The RNA editing core complex (RECC) catalyzes mitochondrial U-insertion/deletion mRNA editing in trypanosomatid flagellates. Some naphthalene-based sulfonated compounds, such as C35 and MrB, competitively inhibit the auto-adenylylation activity of an essential RECC enzyme, kinetoplastid RNA editing ligase 1 (KREL1), required for the final step in editing. Previous studies revealed the ability of these compounds to interfere with the interaction between the editosome and its RNA substrates, consequently affecting all catalytic activities that comprise RNA editing. This observation implicates a critical function for the affected RNA binding proteins in RNA editing. In this study, using the inhibitory compounds, we analyzed the composition and editing activities of functional editosomes and identified the mitochondrial RNA binding proteins 1 and 2 (MRP1/2) as their preferred targets. While the MRP1/2 heterotetramer complex is known to bind guide RNA and promote annealing to its cognate pre-edited mRNA, its role in RNA editing remained enigmatic. We show that the compounds affect the association between the RECC and MRP1/2 heterotetramer. Furthermore, RECC purified post-treatment with these compounds exhibit compromised in vitro RNA editing activity that, remarkably, recovers upon the addition of recombinant MRP1/2 proteins. This work provides experimental evidence that the MRP1/2 heterotetramer is required for in vitro RNA editing activity and substantiates the hypothesized role of these proteins in presenting the RNA duplex to the catalytic complex in the initial steps of RNA editing.

• Klíčová slova
• MRP1/2, RNA editing, RNA editing initiation, RNA-binding protein, inhibitor, trypanosome,
• MeSH
• editace RNA účinky léků   genetika   MeSH
• guide RNA, Kinetoplastida účinky léků   MeSH
• ligasy antagonisté a inhibitory   MeSH
• messenger RNA genetika   MeSH
• mitochondriální proteiny genetika   MeSH
• mitochondrie účinky léků   genetika   MeSH
• proteiny vázající RNA genetika   MeSH
• protozoální proteiny genetika   MeSH
• rekombinantní proteiny genetika   MeSH
• RNA mitochondriální genetika   MeSH
• RNA protozoální genetika   MeSH
• Trypanosoma brucei brucei účinky léků   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• gBP21 protein, Trypanosoma brucei MeSH Prohlížeč
• gBP25 protein, Trypanosoma brucei MeSH Prohlížeč
• guide RNA, Kinetoplastida MeSH
• ligasy MeSH
• messenger RNA MeSH
• mitochondriální proteiny MeSH
• proteiny vázající RNA MeSH
• protozoální proteiny MeSH
• rekombinantní proteiny MeSH
• RNA mitochondriální MeSH
• RNA protozoální MeSH

Trypanosoma brucei is the causative agent of the human and veterinarian diseases African sleeping sickness and nagana. A majority of its mitochondrial-encoded transcripts undergo RNA editing, an essential process of post-transcriptional uridine insertion and deletion to produce translatable mRNA. Besides the well-characterized RNA editing core complex, the mitochondrial RNA-binding 1 (MRB1) complex is one of the key players. It comprises a core complex of about six proteins, guide RNA-associated proteins (GAPs) 1/2, which form a heterotetramer that binds and stabilizes gRNAs, plus MRB5390, MRB3010, and MRB11870, which play roles in initial stages of RNA editing, presumably guided by the first gRNA:mRNA duplex in the case of the latter two proteins. To better understand all functions of the MRB1 complex, we performed a functional analysis of the MRB8620 core subunit, the only one not characterized so far. Here we show that MRB8620 plays a role in RNA editing in both procyclic and bloodstream stages of T. brucei, which reside in the tsetse fly vector and mammalian circulatory system, respectively. While RNAi silencing of MRB8620 does not affect procyclic T. brucei fitness when grown in glucose-containing media, it is somewhat compromised in cells grown in the absence of this carbon source. MRB8620 is crucial for integrity of the MRB1 core, such as its association with GAP1/2, which presumably acts to deliver gRNAs to this complex. In contrast, GAP1/2 is not required for the fabrication of the MRB1 core. Disruption of the MRB1 core assembly is followed by the accumulation of mRNAs associated with GAP1/2.

