title: Balancing Arc synthesis, mRNA decay, and proteasomal degradation: maximal protein expression triggered by rapid eye movement sleep-like bursts of muscarinic cholinergic receptor stimulation.
abstract: Cholinergic signaling induces Arc/Arg3.1, an immediate early gene crucial for synaptic plasticity. However, the molecular mechanisms that dictate Arc mRNA and protein dynamics during and after cholinergic epochs are little understood. Using human SH-SY5Y neuroblastoma cells, we show that muscarinic cholinergic receptor (mAchR) stimulation triggers Arc synthesis, whereas translation-dependent RNA decay and proteasomal degradation strictly limit the amount and duration of Arc expression. Chronic application of the mAchR agonist, carbachol (Cch), induces Arc transcription via ERK signaling and release of calcium from IP(3)-sensitive stores. Arc translation requires ERK activation, but not changes in intracellular calcium. Proteasomal degradation of Arc (half-life ∼37 min) was enhanced by thapsigargin, an inhibitor of the endoplasmic calcium-ATPase pump. Similar mechanisms of Arc protein regulation were observed in cultured rat hippocampal slices. Functionally, we studied the impact of cholinergic epoch duration and temporal pattern on Arc protein expression. Acute Cch treatment (as short as 2 min) induces transient, moderate Arc expression, whereas continuous treatment of more than 30 min induces maximal expression, followed by rapid decline. Cholinergic activity associated with rapid eye movement sleep may function to facilitate long term synaptic plasticity and memory. Employing a paradigm designed to mimic intermittent rapid eye movement sleep epochs, we show that application of Cch in a series of short bursts generates persistent and maximal Arc protein expression. The results demonstrate dynamic, multifaceted control of Arc synthesis during mAchR signaling, and implicate cholinergic epoch duration and repetition as critical determinants of Arc expression and function in synaptic plasticity and behavior.
authors.affiliation: Department of Biomedicine, KG Jebsen Centre for Research on Neuropsychiatric Disorders, University of Bergen, Jonas Lies vei 91, N-5009 Bergen, Norway.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Soulé
authors.forename: Maria
authors.initials: M
authors.lastname: Alme
authors.forename: Craig
authors.initials: C
authors.lastname: Myrum
authors.forename: Manja
authors.initials: M
authors.lastname: Schubert
authors.forename: Tambudzai
authors.initials: T
authors.lastname: Kanhema
authors.forename: Clive R
authors.initials: CR
authors.lastname: Bramham
mesh_terms: D000818:Animals; D002217:Carbachol / Q000378:metabolism / Q000494:pharmacology; D002460:Cell Line; D045744:Cell Line, Tumor; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D006624:Hippocampus / Q000378:metabolism; D006801:Humans; D008568:Memory; D008954:Models, Biological; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009473:Neuronal Plasticity; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011950:Receptors, Cholinergic / Q000378:metabolism; D015398:Signal Transduction; D012890:Sleep; D012895:Sleep, REM; D013569:Synapses / Q000378:metabolism*; D013997:Time Factors
chemical_list: D003598:Cytoskeletal Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D011950:Receptors, Cholinergic; C092069:activity regulated cytoskeletal-associated protein; D002217:Carbachol; D046988:Proteasome Endopeptidase Complex