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A better understanding of the RNA biology and chemistry is necessary to then develop new RNA therapeutic strategies. This review is the synthesis of a series of conferences that took place during the 6th international course on post-transcriptional gene regulation at Institut Curie. This year, the course made a special focus on RNA chemistry., (Copyright © 2024.)

The recognition of polyadenylation signals (PAS) in eukaryotic pre-mRNAs is usually coupled to transcription termination, occurring while pre-mRNA is chromatin-bound. However, for some pre-mRNAs, this 3'-end processing occurs post-transcriptionally, i.e., through a co-transcriptional cleavage (CoTC) event downstream of the PAS, leading to chromatin release and subsequent PAS cleavage in the nucleoplasm. While DNA-damaging agents trigger the shutdown of co-transcriptional chromatin-associated 3'-end processing, specific compensatory mechanisms exist to ensure efficient 3'-end processing for certain pre-mRNAs, including those that encode proteins involved in the DNA damage response, such as the tumor suppressor p53. We show that cleavage at the p53 polyadenylation site occurs in part post-transcriptionally following a co-transcriptional cleavage event. Cells with an engineered deletion of the p53 CoTC site exhibit impaired p53 3'-end processing, decreased mRNA and protein levels of p53 and its transcriptional target p21, and altered cell cycle progression upon UV-induced DNA damage. Using a transcriptome-wide analysis of PAS cleavage, we identify additional pre-mRNAs whose PAS cleavage is maintained in response to UV irradiation and occurring post-transcriptionally. These findings indicate that CoTC-type cleavage of pre-mRNAs, followed by PAS cleavage in the nucleoplasm, allows certain pre-mRNAs to escape 3'-end processing inhibition in response to UV-induced DNA damage., (© 2023 The Authors. Published under the terms of the CC BY 4.0 license.)

Intronic polyadenylation (IPA) isoforms, which contain alternative last exons, are widely regulated in various biological processes and by many factors. However, little is known about their cytoplasmic regulation and translational status. In this study, we provide the first evidence that the genome-wide patterns of IPA isoform regulation during a biological process can be very distinct between the transcriptome and translatome, and between the nucleus and cytosol. Indeed, by 3'-seq analyses on breast cancer cells, we show that the genotoxic anticancer drug, doxorubicin, preferentially down-regulates the IPA to the last-exon (IPA:LE) isoform ratio in whole cells (as previously reported) but preferentially up-regulates it in polysomes. We further show that in nuclei, doxorubicin almost exclusively down-regulates the IPA:LE ratio, whereas in the cytosol, it preferentially up-regulates the isoform ratio, as in polysomes. Then, focusing on IPA isoforms that are up-regulated by doxorubicin in the cytosol and highly translated (up-regulated and/or abundant in polysomes), we identify several IPA isoforms that promote cell survival to doxorubicin. Mechanistically, by using an original approach of condition- and compartment-specific CLIP-seq (CCS-iCLIP) to analyze ELAVL1-RNA interactions in the nucleus and cytosol in the presence and absence of doxorubicin, as well as 3'-seq analyses upon ELAVL1 depletion, we show that the RNA-binding protein ELAVL1 mediates both nuclear down-regulation and cytosolic up-regulation of the IPA:LE isoform ratio in distinct sets of genes in response to doxorubicin. Altogether, these findings reveal differential regulation of the IPA:LE isoform ratio across subcellular compartments during drug response and its coordination by an RNA-binding protein., (© 2022 Chakraborty et al.; Published by Cold Spring Harbor Laboratory Press.)

