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b 1 ‐Adrenergic Receptors in the Golgi Apparatus are Activated by Cell Permeable Agonists and Stimulate PLC‐mediated PI4P Hydrolysis in Cardiac Myocytes
Author(s) -
Wei Wenhui,
Nash Craig,
Smrcka Alan
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.810.1
Subject(s) - golgi apparatus , microbiology and biotechnology , brefeldin a , golgi membrane , biology , receptor , myocyte , chemistry , endoplasmic reticulum , biochemistry
Previously, our laboratory identified a phospholipase C (PLC)‐mediated PI4P hydrolysis pathway at the Golgi apparatus that is important for regulation of cardiac hypertrophy, a pathology associated with development of heart failure. cAMP stimulates this pathway via Epac‐mediated activation of Rap1 which directly binds to PLCɛ. We recently found that a cell membrane permeable β‐adrenergic receptor (βAR) agonist, dobutamine (dob), induces Golgi PI4P hydrolysis in neonatal rat ventricular myocytes (NRVMs) while a cell membrane impermeable β‐adrenergic (βAR) agonist, Isoproterenol, does not. We used a YFP‐tagged mini Gs protein2 which is recruited to Gs‐coupled receptors upon their activation, to monitor the membrane location of these activated receptors. Dobutamine induced robust and rapid recruitment of mini Gs to both the plasma membrane, and the perinuclear region corresponding to the Golgi apparatus. In contrast, Isoproterenol, induced a strong recruitment to the plasma membrane but not to the Golgi. Treatment with brefeldin A significantly reversed mini Gs recruitment to the internal membrane induced by dobutamine, supporting the idea that active β 1 ‐ARs are localized to the Golgi membrane. A membrane permeable βAR antagonist, metoprolol, fully reversed dob‐mediated PI4P hydrolysis and mini Gs recruitment to the Golgi membrane while a membrane impermeable antagonist, sotalol had no effects on dob‐mediated PI4P hydrolysis and only partially reversed the mini Gs recruitment to the Golgi membrane. In addition, an Epac inhibitor HJC0726 completely inhibited dob‐mediated PI4P hydrolysis whereas gallein, a Gβγ inhibitor had no effect. Over expression of the RA1 domain of PLCɛ, which competes PLCɛ away from the mAKAPβ scaffold, also inhibited dobutamine stimulation of PI4P hydrolysis. These data indicate that activation of endogenous intracellular β1ARs stimulates production of a local pool of cAMP that activates the perinuclear Epac‐PLCɛ‐PI4P hydrolysis pathway involved in heart failure. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .