One of the distinctive features of the primate genome is the Alu element, a repetitive short interspersed element, over a million highly similar copies of which account for >10% of the genome. A direct consequence of this feature is that primates' transcriptome is highly enriched in long stable dsRNA structures, the preferred target of adenosine deaminases acting on RNAs (ADARs), which are the enzymes catalyzing A‐to‐I RNA editing. Indeed, A‐to‐I editing by ADARs is extremely abundant in primates: over (...) a hundred million editing sites exist in their genomes. However, there are few essential editing sites conserved across mammals that have maintained their editing level despite the radical change in ADAR target landscape. Here, we review and discuss the cost of having an unusual amount of dsRNA and editing in the transcriptome, as well as the opportunities it presents, which might have contributed to the accelerated evolution of the primates. (shrink)

Genetic variability is considered a key to the evolvability of species. The conversion of an adenosine (A) to inosine (I) in primary RNA transcripts can result in an amino acid change in the encoded protein, a change in secondary structure of the RNA, creation or destruction of a splice consensus site, or otherwise alter RNA fate. Substantial transcriptome and proteome variability is generated by A‐to‐I RNA editing through site‐selective post‐transcriptional recoding of single nucleotides. We posit that this epigenetic source (...) of phenotypic variation is an unrecognized mechanism of adaptive evolution. The genetic variation introduced through editing occurs at low evolutionary cost since predominant production of the wild‐type protein is retained. This property even allows exploration of sequence space that is inaccessible through mutation, leading to increased phenotypic plasticity and provides an evolutionary advantage for acclimatization as well as long‐term adaptation. Furthermore, continuous probing for novel RNA editing sites throughout the transcriptome is an intrinsic property of the editing machinery and represents the molecular basis for increased adaptability. We propose that higher organisms have therefore evolved to systems with increasing RNA editing activity and, as a result, to more complex systems. (shrink)

RNA editing is a newly described genetic phenomenon. It encompasses widely different molecular mechanisms and events. According to the specific RNA modification, RNA editing can be broadly classified into six major types. Type II RNA editing occurs in plants and mammals; it consists predominantly in cytidine to uridine conversions resulting from deamination/transamination or transglycosylation, although in plants other mechanisms have not been excluded. Apolipoprotein B mRNA editing is the only well‐documented editing phenomenon in mammals. It (...) is an intranuclear event that occurs posttranscriptionally, coincident with splicing and polyadenylation. Recent observations indicate that the tissue‐ and sequence‐specific process is mediated by an enzyme that has separate domains for editing and sequence recognition. The presence of apolipoprotein B mRNA editing activity in tissues that do not produce the protein suggests that other RNAs may be edited and RNA editing may be a genetic phenomenon of general biological importance to the cell. (shrink)

RNA editing is a major post-transcriptional mechanism that changes specific nucleotides at the RNA level. The most common RNA editing type in humans is adenosine to inosine editing, which is mediated by ADAR enzymes. RNA editing events can not only change amino acids in proteins, but also affect the functions of non-coding RNAs such as miRNAs. Recent studies have characterized thousands of miRNA RNA editing events across different cancer types. Importantly, individual cases of miRNA (...) class='Hi'>editing have been reported to play a role in cancer development. In this review, we summarize the current knowledge of miRNA editing in cancer, and discuss the mechanisms on how miRNA-related editing events modulate the initiation and progression of human cancer. Finally, we discuss the challenges and future directions of studying miRNA editing in cancer. RNA editing is introduced by ADAR or APOBEC enzymes, leading to specific nucleotide changes, respectively. The interplays between RNA editing and miRNAs may play important roles in cancer. This graphical abstract shows four major mechanisms through which miRNAs interact with RNA editing to confer a functional impact on tumor development. (shrink)

Deamination of adenosine in RNA to form inosine has wide ranging consequences on RNA function including amino acid substitution to give proteins not encoded in the genome. What determines which adenosines in an mRNA are subject to this modification reaction? The answer lies in an understanding of the mechanism and substrate recognition properties of adenosine deaminases that act on RNA (ADARs). Our recent publication of X‐ray crystal structures of the human ADAR2 deaminase domain bound to RNA editing substrates shed (...) considerable light on how the catalytic domains of these enzymes bind RNA and promote adenosine deamination. Here we review in detail the deaminase domain‐RNA contact surfaces and present models of how full length ADARs, bearing double stranded RNA‐binding domains (dsRBDs) and deaminase domains, could process naturally occurring substrate RNAs. (shrink)

The most recent work toward compiling a comprehensive database of adenosine‐to‐inosine RNA editing events suggests that the potential for RNA editing is much more pervasive than previously thought; indeed, it is manifest in more than 100 million potential editing events located primarily within Alu repeat elements of the human transcriptome. Pairs of inverted Alu repeats are found in a substantial number of human genes, and when transcribed, they form long double‐stranded RNA structures that serve as optimal substrates (...) for RNA editing enzymes. A small subset of edited Alu elements has been shown to exhibit diverse functional roles in the regulation of alternative splicing, miRNA repression, and cis‐regulation of distant RNA editing sites. The low level of editing for the remaining majority may be non‐functional, yet their persistence in the primate genome provides enhanced genomic flexibility that may be required for adaptive evolution. (shrink)

Previous studies of Zika virus (ZIKV) pathogenesis have focused primarily on virus‐driven pathology and neurotoxicity, as well as host‐related changes in cell proliferation, autophagy, immunity, and uterine function. It is now hypothesized that ZIKV pathogenesis arises instead as an (unintended) consequence of host innate immunity, specifically, as the side effect of an otherwise well‐functioning machine. The hypothesis presented here suggests a new way of thinking about the role of host immune mechanisms in disease pathogenesis, focusing on dysregulation of post‐transcriptional RNA (...) editing as a candidate driver of a broad range of observed neurodevelopmental defects and neurodegenerative clinical symptoms in both infants and adults linked with ZIKV infections. The authors collect and synthesize existing evidence of ZIKV‐mediated changes in the expression of adenosine deaminases acting on RNA (ADARs), known links between abnormal RNA editing and pathogenesis, as well as ideas for future research directions, including potential treatment strategies. (shrink)

There is increasing evidence that dynamic changes to chromatin, chromosomes and nuclear architecture are regulated by RNA signalling. Although the precise molecular mechanisms are not well understood, they appear to involve the differential recruitment of a hierarchy of generic chromatin modifying complexes and DNA methyltransferases to specific loci by RNAs during differentiation and development. A significant fraction of the genome-wide transcription of non-protein coding RNAs may be involved in this process, comprising a previously hidden layer of intermediary genetic information that (...) underpins developmental ontogeny and the differences between species, ecotypes and individuals. It is also evident that RNA editing is a primary means by which hardwired genetic information in animals can be altered by environmental signals, especially in the brain, indicating a dynamic RNA-mediated interplay between the transcriptome, the environment and the epigenome. Moreover, RNA-directed regulatory processes may also transfer epigenetic information not only within cells but also between cells and organ systems, as well as across generations. (shrink)

The evolution of the human brain has resulted in the emergence of higher-order cognitive abilities, such as reasoning, planning and social awareness. Although there has been a concomitant increase in brain size and complexity, and component diversification, we argue that RNA regulation of epigenetic processes, RNA editing, and the controlled mobilization of transposable elements have provided the major substrates for cognitive advance. We also suggest that these expanded capacities and flexibilities have led to the collateral emergence of psychiatric fragilities (...) and conditions. (shrink)

The RNA editing enzyme ADAR1 seemingly has more functions besides RNA editing. Mouse models lacking ADAR1 and sensors of foreign RNA show that RNA editing by ADAR1 plays a crucial role in the innate immune response. Still, RNA editing alone cannot explain all observed phenotypes. Thus, additional roles for ADAR1 must exist. Binding of ADAR1 to RNA is independent of its RNA editing function. Thus, ADAR1 may compete with other RNA-binding proteins. A very recent manuscript (...) elaborates on this and reports competition of ADAR1 with STAUFEN1, thereby modulating RNA-degradation. ADAR1 is also known to recruit proteins such as DROSHA to nascent transcripts. Still, many open questions remain. For instance, the biological role of the Z-DNA binding domains in ADAR1 is not defined. Moreover, the impact of ADAR1 on the RNA-folding landscape is unclear. In sum, moonlighting functions of ADAR1 may be manifold and have a great impact on the transcriptome. Adenosine to inosine RNA editing by ADAR1 is mostly known for its role in the innate immune response to help discriminate self from non-self RNA. Here we discuss the other face of ADAR1 that impacts on cellular processes independent of its editing function. These include Staufen-mediated-decay, mRNA processing, or miRNA maturation. (shrink)

Most molecular biological concepts derive from physical chemical assumptions about the genetic code that are basically more than 40 years old. Additionally, systems biology, another quantitative approach, investigates the sum of interrelations to obtain a more holistic picture of nucleotide sequence order. Recent empirical data on genetic code compositions and rearrangements by mobile genetic elements and non-coding RNAs, together with results of virus research and their role in evolution, does not really fit into these concepts and compel a re-examination. In (...) this review we try to find an alternate hypothesis. It seems plausible now that if we look at the abundance of regulatory RNAs and persistent viruses in host genomes, we will find more and more evidence that the key players that edit the genetic codes of host genomes are consortia of RNA agents and viruses that drive evolutionary novelty and regulation of cellular processes in all steps of development. This agent-based approach may lead to a qualitative RNA sociology that investigates and identifies relevant behavioural motifs of cooperative RNA consortia. In addition to molecular biological perspectives this may lead to a better understanding of genetic code evolution and dynamics. (shrink)

