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Homocysteine modulates 5-lipoxygenase expression level via DNA methylation
Aging Cell. 2017 Apr;16(2) :273-280
PMID: 27896923 PMCID: PMC5334532 URL: https://www.ncbi.nlm.nih.gov/pubmed/27896923
AbstractElevated levels of homocysteinemia (Hcy), a risk factor for late-onset Alzheimer's disease (AD), have been associated with changes in cell methylation. Alzheimer's disease is characterized by an upregulation of the 5-lipoxygenase (5LO), whose promoter is regulated by methylation. However, whether Hcy activates 5LO enzymatic pathway by influencing the methylation status of its promoter remains unknown. Brains from mice with high Hcy were assessed for the 5LO pathway and neuronal cells exposed to Hcy implemented to study the mechanism(s) regulating 5LO expression levels and the effect on amyloid beta formation. Diet- and genetically induced high Hcy resulted in 5LO protein and mRNA upregulation, which was associated with a significant increase of the S-adenosylhomocysteine (SAH)/S-adenosylmethionine ratio, and reduced DNA methyltrasferases and hypomethylation of 5-lipoxygenase DNA. In vitro studies confirmed these results and demonstrated that the mechanism involved in the Hcy-dependent 5LO activation and amyloid beta formation is DNA hypomethylation secondary to the elevated levels of SAH. Taken together these findings represent the first demonstration that Hcy directly influences 5LO expression levels and establish a previously unknown cross talk between these two pathways, which is highly relevant for AD pathogenesis. The discovery of such a novel link not only provides new mechanistic insights in the neurobiology of Hcy, but most importantly new therapeutic opportunities for the individuals bearing this risk factor for the disease.
Notes1474-9726 Li, Jian-Guo Barrero, Carlos Gupta, Sapna Kruger, Warren D Merali, Salim Pratico, Domenico Journal Article England Aging Cell. 2016 Nov 29. doi: 10.1111/acel.12550.