Muscarinic acetylcholine receptors induce neurite outgrowth and activate the synapsin I gene promoter in neuroblastoma clones.
The possible role of acetylcholine as a modulator of neuronal differentiation has been tested using a neuroblastoma cell line (N18TG2), which does not synthesize any neurotransmitter. Acetylcholine synthesis has been activated in this line by transfection with a construct containing a choline acetyltransferase (ChAT) cDNA; ChAT-positive clones share a higher ability to grow fibers and an activation of synapsin I expression compared to the parental cells. Atropine, a muscarinic antagonist, abolishes the higher ability to grow fibers of ChAT-positive transfected clones, and the cholinergic agonist carbachol induces higher neurite outgrowth in the parental line. In transient transfections of ChAT-positive clones, the expression of a reporter gene under the control of synapsin I promoter is considerably reduced by atropine, while it is not modified by carbachol; in contrast, in the parental cells, which do not synthesize acetylcholine, the reporter gene expression is induced by carbachol and this effect is abolished by atropine. The data presented provide evidence for the existence of a direct modulation of fiber outgrowth and synapsin I expression by muscarinic receptor activation, which may be related to early growth response gene-1 (EGR-1) levels.
Dipartimento di Biologia Cellulare e dello Sviluppo, Università La Sapienza, Piazzale A. Moro 5, 00185, Rome, Italy.
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De Jaco
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Augusti-Tocco
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Biagioni
D000109:Acetylcholine / Q000502:physiology; D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation / Q000502:physiology; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D051766:Early Growth Response Protein 1; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D017874:Immediate-Early Proteins; D051379:Mice; D009116:Muscarine / Q000378:metabolism; D018721:Muscarinic Agonists / Q000494:pharmacology; D009412:Nerve Fibers / Q000502:physiology; D016501:Neurites / Q000502:physiology*; D009474:Neurons / Q000166:cytology; D011401:Promoter Regions, Genetic / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000502:physiology*; D016704:Synapsins / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; D017874:Immediate-Early Proteins; D018721:Muscarinic Agonists; D011976:Receptors, Muscarinic; D016704:Synapsins; D014157:Transcription Factors; D009116:Muscarine; D002795:Choline O-Acetyltransferase; D000109:Acetylcholine