title: A HuD-ZBP1 ribonucleoprotein complex localizes GAP-43 mRNA into axons through its 3' untranslated region AU-rich regulatory element.
abstract: Localized translation of axonal mRNAs contributes to developmental and regenerative axon growth. Although untranslated regions (UTRs) of many different axonal mRNAs appear to drive their localization, there has been no consensus RNA structure responsible for this localization. We recently showed that limited expression of ZBP1 protein restricts axonal localization of both β-actin and GAP-43 mRNAs. β-actin 3'UTR has a defined element for interaction with ZBP1, but GAP-43 mRNA shows no homology to this RNA sequence. Here, we show that an AU-rich regulatory element (ARE) in GAP-43's 3'UTR is necessary and sufficient for its axonal localization. Axonal GAP-43 mRNA levels increase after in vivo injury, and GAP-43 mRNA shows an increased half-life in regenerating axons. GAP-43 mRNA interacts with both HuD and ZBP1, and HuD and ZBP1 co-immunoprecipitate in an RNA-dependent fashion. Reporter mRNA with the GAP-43 ARE competes with endogenous β-actin mRNA for axonal localization and decreases axon length and branching similar to the β-actin 3'UTR competing with endogenous GAP-43 mRNA. Conversely, over-expressing GAP-43 coding sequence with its 3'UTR ARE increases axonal elongation and this effect is lost when just the ARE is deleted from GAP-43's 3'UTR. We have recently found that over-expression of GAP-43 using an axonally targeted construct with the 3'UTRs of GAP-43 promoted elongating growth of axons, while restricting the mRNA to the cell body with the 3'UTR of γ-actin had minimal effect on axon length. In this study, we show that the ARE in GAP-43's 3'UTR is responsible for localization of GAP-43 mRNA into axons and is sufficient for GAP-43 protein's role in elongating axonal growth.
authors.affiliation: Nemours Biomedical Research, Alfred I. duPont Hosp. for Children, Wilmington, Delaware, USA. yoo@medsci.udel.edu
authors.forename: Soonmoon
authors.initials: S
authors.lastname: Yoo
authors.forename: Hak H
authors.initials: HH
authors.lastname: Kim
authors.forename: Paul
authors.initials: P
authors.lastname: Kim
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Donnelly
authors.forename: Ashley L
authors.initials: AL
authors.lastname: Kalinski
authors.forename: Deepika
authors.initials: D
authors.lastname: Vuppalanchi
authors.forename: Michael
authors.initials: M
authors.lastname: Park
authors.forename: Seung J
authors.initials: SJ
authors.lastname: Lee
authors.forename: Tanuja T
authors.initials: TT
authors.lastname: Merianda
authors.forename: Nora I
authors.initials: NI
authors.lastname: Perrone-Bizzozero
authors.forename: Jeffery L
authors.initials: JL
authors.lastname: Twiss
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics*; D063307:AU Rich Elements / Q000235:genetics*; D000199:Actins / Q000096:biosynthesis / Q000235:genetics; D000818:Animals; D001369:Axons / Q000378:metabolism* / Q000648:ultrastructure; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis / Q000302:isolation & purification; D036681:Fluorescence Recovery After Photobleaching; D019922:GAP-43 Protein / Q000235:genetics* / Q000378:metabolism*; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism; D047468:Immunoprecipitation; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D012313:RNA / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D050436:Regulatory Elements, Transcriptional; D012584:Sciatic Nerve / Q000378:metabolism
chemical_list: D020413:3' Untranslated Regions; D000199:Actins; D019922:GAP-43 Protein; C498634:Igf2bp1 protein, rat; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012313:RNA; D004247:DNA
keywords: GAP-43; HuD; RNA-immunoprecipitation; ZBP1; axon regeneration; mRNA transport