scholarly journals Global accumulation of circRNAs during aging in Caenorhabditis elegans

2017 ◽  
Author(s):  
Mariela Cortés-López ◽  
Matthew Gruner ◽  
Daphne A. Cooper ◽  
Hannah N. Gruner ◽  
Alexandru-Ioan Voda ◽  
...  
Keyword(s):  
Global Scale ◽  
Circular Rnas ◽  
Rna Seq ◽  
Aging Research ◽  
C Elegans ◽  
Fourth Larval Stage ◽  
Functional Consequences ◽  
Exceptional Stability ◽  
Massive Accumulation

SummaryCircular RNAs (CircRNAs) are a newly appreciated class of RNAs that lack free 5´ and 3´ ends, are expressed by the thousands in diverse forms of life, and are mostly of enigmatic function. Ostensibly due to their resistance to exonucleases, circRNAs are known to be exceptionally stable. Here, we examined the global profile of circRNAs in C. elegans during aging by performing ribo-depleted total RNA-seq from the fourth larval stage (L4) through 10-day old adults. Using stringent bioinformatic criteria and experimental validation, we annotated 1,166 circRNAs, including 575 newly discovered circRNAs. These circRNAs were derived from 797 genes with diverse functions, including genes involved in the determination of lifespan. A massive accumulation of circRNAs during aging was uncovered. Many hundreds of circRNAs were significantly increased among the aging time-points and increases of select circRNAs by over 40-fold during aging were quantified by qRT-PCR. The age-accumulation of circRNAs was not accompanied by increased expression of linear RNAs from the same host genes. We attribute the global scale of circRNA age-accumulation to the high composition of postmitotic cells in adult C. elegans, coupled with the high resistance of circRNAs to decay. These findings suggest that the exceptional stability of circRNAs might explain age-accumulation trends observed from neural tissues of other organisms, which also have a high composition of post-mitotic cells. Given the suitability of C. elegans for aging research, it is now poised as an excellent model system to determine if there are functional consequences of circRNA accumulation during aging.

scholarly journals Reverse complementary matches simultaneously promote both back-splicing and exon-skipping

2021 ◽  
Author(s):  
Dong Cao
Keyword(s):  
Larval Stage ◽  
Large Scale ◽  
Exon Skipping ◽  
The Other ◽  
Circular Rnas ◽  
Branch Points ◽  
Rna Seq ◽  
C Elegans ◽  
Neuronal Genes ◽  
Whole Transcriptome

Circular RNAs (circRNAs) play diverse roles in different biological and physiological environments. Understanding circRNA expression profile and how circRNAs are regulated help make better use of them. Here, using large-scale neuron isolation from the first larval stage (L1) of Caenorhabditis elegans (C. elegans) followed by whole-transcriptome RNA sequencing (RNA-seq), we provide the first neuronal circRNA data in C. elegans. We show that circRNAs are highly expressed in the neurons of C. elegans and are preferably derived from neuronal genes. More importantly, reverse complementary matches (RCMs) in circRNA-flanking introns are not only required for back-splicing but also promote the skipping of exon(s) to be circularized. Finally, through one-by-one mutagenesis of all the splicing sites and branch points required for exon-skipping and back-splicing, we show that exon-skipping is not absolutely required for back-splicing, neither the other way. Instead, the coupled exon-skipping and back-splicing are happening at the same time and the two pathways work together to regulate the levels of the circular and the skipped transcripts.

scholarly journals iCLIP analysis of RNA substrates of the archaeal exosome

BMC Genomics ◽  
2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Jochen Bathke ◽  
A. Susann Gauernack ◽  
Oliver Rupp ◽  
Lennart Weber ◽  
Christian Preusser ◽  
...  
Keyword(s):  
Rna Binding ◽  
Transcript Abundance ◽  
Global Scale ◽  
Circular Rnas ◽  
Rna Seq ◽  
Uv Crosslinking ◽  
Rna Targets ◽  
Nucleotide Resolution

