55 research outputs found

    CLIP-Seq analysis enables the design of protective ribosomal RNA bait oligonucleotides against C9ORF72 ALS/FTD poly-GR pathophysiology

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    Amyotrophic lateral sclerosis and frontotemporal dementia patients with a hexanucleotide repeat expansion in C9ORF72 (C9-HRE) accumulate poly-GR and poly-PR aggregates. The pathogenicity of these arginine-rich dipeptide repeats (R-DPRs) is thought to be driven by their propensity to bind low-complexity domains of multivalent proteins. However, the ability of R-DPRs to bind native RNA and the significance of this interaction remain unclear. Here, we used computational and experimental approaches to characterize the physicochemical properties of R-DPRs and their interaction with RNA. We find that poly-GR predominantly binds ribosomal RNA (rRNA) in cells and exhibits an interaction that is predicted to be energetically stronger than that for associated ribosomal proteins. Critically, modified rRNA “bait” oligonucleotides restore poly-GR–associated ribosomal deficits and ameliorate poly-GR toxicity in patient neurons and Drosophila models. Our work strengthens the hypothesis that ribosomal function is impaired by R-DPRs, highlights a role for direct rRNA binding in mediating ribosomal dysfunction, and presents a strategy for protecting against C9-HRE pathophysiological mechanisms.This work was supported by the U.S. National Institutes of Health (NIH) National Institute of Neurological Disorders and Stroke (NINDS) and National Institute of Aging (NIA) grant R01NS104219 (E.K.); NIH/NINDS grant R21NS107761 (E.K.); AFM-Telethon French Muscular Dystrophy Association Trampoline Grant #23648 (J.A.O.); AFM-Telethon postdoctoral fellowship (J.A.O.); Ramon y Cajal fellowships RYC2019-026980-I (J.A.O.) and RYC2021-033294-I (I.R.S.); Gipuzkoa Foru Aldundia 2019-FELL-000017-01 (I.R.S.); Maria de Maeztu Units of Excellence CEX2021-001159-M (J.A.O.) and MDM-2017-0720 (I.R.S.); NINDS grants R01NS097850 and R01NS131409 (J.K.I.); Department of Defense grants PR211919 and W81XWH2110131 (J.K.I.); John Douglas French Alzheimer’s Foundation (J.K.I.); Center for Regenerative Nanomedicine at the Simpson Querrey Institute (S.I.S. and T.D.C.); Intramural Research Program, NIH, National Cancer Institute (NCI), Center for Cancer Research (M.B. and S.L.W.); Les Turner ALS Foundation (E.K.); and New York Stem Cell Foundation (J.K.I. and E.K.).With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001159-M (J.A.O.)).Peer reviewe

    The Host RNAs in Retroviral Particles

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    As they assemble, retroviruses encapsidate both their genomic RNAs and several types of host RNA. Whereas limited amounts of messenger RNA (mRNA) are detectable within virion populations, the predominant classes of encapsidated host RNAs do not encode proteins, but instead include endogenous retroelements and several classes of non-coding RNA (ncRNA), some of which are packaged in significant molar excess to the viral genome. Surprisingly, although the most abundant host RNAs in retroviruses are also abundant in cells, unusual forms of these RNAs are packaged preferentially, suggesting that these RNAs are recruited early in their biogenesis: before associating with their cognate protein partners, and/or from transient or rare RNA populations. These RNAs’ packaging determinants differ from the viral genome’s, and several of the abundantly packaged host ncRNAs serve cells as the scaffolds of ribonucleoprotein particles. Because virion assembly is equally efficient whether or not genomic RNA is available, yet RNA appears critical to the structural integrity of retroviral particles, it seems possible that the selectively encapsidated host ncRNAs might play roles in assembly. Indeed, some host ncRNAs appear to act during replication, as some transfer RNA (tRNA) species may contribute to nuclear import of human immunodeficiency virus 1 (HIV-1) reverse transcription complexes, and other tRNA interactions with the viral Gag protein aid correct trafficking to plasma membrane assembly sites. However, despite high conservation of packaging for certain host RNAs, replication roles for most of these selectively encapsidated RNAs—if any—have remained elusive

    Two for the price of one: RNA modification enzymes as chaperones

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    The La protein functions redundantly with tRNA modification enzymes to ensure tRNA structural stability

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    Although the La protein stabilizes nascent pre-tRNAs from nucleases, influences the pathway of pre-tRNA maturation, and assists correct folding of certain pre-tRNAs, it is dispensable for growth in both budding and fission yeast. Here we show that the Saccharomyces cerevisiae La shares functional redundancy with both tRNA modification enzymes and other proteins that contact tRNAs during their biogenesis. La is important for growth in the presence of mutations in either the arginyl tRNA synthetase or the tRNA modification enzyme Trm1p. In addition, two pseudouridine synthases, PUS3 and PUS4, are important for growth in strains carrying a mutation in tRNA(Arg)(CCG) and are essential when La is deleted in these strains. Depletion of Pus3p results in accumulation of the aminoacylated mutant tRNA(Arg)(CCG) in nuclei, while depletion of Pus4p results in decreased stability of the mutant tRNA. Interestingly, the degradation of mutant unstable forms of tRNA(Arg)(CCG) does not require the Trf4p poly(A) polymerase, suggesting that yeast cells possess multiple pathways for tRNA decay. These data demonstrate that La functions redundantly with both tRNA modifications and proteins that associate with tRNAs to achieve tRNA structural stability and efficient biogenesis
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