1 Nicotinic drug treatment can affect the expression of neuronal nicotinic acetylcholine receptors (nAChR) both in vivo and in vitro through molecular mechanisms not fully understood. The present study investigated the effect of the novel cytisine dimer 1,2-bisN-cytisinylethane (CC4) on nAChR natively expressed by SH-SY5Y neuroblastoma cells in culture. 2 CC4 lacked the agonist properties of cytisine and was a potent antagonist (IC 50 = 220 nM) on nAChRs. Chronic treatment of SH-SY5Y cells with 1 mM CC4 for 48 h increased the expression of 3H-epibatidine ( 3H-Epi; 3-4-fold) or 125I-α-bungarotoxin ( 125I-αBgtx; 1.2-fold) sensitive receptors present on the cell membrane and in the intracellular pool. Comparable data were obtained with nicotine or cytisine, but not with carbamylcholine, d-tubocurarine, di-hydro-β-erythroidine or hexametonium. 3 Immunoprecipitation and immunopurification studies showed that the increase in 3H-Epi-binding receptors was due to the enhanced expression of α3β2 and α3β2β4 subtypes without changes in subunit mRNA transcription or receptor half-life. The upregulation was not dependent on agonist/antagonist properties of the drugs, and did not concern muscarinic or serotonin receptors. 4 Whole-cell patch clamp analysis of CC4-treated cells demonstrated larger nicotine-evoked inward currents with augmented sensitivity to the blockers α-conotoxin MII or methyllycaconitine. 5 In conclusion, chronic treatment with CC4 increased the number of nAChRs containing β2 and α7 subunits on the plasma membrane, where they were functionally active. In the case of β2-containing receptors, we propose that CC4, by binding to intracellular receptors, triggered a conformational reorganisation of intracellular subunits that stimulated preferential assembly and membrane-directed trafficking of β2-containing receptor subtypes. © 2005 Nature Publishing Group. All rights reserved.
Long-term exposure to the new nicotinic antagonist 1,2-bisN-cytisinylethane upregulates nicotinic receptor subtypes of SH-SY5Y human neuroblastoma cells / L., Riganti; C., Matteoni; DI ANGELANTONIO, Silvia; A., Nistri; A., Gaimarri; F., Sparatore; C., Canu Boido; F., Clementi; C., Gotti. - In: BRITISH JOURNAL OF PHARMACOLOGY. - ISSN 0007-1188. - 146:8(2005), pp. 1096-1109. [10.1038/sj.bjp.0706434]
Long-term exposure to the new nicotinic antagonist 1,2-bisN-cytisinylethane upregulates nicotinic receptor subtypes of SH-SY5Y human neuroblastoma cells
DI ANGELANTONIO, SILVIA;
2005
Abstract
1 Nicotinic drug treatment can affect the expression of neuronal nicotinic acetylcholine receptors (nAChR) both in vivo and in vitro through molecular mechanisms not fully understood. The present study investigated the effect of the novel cytisine dimer 1,2-bisN-cytisinylethane (CC4) on nAChR natively expressed by SH-SY5Y neuroblastoma cells in culture. 2 CC4 lacked the agonist properties of cytisine and was a potent antagonist (IC 50 = 220 nM) on nAChRs. Chronic treatment of SH-SY5Y cells with 1 mM CC4 for 48 h increased the expression of 3H-epibatidine ( 3H-Epi; 3-4-fold) or 125I-α-bungarotoxin ( 125I-αBgtx; 1.2-fold) sensitive receptors present on the cell membrane and in the intracellular pool. Comparable data were obtained with nicotine or cytisine, but not with carbamylcholine, d-tubocurarine, di-hydro-β-erythroidine or hexametonium. 3 Immunoprecipitation and immunopurification studies showed that the increase in 3H-Epi-binding receptors was due to the enhanced expression of α3β2 and α3β2β4 subtypes without changes in subunit mRNA transcription or receptor half-life. The upregulation was not dependent on agonist/antagonist properties of the drugs, and did not concern muscarinic or serotonin receptors. 4 Whole-cell patch clamp analysis of CC4-treated cells demonstrated larger nicotine-evoked inward currents with augmented sensitivity to the blockers α-conotoxin MII or methyllycaconitine. 5 In conclusion, chronic treatment with CC4 increased the number of nAChRs containing β2 and α7 subunits on the plasma membrane, where they were functionally active. In the case of β2-containing receptors, we propose that CC4, by binding to intracellular receptors, triggered a conformational reorganisation of intracellular subunits that stimulated preferential assembly and membrane-directed trafficking of β2-containing receptor subtypes. © 2005 Nature Publishing Group. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