Abstract Background The archaeal exosome is an exoribonucleolytic multiprotein complex, which degrades single-stranded RNA in 3′ to 5′ direction phosphorolytically. In a reverse reaction, it can add A-rich tails to the 3′-end of RNA. The catalytic center of the exosome is in the aRrp41 subunit of its hexameric core. Its RNA-binding subunits aRrp4 and aDnaG confer poly(A) preference to the complex. The archaeal exosome was intensely characterized in vitro, but still little is known about its interaction with natural substrates in the cell, particularly because analysis of the transcriptome-wide interaction of an exoribonuclease with RNA is challenging. Results To determine binding sites of the exosome to RNA on a global scale, we performed individual-nucleotide resolution UV crosslinking and immunoprecipitation (iCLIP) analysis with antibodies directed against aRrp4 and aRrp41 of the chrenarchaeon Sulfolobus solfataricus. A relatively high proportion (17–19%) of the obtained cDNA reads could not be mapped to the genome. Instead, they corresponded to adenine-rich RNA tails, which are post-transcriptionally synthesized by the exosome, and to circular RNAs (circRNAs). We identified novel circRNAs corresponding to 5′ parts of two homologous, transposase-related mRNAs. To detect preferred substrates of the exosome, the iCLIP reads were compared to the transcript abundance using RNA-Seq data. Among the strongly enriched exosome substrates were RNAs antisense to tRNAs, overlapping 3′-UTRs and RNAs containing poly(A) stretches. The majority of the read counts and crosslink sites mapped in mRNAs. Furthermore, unexpected crosslink sites clustering at 5′-ends of RNAs was detected. Conclusions In this study, RNA targets of an exoribonuclease were analyzed by iCLIP. The data documents the role of the archaeal exosome as an exoribonuclease and RNA-tailing enzyme interacting with all RNA classes, and underlines its role in mRNA turnover, which is important for adaptation of prokaryotic cells to changing environmental conditions. The clustering of crosslink sites near 5′-ends of genes suggests simultaneous binding of both RNA ends by the S. solfataricus exosome. This may serve to prevent translation of mRNAs dedicated to degradation in 3′-5′ direction.

scholarly journals nanotatoR: a tool for enhanced annotation of genomic structural variants

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Surajit Bhattacharya ◽  
Hayk Barseghyan ◽  
Emmanuèle C. Délot ◽  
Eric Vilain
Keyword(s):  
De Novo ◽  
Genome Mapping ◽  
Gene List ◽  
Sufficient Information ◽  
Rna Seq ◽  
Structural Variants ◽  
De Novo Genome Assembly ◽  
Pathogenic Variants ◽  
Increased Sensitivity

Abstract Background Whole genome sequencing is effective at identification of small variants, but because it is based on short reads, assessment of structural variants (SVs) is limited. The advent of Optical Genome Mapping (OGM), which utilizes long fluorescently labeled DNA molecules for de novo genome assembly and SV calling, has allowed for increased sensitivity and specificity in SV detection. However, compared to small variant annotation tools, OGM-based SV annotation software has seen little development, and currently available SV annotation tools do not provide sufficient information for determination of variant pathogenicity. Results We developed an R-based package, nanotatoR, which provides comprehensive annotation as a tool for SV classification. nanotatoR uses both external (DGV; DECIPHER; Bionano Genomics BNDB) and internal (user-defined) databases to estimate SV frequency. Human genome reference GRCh37/38-based BED files are used to annotate SVs with overlapping, upstream, and downstream genes. Overlap percentages and distances for nearest genes are calculated and can be used for filtration. A primary gene list is extracted from public databases based on the patient’s phenotype and used to filter genes overlapping SVs, providing the analyst with an easy way to prioritize variants. If available, expression of overlapping or nearby genes of interest is extracted (e.g. from an RNA-Seq dataset, allowing the user to assess the effects of SVs on the transcriptome). Most quality-control filtration parameters are customizable by the user. The output is given in an Excel file format, subdivided into multiple sheets based on SV type and inheritance pattern (INDELs, inversions, translocations, de novo, etc.). nanotatoR passed all quality and run time criteria of Bioconductor, where it was accepted in the April 2019 release. We evaluated nanotatoR’s annotation capabilities using publicly available reference datasets: the singleton sample NA12878, mapped with two types of enzyme labeling, and the NA24143 trio. nanotatoR was also able to accurately filter the known pathogenic variants in a cohort of patients with Duchenne Muscular Dystrophy for which we had previously demonstrated the diagnostic ability of OGM. Conclusions The extensive annotation enables users to rapidly identify potential pathogenic SVs, a critical step toward use of OGM in the clinical setting.