• Klíčová slova
• RNA editing, mitochondrion, trypanosome,
• MeSH
• buněčné linie MeSH
• editace RNA * MeSH
• messenger RNA genetika   metabolismus   MeSH
• mitochondriální proteiny fyziologie   MeSH
• mitochondrie MeSH
• protozoální proteiny fyziologie   MeSH
• Trypanosoma brucei brucei genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• messenger RNA MeSH
• mitochondriální proteiny MeSH
• protozoální proteiny MeSH

ADAR RNA editing enzymes (adenosine deaminases acting on RNA) that convert adenosine bases to inosines were first identified biochemically 30 years ago. Since then, studies on ADARs in genetic model organisms, and evolutionary comparisons between them, continue to reveal a surprising range of pleiotropic biological effects of ADARs. This review focuses on Drosophila melanogaster, which has a single Adar gene encoding a homolog of vertebrate ADAR2 that site-specifically edits hundreds of transcripts to change individual codons in ion channel subunits and membrane and cytoskeletal proteins. Drosophila ADAR is involved in the control of neuronal excitability and neurodegeneration and, intriguingly, in the control of neuronal plasticity and sleep. Drosophila ADAR also interacts strongly with RNA interference, a key antiviral defense mechanism in invertebrates. Recent crystal structures of human ADAR2 deaminase domain-RNA complexes help to interpret available information on Drosophila ADAR isoforms and on the evolution of ADARs from tRNA deaminase ADAT proteins. ADAR RNA editing is a paradigm for the now rapidly expanding range of RNA modifications in mRNAs and ncRNAs. Even with recent progress, much remains to be understood about these groundbreaking ADAR RNA modification systems.

• Klíčová slova
• ADAR, Drosophila melanogaster, RNA editing, RNA modification, dsRNA, epitranscriptome,
• MeSH
• adenosindeaminasa chemie   genetika   metabolismus   MeSH
• Drosophila melanogaster genetika   metabolismus   MeSH
• editace RNA * MeSH
• exprese genu MeSH
• interakční proteinové domény a motivy MeSH
• izoenzymy MeSH
• lidé MeSH
• messenger RNA genetika   MeSH
• molekulární evoluce MeSH
• nervový systém metabolismus   MeSH
• obratlovci MeSH
• proteiny Drosophily genetika   metabolismus   MeSH
• proteiny vázající RNA genetika   metabolismus   MeSH
• RNA interference MeSH
• substrátová specifita MeSH
• vazba proteinů MeSH
• vztahy mezi strukturou a aktivitou MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• Adar protein, Drosophila MeSH Prohlížeč
• adenosindeaminasa MeSH
• izoenzymy MeSH
• messenger RNA MeSH
• proteiny Drosophily MeSH
• proteiny vázající RNA MeSH

RNA editing is one of the most prevalent and abundant forms of post-transcriptional RNA modification observed in normal physiological processes and often aberrant in diseases including cancer. RNA editing changes the sequences of mRNAs, making them different from the source DNA sequence. Edited mRNAs can produce editing-recoded protein isoforms that are functionally different from the corresponding genome-encoded protein isoforms. The major type of RNA editing in mammals occurs by enzymatic deamination of adenosine to inosine (A-to-I) within double-stranded RNAs (dsRNAs) or hairpins in pre-mRNA transcripts. Enzymes that catalyse these processes belong to the adenosine deaminase acting on RNA (ADAR) family. The vast majority of knowledge on the RNA editing landscape relevant to human disease has been acquired using in vitro cancer cell culture models. The limitation of such in vitro models, however, is that the physiological or disease relevance of results obtained is not necessarily obvious. In this review we focus on discussing in vivo occurring RNA editing events that have been identified in human cancer tissue using samples surgically resected or clinically retrieved from patients. We discuss how RNA editing events occurring in tumours in vivo can identify pathological signalling mechanisms relevant to human cancer physiology which is linked to the different stages of cancer progression including initiation, promotion, survival, proliferation, immune escape and metastasis.