Targeting the translation initiation complex eIF4F, which binds the 5' cap of mRNAs, is a promising anti-cancer approach. Silvestrol, a small molecule inhibitor of eIF4A, the RNA helicase component of eIF4F, inhibits the translation of the mRNA encoding the signal transducer and activator of transcription 1 (STAT1) transcription factor, which, in turn, reduces the transcription of the gene encoding one of the major immune checkpoint proteins, i.e., programmed death ligand-1 (PD-L1) in melanoma cells. A large proportion of human genes produce multiple mRNAs differing in their 3'-ends through the use of alternative polyadenylation (APA) sites, which, when located in alternative last exons, can generate protein isoforms, as in the STAT1 gene. Here, we provide evidence that the STAT1α, but not STAT1β protein isoform generated by APA, is required for silvestrol-dependent inhibition of PD-L1 expression in interferon-γ-treated melanoma cells. Using polysome profiling in activated T cells we find that, beyond STAT1, eIF4A inhibition downregulates the translation of some important immune-related mRNAs, such as the ones encoding TIM-3, LAG-3, IDO1, CD27 or CD137, but with little effect on the ones for BTLA and ADAR-1 and no effect on the ones encoding CTLA-4, PD-1 and CD40-L. We next apply RT-qPCR and 3'-seq (RNA-seq focused on mRNA 3' ends) on polysomal RNAs to analyze in a high throughput manner the effect of eIF4A inhibition on the translation of APA isoforms. We identify about 150 genes, including TIM-3, LAG-3, AHNAK and SEMA4D, for which silvestrol differentially inhibits the translation of APA isoforms in T cells. It is therefore crucial to consider 3'-end mRNA heterogeneity in the understanding of the anti-tumor activities of eIF4A inhibitors.

Objectives: COVID-19 vaccines have become the new hope for stemming the pandemic. We aimed to assess pre-launch vaccine acceptance among hospital workers in the Auvergne-Rhône-Alpes Administrative Region of France., Methods: We performed a cross sectional study involving all hospital workers in 11 Auvergne-Rhône-Alpes hospitals in December 2020. Univariate and multivariate analyses were performed to identify factors associated with vaccine hesitancy., Results: We analyzed completed questionnaires from 1,964 respondents (78% women, mean age 42 years, 21.5% physicians, 41% private care centers). A total of 1,048 (53%) hospital workers were in favor of COVID-19 vaccination. Vaccine hesitancy was associated with: female gender; young age; paramedical, technical, and administrative professions (i.e., all non-medical professions); no prior flu vaccination; and employment in the private medical care sector (p<0.05). Distrust of health authorities and pharmaceutical lobbying were the main obstacles to vaccination. Inversely, creating herd immunity and protecting patients and household members were the most frequently cited reasons in favor of vaccination. More than two-thirds of participants feared that the clinical and biological research was too rapid and worried about serious adverse effects. Most participants were interested in written information on the available vaccines, but the most vaccine-hesitant categories preferred oral information. Only 35% supported mandatory vaccination., Conclusions: Targeted written and oral information campaigns will be necessary to improve vaccination coverage among hospital workers who show a surprisingly high hesitancy rate. Imposing mandatory vaccination could be counterproductive., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

The 3'-end processing of most pre-messenger RNAs (pre-mRNAs) involves RNA cleavage and polyadenylation and is coupled to transcription termination. In both yeast and human cells, pre-mRNA 3'-end cleavage is globally inhibited by DNA damage. Recently, further links between pre-mRNA 3'-end processing and the control of genome stability have been uncovered, as reviewed here. Upon DNA damage, various genes related to the DNA damage response (DDR) escape 3'-end processing inhibition or are regulated through alternative polyadenylation (APA). Conversely, various pre-mRNA 3'-end processing factors prevent genome instability and are found at sites of DNA damage. Finally, the reciprocal link between pre-mRNA 3'-end processing and genome stability control seems important because it is conserved in evolution and involved in disease development., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

