Effect of Resveratrol, a SIRT1 Activator, on the Interactions of the CLOCK/BMAL1 Complex.
10.3803/EnM.2014.29.3.379
- Author:
Insung PARK
1
;
Yool LEE
;
Hee Dae KIM
;
Kyungjin KIM
Author Information
1. Department of Biological Sciences and Brain Research Center for 21st Frontier Program in Neuroscience, Seoul National University College of Natural Sciences, Seoul, Korea. kyungjin@snu.ac.kr
- Publication Type:Original Article
- Keywords:
Circadian clocks;
CLOCK/BMAL1 heterodimer;
SIRT1;
BiFC analysis;
Resveratrol
- MeSH:
Cell Nucleus;
Circadian Clocks;
Complement System Proteins;
Fluorescence;
Gene Expression;
Immunohistochemistry;
Luciferases;
Mammals;
Metabolism;
Transcription Factors
- From:Endocrinology and Metabolism
2014;29(3):379-387
- CountryRepublic of Korea
- Language:English
-
Abstract:
BACKGROUND: In mammals, the CLOCK/BMAL1 heterodimer is a key transcription factor complex that drives the cyclic expression of clock-controlled genes involved in various physiological functions and behavioral consequences. Recently, a growing number of studies have reported a molecular link between the circadian clock and metabolism. In the present study, we explored the regulatory effects of SIRTUIN1 (SIRT1), an NAD+-dependent deacetylase, on CLOCK/BMAL1-mediated clock gene expression. METHODS: To investigate the interaction between SIRT1 and CLOCK/BMAL1, we conducted bimolecular fluorescence complementation (BiFC) analyses supplemented with immunocytochemistry assays. BiFC experiments employing deletion-specific mutants of BMAL1 were used to elucidate the specific domains that are necessary for the SIRT1-BMAL1 interaction. Additionally, luciferase reporter assays were used to delineate the effects of SIRT1 on circadian gene expression. RESULTS: BiFC analysis revealed that SIRT1 interacted with both CLOCK and BMAL1 in most cell nuclei. As revealed by BiFC assays using various BMAL1 deletion mutants, the PAS-B domain of BMAL1 was essential for interaction with SIRT1. Activation of SIRT1 with resveratrol did not exert any significant change on the interaction with the CLOCK/BMAL1 complex. However, promoter analysis using Per1-Luc and Ebox-Luc reporters showed that SIRT1 significantly downregulated both promoter activities. This inhibitory effect was intensified by treatment with resveratrol, indicating a role for SIRT1 and its activator in CLOCK/BMAL1-mediated transcription of clock genes. CONCLUSION: These results suggest that SIRT1 may form a regulatory complex with CLOCK/BMAL1 that represses clock gene expression, probably via deacetylase activity.
