title: Disrupting Dimerization Translocates Soluble Epoxide Hydrolase to Peroxisomes.
abstract: The epoxyeicosatrienoic acid (EET) neutralizing enzyme soluble epoxide hydrolase (sEH) is a neuronal enzyme, which has been localized in both the cytosol and peroxisomes. The molecular basis for its dual localization remains unclear as sEH contains a functional peroxisomal targeting sequence (PTS). Recently, a missense polymorphism was identified in human sEH (R287Q) that enhances its peroxisomal localization. This same polymorphism has also been shown to generate weaker sEH homo-dimers. Taken together, these observations suggest that dimerization may mask the sEH PTS and prevent peroxisome translocation. In the current study, we test the hypothesis that dimerization is a key regulator of sEH subcellular localization. Specifically, we altered the dimerization state of sEH by introducing substitutions in amino acids responsible for the dimer-stabilizing salt-bridge. Green Fluorescent Protein (GFP) fusions of each of mutants were co-transfected into mouse primary cultured cortical neurons together with a PTS-linked red fluorescent protein to constitutively label peroxisomes. Labeled neurons were analyzed using confocal microscopy and co-localization of sEH with peroxisomes was quantified using Pearson's correlation coefficient. We find that dimer-competent sEH constructs preferentially localize to the cytosol, whereas constructs with weakened or disrupted dimerization were preferentially targeted to peroxisomes. We conclude that the sEH dimerization status is a key regulator of its peroxisomal localization.
authors.affiliation: Department of Anesthesiology & Perioperative Medicine, Oregon Health & Science University, Portland, OR, 97239-3098, United States of America.|Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR, 97239-3098, United States of America.|The Knight Cardiovascular Institute, Oregon Health & Science University, Portland, OR, 97239-3098, United States of America.
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Nelson
authors.affiliation: Department of Anesthesiology & Perioperative Medicine, Oregon Health & Science University, Portland, OR, 97239-3098, United States of America.
authors.forename: Anjali J
authors.initials: AJ
authors.lastname: Das
authors.affiliation: The Knight Cardiovascular Institute, Oregon Health & Science University, Portland, OR, 97239-3098, United States of America.|Pape Family Research Center, Department of Pediatrics Oregon Health & Science University, Portland, OR, 97239-3098, United States of America.
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Barnes
authors.affiliation: Department of Anesthesiology & Perioperative Medicine, Oregon Health & Science University, Portland, OR, 97239-3098, United States of America.|The Knight Cardiovascular Institute, Oregon Health & Science University, Portland, OR, 97239-3098, United States of America.
authors.forename: Nabil J
authors.initials: NJ
authors.lastname: Alkayed
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D019281:Dimerization; D004851:Epoxide Hydrolases / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000378:metabolism; D020675:Peroxisomes / Q000378:metabolism*; D021381:Protein Transport; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D004851:Epoxide Hydrolases