• Klíčová slova
• ADARs, RNA editing, RNA editing in cancer, cancer development,
• MeSH
• adenosin genetika   MeSH
• dvouvláknová RNA genetika   MeSH
• editace RNA * MeSH
• inosin genetika   MeSH
• karcinogeneze genetika   patologie   MeSH
• lidé MeSH
• nádory genetika   metabolismus   patologie   MeSH
• proteiny vázající RNA genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• adenosin MeSH
• dvouvláknová RNA MeSH
• inosin MeSH
• proteiny vázající RNA MeSH

Trypanosoma cruzi is a unicellular protistan parasitic species that is comprised of strains and isolates exhibiting high levels of genetic and metabolic variability. In the insect vector, it is known to be highly responsive to starvation, a signal for progression to a life stage in which it can infect mammalian cells. Most mRNAs encoded in its mitochondrion require the targeted insertion and deletion of uridines to become translatable transcripts. This study defined differences in uridine-insertion/deletion RNA editing among three strains and established the mechanism whereby abundances of edited (and, thus, translatable) mitochondrial gene products increase during starvation. Our approach utilized our custom T-Aligner toolkit to describe transcriptome-wide editing events and reconstruct editing products from high-throughput sequencing data. We found that the relative abundance of mitochondrial transcripts and the proportion of mRNAs that are edited varies greatly between analyzed strains, a characteristic that could potentially impact metabolic capacity. Starvation typically led to an increase in overall editing activity rather than affecting a specific step in the process. We also determined that transcripts CR3, CR4, and ND3 produce multiple open reading frames that, if translated, would generate different proteins. Finally, we quantitated the inherent flexibility of editing in T. cruzi and found it to be higher relative to that in a related trypanosomatid lineage. Over time, new editing domains or patterns could prove advantageous to the organism and become more widespread within individual transcriptomes or among strains.

• Klíčová slova
• Chagas disease, RNA editing, electron transport chain, epimastigote, metabolism,
• MeSH
• editace RNA MeSH
• messenger RNA genetika   metabolismus   MeSH
• protozoální proteiny genetika   metabolismus   MeSH
• RNA mitochondriální genetika   metabolismus   MeSH
• RNA protozoální genetika   metabolismus   MeSH
• RNA metabolismus   MeSH
• savci genetika   MeSH
• transkriptom MeSH
• Trypanosoma brucei brucei * genetika   MeSH
• Trypanosoma cruzi * genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• messenger RNA MeSH
• protozoální proteiny MeSH
• RNA mitochondriální MeSH
• RNA protozoální MeSH
• RNA MeSH

RNA editing, which adds sequence information to RNAs post-transcriptionally, is a widespread phenomenon throughout eukaryotes. The most complex form of this process is the uridine (U) insertion/deletion editing that occurs in the mitochondria of kinetoplastid protists. RNA editing in these flagellates is specified by trans-acting guide RNAs and entails the insertion of hundreds and deletion of dozens of U residues from mitochondrial RNAs to produce mature, translatable mRNAs. An emerging model indicates that the machinery required for trypanosome RNA editing is much more complicated than previously appreciated. A family of RNA editing core complexes (RECCs), which contain the required enzymes and several structural proteins, catalyze cycles of U insertion and deletion. A second, dynamic multiprotein complex, the Mitochondrial RNA Binding 1 (MRB1) complex, has recently come to light as another essential component of the trypanosome RNA editing machinery. MRB1 likely serves as the platform for kinetoplastid RNA editing, and plays critical roles in RNA utilization and editing processivity. MRB1 also appears to act as a hub for coordination of RNA editing with additional mitochondrial RNA processing events. This review highlights the current knowledge regarding the complex molecular machinery involved in trypanosome RNA editing. WIREs RNA 2016, 7:33-51. doi: 10.1002/wrna.1313 For further resources related to this article, please visit the WIREs website.

