title: More than one way to toy with ChAT and VAChT.
abstract: Expression of choline acetyltransferase (ChAT) and of the vesicular acetylcholine transporter (VAChT) is required for the acquisition and the maintenance of the cholinergic phenotype. The ChAT and VAChT genes have been demonstrated to share a common gene locus and this suggests a coordinate regulation of their expression. In the present work, we examined the effects of several differentiating treatments on the modulation of ChAT and VAChT expression at the mRNA and protein levels in growing and differentiating NG108-15 cells. In cells grown in the presence of serum, all the agents tested-retinoic acid, dexamethasone and dibutyrylcyclicAMP (dbcAMP)-induced an increase of ChAT and VAChT mRNA levels but with different efficacy. Treatment with dbcAMP plus dexamethasone resulted in the largest increase of VAChT mRNA amount while retinoic acid mostly enhanced ChAT mRNA level. However, while ChAT activity was increased by all agents, no change in the VAChT protein level was detected. In cells differentiated by serum deprivation, only retinoic acid was effective in inducing an increase of VAChT and ChAT mRNA and ChAT activity, while we observed a downregulation by dbcAMP and dexamethasone. Treatment with the antimitotic agent cytosine arabinoside led to an increase of ChAT activity which was further largely enhanced by the addition of dbcAMP plus dexamethasone, but to only a slight change in VAChT activity. We further showed that complex glycosylation processes which might play a role in targeting and/or stability of the membrane protein VAChT are deficient in these cells. Indeed, in transient transfection assays with the reporter soluble enzyme luciferase placed under regulatory and promoter regions of the VAChT gene, we observed a modulation of luciferase expression by differentiating agents. These data illustrate the complexity of the processes which participate to the expression of the ChAT and VAChT genes, both at the transcriptional and posttranslational levels.
authors.affiliation: Laboratoire de Neurobiologie Cellulaire et Moléculaire, CNRS, 91198 Gif-sur-Yvette, Cedex, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Castell
authors.forename: Marie Françoise
authors.initials: MF
authors.lastname: Diebler
authors.forename: Monique
authors.initials: M
authors.lastname: Tomasi
authors.forename: Claire
authors.initials: C
authors.lastname: Bigari
authors.forename: Stéphanie
authors.initials: S
authors.lastname: De Gois
authors.forename: Sylvie
authors.initials: S
authors.lastname: Berrard
authors.forename: Jacques
authors.initials: J
authors.lastname: Mallet
authors.forename: Maurice
authors.initials: M
authors.lastname: Israël
authors.forename: Vladimír
authors.initials: V
authors.lastname: Dolezal
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D015415:Biomarkers; D003994:Bucladesine / Q000494:pharmacology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000502:physiology; D002460:Cell Line / Q000166:cytology; D002795:Choline O-Acetyltransferase / Q000235:genetics / Q000378:metabolism*; D016895:Culture Media, Serum-Free; D003561:Cytarabine / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D004338:Drug Combinations; D005938:Glucocorticoids / Q000494:pharmacology; D006031:Glycosylation; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D009474:Neurons / Q000166:cytology; D011493:Protein Kinase C / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology; D050494:Vesicular Acetylcholine Transport Proteins; D033921:Vesicular Transport Proteins
chemical_list: D000970:Antineoplastic Agents; D015415:Biomarkers; D002352:Carrier Proteins; D016895:Culture Media, Serum-Free; D004338:Drug Combinations; D005938:Glucocorticoids; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D012333:RNA, Messenger; D050494:Vesicular Acetylcholine Transport Proteins; D033921:Vesicular Transport Proteins; D003561:Cytarabine; D014212:Tretinoin; D003994:Bucladesine; D003907:Dexamethasone; D002795:Choline O-Acetyltransferase; D011493:Protein Kinase C