title: The Golgi apparatus is a functionally distinct Ca2+ store regulated by the PKA and Epac branches of the β1-adrenergic signaling pathway.
abstract: Ca(2+) release from the Golgi apparatus regulates key functions of the organelle, including vesicle trafficking. We found that the Golgi apparatus was the source of prolonged Ca(2+) release events that originated near the nuclei of primary cardiomyocytes. Golgi Ca(2+) release was unaffected by depletion of sarcoplasmic reticulum Ca(2+), and disruption of the Golgi apparatus abolished Golgi Ca(2+) release without affecting sarcoplasmic reticulum function, suggesting functional and spatial independence of Golgi and sarcoplasmic reticulum Ca(2+) stores. β1-Adrenoceptor stimulation triggers the production of the second messenger cAMP, which activates the Epac family of Rap guanine nucleotide exchange factors and the kinase PKA (protein kinase A). Phosphodiesterases (PDEs), including those in the PDE3 and PDE4 families, degrade cAMP. Activation of β1-adrenoceptors stimulated Golgi Ca(2+) release, an effect that required activation of Epac, PKA, and the kinase CaMKII. Inhibition of PDE3s or PDE4s potentiated β1-adrenergic-induced Golgi Ca(2+) release, which is consistent with compartmentalization of cAMP signaling near the Golgi apparatus. Interventions that stimulated Golgi Ca(2+) release appeared to increase the trafficking of vascular endothelial growth factor receptor-1 (VEGFR-1) from the Golgi apparatus to the surface membrane of cardiomyocytes. In cardiomyocytes from rats with heart failure, decreases in the abundance of PDE3s and PDE4s were associated with increased Golgi Ca(2+) release events. These data suggest that the Golgi apparatus is a focal point for β1-adrenergic-stimulated Ca(2+) signaling and that the Golgi Ca(2+) store functions independently from the sarcoplasmic reticulum and the global Ca(2+) transients that trigger contraction in cardiomyocytes.
authors.affiliation: School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK. d.steele@leeds.ac.uk.
authors.forename: Zhaokang
authors.initials: Z
authors.lastname: Yang
authors.affiliation: School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Hannah M
authors.initials: HM
authors.lastname: Kirton
authors.affiliation: School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: David A
authors.initials: DA
authors.lastname: MacDougall
authors.affiliation: Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: John P
authors.initials: JP
authors.lastname: Boyle
authors.affiliation: School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: James
authors.initials: J
authors.lastname: Deuchars
authors.affiliation: School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Brenda
authors.initials: B
authors.lastname: Frater
authors.affiliation: School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Sreenivasan
authors.initials: S
authors.lastname: Ponnambalam
authors.affiliation: School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Matthew E
authors.initials: ME
authors.lastname: Hardy
authors.affiliation: School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Edward
authors.initials: E
authors.lastname: White
authors.affiliation: School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Calaghan
authors.affiliation: Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Peers
authors.affiliation: School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK. d.steele@leeds.ac.uk.
authors.forename: Derek S
authors.initials: DS
authors.lastname: Steele
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006056:Golgi Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D006333:Heart Failure / Q000139:chemically induced / Q000378:metabolism; D015151:Immunoblotting; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D016686:Monocrotaline; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D017208:Rats, Wistar; D018342:Receptors, Adrenergic, beta-1 / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: C547789:Adrb1 protein, rat; D000318:Adrenergic beta-Agonists; D004791:Enzyme Inhibitors; D020662:Guanine Nucleotide Exchange Factors; C526973:Rapgef3 protein, rat; D018342:Receptors, Adrenergic, beta-1; D019284:Thapsigargin; D016686:Monocrotaline; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D010727:Phosphoric Diester Hydrolases; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D007545:Isoproterenol; D002118:Calcium