The nomination of candidate genes underlying complex traits is often focused on genetic variations that alter mRNA abundance or result in non‐conservative changes in amino acids. Although inconspicuous in complex trait analysis, genetic variants that affect splicing or RNA editing can also generate proteomic diversity and impact genetic traits. Indeed, it is known that splicing and RNA editing modulate several traits in humans and model organisms. Using high‐throughput RNA sequencing (RNA‐seq) analysis, it is now possible to integrate the (...) genetics of transcript abundance, alternative splicing (AS) and editing with the analysis of complex traits. We recently demonstrated that both AS and mRNA editing are modulated by genetic and environmental factors, and potentially engender phenotypic diversity in a genetically segregating mouse population. Therefore, the analysis of splicing and RNA editing can expand not only the regulatory landscape of transcriptome and proteome complexity, but also the repertoire of candidate genes for complex traits. (shrink)

The Streptococcus pyogenes CRISPR‐Cas system has gained widespread application as a genome editing and gene regulation tool as simultaneous cellular delivery of the Cas9 protein and guide RNAs enables recognition of specific DNA sequences. The recent discovery that Cas9 can also bind and cleave RNA in an RNA‐programmable manner indicates the potential utility of this system as a universal nucleic acid‐recognition technology. RNA‐targeted Cas9 (RCas9) could allow identification and manipulation of RNA substrates in live cells, empowering the study of (...) cellular gene expression, and could ultimately spawn patient‐ and disease‐specific diagnostic and therapeutic tools. Here we describe the development of RCas9 and compare it to previous methods for RNA targeting, including engineered RNA‐binding proteins and other types of CRISPR‐Cas systems. We discuss potential uses ranging from live imaging of transcriptional dynamics to patient‐specific therapies and applications in synthetic biology. (shrink)

In the last 10 years, we have witnessed a blooming of targeted genome editing systems and applications. The area was revolutionized by the discovery and characterization of the transcription activator‐like effector proteins, which are easier to engineer to target new DNA sequences than the previously available DNA binding templates, zinc fingers and meganucleases. Recently, the area experimented a quantum leap because of the introduction of the clustered regularly interspaced short palindromic repeats (CRISPR)‐associated protein (Cas) system (clustered regularly interspaced short (...) palindromic sequence). This ribonucleoprotein complex protects bacteria from invading DNAs, and it was adapted to be used in genome editing. The CRISPR ribonucleic acid (RNA) molecule guides to the specific DNA site the Cas9 nuclease to cleave the DNA target. Two years and more than 1000 publications later, the CRISPR‐Cas system has become the main tool for genome editing in many laboratories. Currently the targeted genome editing technology has been used in many fields and may be a possible approach for human gene therapy. Furthermore, it can also be used to modifying the genomes of model organisms for studying human pathways or to improve key organisms for biotechnological applications, such as plants, livestock genome as well as yeasts and bacterial strains. (shrink)

Natural genome editing from a biocommunicative perspective is the competent agent-driven generation and integration of meaningful nucleotide sequences into pre-existing genomic content arrangements, and the ability to (re-)combine and (re-)regulate them according to context-dependent (i.e. adaptational) purposes of the host organism. Natural genome editing integrates both natural editing of genetic code and epigenetic marking that determines genetic reading patterns. As agents that edit genetic code and epigenetically mark genomic structures, viral and subviral agents have been suggested because (...) they may be evolutionarily older than cellular life. This hypothesis that viruses and viral-like agents edit genetic code is developed according to three well investigated examples that represent key evolutionary inventions in which non-lytic viral swarms act symbiotically in a persistent lifestyle within cellular host genomes: origin of eukaryotic nucleus, adaptive immunity, placental mammals. Additionally an abundance of various RNA elements cooperate in a variety of steps and substeps as regulatory and catalytic units with multiple competencies to act on the genetic code. Most of these RNA agents such as transposons, retroposons and small non-coding RNAs act consortially and are remnants of persistent viral infections that now act as co-opted adaptations in cellular key processes. (shrink)

Recently, constructive neutral evolution has been touted as an important concept for the understanding of the emergence of cellular complexity. It has been invoked to help explain the development and retention of, amongst others, RNA splicing, RNA editing and ribosomal and mitochondrial respiratory chain complexity. The theory originated as a welcome explanation of isolated small scale cellular idiosyncrasies and as a reaction to ‘overselectionism’. Here I contend, that in its extended form, it has major conceptual problems, can not explain (...) observed patterns of complex processes, is too easily dismissive of alternative selectionist models, underestimates the creative force of complexity as such, and – if seen as a major evolutionary mechanism for all organisms – could stifle further thought regarding the evolution of highly complex biological processes. (shrink)

Research on the semantics of spatial markers in French is known mainly through Vandeloise’s work on static prepositions. However, interest in the expression of space in French goes back to the mid-1970s and focused first on verbs denoting changes in space, whose syntactic properties were related to specific semantic distinctions, such as the opposition between “movement” and “displacement”. This volume provides an overview of recent studies on the semantics of dynamic space in Fr...

