Homocysteine inhibits endothelial cell growth via DNA hypomethylation of the cyclin A gene.
We reported previously that homocysteine (Hcy) inhibits endothelial cell (EC) growth by transcriptional inhibition of the cyclin A gene via a hypomethylation-related mechanism. In this study, we examined the effect of Hcy on epigenetic modification of the cyclin A gene and its biologic role in human ECs. Cyclin A mRNA levels were significantly suppressed by Hcy and a DNA methyltransferase inhibitor. The cyclin A promoter contains a CpG island spanning a 477-bp region (-277/200). Bisulfite sequencing followed by polymerase chain reaction (PCR) amplification of the cyclin A promoter (-267/37) showed that Hcy eliminated methylation at 2 CpG sites in the cyclin A promoter, one of which is located on the cycle-dependent element (CDE). Mutation of CG sequence on the CDE leads to a 6-fold increase in promoter activity. Hcy inhibited DNA methyltransferase 1 (DNMT1) activity by 30%, and reduced the binding of methyl CpG binding protein 2 (MeCP2) and increased the bindings of acetylated histone H3 and H4 in the cyclin A promoter. Finally, adenovirus-transduced DNMT1 gene expression reversed the inhibitory effect of Hcy on cyclin A expression and EC growth inhibition. In conclusion, Hcy inhibits cyclin A transcription and cell growth by inhibiting DNA methylation through suppression of DNMT1 in ECs.
Jamaluddin
M D S
MD
Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA.
Chen
Irene
I
Yang
Fan
F
Jiang
Xiaohua
X
Jan
Michael
M
Liu
Xiaoming
X
Schafer
Andrew I
AI
Durante
William
W
Yang
Xiaofeng
X
Wang
Hong
H
D001374:Azacitidine / Q000494:pharmacology; D001483:Base Sequence; D002087:Butyrates / Q000494:pharmacology; D049109:Cell Proliferation; D002478:Cells, Cultured; D018899:CpG Islands / Q000187:drug effects; D019925:Cyclin A / Q000235:genetics*; D004247:DNA / Q000096:biosynthesis; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects*; D042783:Endothelial Cells / Q000187:drug effects* / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects; D006710:Homocysteine / Q000494:pharmacology*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000187:drug effects; D014162:Transfection
D002087:Butyrates; D019925:Cyclin A; D006877:Hydroxamic Acids; D006710:Homocysteine; C012589:trichostatin A; D004247:DNA; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human; D001374:Azacitidine
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