• MeSH
• editace RNA * MeSH
• protozoální proteiny genetika   MeSH
• RNA protozoální genetika   MeSH
• Trypanosoma brucei brucei genetika   MeSH
• uridin genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• protozoální proteiny MeSH
• RNA protozoální MeSH
• uridin MeSH

The ADAR proteins deaminate adenosine to inosine in double-stranded RNA which is one of the most abundant modifications present in mammalian RNA. Inosine can have a profound effect on the RNAs that are edited, not only changing the base-pairing properties, but can also result in recoding, as inosine behaves as if it were guanosine. In mammals there are three ADAR proteins and two ADAR-related proteins (ADAD) expressed. All have a very similar modular structure; however, both their expression and biological function differ significantly. Only two of the ADAR proteins have enzymatic activity. However, both ADAR and ADAD proteins possess the ability to bind double-strand RNA. Mutations in ADARs have been associated with many diseases ranging from cancer, innate immunity to neurological disorders. Here, we will discuss in detail the domain structure of mammalian ADARs, the effects of RNA editing, and the role of ADARs in human diseases.

• Klíčová slova
• ADAR, Alu elements, RNA editing, cancer, deaminase domain, dsRBDs,
• MeSH
• adenosindeaminasa metabolismus   MeSH
• dvouvláknová RNA metabolismus   MeSH
• editace RNA genetika   MeSH
• lidé MeSH
• proteiny vázající RNA metabolismus   MeSH
• savci MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• adenosindeaminasa MeSH
• dvouvláknová RNA MeSH
• proteiny vázající RNA MeSH

In eukaryotes mRNA transcripts are extensively processed by different post-transcriptional events such as alternative splicing and RNA editing in order to generate many different mRNAs from the same gene, increasing the transcriptome and then the proteome diversity. The most frequent RNA editing mechanism in mammals involves the conversion of specific adenosines into inosines by the ADAR family of enzymes. This editing event can alter the sequence and the secondary structure of RNA molecules, with consequences for final proteins and regulatory RNAs. Alteration in RNA editing has been connected to tumor progression and many other important human diseases. Analysis of many editing sites in various cancer types is expected to provide new diagnostic and prognostic markers and might contribute to early detection of cancer, the monitoring of response to therapy, and to the detection of minimal residual disease.

• MeSH
• adenosindeaminasa chemie   genetika   metabolismus   MeSH
• apolipoprotein B-100 chemie   metabolismus   MeSH
• apolipoprotein B-48 chemie   metabolismus   MeSH
• editace RNA genetika   fyziologie   MeSH
• glutamátové receptory chemie   metabolismus   MeSH
• lidé MeSH
• messenger RNA chemie   metabolismus   MeSH
• nádory metabolismus   MeSH
• proteiny vázající RNA MeSH
• tyrosinfosfatasy metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• odvolaná publikace MeSH
• přehledy MeSH
• Názvy látek
• ADARB1 protein, human MeSH Prohlížeč
• adenosindeaminasa MeSH
• apolipoprotein B-100 MeSH
• apolipoprotein B-48 MeSH
• glutamátové receptory MeSH
• messenger RNA MeSH
• proteiny vázající RNA MeSH
• tyrosinfosfatasy MeSH

The trypanosomatid flagellates possess in their single mitochondrion a highly complex kinetoplast (k)DNA, which is composed of interlocked circular molecules of two types. Dozens of maxicircles represent a classical mitochondrial genome, and thousands of minicircles encode guide (g)RNAs, which direct the processive and essential uridine insertion/deletion messenger RNA (mRNA) editing of maxicircle transcripts. While the details of kDNA structure and this type of RNA editing are well established, our knowledge mostly relies on a narrow foray of intensely studied human parasites of the genera Leishmania and Trypanosoma. Here, we analyzed kDNA, its expression, and RNA editing of two members of the poorly characterized genus Vickermania with very different cultivation histories. In both Vickermania species, the gRNA-containing heterogeneous large (HL)-circles are atypically large with multiple gRNAs each. Examination of Vickermania spadyakhi HL-circle loci revealed a massive redundancy of gRNAs relative to the editing needs. In comparison, the HL-circle repertoire of extensively cultivated Vickermania ingenoplastis is greatly reduced. It correlates with V. ingenoplastis-specific loss of productive editing of transcripts encoding subunits of respiratory chain complex I and corresponding lack of complex I activity. This loss in a parasite already lacking genes for subunits of complexes III and IV suggests an apparent requirement for its mitochondrial adenosine triphosphate (ATP) synthase to work in reverse to maintain membrane potential. In contrast, V. spadyakhi retains a functional complex I that allows ATP synthase to work in its standard direction.