scholarly journals Health and longevity studies in C. elegans: the “healthy worm database” reveals strengths, weaknesses and gaps of test compound-based studies

2021 ◽  
Vol 22 (2) ◽  
pp. 215-236
Author(s):  
Nadine Saul ◽  
Steffen Möller ◽  
Francesca Cirulli ◽  
Alessandra Berry ◽  
Walter Luyten ◽  
...  
Keyword(s):  
Healthy Aging ◽  
Model Organism ◽  
Research Field ◽  
Aging Research ◽  
Genetic Manipulations ◽  
C Elegans ◽  
Starting Point ◽  
Health Related ◽  
Phenotype Measurement ◽  
Or Gene

AbstractSeveral biogerontology databases exist that focus on genetic or gene expression data linked to health as well as survival, subsequent to compound treatments or genetic manipulations in animal models. However, none of these has yet collected experimental results of compound-related health changes. Since quality of life is often regarded as more valuable than length of life, we aim to fill this gap with the “Healthy Worm Database” (http://healthy-worm-database.eu). Literature describing health-related compound studies in the aging model Caenorhabditis elegans was screened, and data for 440 compounds collected. The database considers 189 publications describing 89 different phenotypes measured in 2995 different conditions. Besides enabling a targeted search for promising compounds for further investigations, this database also offers insights into the research field of studies on healthy aging based on a frequently used model organism. Some weaknesses of C. elegans-based aging studies, like underrepresented phenotypes, especially concerning cognitive functions, as well as the convenience-based use of young worms as the starting point for compound treatment or phenotype measurement are discussed. In conclusion, the database provides an anchor for the search for compounds affecting health, with a link to public databases, and it further highlights some potential shortcomings in current aging research.

scholarly journals Evolution of Sex Determination in Caenorhabditis: Unusually High Divergence of tra-1 and Its Functional Consequences

Genetics ◽  
1996 ◽  
Vol 144 (2) ◽  
pp. 587-595 ◽  
Author(s):  
Mario de Bono ◽  
Jonathan Hodgkin
Keyword(s):  
Sex Determination ◽  
Germ Line ◽  
Amino Acid Identity ◽  
Evolution Of Sex ◽  
Phenotypic Differences ◽  
C Elegans ◽  
Functional Studies ◽  
Somatic Gonad ◽  
Functional Consequences ◽  
Significant Divergence

Abstract The tra-1 gene is a terminal regulator of somatic sex in Caenorhabditis elegans: high tra-1 activity elicits female development, low tra-1 activity elicits male development. To investigate the function and evolution of tra-1, we examined the tra-1 gene from the closely related nematode C. briggsae. Ce-tra-1 and Cb-tra-1 are unusually divergent. Each gene generates two transcripts, but only one of these is present in both species. This common transcript encodes TRA-1A, which shows only 44% amino acid identity between the species, a figure much lower than that for previously compared genes. A Cb-tra-1 transgene rescues many tissues of tra-1(nul1) mutants of C. elegans but not the somatic gonad or germ line. This transgene also causes nongonadal feminization of XO animals, indicating incorrect sexual regulation. Alignment of Ce-TRA-1A and Cb-TRA-1A defines several conserved regions likely to be important for tra-1 function. The phenotypic differences between Ce-tra-1(null) mutants rescued by Cb-tra-1 transgenes and wild-type C. elegans indicate significant divergence of regulatory regions. These molecular and functional studies suggest that evolution of sex determination in nematodes is rapid and genetically complex.

