title: The expression level of ecto-NTP diphosphohydrolase1/CD39 modulates exocytotic and ischemic release of neurotransmitters in a cellular model of sympathetic neurons.
abstract: Once released, norepinephrine is removed from cardiac synapses via reuptake into sympathetic nerves, whereas transmitter ATP is catabolized by ecto-NTP diphosphohydrolase 1 (E-NTPDase1)/CD39, an ecto-ATPase. Because ATP is known to modulate neurotransmitter release at prejunctional sites, we questioned whether this action may be ultimately controlled by the expression of E-NTPDase1/CD39 at sympathetic nerve terminals. Accordingly, we silenced E-NTPDase1/CD39 expression in nerve growth factor-differentiated PC12 cells, a cellular model of sympathetic neuron, in which dopamine is the predominant catecholamine. We report that E-NTPDase1/CD39 deletion markedly increases depolarization-induced exocytosis of ATP and dopamine and increases ATP-induced dopamine release. Moreover, overexpression of E-NTPDase1/CD39 resulted in enhanced removal of exogenous ATP, a marked decrease in exocytosis of ATP and dopamine, and a large decrease in ATP-induced dopamine release. Administration of a recombinant form of E-NTPDase1/CD39 reproduced the effects of E-NTPDase1/CD39 overexpression. Exposure of PC12 cells to simulated ischemia elicited a release of ATP and dopamine that was markedly increased in E-NTPDase1/CD39-silenced cells and decreased in E-NTPDase1/CD39-overexpressing cells. Therefore, transmitter ATP acts in an autocrine manner to promote its own release and that of dopamine, an action that is controlled by the level of E-NTPDase1/CD39 expression. Because ATP availability greatly increases in myocardial ischemia, recombinant E-NTPDase1/CD39 therapeutically used may offer a novel approach to reduce cardiac dysfunctions caused by excessive catecholamine release.
authors.affiliation: Department of Pharmacology, Weill Cornell Medical College, 1300 York Ave., New York, NY 10065-4896, USA.
authors.forename: Federico
authors.initials: F
authors.lastname: Corti
authors.forename: Kim E
authors.initials: KE
authors.lastname: Olson
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Marcus
authors.forename: Roberto
authors.initials: R
authors.lastname: Levi
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis* / Q000235:genetics; D001081:Apyrase / Q000096:biosynthesis* / Q000235:genetics; D015153:Blotting, Western; D017931:DNA Primers; D004298:Dopamine / Q000378:metabolism; D005089:Exocytosis / Q000235:genetics / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D020868:Gene Silencing; D007511:Ischemia / Q000378:metabolism; D009414:Nerve Growth Factors / Q000494:pharmacology; D009474:Neurons / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D016716:PC12 Cells; D011188:Potassium / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D058469:Receptors, Purinergic P2X / Q000187:drug effects / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013564:Sympathetic Nervous System / Q000166:cytology / Q000378:metabolism*
chemical_list: D015703:Antigens, CD; D017931:DNA Primers; D009414:Nerve Growth Factors; D018377:Neurotransmitter Agents; D034741:RNA, Small Interfering; D058469:Receptors, Purinergic P2X; D000255:Adenosine Triphosphate; D001081:Apyrase; C067869:CD39 antigen; D011188:Potassium; D004298:Dopamine; D009638:Norepinephrine