ERG family proteins (ERG, FLI1 and FEV) are a subfamily of ETS transcription factors with key roles in physiology and development. In Ewing sarcoma, the oncogenic fusion protein EWS-FLI1 regulates both transcription and alternative splicing of pre-messenger RNAs. However, whether wild-type ERG family proteins might regulate splicing is unknown. Here, we show that wild-type ERG proteins associate with spliceosomal components, are found on nascent RNAs, and induce alternative splicing when recruited onto a reporter minigene. Transcriptomic analysis revealed that ERG and FLI1 regulate large numbers of alternative spliced exons (ASEs) enriched with RBFOX2 motifs and co-regulated by this splicing factor. ERG and FLI1 are associated with RBFOX2 via their conserved carboxy-terminal domain, which is present in EWS-FLI1. Accordingly, EWS-FLI1 is also associated with RBFOX2 and regulates ASEs enriched in RBFOX2 motifs. However, in contrast to wild-type ERG and FLI1, EWS-FLI1 often antagonizes RBFOX2 effects on exon inclusion. In particular, EWS-FLI1 reduces RBFOX2 binding to the ADD3 pre-mRNA, thus increasing its long isoform, which represses the mesenchymal phenotype of Ewing sarcoma cells. Our findings reveal a RBFOX2-mediated splicing regulatory function of wild-type ERG family proteins, that is altered in EWS-FLI1 and contributes to the Ewing sarcoma cell phenotype., (© The Author(s) 2021. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Thermococcus gammatolerans EJ3 is an extremophile archaeon which was revealed as one of the most radioresistant organisms known on Earth, withstanding up to 30 kGy gamma-ray radiations. While its theoretical proteome is rather small, T. gammatolerans may enhance its toolbox by post-translational modification of its proteins. Here, we explored its extent of Nε-acetylation of lysines. For this, we immunopurified with two acetylated-lysine antibodies the acetylated peptides resulting from a proteolysis of soluble proteins with trypsin. The comparison of acetylated proteomes of two archaea highlights some common acetylation patterns but only 4 out of 26 orthologous proteins found to be acetylated in both species, are acetylated on the same lysine site. We evidenced that histone B is acetylated in T. gammatolerans at least at two different sites (K27 and K36), and a peptide common at the C-terminus of histones A and B is also acetylated. We verified that acetylation of histones is a common trait among Thermococcales after recording data on Thermococcus kodakaraensis histones and identifying three acetylated sites. This discovery reinforces the strong evolutionary link between Archaea and Eukaryotes and should be an incentive for further investigation on the extent and role of acetylation of histones in Archaea. SIGNIFICANCE: Acetylation is an important post-translational modification of proteins that has been extensively described in Eukaryotes, and more recently in Bacteria. Here, we report for the first time ever that histones in Archaea are also modified by acetylation after a systematic survey of acetylated peptides in Thermococcus gammatolerans. Structural models of histones A and B indicates that acetylation of the identified modified residues may play an important role in histone assembly and/or interaction with DNA. The in-depth protein acetylome landscape in T. gammatolerans includes at least 181 unique protein sequences, some of them being modified on numerous residues. Proteins involved in metabolic processes, information storage and processing mechanisms are over-represented categories in this dataset, highlighting the ancient role of this protein post-translational modification in primitive cells., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Besides analyses of specific alternative splicing (AS) variants, little is known about AS regulatory pathways and programs involved in anticancer drug resistance. Doxorubicin is widely used in breast cancer chemotherapy. Here, we identified 1723 AS events and 41 splicing factors regulated in a breast cancer cell model of acquired resistance to doxorubicin. An RNAi screen on splicing factors identified the little studied ZRANB2 and SYF2, whose depletion partially reversed doxorubicin resistance. By RNAi and RNA-seq in resistant cells, we found that the AS programs controlled by ZRANB2 and SYF2 were enriched in resistance-associated AS events, and converged on the ECT2 splice variant including exon 5 (ECT2-Ex5+). Both ZRANB2 and SYF2 were found associated with ECT2 pre-messenger RNA, and ECT2-Ex5+ isoform depletion reduced doxorubicin resistance. Following doxorubicin treatment, resistant cells accumulated in S phase, which partially depended on ZRANB2, SYF2 and the ECT2-Ex5+ isoform. Finally, doxorubicin combination with an oligonucleotide inhibiting ECT2-Ex5 inclusion reduced doxorubicin-resistant tumor growth in mouse xenografts, and high ECT2-Ex5 inclusion levels were associated with bad prognosis in breast cancer treated with chemotherapy. Altogether, our data identify AS programs controlled by ZRANB2 and SYF2 and converging on ECT2, that participate to breast cancer cell resistance to doxorubicin., (© The Author(s) 2020. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Upon DNA damage, cells trigger an early DNA-damage response (DDR) involving DNA repair and cell cycle checkpoints, and late responses involving gene expression regulation that determine cell fate. Screens for genes involved in the DDR have found many RNA-binding proteins (RBPs), while screens for novel RBPs have identified DDR proteins. An increasing number of RBPs are involved in early and/or late DDR. We propose to call this new class of actors of the DDR, which contain an RNA-binding activity, DNA-damage response RNA-binding proteins (DDRBPs). We then discuss how DDRBPs contribute not only to gene expression regulation in the late DDR but also to early DDR signaling, DNA repair, and chromatin modifications at DNA-damage sites through interactions with both long and short noncoding RNAs., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

