title: Reciprocal interaction of serotonin and neuronal activity in regulation of cAMP-responsive element-dependent gene expression.
abstract: Neuronal activity triggers multiple signal transduction pathways and potently regulates gene expression in the brain. In the central nervous system, in addition to the synaptic input, neurons are subject to neuromodulatory influences that can activate the same signaling elements. However, the principles that govern the interaction of neuromodulators and neuronal activity in the regulation of gene expression are unclear. Here, we examine how serotonergic neuromodulation interacts with neuronal activity in the regulation of gene expression in hippocampal neurons. We show that cAMP-response element binding protein (CREB) phosphorylation and gene expression were stimulated by serotonin (5-HT) in the absence of neuronal activity. In contrast, in the presence of neuronal activity, 5-HT inhibited gene expression down to the baseline, although neuronal activity alone was sufficient to maximally activate gene expression. The ability of 5-HT to stimulate CREB phosphorylation in the absence of neuronal activity or inhibit CREB phosphorylation during activity was due to a tight balance between protein kinases and phosphatases that could be physiologically tilted by different serotonergic receptors or exogenously influenced by phosphatase and kinase inhibitors. Taken together, these results suggest a reciprocal inhibitory interaction between neuronal activity and 5-HT in the regulation of cAMP response element-dependent gene expression in hippocampal neurons.
authors.affiliation: Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, 75390-9070, USA.
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Mahgoub
authors.forename: Yildirim
authors.initials: Y
authors.lastname: Sara
authors.forename: Ege T
authors.initials: ET
authors.lastname: Kavalali
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Monteggia
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D050882:CREB-Binding Protein / Q000378:metabolism; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects*; D006624:Hippocampus / Q000166:cytology; D007150:Immunohistochemistry; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D013004:Somatostatin / Q000096:biosynthesis; D013997:Time Factors
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D016760:Proto-Oncogene Proteins c-fos; D012701:Serotonin; D013004:Somatostatin; D050882:CREB-Binding Protein