Eric Scerri is the world-leading expert on Periodic Table and was quite recently named the second-most influential academic in the field of chemistry over the last decade by Academic Influence. In this interview we discuss his main questions of interest in the philosophy of chemistry—the question of reduction of chemistry to physics and the dual sense of chemical element—in the context of his main study object, the periodic table of elements. Among other things, we touch upon the more specific issues (...) related to chemical classification, such as pair reversal, the placement and order of certain elements, the structure and shape of periodic table, etc. We also discuss the status of chemical kinds as a traditional epitome of ‘natural kinds’, the relevance of philosophy of chemistry for chemical science, the implications of ‘turn to practice’ for philosophy of chemistry, and many other issues. Finally, Eric Scerri also discusses his most recent book, ‘What is a Chemical Element?’, co-edited with Elena Ghibaudi and published by Oxford University Press in 2020. (shrink)

Analytic philosophy - arguably the most important philosophical movement in the 20th century - has gained a new historical self-consciousness, particularly about it's own origins. The period between 1880 and 1930 saw the most important work of its founding figures (Frege, Russell, Moore, Wittgenstein) take root and flourish. The fifteen previously-unpublished essays in this collection explore different facets of this period, with an emphasis on the vital intellectual relationship between Frege and the early Wittgenstein.

An insightful reading of Deleuze, from the point of view of a student, a reader and a fellow philosopher with whom Deleuze himself corresponded about his work.

Ever since Proclus wrote his commentary on Plato's Republic, repeated attempts have been made to find a hidden number of cosmic significance in Rep. 8.546. For the Neo-Platonist it was natural to look for esoteric secrets in ancient works; among the men of the New Learning at the end of the Middle Ages there were enough astrologers and necromancers to ensure respect for the proposition; we are now again enamoured of irrationality. But the scholars who attempted such calculations around 1900 (...) must have considered Plato himself a mystery-monger. In this article I propose: to show why such attempts are mistaken, to discuss what early writers who mention the passage say about its meaning, to provide a mathematician's translation that fits the context, and to comment on it; for the currently accepted explanation is unsatisfactory. ‘There is fairly widespread agreement that the geometrical number is 12,960,000 = 3,6002 = 4,800 × 2,700, but on the method by which this number is reached the widest divergence exists’ or, from an earlier, different guess: ‘…one can, so to speak, state a priori that Plato's number is a multiple of 19 ten thousands’, i.e. the text is approached with a ready-made answer in mind. There are three further objections to the conventional view, It takes the text out of its context as if it had strayed from the Timaeus. (shrink)

In the corollaries to Book I, Chapter 5 of De causa Dei, Thomas Bradwardine assumes the existence of an actual, infinite, God-filled extramundane void. Thomas Buckingham, Bradwardine’s former student, develops in the unedited Question 23 of his Quaestiones theologicae a rejection of the void’s existence precisely in opposition to the theory of his master. His argumentation is not only remarkable in its own; it also allows us to reassess essential concepts from Bradwardine’s De causa Dei, such as divine power, causality (...) and ubiquity. This paper first presents the Aristotelian notion of the void in rendering it in the context of the philosophy of nature at fourteenth-century Oxford; it is then dedicated to the analysis of the chapter in question from De causa Dei along with Buckingham’s answer. It is accompanied by a critical edition of Question 23 from Buckingham’s Quaestiones theologicae, »Utrum sit necesse ponere Deum esse extra mundum in situ seu vacuo imaginario infinito«. (shrink)

The paper presents the results of the study of the impact and effects of communication models of public relations and organization–public relationships on company credibility and financial performance in companies in Serbia. The data were obtained by interviewing 415 respondents (PR managers, PR practitioners and marketing experts) working in 93 companies in Serbia. The dimensions of the organization–public relationships have stronger positive influences and effects on company credibility and financial performance than the dimensions of communication models of public relations. The (...) influence of the dimensions of trust, commitment, satisfaction and communal relationship is particularly emphasized. Of the four communication models, the strongest positive impact on company credibility and financial performance is achieved by the two-way symmetrical dimension, and then the two-way asymmetrical dimension. The dimensions of communication models of public relations and organization–public relationships have the greatest influence and predictive effect on the dimension of trustworthiness, followed by the dimension of expertise, and finally the dimension of financial performance. Therefore, a greater impact exists on company credibility than on financial performance. (shrink)