title: Tissue-specific modification of clock methylation in aging mice.
abstract: BACKGROUND
  Circadian rhythms tend to change as animals age; however, the molecular mechanisms underlying these are not yet fully understood.
  
  
  OBJECTIVE
  To investigate whether the DNA methylation of clock genes changes with age and contributes to circadian dysfunction in aged animals.
  
  
  METHODS
  We examined the methylation of clock promoters in the stomach, kidney, striatum, and spleen by using a methylation-specific polymerase chain reaction (MSP) assay.
  
  
  RESULTS
  Our results show that different tissues exhibit specific patterns of clock methylation. Additionally, methylation frequency decreased significantly in older mice at the Per1 promoter in the stomach, but it was significantly increased in older mice at the Cry1, Bmal2, and Npas2 promoters in the spleen.
  
  
  CONCLUSIONS
  The findings from our study suggest that DNA methylation contribute to age-related changes in circadian rhythms in certain slave oscillators.
authors.affiliation: Department of Pharmacology, Xuanwu Hospital of Capital Medical University, Beijing, People's Republic of China.
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.forename: Q-L
authors.initials: QL
authors.lastname: Lin
authors.forename: L
authors.initials: L
authors.lastname: Lu
authors.forename: C-C
authors.initials: CC
authors.lastname: Yang
authors.forename: Y-L
authors.initials: YL
authors.lastname: Li
authors.forename: F-L
authors.initials: FL
authors.lastname: Sun
authors.forename: D-H
authors.initials: DH
authors.lastname: Wang
authors.forename: Y-N
authors.initials: YN
authors.lastname: Cai
authors.forename: L
authors.initials: L
authors.lastname: Li
mesh_terms: D000375:Aging / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D056926:CLOCK Proteins / Q000378:metabolism*; D004247:DNA / Q000235:genetics; D017931:DNA Primers; D005753:Gastric Mucosa / Q000378:metabolism; D008297:Male; D008745:Methylation; D051379:Mice; D008810:Mice, Inbred C57BL; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000187:drug effects; D013447:Sulfites / Q000737:chemistry
chemical_list: D017931:DNA Primers; D013447:Sulfites; D004247:DNA; D056926:CLOCK Proteins