title: Characterization of an RNA granule from developing brain.
abstract: In brain, mRNAs are transported from the cell body to the processes, allowing for local protein translation at sites distant from the nucleus. Using subcellular fractionation, we isolated a fraction from rat embryonic day 18 brains enriched for structures that resemble amorphous collections of ribosomes. This fraction was enriched for the mRNA encoding beta-actin, an mRNA that is transported in dendrites and axons of developing neurons. Abundant protein components of this fraction, determined by tandem mass spectrometry, include ribosomal proteins, RNA-binding proteins, microtubule-associated proteins (including the motor protein dynein), and several proteins described only as potential open reading frames. The conjunction of RNA-binding proteins, transported mRNA, ribosomal machinery, and transporting motor proteins defines these structures as RNA granules. Expression of a subset of the identified proteins in cultured hippocampal neurons confirmed that proteins identified in the proteomics were present in neurites associated with ribosomes and mRNAs. Moreover many of the expressed proteins co-localized together. Time lapse video microscopy indicated that complexes containing one of these proteins, the DEAD box 3 helicase, migrated in dendrites of hippocampal neurons at the same speed as that reported for RNA granules. Although the speed of the granules was unchanged by activity or the neurotrophin brain-derived neurotrophic factor, brain-derived neurotrophic factor, but not activity, increased the proportion of moving granules. These studies define the isolation and composition of RNA granules expressed in developing brain.
authors.affiliation: Département de Biochimie, Université de Montréal, 2900 Edouard-Montpetit, Montreal, Quebec H3C3J7, Canada.
authors.forename: George
authors.initials: G
authors.lastname: Elvira
authors.forename: Sylwia
authors.initials: S
authors.lastname: Wasiak
authors.forename: Vanessa
authors.initials: V
authors.lastname: Blandford
authors.forename: Xin-Kang
authors.initials: XK
authors.lastname: Tong
authors.forename: Alexandre
authors.initials: A
authors.lastname: Serrano
authors.forename: Xiaotang
authors.initials: X
authors.lastname: Fan
authors.forename: Maria
authors.initials: M
authors.lastname: del Rayo Sánchez-Carbente
authors.forename: Florence
authors.initials: F
authors.lastname: Servant
authors.forename: Alexander W
authors.initials: AW
authors.lastname: Bell
authors.forename: Daniel
authors.initials: D
authors.lastname: Boismenu
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Lacaille
authors.forename: Peter S
authors.initials: PS
authors.lastname: McPherson
authors.forename: Luc
authors.initials: L
authors.lastname: DesGroseillers
authors.forename: Wayne S
authors.initials: WS
authors.lastname: Sossin
mesh_terms: D000199:Actins / Q000235:genetics; D000818:Animals; D001921:Brain / Q000196:embryology / Q000378:metabolism*; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism; D007150:Immunohistochemistry; D016253:Microscopy, Immunoelectron; D016501:Neurites / Q000378:metabolism; D012333:RNA, Messenger / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012270:Ribosomes / Q000378:metabolism
chemical_list: D000199:Actins; D019208:Brain-Derived Neurotrophic Factor; D012333:RNA, Messenger