5-Fluorouracil (5-FU) is a widely used chemotherapeutic drug in colorectal cancer. Previous studies showed that 5-FU modulates RNA metabolism and mRNA expression. In addition, it has been reported that 5-FU incorporates into the RNAs constituting the translational machinery and that 5-FU affects the amount of some mRNAs associated with ribosomes. However, the impact of 5-FU on translational regulation remains unclear. Using translatome profiling, we report that a clinically relevant dose of 5-FU induces a translational reprogramming in colorectal cancer cell lines. Comparison of mRNA distribution between polysomal and non-polysomal fractions in response to 5-FU treatment using microarray quantification identified 313 genes whose translation was selectively regulated. These regulations were mostly stimulatory (91%). Among these genes, we showed that 5-FU increases the mRNA translation of HIVEP2, which encodes a transcription factor whose translation in normal condition is known to be inhibited by mir-155. In response to 5-FU, the expression of mir-155 decreases thus stimulating the translation of HIVEP2 mRNA. Interestingly, the 5-FU-induced increase in specific mRNA translation was associated with reduction of global protein synthesis. Altogether, these findings indicate that 5-FU promotes a translational reprogramming leading to the increased translation of a subset of mRNAs that involves at least for some of them, miRNA-dependent mechanisms. This study supports a still poorly evaluated role of translational control in drug response.

Backgroud: Small metallic nanoparticles are proposed as potential nanodrugs to optimize the performances of radiotherapy. This strategy, based on the enrichment of tumours with nanoparticles to amplify radiation effects in the tumour, aims at increasing the cytopathic effect in tumours while healthy tissue is preserved, an important challenge in radiotherapy. Another major cause of radiotherapy failure is the radioresistance of certain cancers. Surprisingly, the use of nanoparticles to overcome radioresistance has not, to the best of our knowledge, been extensively investigated. The mechanisms of radioresistance have been extensively studied using Deinococcus radiodurans , the most radioresistant organism ever reported, as a model., Methods: In this work, we investigated the impact of ultra-small platinum nanoparticles (1.7 nm) on this organism, including uptake, toxicity, and effects on radiation responses., Results: We showed that the nanoparticles penetrate D. radiodurans cells, despite the 150 nm cell wall thickness with a minimal inhibition concentration on the order of 4.8 mg L -1 . We also found that the nanoparticles amplify gamma ray radiation effects by >40%., Conclusions: Finally, this study demonstrates the capacity of metallic nanoparticles to amplify radiation in radioresistant organisms, thus opening the perspective to use nanoparticles not only to improve tumour targeting but also to overcome radioresistance.

