Project description:SIRT1 is involved in both aging and circadian clock regulation, yet the link between the two processes in relation to SIRT1 function is unclear. Analyzing SIRT1-deficient cells and mice, we demonstrated that SIRT1 and Per2 constitute a reciprocal negative regulation loop that plays important roles in modulating circadian rhythmicity, metabolism and aging. SIRT1-deficient mice exhibit profound premature aging and enhanced H4K16 acetylation in the promoter of Per2 leading to its overexpression; in turn, Per2 suppresses SIRT1 transcription through binding to SIRT1 promoter at the CLOCK/BMAL1 site. We further demonstrated that absence of SIRT1 or ectopic overexpression of Per2 in the liver resulted in an accelerated pace of circadian rhythm and dysregulated amplitude, mimicking the natural process of circadian shortening in aged mice. Thus the interplay between SIRT1 and Per2 provides a link between the life-long sequence of aging and circadian clock maintenance.
Project description:Sirtuin 1 (SIRT1) is involved in both aging and circadian-clock regulation, yet the link between the two processes in relation to SIRT1 function is not clear. Using Sirt1-deficient mice, we found that Sirt1 and Period 2 (Per2) constitute a reciprocal negative regulation loop that plays important roles in modulating hepatic circadian rhythmicity and aging. Sirt1-deficient mice exhibited profound premature aging and enhanced acetylation of histone H4 on lysine16 (H4K16) in the promoter of Per2, the latter of which leads to its overexpression; in turn, Per2 suppresses Sirt1 transcription through binding to the Sirt1 promoter at the Clock/Bmal1 site. This negative reciprocal relationship between SIRT1 and PER2 was also observed in human hepatocytes. We further demonstrated that the absence of Sirt1 or the ectopic overexpression of Per2 in the liver resulted in a dysregulated pace of the circadian rhythm. The similar circadian rhythm was also observed in aged wild type mice. The interplay between Sirt1 and Per2 modulates aging gene expression and circadian-clock maintenance. To investigate hepatic SIRT1-dependent aging related genes, livers from wild type mice at 3 months (young), 12 months (middle age), and 19 months (old) of age, as well as Sirt1-deficient mice at 3 months of age were snap frozen and subject to RNA isolation and microarray analysis.
Project description:Sirtuin 1 (SIRT1) is involved in both aging and circadian-clock regulation, yet the link between the two processes in relation to SIRT1 function is not clear. Using Sirt1-deficient mice, we found that Sirt1 and Period 2 (Per2) constitute a reciprocal negative regulation loop that plays important roles in modulating hepatic circadian rhythmicity and aging. Sirt1-deficient mice exhibited profound premature aging and enhanced acetylation of histone H4 on lysine16 (H4K16) in the promoter of Per2, the latter of which leads to its overexpression; in turn, Per2 suppresses Sirt1 transcription through binding to the Sirt1 promoter at the Clock/Bmal1 site. This negative reciprocal relationship between SIRT1 and PER2 was also observed in human hepatocytes. We further demonstrated that the absence of Sirt1 or the ectopic overexpression of Per2 in the liver resulted in a dysregulated pace of the circadian rhythm. The similar circadian rhythm was also observed in aged wild type mice. The interplay between Sirt1 and Per2 modulates aging gene expression and circadian-clock maintenance.
Project description:We propose that the clock plays an important role in fine-tuning the hypoxic response under pathophysiological conditions, which can serve as a strategy to reduce the severity of fatal hypoxia-related diseases.