title: Overexpression of Sarcoendoplasmic Reticulum Calcium ATPase 2a Promotes Cardiac Sympathetic Neurotransmission via Abnormal Endoplasmic Reticulum and Mitochondria Ca2+Regulation.
abstract: Reduced cardiomyocyte excitation-contraction coupling and downregulation of the SERCA2a (sarcoendoplasmic reticulum calcium ATPase 2a) is associated with heart failure. This has led to viral transgene upregulation of SERCA2a in cardiomyocytes as a treatment. We hypothesized that SERCA2a gene therapy expressed under a similar promiscuous cytomegalovirus promoter could also affect the cardiac sympathetic neural axis and promote sympathoexcitation. Stellate neurons were isolated from 90 to 120 g male, Sprague-Dawley, Wistar Kyoto, and spontaneously hypertensive rats. Neurons were infected with Ad-mCherry or Ad-mCherry-hATP2Aa (SERCA2a). Intracellular Ca2+changes were measured using fura-2AM in response to KCl, caffeine, thapsigargin, and carbonylcyanide-p-trifluoromethoxyphenylhydrazine to mobilize intracellular Ca2+stores. The effect of SERCA2a on neurotransmitter release was measured using [3H]-norepinephrine overflow from 340 to 360 g Sprague-Dawley rat atria in response to right stellate ganglia stimulation. Upregulation of SERCA2a resulted in greater neurotransmitter release in response to stellate stimulation compared with control (empty: 98.7±20.5 cpm, n=7; SERCA: 186.5±28.41 cpm, n=8;P<0.05). In isolated Sprague-Dawley rat stellate neurons, SERCA2a overexpression facilitated greater depolarization-induced Ca2+transients (empty: 0.64±0.03 au, n=57; SERCA: 0.75±0.03 au, n=68;P<0.05), along with increased endoplasmic reticulum and mitochondria Ca2+load. Similar results were observed in Wistar Kyoto and age-matched spontaneously hypertensive rats, despite no further increase in endoplasmic reticulum load being observed in the spontaneously hypertensive rat (spontaneously hypertensive rats: empty, 0.16±0.04 au, n=18; SERCA: 0.17±0.02 au, n=25). In conclusion, SERCA2a upregulation in cardiac sympathetic neurons resulted in increased neurotransmission and increased Ca2+loading into intracellular stores. Whether the increased Ca2+transient and neurotransmission after SERCA2A overexpression contributes to enhanced sympathoexcitation in heart failure patients remains to be determined.
authors.affiliation: From the Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre and BHF Centre of Research Excellence, Oxford, United Kingdom (J.S., N.H., K.L., D.L., D.J.P.); and Sir William Dunn School of Pathology, Oxford, United Kingdom (E.J.).
authors.forename: Julia
authors.initials: J
authors.lastname: Shanks
authors.affiliation: From the Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre and BHF Centre of Research Excellence, Oxford, United Kingdom (J.S., N.H., K.L., D.L., D.J.P.); and Sir William Dunn School of Pathology, Oxford, United Kingdom (E.J.).
authors.forename: Neil
authors.initials: N
authors.lastname: Herring
authors.affiliation: From the Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre and BHF Centre of Research Excellence, Oxford, United Kingdom (J.S., N.H., K.L., D.L., D.J.P.); and Sir William Dunn School of Pathology, Oxford, United Kingdom (E.J.).
authors.forename: Errin
authors.initials: E
authors.lastname: Johnson
authors.affiliation: From the Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre and BHF Centre of Research Excellence, Oxford, United Kingdom (J.S., N.H., K.L., D.L., D.J.P.); and Sir William Dunn School of Pathology, Oxford, United Kingdom (E.J.).
authors.forename: Kun
authors.initials: K
authors.lastname: Liu
authors.affiliation: From the Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre and BHF Centre of Research Excellence, Oxford, United Kingdom (J.S., N.H., K.L., D.L., D.J.P.); and Sir William Dunn School of Pathology, Oxford, United Kingdom (E.J.).
authors.forename: Dan
authors.initials: D
authors.lastname: Li
authors.affiliation: From the Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre and BHF Centre of Research Excellence, Oxford, United Kingdom (J.S., N.H., K.L., D.L., D.J.P.); and Sir William Dunn School of Pathology, Oxford, United Kingdom (E.J.). david.paterson@dpag.ox.ac.uk.
authors.forename: David J
authors.initials: DJ
authors.lastname: Paterson
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004195:Disease Models, Animal; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000648:ultrastructure; D005786:Gene Expression Regulation; D006321:Heart / Q000294:innervation; D006333:Heart Failure / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008297:Male; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000378:metabolism* / Q000648:ultrastructure; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000648:ultrastructure; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017207:Rats, Sprague-Dawley; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000096:biosynthesis / Q000235:genetics*; D013564:Sympathetic Nervous System / Q000378:metabolism* / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000235:genetics*
chemical_list: D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D002118:Calcium
keywords: hypertension; rats, inbred SHR; sarcoplasmic reticulum calcium-transporting ATPases; stellate ganglion; sympathetic nervous system