title: Enhancement of cardiac L-type Ca2+ currents in transgenic mice with cardiac-specific overexpression of CYP2J2.
abstract: CYP2J2 is abundant in cardiomyocytes and is involved in the metabolism of arachidonic acid (AA) to epoxyeicosatrienoic acids (EETs), which affect multiple cell functions. In this study, we investigated the effect of overexpression of CYP2J2 on cardiac L-type Ca2+ currents (ICa) in adult transgenic mice. Cardiac-specific overexpression of CYP2J2 was achieved using the alpha-myosin heavy chain promoter. ICa was recorded from isolated ventricular cardiomyocytes. Compared with the wild-type cardiomyocytes (n = 60), the density of ICa was significantly increased by 40 +/- 9% in the CYP2J2 transgenic cardiomyocytes (n = 71; P < 0.001). N-Methylsulfonyl-6-(2-proparglyloxyphenyl)hexanamide (MS-PPOH), a specific inhibitor of EET biosynthesis, and clotrimazole, a cytochrome P450 inhibitor, significantly reduced ICa in both wild-type and transgenic cardiomyocytes; however, MS-PPOH inhibited ICa to a greater extent in the CYP2J2 transgenic cells (n = 10) than in the wild-type cells (n = 10; P < 0.01). Addition of 11,12-EET significantly restored ICa in MS-PPOH-treated cells. Intracellular dialysis with either of two inhibitory monoclonal antibodies against CYP2J2 significantly reduced ICa in both wild-type and transgenic mice. Membrane-permeable 8-bromo-cAMP and the beta-adrenergic agonist isoproterenol significantly reversed the monoclonal antibody-induced inhibition of ICa. In addition, the total protein level of the alpha1 subunit of the Cav1.2 L-type Ca2+ channel was not altered in CYP2J2 transgenic hearts, but the phosphorylated portion was markedly increased. In conclusion, overexpression of CYP2J2 increases ICa in CYP2J2 transgenic cardiomyocytes via a mechanism that involves cAMP-protein kinase A-dependent phosphorylation of the L-type Ca2+ channel.
authors.affiliation: Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA. yongfu.xiao@medtronic.com
authors.forename: Yong-Fu
authors.initials: YF
authors.lastname: Xiao
authors.forename: Qingen
authors.initials: Q
authors.lastname: Ke
authors.forename: John M
authors.initials: JM
authors.lastname: Seubert
authors.forename: J Alyce
authors.initials: JA
authors.lastname: Bradbury
authors.forename: Joan
authors.initials: J
authors.lastname: Graves
authors.forename: Laura M
authors.initials: LM
authors.lastname: Degraff
authors.forename: John R
authors.initials: JR
authors.lastname: Falck
authors.forename: Kris
authors.initials: K
authors.lastname: Krausz
authors.forename: Harry V
authors.initials: HV
authors.lastname: Gelboin
authors.forename: James P
authors.initials: JP
authors.lastname: Morgan
authors.forename: Darryl C
authors.initials: DC
authors.lastname: Zeldin
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D020746:Calcium Channels, L-Type / Q000502:physiology*; D000090762:Cytochrome P-450 CYP2J2; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D006321:Heart / Q000502:physiology; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D051379:Mice; D008822:Mice, Transgenic; D009206:Myocardium / Q000201:enzymology*; D010105:Oxygenases / Q000235:genetics*; D010766:Phosphorylation; D021122:Protein Subunits / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D016276:Ventricular Function
chemical_list: C000717350:CYP2J2 protein, human; D020746:Calcium Channels, L-Type; D021122:Protein Subunits; D011994:Recombinant Proteins; D015124:8-Bromo Cyclic Adenosine Monophosphate; D003577:Cytochrome P-450 Enzyme System; D010105:Oxygenases; D000090762:Cytochrome P-450 CYP2J2; D007545:Isoproterenol