title: LINE-1 ORF1 protein localizes in stress granules with other RNA-binding proteins, including components of RNA interference RNA-induced silencing complex.
abstract: LINE-1 retrotransposons constitute one-fifth of human DNA and have helped shape our genome. A full-length L1 encodes a 40-kDa RNA-binding protein (ORF1p) and a 150-kDa protein (ORF2p) with endonuclease and reverse transcriptase activities. ORF1p is distinctive in forming large cytoplasmic foci, which we identified as cytoplasmic stress granules. A phylogenetically conserved central region of the protein is critical for wild-type localization and retrotransposition. Yeast two-hybrid screens revealed several RNA-binding proteins that coimmunoprecipitate with ORF1p and colocalize with ORF1p in foci. Two of these proteins, YB-1 and hnRNPA1, were previously reported in stress granules. We identified additional proteins associated with stress granules, including DNA-binding protein A, 9G8, and plasminogen activator inhibitor RNA-binding protein 1 (PAI-RBP1). PAI-RBP1 is a homolog of VIG, a part of the Drosophila melanogaster RNA-induced silencing complex (RISC). Other RISC components, including Ago2 and FMRP, also colocalize with PAI-RBP1 and ORF1p. We suggest that targeting ORF1p, and possibly the L1 RNP, to stress granules is a mechanism for controlling retrotransposition and its associated genetic and cellular damage.
authors.affiliation: Dept. of Genetics, University of Pennsylvania School of Medicine, Rm. 515 CRB, 415 Curie Blvd., Philadelphia, PA 19104, USA. jgoodier@mail.med.upenn.edu
authors.forename: John L
authors.initials: JL
authors.lastname: Goodier
authors.forename: Lili
authors.initials: L
authors.lastname: Zhang
authors.forename: Melissa R
authors.initials: MR
authors.lastname: Vetter
authors.forename: Haig H
authors.initials: HH
authors.lastname: Kazazian
mesh_terms: D002460:Cell Line; D045744:Cell Line, Tumor; D003594:Cytoplasmic Granules / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000166:cytology; D020084:Long Interspersed Nucleotide Elements / Q000235:genetics*; D008970:Molecular Weight; D016366:Open Reading Frames / Q000235:genetics*; D012516:Osteosarcoma / Q000473:pathology; D011233:Precipitin Tests; D012313:RNA / Q000378:metabolism*; D034622:RNA Interference; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D034743:RNA-Induced Silencing Complex / Q000235:genetics; D018626:Retroelements; D020798:Two-Hybrid System Techniques
chemical_list: D016601:RNA-Binding Proteins; D034743:RNA-Induced Silencing Complex; D018626:Retroelements; D049452:Green Fluorescent Proteins; D012313:RNA