title: Homocysteine modulates 5-lipoxygenase expression level via DNA methylation.
abstract: Elevated 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 β 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 β 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.
authors.affiliation: Department of Pharmacology and Center for Translational Medicine, Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA.
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Li
authors.affiliation: Department of Pharmaceutical Sciences, Temple University Philadelphia, Philadelphia, PA, 19140, USA.
authors.forename: Carlos
authors.initials: C
authors.lastname: Barrero
authors.affiliation: Cancer Biology Program Fox Chase Cancer Center, Temple University Philadelphia, Philadelphia, PA, 19140, USA.
authors.forename: Sapna
authors.initials: S
authors.lastname: Gupta
authors.affiliation: Cancer Biology Program Fox Chase Cancer Center, Temple University Philadelphia, Philadelphia, PA, 19140, USA.
authors.forename: Warren D
authors.initials: WD
authors.lastname: Kruger
authors.affiliation: Department of Pharmaceutical Sciences, Temple University Philadelphia, Philadelphia, PA, 19140, USA.
authors.forename: Salim
authors.initials: S
authors.lastname: Merali
authors.affiliation: Department of Pharmacology and Center for Translational Medicine, Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA.
authors.forename: Domenico
authors.initials: D
authors.lastname: Praticò
mesh_terms: D016229:Amyloid beta-Peptides / Q000378:metabolism; D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D001921:Brain / Q000187:drug effects / Q000201:enzymology; D019175:DNA Methylation / Q000187:drug effects / Q000235:genetics*; D004032:Diet; D006710:Homocysteine / Q000494:pharmacology*; D006801:Humans; D020138:Hyperhomocysteinemia / Q000201:enzymology / Q000235:genetics; D008297:Male; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D016229:Amyloid beta-Peptides; D012333:RNA, Messenger; D006710:Homocysteine; D001094:Arachidonate 5-Lipoxygenase
keywords: 5-lipoxygenase; Alzheimer's disease; S-adenosylmethionine; amyloid beta; homocysteine; methylation