A Cuticle Collagen Encoded by the lon-3 Gene May Be a Target of TGF-β Signaling in Determining Caenorhabditis elegans Body Shape

Genetics ◽  
2002 ◽  
Vol 162 (4) ◽  
pp. 1631-1639
Author(s):  
Yo Suzuki ◽  
Gail A Morris ◽  
Min Han ◽  
William B Wood
Keyword(s):  
Caenorhabditis Elegans ◽  
Body Shape ◽  
Small Body ◽  
Dependent Manner ◽  
Loss Of Function ◽  
Cellular Mechanisms ◽  
C Elegans ◽  
Gene Expression Analyses ◽  
Dose Dependent

Abstract The signaling pathway initiated by the TGF-β family member DBL-1 in Caenorhabditis elegans controls body shape in a dose-dependent manner. Loss-of-function (lf) mutations in the dbl-1 gene cause a short, small body (Sma phenotype), whereas overexpression of dbl-1 causes a long body (Lon phenotype). To understand the cellular mechanisms underlying these phenotypes, we have isolated suppressors of the Sma phenotype resulting from a dbl-1(lf) mutation. Two of these suppressors are mutations in the lon-3 gene, of which four additional alleles are known. We show that lon-3 encodes a collagen that is a component of the C. elegans cuticle. Genetic and reporter-gene expression analyses suggest that lon-3 is involved in determination of body shape and is post-transcriptionally regulated by the dbl-1 pathway. These results support the possibility that TGF-β signaling controls C. elegans body shape by regulating cuticle composition.

scholarly journals DEBKS: A Tool to Detect Differentially Expressed Circular RNA

2020 ◽  
Author(s):  
Zelin Liu ◽  
Huiru Ding ◽  
Jianqi She ◽  
Chunhua Chen ◽  
Weiguang Zhang ◽  
...  
Keyword(s):  
Open Source ◽  
Rna Sequencing ◽  
Open Source Software ◽  
Simulated Data ◽  
Circular Rna ◽  
Host Gene ◽  
Circular Rnas ◽  
Biological Processes ◽  
Rna Seq ◽  
Disease Pathogenesis

AbstractCircular RNAs (circRNAs) are involved in various biological processes and in disease pathogenesis. However, only a small number of functional circRNAs have been identified among hundreds of thousands of circRNA species, partly because most current methods are based on circular junction counts and overlook the fact that circRNA is formed from the host gene by back-splicing (BS). To distinguish between expression originating from BS and that from the host gene, we present DEBKS, a software program to streamline the discovery of differential BS between two rRNA-depleted RNA sequencing (RNA-seq) sample groups. By applying real and simulated data and employing RT-qPCR for validation, we demonstrate that DEBKS is efficient and accurate in detecting circRNAs with differential BS events between paired and unpaired sample groups. DEBKS is available at https://github.com/yangence/DEBKS as open-source software.

scholarly journals Identification and Characterization of Circular RNAs in Longissimus Dorsi Muscle Tissue from Two Goat Breeds using RNA-Seq

2021 ◽  
Author(s):  
Jiyuan Shen ◽  
Huimin Zhen ◽  
Lu Li ◽  
Yuting Zhang ◽  
Jiqing Wang ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fiber ◽  
Muscle Development ◽  
Production Performance ◽  
Differentially Expressed ◽  
Circular Rnas ◽  
Longissimus Dorsi ◽  
Rna Seq ◽  
Skeletal Muscle Development ◽  
Fiber Size

Abstract Background: Circular RNAs (circRNAs) are a class of non-coding RNA that play crucial roles in the development of skeletal muscle. However, little is known about the role of circRNAs in caprine skeletal muscle. In this study, the muscle fiber size and expression profiles of circRNAs were compared in Longissimus dorsi muscle of Liaoning cashmere (LC) goats and Ziwuling black (ZB) goats with significant phenotypic differences in meat production performance, using hematoxylin and eosin staining and RNA-Seq, respectively.Results: The muscle fiber size in LC goats were larger than those in ZB goats (P < 0.05). A total of 10,875 circRNAs were identified and 214 of these were differentially expressed between the two caprine breeds. The authentication and expression levels of 20 circRNAs were confirmed using reverse transcriptase-polymerase chain reaction (RT-PCR) and DNA sequencing. The parent genes of differentially expressed circRNAs were mainly enriched in connective tissue development, Rap1, cGMP-PKG, cAMP and Ras signaling pathway. Some miRNAs reportedly associated with skeletal muscle development and intramuscular fat deposition would be targeted by several differentially expressed circRNAs and the most highly expressed circRNA (circ_001086).Conclusion: These results provide an improved understanding of the functions of circRNAs in skeletal muscle development of goats.

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