H3K56 in the promoter region. MiR-122 binds to three sites on the SIRT6 3' UTR and reduces its levels. The interplay between SIRT6 and miR-122 is manifested in two physiologically relevant ways in the liver. First, they oppositely regulate a similar set of metabolic genes and fatty acid β-oxidation. Second, in hepatocellular carcinoma patients, loss of a negative correlation between SIRT6 and miR-122 expression is significantly associated with better prognosis. These findings show that SIRT6 and miR-122 negatively regulate each other to control various aspects of liver physiology and SIRT6-miR-122 correlation may serve as a biomarker for hepatocarcinoma prognosis.