title: Daily variations of homocysteine concentration may influence methylation of DNA in normal healthy individuals.
abstract: The regulation of genetic expression is tightly controlled and well balanced in the organism by different epigenetic mechanisms such as DNA methylation and histone modifications. DNA methylation occurring after embryogenesis is seen mainly as an irreversible event. Even small changes in genomic DNA methylation might be of biological relevance, and several factors influencing DNA methylation have been identified so far, one being homocysteine. In this study, genomic DNA methylation was analyzed and homocysteine plasma levels were measured over a 24 h period in 30 healthy students (15 males and 15 females) exposed to a standard 24 h regime of daytime activity alternating with nighttime sleep. Plasma homocysteine concentrations were measured using HPLC detection. DNA was extracted from whole EDTA blood, and genomic DNA methylation was assessed by fluorescently labeled cytosine extension assay. Both homocysteine and DNA methylation showed 24 h variation. Homocysteine showed a significant daily rhythm with an evening peak and nocturnal nadir in all subjects (p<0.001). Males showed higher overall homocysteine levels compared to females (p=0.002). Genomic DNA methylation showed a significant rhythm with increased levels at night (p=0.021), which was inverse to plasma homocysteine levels.
authors: Department of Psychiatry and Psychotherapy, Friedrich-Alexander-University of Erlangen-Nuremberg, Erlangen, Germany. dominikus.boensch@uk-erlangen.de
authors: Dominikus
authors: D
authors: Bönsch
authors: Torsten
authors: T
authors: Hothorn
authors: Christian
authors: C
authors: Krieglstein
authors: Marlene
authors: M
authors: Koch
authors: Christina
authors: C
authors: Nehmer
authors: Bernd
authors: B
authors: Lenz
authors: Udo
authors: U
authors: Reulbach
authors: Johannes
authors: J
authors: Kornhuber
authors: Stefan
authors: S
authors: Bleich
mesh_terms: D000328:Adult; D002940:Circadian Rhythm / Q000235:genetics* / Q000502:physiology*; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D005260:Female; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012727:Sex Characteristics
chemical_list: D006710:Homocysteine