• Klíčová slova
• ATP synthase, RNA editing, Vickermania, kinetoplast DNA, trypanosomatids,
• MeSH
• editace RNA * genetika   MeSH
• genom mitochondriální MeSH
• genom protozoální * MeSH
• kinetoplastová DNA * genetika   MeSH
• molekulární evoluce * MeSH
• Trypanosomatina * genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kinetoplastová DNA * MeSH

The ADARB1 gene encodes the adenosine deaminase acting on RNA 2 (ADAR2) RNA editing enzyme, which edits the GRIA2 transcript Q/R editing site with almost 100% efficiency in the nervous system. The edited GRIA2 R transcript encodes the GLUA2 R subunit isoform of tetrameric α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, which is essential to prevent seizures associated with aberrantly elevated AMPA receptor cation permeability. Rare biallelic variants in ADARB1 cause severe infant and childhood seizures and developmental delays in seven cases we previously described. Here, we report two new homozygous ADARB1 variants and study ADAR2 variant editing activities at the GRIA2 Q/R site and other editing sites in cell cultures. One new variant in the second double-stranded RNA binding domain (dsRBD II) retains up to 60% editing activity, whereas another, in the deaminase domain, eliminates RNA editing activity. Reduced GRIA2 Q/R site editing increases AMPA receptor permeability by upregulating the expression of the GLUA2 Q isoform and reducing overall GLUA2 subunit levels, resulting in AMPA receptors that lack GLUA2 and are calcium-permeable. Because failure to edit the GRIA2 Q/R site leads to failure of intron 11 splicing, we also examined the effects of ADAR2 variants on the splicing of a mouse Gria2-based reporter and concluded that ADAR2 variants affect splicing only through their effects on RNA editing activity. To expand the number of variants in ADARB1, some variants reported in ClinVar have also been analyzed by in silico methods to predict which are likely to be most deleterious and associated with seizures in patients.

• Klíčová slova
• ADAR2, ADARB1, RNA editing, seizures,
• MeSH
• adenosindeaminasa * genetika   metabolismus   MeSH
• AMPA receptory genetika   metabolismus   MeSH
• dítě MeSH
• editace RNA genetika   MeSH
• HEK293 buňky MeSH
• HeLa buňky MeSH
• jednonukleotidový polymorfismus MeSH
• kojenec MeSH
• lidé MeSH
• mentální retardace * komplikace   genetika   metabolismus   MeSH
• motorické poruchy * komplikace   genetika   metabolismus   MeSH
• novorozenec MeSH
• počítačová simulace MeSH
• předškolní dítě MeSH
• protein - isoformy genetika   metabolismus   MeSH
• proteiny vázající RNA * genetika   metabolismus   MeSH
• regulace genové exprese MeSH
• sestřih RNA genetika   MeSH
• záchvaty * komplikace   genetika   metabolismus   MeSH
• Check Tag
• dítě MeSH
• kojenec MeSH
• lidé MeSH
• mužské pohlaví MeSH
• novorozenec MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ADARB1 protein, human MeSH Prohlížeč
• adenosindeaminasa * MeSH
• AMPA receptory MeSH
• glutamate receptor ionotropic, AMPA 2 MeSH Prohlížeč
• protein - isoformy MeSH
• proteiny vázající RNA * MeSH