|Epigenetic suppression of mouse Per2 expression in the suprachiasmatic nucleus by the inhalational anesthetic, sevoflurane.|
Mori, K; Iijima, N; Higo, S; Aikawa, S; Matsuo, I; Takumi, K; Sakamoto, A; Ozawa, H
We previously reported that sevoflurane anesthesia reversibly suppresses the expression of the clock gene, Period2 (Per2), in the mouse suprachiasmatic nucleus (SCN). However, the molecular mechanisms underlying this suppression remain unclear. In this study, we examined the possibility that sevoflurane suppresses Per2 expression via epigenetic modification of the Per2 promoter.Mice were anesthetized with a gas mixture of 2.5% sevoflurane/40% oxygen at a 6 L/min flow for 1 or 4 h. After termination, brains were removed and samples of SCN tissue were derived from frozen brain sections. Chromatin immunoprecipitation (ChIP) assays using anti-acetylated-histone antibodies were performed to investigate the effects of sevoflurane on histone acetylation of the Per2 promoter. Interaction between the E'-box (a cis-element in the Per2 promoter) and CLOCK (the Clock gene product) was also assessed by a ChIP assay using an anti-CLOCK antibody. The SCN concentration of nicotinamide adenine dinucleotide (NAD(+)), a CLOCK regulator, was assessed by liquid chromatography-mass spectrometry.Acetylation of histone H4 in the proximal region of the Per2 promoter was significantly reduced by sevoflurane. This change in the epigenetic profile of the Per2 gene was observed prior to suppression of Per2 expression. Simultaneously, a reduction in the CLOCK-E'-box interaction in the Per2 promoter was observed. Sevoflurane treatment did not affect the concentration of NAD(+) in the SCN.Independent of NAD(+) concentration in the SCN, sevoflurane decreases CLOCK binding to the Per2 promoter E'-box motif, reducing histone acetylation and leading to suppression of Per2 expression.
|Polyamine analogs modulate gene expression by inhibiting lysine-specific demethylase 1 (LSD1) and altering chromatin structure in human breast cancer cells.|
Zhu, Q; Huang, Y; Marton, LJ; Woster, PM; Davidson, NE; Casero, RA
Aberrant epigenetic repression of gene expression has been implicated in most cancers, including breast cancer. The nuclear amine oxidase, lysine-specific demethylase 1 (LSD1) has the ability to broadly repress gene expression by removing the activating mono- and di-methylation marks at the lysine 4 residue of histone 3 (H3K4me1 and me2). Additionally, LSD1 is highly expressed in estrogen receptor α negative (ER-) breast cancer cells. Since epigenetic marks are reversible, they make attractive therapeutic targets. Here we examine the effects of polyamine analog inhibitors of LSD1 on gene expression, with the goal of targeting LSD1 as a therapeutic modality in the treatment of breast cancer. Exposure of the ER-negative human breast cancer cells, MDA-MB-231 to the LSD1 inhibitors, 2d or PG11144, significantly increases global H3K4me1 and H3K4me2, and alters gene expression. Array analysis indicated that 98 (75 up and 23 down) and 477 (237 up and 240 down) genes changed expression by at least 1.5-fold or greater after treatment with 2d and PG11144, respectively. The expression of 12 up-regulated genes by 2d and 14 up-regulated genes by PG11144 was validated by quantitative RT-PCR. Quantitative chromatin immunoprecipitation (ChIP) analysis demonstrated that up-regulated gene expression by polyamine analogs is associated with increase of the active histone marks H3K4me1, H3K4me2 and H3K9act, and decrease of the repressive histone marks H3K9me2 and H3K27me3, in the promoter regions of the relevant target genes. These data indicate that the pharmacologic inhibition of LSD1 can effectively alter gene expression and that this therapeutic strategy has potential.