Differential regulation of neuronal nicotinic ACh receptor subunit genes in cultured neonatal rat sympathetic neurons: specific induction of alpha 7 by membrane depolarization through a Ca2+/calmodulin-dependent kinase pathway.

TitleDifferential regulation of neuronal nicotinic ACh receptor subunit genes in cultured neonatal rat sympathetic neurons: specific induction of alpha 7 by membrane depolarization through a Ca2+/calmodulin-dependent kinase pathway.
Publication TypeJournal Article
Year of Publication1995
AuthorsDe Koninck P, Cooper E
JournalJ Neurosci
Volume15
Issue12
Pagination7966-78
Date Published1995 Dec
ISSN0270-6474
Keywords1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine, Acetylcholine, Animals, Animals, Newborn, Bungarotoxins, Calcium, Calcium Channels, Calcium-Calmodulin-Dependent Protein Kinases, Cells, Cultured, Choline, Electrophysiology, Ganglia, Sympathetic, Gene Expression Regulation, Isoquinolines, Neurons, Piperazines, Protein Kinases, Rats, Rats, Sprague-Dawley, Receptors, Nicotinic, RNA, Messenger, Transcription, Genetic
Abstract

We have examined the regulation of neuronal nicotinic ACh receptor (nAChR) genes and ACh-evoked currents by neonatal rat sympathetic neurons developing in culture. These neurons contain 5 nAChR transcripts: alpha 3, alpha 5, alpha 7, beta 2, and beta 4. When developing in culture, the neurons express 4 of these transcripts, alpha 3, alpha 5, beta 2, and beta 4, at levels similar to those in neurons developing in vivo: alpha 3 mRNA levels increase two- to threefold over the first week, whereas the levels for alpha 5, beta 2, and beta 4 remain essentially constant. In contrast, alpha 7 mRNA levels drop by 60-75% within the first 48 hr and remain low. We show that during the first week, the ACh-evoked current densities on these cultured neurons increase twofold and correlate well with the increase in alpha 3 mRNA levels. Depolarizing the neurons with 40 mM KCl for 1-2 d upregulates the alpha 7 gene; this specific change in alpha 7 mRNA level correlates with an increase in alpha-bungarotoxin (alpha-BTX) binding on the surface of the neurons. Depolarization has little effect on the expression of the other four transcripts, or on the magnitude or kinetics of the ACh-evoked currents. Furthermore, activators or inhibitors of protein kinase A (PKA), protein kinase C (PKC), or tyrosine kinase do not affect nAChR transcript levels in these cultured neurons. The effect of membrane depolarization on alpha 7 expression is a result of Ca2+ influx through L-type Ca2+ channels, and we show that alpha 7 is upregulated through a Ca2+/calmodulin-dependent protein kinase (CaM kinase) pathway. The identification of CaM kinase as a link between activity and neurotransmitter receptor expression may indicate a novel mechanism that underlies some forms of synaptic plasticity.

Alternate JournalJ. Neurosci.
PubMed ID8613734

Funding

Our research endeavors are made possible by the following agencies:

Canadian Institutes of Health Research - Instituts de recherche en santé du Canada Fonds de recherche du Québec – Nature et technologies (FRQNT)Fonds de la recherche en santé du Québec NARSAD Natural Sciences and Engineering Research Council of Canada (NSERC) - Conseil de recherche en sciences naturelles et en génie du Canada (CRSNG)innovation.caHuman Frontier Science Program