title: cAMP acts on exchange protein activated by cAMP/cAMP-regulated guanine nucleotide exchange protein to regulate transmitter release at the crayfish neuromuscular junction.
abstract: Glutamatergic synapses are highly modifiable, suiting them for key roles in processes such as learning and memory. At crayfish glutamatergic neuromuscular junctions, hyperpolarization and cyclic nucleotide-activated (HCN) ion channels mediate hormonal modulation of glutamatergic synapses and a form activity-dependent long-term facilitation (LTF) of synaptic transmission. Here, we show that a new target for cAMP, exchange protein activated by cAMP (Epac) or cAMP-regulated guanine nucleotide exchange protein, is involved in the hormonal enhancement of synaptic transmission by serotonin. Induction of LTF "tags" synapses, rendering them responsive to cAMP in an HCN-independent manner. Epac also mediates the enhancement of tagged synapses. Thus, the cAMP-dependent enhancement of transmission is mediated by two separate pathways, neither of which involves protein kinase A.
authors.affiliation: Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, California 9472, USA.
authors.forename: Ning
authors.initials: N
authors.lastname: Zhong
authors.forename: Robert S
authors.initials: RS
authors.lastname: Zucker
mesh_terms: D000818:Animals; D003400:Astacoidea; D020126:Brefeldin A / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000502:physiology*; D020662:Guanine Nucleotide Exchange Factors / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology*; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology; D000077213:Lamotrigine; D009469:Neuromuscular Junction / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D014227:Triazines / Q000494:pharmacology
chemical_list: C473217:8-(4-chloro-phenylthio)-2'-O-methyladenosine-3'-5'-cyclic monophosphate; D020662:Guanine Nucleotide Exchange Factors; D007473:Ion Channels; D014227:Triazines; D005576:Colforsin; D020126:Brefeldin A; D000242:Cyclic AMP; D000077213:Lamotrigine