Liscovitch-Brauer Noa

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Liscovitch-Brauer
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Noa
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  • Article
    Spatially regulated editing of genetic information within a neuron
    (Oxford University Press, 2020-03-23) Vallecillo-Viejo, Isabel C. ; Liscovitch-Brauer, Noa ; Diaz Quiroz, Juan F. ; Montiel-González, Maria Fernanda ; Nemes, Sonya E. ; Rangan, Kavita J. ; Levinson, Simon R. ; Eisenberg, Eli ; Rosenthal, Joshua J. C.
    In eukaryotic cells, with the exception of the specialized genomes of mitochondria and plastids, all genetic information is sequestered within the nucleus. This arrangement imposes constraints on how the information can be tailored for different cellular regions, particularly in cells with complex morphologies like neurons. Although messenger RNAs (mRNAs), and the proteins that they encode, can be differentially sorted between cellular regions, the information itself does not change. RNA editing by adenosine deamination can alter the genome’s blueprint by recoding mRNAs; however, this process too is thought to be restricted to the nucleus. In this work, we show that ADAR2 (adenosine deaminase that acts on RNA), an RNA editing enzyme, is expressed outside of the nucleus in squid neurons. Furthermore, purified axoplasm exhibits adenosine-to-inosine activity and can specifically edit adenosines in a known substrate. Finally, a transcriptome-wide analysis of RNA editing reveals that tens of thousands of editing sites (>70% of all sites) are edited more extensively in the squid giant axon than in its cell bodies. These results indicate that within a neuron RNA editing can recode genetic information in a region-specific manner.
  • Preprint
    Trade-off between transcriptome plasticity and genome evolution in cephalopods
    ( 2017-03) Liscovitch-Brauer, Noa ; Alon, Shahar ; Porath, Hagit T. ; Elstein, Boaz ; Unger, Ron ; Ziv, Tamar ; Admon, Arie ; Levanon, Erez ; Rosenthal, Joshua J. C. ; Eisenberg, Eli
    RNA editing, a post-transcriptional process, allows the diversification of proteomes beyond the genomic blueprint; however it is infrequently used among animals. Recent reports suggesting increased levels of RNA editing in squids thus raise the question of their nature and effects in these organisms. We here show that RNA editing is particularly common in behaviorally sophisticated coleoid cephalopods, with tens of thousands of evolutionarily conserved sites. Editing is enriched in the nervous system affecting molecules pertinent for excitability and neuronal morphology. The genomic sequence flanking editing sites is highly conserved, suggesting that the process confers a selective advantage. Due to the large number of sites, the surrounding conservation greatly reduces the number of mutations and genomic polymorphisms in protein coding regions. This trade-off between genome evolution and transcriptome plasticity highlights the importance of RNA recoding as a strategy for diversifying proteins, particularly those associated with neural function.
  • Article
    Adaptive proteome diversification by nonsynonymous A-to-I RNA editing in coleoid cephalopods
    (Oxford University Press, 2021-05-22) Shoshan, Yoav ; Liscovitch-Brauer, Noa ; Rosenthal, Joshua J. C. ; Eisenberg, Eli
    RNA editing by the ADAR enzymes converts selected adenosines into inosines, biological mimics for guanosines. By doing so, it alters protein-coding sequences, resulting in novel protein products that diversify the proteome beyond its genomic blueprint. Recoding is exceptionally abundant in the neural tissues of coleoid cephalopods (octopuses, squids, and cuttlefishes), with an over-representation of nonsynonymous edits suggesting positive selection. However, the extent to which proteome diversification by recoding provides an adaptive advantage is not known. It was recently suggested that the role of evolutionarily conserved edits is to compensate for harmful genomic substitutions, and that there is no added value in having an editable codon as compared with a restoration of the preferred genomic allele. Here, we show that this hypothesis fails to explain the evolutionary dynamics of recoding sites in coleoids. Instead, our results indicate that a large fraction of the shared, strongly recoded, sites in coleoids have been selected for proteome diversification, meaning that the fitness of an editable A is higher than an uneditable A or a genomically encoded G.