title: MicroRNA regulation of the synaptic plasticity-related gene Arc.
abstract: Expression of activity-regulated cytoskeleton associated protein (Arc) is crucial for diverse types of experience-dependent synaptic plasticity and long-term memory in mammals. However, the mechanisms governing Arc-specific translation are little understood. Here, we asked whether Arc translation is regulated by microRNAs. Bioinformatic analysis predicted numerous candidate miRNA binding sites within the Arc 3'-untranslated region (UTR). Transfection of the corresponding microRNAs in human embryonic kidney cells inhibited expression of an Arc 3'UTR luciferase reporter from between 10 to 70% across 16 microRNAs tested. Point mutation and deletion of the microRNA-binding seed-region for miR-34a, miR-326, and miR-19a partially or fully rescued reporter expression. In addition, expression of specific microRNA pairs synergistically modulated Arc reporter expression. In primary rat hippocampal neuronal cultures, ectopic expression of miR-34a, miR-193a, or miR-326, downregulated endogenous Arc protein expression in response to BDNF treatment. Conversely, treatment of neurons with cell-penetrating, peptide nucleic acid (PNA) inhibitors of miR-326 enhanced Arc mRNA expression. BDNF dramatically upregulated neuronal expression of Arc mRNA and miR-132, a known BDNF-induced miRNA, without affecting expression of Arc-targeting miRNAs. Developmentally, miR-132 was upregulated at day 10 in vitro whereas Arc-targeting miRNAs were downregulated. In the adult brain, LTP induction in the dentate gyrus triggered massive upregulation of Arc and upregulation of miR-132 without affecting levels of mature Arc-targeting miRNAs. Turning to examine miRNA localization, qPCR analysis of dentate gyrus synaptoneurosome and total lysates fractions demonstrated synaptic enrichment relative to small nucleolar RNA. In conclusion, we find that Arc is regulated by multiple miRNAs and modulated by specific miRNA pairs in vitro. Furthermore, we show that, in contrast to miR-132, steady state levels of Arc-targeting miRNAs do not change in response to activity-dependent expression of Arc in hippocampal neurons in vitro or during LTP in vivo.
authors: Department of Biomedicine and K.G. Jebsen Centre for Research on Neuropsychiatric Disorders, University of Bergen, Bergen, Norway.
authors: Karin
authors: K
authors: Wibrand
authors: Balagopal
authors: B
authors: Pai
authors: Taweeporn
authors: T
authors: Siripornmongcolchai
authors: Margarethe
authors: M
authors: Bittins
authors: Birgitte
authors: B
authors: Berentsen
authors: May Lillian
authors: ML
authors: Ofte
authors: Arwed
authors: A
authors: Weigel
authors: Kai Ove
authors: KO
authors: Skaftnesmo
authors: Clive R
authors: CR
authors: Bramham
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics* / Q000378:metabolism; D003712:Dendrites / Q000378:metabolism; D057809:HEK293 Cells; D006624:Hippocampus / Q000166:cytology / Q000502:physiology; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism; D017774:Long-Term Potentiation / Q000235:genetics; D008297:Male; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D009473:Neuronal Plasticity / Q000235:genetics*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000235:genetics; D017354:Point Mutation; D021381:Protein Transport; D051381:Rats; D017207:Rats, Sprague-Dawley; D017384:Sequence Deletion; D013569:Synapses / Q000378:metabolism*; D059467:Transcriptome; D015854:Up-Regulation / Q000235:genetics
chemical_list: D020413:3' Untranslated Regions; D019208:Brain-Derived Neurotrophic Factor; D003598:Cytoskeletal Proteins; D035683:MicroRNAs; D009419:Nerve Tissue Proteins; D016376:Oligonucleotides, Antisense; C092069:activity regulated cytoskeletal-associated protein