title: Deletion of the C-terminal phosphorylation sites in the cardiac β-subunit does not affect the basic β-adrenergic response of the heart and the Ca(v)1.2 channel.
abstract: Phosphorylation of the cardiac β subunit (Ca(v)β(2)) of the Ca(v)1.2 L-type Ca(2+) channel complex has been proposed as a mechanism for regulation of L-type Ca(2+) channels by various protein kinases including PKA, CaMKII, Akt/PKB, and PKG. To test this hypothesis directly in vivo, we generated a knock-in mouse line with targeted mutation of the Ca(v)β(2) gene by insertion of a stop codon after proline 501 in exon 14 (mouse sequence Cacnb2; βStop mouse). This mutation prevented translation of the Ca(v)β(2) C terminus that contains the relevant phosphorylation sites for the above protein kinases. Homozygous cardiac βStop mice were born at Mendelian ratio, had a normal life expectancy, and normal basal L-type I(Ca). The regulation of the L-type current by stimulation of the β-adrenergic receptor was unaffected in vivo and in cardiomyocytes (CMs). βStop mice were cross-bred with mice expressing the Ca(v)1.2 gene containing the mutation S1928A (SAβStop) or S1512A and S1570A (SFβStop) in the C terminus of the α(1C) subunit. The β-adrenergic regulation of the cardiac I(Ca) was unaltered in these mouse lines. In contrast, truncation of the Ca(v)1.2 at Asp(1904) abolished β-adrenergic up-regulation of I(Ca) in murine embryonic CMs. We conclude that phosphorylation of the C-terminal sites in Ca(v)β(2), Ser(1928), Ser(1512), and Ser(1570) of the Ca(v)1.2 protein is functionally not involved in the adrenergic regulation of the murine cardiac Ca(v)1.2 channel.
authors.affiliation: Forschergruppe 923, Institut für Pharmakologie und Toxikologie, Technische Universität München, 80802 München, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Brandmayr
authors.forename: Montatip
authors.initials: M
authors.lastname: Poomvanicha
authors.forename: Katrin
authors.initials: K
authors.lastname: Domes
authors.forename: Jie
authors.initials: J
authors.lastname: Ding
authors.forename: Anne
authors.initials: A
authors.lastname: Blaich
authors.forename: Jörg W
authors.initials: JW
authors.lastname: Wegener
authors.forename: Sven
authors.initials: S
authors.lastname: Moosmang
authors.forename: Franz
authors.initials: F
authors.lastname: Hofmann
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D020746:Calcium Channels, L-Type / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004562:Electrocardiography; D005260:Female; D017353:Gene Deletion; D006321:Heart / Q000502:physiology*; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008969:Molecular Sequence Data; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D010766:Phosphorylation / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D011943:Receptors, Adrenergic, beta / Q000502:physiology*
chemical_list: D000318:Adrenergic beta-Agonists; C491528:Cacnb2 protein, mouse; D020746:Calcium Channels, L-Type; D011943:Receptors, Adrenergic, beta; D017868:Cyclic AMP-Dependent Protein Kinases; D007545:Isoproterenol