The hyperthermophilic archaeon Thermococcus gammatolerans can resist huge doses of γ-irradiation, up to 5.0 kGy, without loss of viability. The potential to withstand such harsh conditions is probably due to complementary passive and active mechanisms, including repair of damaged chromosomes. In this work, we documented the formation and repair of oxidative DNA lesions in T. gammatolerans. The basal level of the oxidized nucleoside, 8-oxo-2'-deoxyguanosine (8-oxo-dGuo), was established at 9.2 (± 0.9) 8-oxo-dGuo per 10 6 nucleosides, a higher level than those usually measured in eukaryotic cells or bacteria. A significant increase in oxidative damage, i.e., up to 24.2 (± 8.0) 8-oxo-dGuo/10 6 nucleosides, was measured for T. gammatolerans exposed to a 5.0 kGy dose of γ-rays. Surprisingly, the yield of radiation-induced modifications was lower than those previously observed for human cells exposed to doses corresponding to a few grays. One hour after irradiation, 8-oxo-dGuo levels were significantly reduced, indicating an efficient repair. Two putative base excision repair (BER) enzymes, TGAM&#95;1277 and TGAM&#95;1653, were demonstrated both by proteomics and transcriptomics to be present in the cells without exposure to ionizing radiation. Their transcripts were moderately upregulated after gamma irradiation. After heterologous production and purification of these enzymes, biochemical assays based on electrophoresis and MALDI-TOF (matrix-assisted laser desorption ionization-time of flight) mass spectrometry indicated that both have a β-elimination cleavage activity. TGAM&#95;1653 repairs 8-oxo-dGuo, whereas TGAM&#95;1277 is also able to remove lesions affecting pyrimidines (1-[2-deoxy-β-d-erythro-pentofuranosyl]-5-hydroxyhydantoin (5-OH-dHyd) and 1-[2-deoxy-β-d-erythro-pentofuranosyl]-5-hydroxy-5-methylhydantoin (5-OH-5-Me-dHyd)). This work showed that in normal growth conditions or in the presence of a strong oxidative stress, T. gammatolerans has the potential to rapidly reduce the extent of DNA oxidation, with at least these two BER enzymes as bodyguards with distinct substrate ranges.

While the rapid spread of Zika virus (ZIKV) in South America has been declared a public health emergency few data are available on the kinetics of the virus load and the specific antibodies in individual patients. This report describes the kinetics of ZIKV decay in the body compartments and the kinetics of anti ZIKV IgG and IgM of two people returning from Martinique, French West Indies. ZIKV remained detectable in the plasma for roughly 2 weeks indicating that mosquito control measures should be prolonged accordingly. Remarkably, their urine samples consistently tested positive for even longer. The antibodies responses were different between the two patients but for both the rapid onset of IgM allowed a diagnosis from the end of the first week., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Mastocytosis is a heterogeneous group of diseases with a young median age at diagnosis. Usually indolent and self-limited in childhood, the disease can exhibit aggressive progression in mid-adulthood. Our objectives were to describe the characteristics of the disease when diagnosed among elderly patients, for which rare data are available.The French Reference Center conducted a retrospective multicenter study on 53 patients with mastocytosis >69 years of age, to describe their clinical, biological, and genetic features.The median age of our cohort of patients was 75 years. Mastocytosis variants included were cutaneous (n = 1), indolent systemic (n = 5), aggressive systemic (n = 11), associated with a hematological non-mast cell disease (n = 34), and mast cell leukemia (n = 2). Clinical manifestations were predominantly mast cell activation symptoms (75.5%), poor performance status (50.9%), hepatosplenomegaly (50.9%), skin involvement (49.1%), osteoporosis (47.2%), and portal hypertension and ascites (26.4%). The main biological features were anemia (79.2%), thrombocytopenia (50.9%), leucopenia (20.8%), and liver enzyme abnormalities (32.1%). Of the 40 patients tested, 34 (85%), 2 (5%), and 4 (10%) exhibited the KIT D816V mutant, other KIT mutations and the wild-type form of the KIT gene, respectively. Additional sequencing detected significant genetic defects in 17 of 26 (65.3%) of the patients with associated hematological non-mast cell disease, including TET2, SRSF2, IDH2, and ASLX1 mutations. Death occurred in 19 (35.8%) patients, within a median delay of 9 months, despite the different treatment options available.Mastocytosis among elderly patients has a challenging early detection, rare skin involvement, and/or limited skin disease; it is heterogeneous and has often an aggressive presentation with nonfortuitous associated myeloid lineage malignant clones, and thus a poor overall prognosis., Competing Interests: The authors report no conflicts of interest.

