title: Translational regulation of acetylcholinesterase by the RNA-binding protein Pumilio-2 at the neuromuscular synapse.
abstract: Acetylcholinesterase (AChE) is highly expressed at sites of nerve-muscle contact where it is regulated at both the transcriptional and post-transcriptional levels. Our understanding of the molecular mechanisms underlying its regulation is incomplete, but they appear to involve both translational and post-translational events as well. Here, we show that Pumilio-2 (PUM2), an RNA binding translational repressor, is highly localized at the neuromuscular junction where AChE mRNA concentrates. Immunoprecipitation of muscle cell extracts with a PUM2 specific antibody precipitated AChE mRNA, suggesting that PUM2 binds to the AChE transcripts in a complex. Gel shift assays using a bacterially expressed PUM2 RNA binding domain showed specific binding using wild type AChE 3'-UTR RNA segment that was abrogated by mutation of the consensus recognition site. Transfecting skeletal muscle cells with shRNAs specific for PUM2 up-regulated AChE expression, whereas overexpression of PUM2 decreased AChE activity. We conclude that PUM2 binds to AChE mRNA and regulates AChE expression translationally at the neuromuscular synapse. Finally, we found that PUM2 is regulated by the motor nerve suggesting a trans-synaptic mechanism for locally regulating translation of specific proteins involved in modulating synaptic transmission, analogous to CNS synapses.
authors.affiliation: Department of Cell Biology and Anatomy, University of Miami Miller School of Medicine, Miami, Florida 33136, USA.
authors.forename: Emilio
authors.initials: E
authors.lastname: Marrero
authors.forename: Susana G
authors.initials: SG
authors.lastname: Rossi
authors.forename: Andrew
authors.initials: A
authors.lastname: Darr
authors.forename: Pantelis
authors.initials: P
authors.lastname: Tsoulfas
authors.forename: Richard L
authors.initials: RL
authors.lastname: Rotundo
mesh_terms: D020413:3' Untranslated Regions / Q000502:physiology*; D000110:Acetylcholinesterase / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D051379:Mice; D018482:Muscle, Skeletal / Q000378:metabolism*; D009469:Neuromuscular Junction / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis / Q000502:physiology*; D011784:Quail; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology
chemical_list: D020413:3' Untranslated Regions; C445087:Pum2 protein, mouse; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D000110:Acetylcholinesterase