title: The miRNA pathway controls rapid changes in activity-dependent synaptic structure at the Drosophila melanogaster neuromuscular junction.
abstract: It is widely accepted that long-term changes in synapse structure and function are mediated by rapid activity-dependent gene transcription and new protein synthesis. A growing amount of evidence suggests that the microRNA (miRNA) pathway plays an important role in coordinating these processes. Despite recent advances in this field, there remains a critical need to identify specific activity-regulated miRNAs as well as their key messenger RNA (mRNA) targets. To address these questions, we used the larval Drosophila melanogaster neuromuscular junction (NMJ) as a model synapse in which to identify novel miRNA-mediated mechanisms that control activity-dependent synaptic growth. First, we developed a screen to identify miRNAs differentially regulated in the larval CNS following spaced synaptic stimulation. Surprisingly, we identified five miRNAs (miRs-1, -8, -289, -314, and -958) that were significantly downregulated by activity. Neuronal misexpression of three miRNAs (miRs-8, -289, and -958) suppressed activity-dependent synaptic growth suggesting that these miRNAs control the translation of biologically relevant target mRNAs. Functional annotation cluster analysis revealed that putative targets of miRs-8 and -289 are significantly enriched in clusters involved in the control of neuronal processes including axon development, pathfinding, and growth. In support of this, miR-8 regulated the expression of a wingless 3'UTR (wg 3' untranslated region) reporter in vitro. Wg is an important presynaptic regulatory protein required for activity-dependent axon terminal growth at the fly NMJ. In conclusion, our results are consistent with a model where key activity-regulated miRNAs are required to coordinate the expression of genes involved in activity-dependent synaptogenesis.
authors.affiliation: Department of Biological Sciences and Eleanor Roosevelt Institute, University of Denver, Denver, Colorado, United States of America.
authors.forename: Katherine R
authors.initials: KR
authors.lastname: Nesler
authors.forename: Robert I
authors.initials: RI
authors.lastname: Sand
authors.forename: Breanna A
authors.initials: BA
authors.lastname: Symmes
authors.forename: Sarala J
authors.initials: SJ
authors.lastname: Pradhan
authors.forename: Nathan G
authors.initials: NG
authors.lastname: Boin
authors.forename: Anna E
authors.initials: AE
authors.lastname: Laun
authors.forename: Scott A
authors.initials: SA
authors.lastname: Barbee
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D063990:Gene Ontology; D007814:Larva / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D035683:MicroRNAs / Q000235:genetics*; D009046:Motor Neurons / Q000378:metabolism; D009469:Neuromuscular Junction / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics; D013569:Synapses / Q000235:genetics* / Q000378:metabolism / Q000502:physiology
chemical_list: C574927:MIRN1 microRNA, Drosophila; C586148:MIRN289 microRNA, Drosophila; C586149:MIRN314 microRNA, Drosophila; C586150:MIRN958 microRNA, human; D035683:MicroRNAs; D012333:RNA, Messenger; C526630:MIRN8 microRNA, Drosophila