Hotspot mutations in the spliceosome gene SF3B1 are reported in ∼20% of uveal melanomas. SF3B1 is involved in 3'-splice site (3'ss) recognition during RNA splicing; however, the molecular mechanisms of its mutation have remained unclear. Here we show, using RNA-Seq analyses of uveal melanoma, that the SF3B1(R625/K666) mutation results in deregulated splicing at a subset of junctions, mostly by the use of alternative 3'ss. Modelling the differential junctions in SF3B1(WT) and SF3B1(R625/K666) cell lines demonstrates that the deregulated splice pattern strictly depends on SF3B1 status and on the 3'ss-sequence context. SF3B1(WT) knockdown or overexpression do not reproduce the SF3B1(R625/K666) splice pattern, qualifying SF3B1(R625/K666) as change-of-function mutants. Mutagenesis of predicted branchpoints reveals that the SF3B1(R625/K666)-promoted splice pattern is a direct result of alternative branchpoint usage. Altogether, this study provides a better understanding of the mechanisms underlying splicing alterations induced by mutant SF3B1 in cancer, and reveals a role for alternative branchpoints in disease.

Here, we have developed an extremely efficient in vivo Tn5-based mutagenesis procedure to construct a Deinococcus radiodurans insertion mutant library subsequently screened for sensitivity to genotoxic agents such as γ and UV radiations or mitomycin C. The genes inactivated in radiosensitive mutants belong to various functional categories, including DNA repair functions, stress responses, signal transduction, membrane transport, several metabolic pathways, and genes of unknown function. Interestingly, preliminary characterization of previously undescribed radiosensitive mutants suggests the contribution of cyclic di-AMP signaling in the recovery of D. radiodurans cells from genotoxic stresses, probably by modulating several pathways involved in the overall cell response. Our analyses also point out a new transcriptional regulator belonging to the GntR family, encoded by DR0265, and a predicted RNase belonging to the newly described Y family, both contributing to the extreme radioresistance of D. radiodurans. Altogether, this work has revealed new cell responses involved either directly or indirectly in repair of various cell damage and confirmed that D. radiodurans extreme radiation resistance is determined by a multiplicity of pathways acting as a complex network.

Objective: This study aims to evaluate the response to rituximab (RTX) treatment in auto-immune hemolytic anemia (AIHA) patients., Methods: Studies were selected from MEDLINE up to March 2014. Two investigators independently extracted data on study design, patient characteristics, clinical features (AIHA type, disease duration, previous treatments), dose-schedule of rituximab, duration of treatment follow-up, and toxicities. Pooled overall response rate (ORR) and complete response (CR) rates were evaluated to determine RTX efficacy and toxicity by calculating the weighted mean proportion with fixed or random-effects models in case of heterogeneity (p<0.1 or I(2)>50%)., Results: Twenty-one studies encompassing 409 patients were included in the meta-analysis. The characteristics of the entire analyzed cohort reported were as follows: mean male proportion: 43%, mean age: 50 years, splenectomized patients range: 0-50%. Warm AIHA, primary AIHA and adults were mostly represented. With the random-effect model, the overall response rate (ORR) was 73% (95% CI 64-81%, 20 studies encompassing 402 patients). CR rate was 37% (95% CI 26-49%, 20 studies including 397 patients). The ORRs were close to 70% for warm AIHA (79%, 95% CI 60-90%, 11 studies, 154 patients), primary AIHA (67%, 95% CI 49-81%, 10 studies, 161 patients), and secondary AIHA (72%, 95% CI 60-82%, 8 studies, 66 patients). The ORR was 57% (95% CI 47-66%, 6 studies, 109 patients) for cold agglutinin disease (CAD). The CR rate was 42% (95% CI 27-58%, 11 studies, 154 patients) for warm AHAI, 32% (95% CI 17-51%, 11 studies, 176 patients) for primary AIHA, 46% (95% CI 30-62%, 9 studies, 87 patients) for secondary AIHA and only 21% (95% CI 6-51%, 7 studies, 118 patients) for CAD. Definitive response rates were evaluated during follow-up. CR rate was the highest within 2 to 4 months after RTX (13 studies, 203 patients, CR=70% [57-80%]). As for toxicities, 38 adverse events in 364 patients were noted (14% (95% CI 9-21%)). Sixteen events were infusion-linked side effects, mostly chills and fever, whereas twenty-two were severe. Only one opportunistic Pneumocystis jiroveci pneumonia was reported. Seventeen patients out of 364 (4.6%) died during follow-up. In univariate mixed-effect meta-regressions, ORR and CR were significantly associated with warm AIHA (p=0.002) and mean age (p<0.001), and marginally associated with disease type (p=0.06 and 0.005, respectively)., Conclusions: Rituximab seems to be a safe and effective therapy for AIHA in this meta-analysis of observational studies. The authors suggest that it could be used at an earlier point in therapy, before more toxic immunosuppressive drugs, or in place of splenectomy in some cases., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Objective: To describe the clinical spectrum associated with aminoacyl-transfer RNA synthetase (ARS) autoantibodies in patients with idiopathic inflammatory myositis defined according to Peter and Bohan's criteria., Methods: Cohort studies were selected from MEDLINE and Embase up to August 2013. Two investigators independently extracted data on study design, patient characteristics, and clinical features (interstitial lung disease [ILD], fever, mechanic's hands [MH], Raynaud's phenomenon [RPh], arthralgia, sclerodactyly, cancer and dermatomyositis-specific rash) according to the presence of myositis-specific (anti-aminoacyl-transfer RNA synthetase [ARS], anti-signal recognition particle [anti-SRP] and anti-Mi2) and myositis-associated (anti-PM/Scl, anti-U1-RNP and anti-Ku) autoantibodies., Results: 27 studies (3487 patients) were included in the meta-analysis. Arthralgia (75%, CI 67-81) and ILD (69%, CI 63-74) were the most prevalent clinical signs associated with anti-ARS autoantibodies. Anti-Mi2 and anti-SRP autoantibodies were associated with few extramuscular signs. ARS autoantibodies were identified in 13% of patients with cancer-associated myositis (5-25). Patients with non-anti-Jo1 ARS had greater odds of presenting fever (RR 0.63, CI 0.52-0.90) and ILD (RR 0.87, CI 0.81-0.93) compared to those with anti-Jo1 autoantibodies. The frequencies of myositis (RR 1.60, CI 1.38-1.85), arthralgia (RR 1.52, CI 1.32-1.76) and MH (RR 1.47, CI 1.11-1.94) were almost 50% higher in patients with anti-Jo1 compared to non-anti-Jo1 ARS autoantibodies. Patients with anti-PM/Scl differed from those with anti-ARS autoantibodies by a greater prevalence of RPh (RR 0.70, CI 0.53-0.94) and sclerodactyly (RR 0.47, CI 0.25-0.89). ILD was less frequent in patients with anti-U1-RNP autoantibodies (RR 3.35, CI 1.07-10.43). No difference was observed between anti-ARS and myositis-associated autoantibodies for other outcomes., Conclusions: The presence of anti-ARS autoantibodies delimits a heterogeneous subset of patients with a high prevalence of myositis, MH, arthralgia in anti-Jo1 patients, and RPh and fever in non-anti-Jo1 patients. The clinical signs of populations positive for anti-PM/Scl and anti-ARS autoantibodies largely overlap, especially with regard to ILD, challenging the clinical delimitation of the antisynthetase syndrome., (Copyright © 2014 Elsevier B.V. All rights reserved.)