Single-Cell RNA Sequencing Identifies WARS1+ Mesenchymal Stem Cells with Enhanced Immunomodulatory Capacity and Improved Therapeutic Efficacy.

Psoriasis is a common inflammatory skin disorder with no cure. Mesenchymal stem cells (MSCs) have immunomodulatory properties for psoriasis, but the therapeutic efficacies varied, and the molecular mechanisms were unknown. In this study, we improved the efficacy by enhancing the immunomodulatory effects of umbilical cord-derived MSCs (UC-MSCs). UC-MSCs stimulated by TNF-α and IFN-γ exhibited a better therapeutic effect in a mouse model of psoriasis. Single-cell RNA sequencing revealed that the stimulated UC-MSCs overrepresented a subpopulation expressing high tryptophanyl-tRNA synthetase 1 (WARS1). WARS1-overexpressed UC-MSCs treat psoriasis-like skin inflammation more efficiently than control UC-MSCs by restraining the proinflammatory macrophages. Mechanistically, WARS1 maintained a RhoA-Akt axis and governed the immunomodulatory properties of UC-MSCs. Together, we identify WARS1 as a master regulator of UC-MSCs with enhanced immunomodulatory capacities, which paves the way for the directed modification of UC-MSCs for escalated therapeutic efficacy.

Pseudorabies virus manipulates mitochondrial tryptophanyl-tRNA synthetase 2 for viral replication.

The pseudorabies virus (PRV) is identified as a double-helical DNA virus responsible for causing Aujeszky's disease, which results in considerable economic impacts globally. The enzyme tryptophanyl-tRNA synthetase 2 (WARS2), a mitochondrial protein involved in protein synthesis, is recognized for its broad expression and vital role in the translation process. The findings of our study showed an increase in both mRNA and protein levels of WARS2 following PRV infection in both cell cultures and animal models. Suppressing WARS2 expression via RNA interference in PK-15 â€‹cells led to a reduction in PRV infection rates, whereas enhancing WARS2 expression resulted in increased infection rates. Furthermore, the activation of WARS2 in response to PRV was found to be reliant on the cGAS/STING/TBK1/IRF3 signaling pathway and the interferon-alpha receptor-1, highlighting its regulation via the type I interferon signaling pathway. Further analysis revealed that reducing WARS2 levels hindered PRV's ability to promote protein and lipid synthesis. Our research provides novel evidence that WARS2 facilitates PRV infection through its management of protein and lipid levels, presenting new avenues for developing preventative and therapeutic measures against PRV infections.

Indole Propionic Acid Disturbs the Normal Function of Tryptophanyl-tRNA Synthetase in Mycobacterium tuberculosis.

Tuberculosis (TB) is the leading infectious disease caused by Mycobacterium tuberculosis and the second-most contagious killer after COVID-19. The emergence of drug-resistant TB has caused a great need to identify and develop new anti-TB drugs with novel targets. Indole propionic acid (IPA), a structural analog of tryptophan (Trp), is active against M. tuberculosis in vitro and in vivo. It has been verified that IPA exerts its antimicrobial effect by mimicking Trp as an allosteric inhibitor of TrpE, which is the first enzyme in the Trp synthesis pathway of M. tuberculosis. However, other Trp structural analogs, such as indolmycin, also target tryptophanyl-tRNA synthetase (TrpRS), which has two functions in bacteria: synthesis of tryptophanyl-AMP by catalyzing ATP + Trp and producing Trp-tRNATrp by transferring Trp to tRNATrp. So, we speculate that IPA may also target TrpRS. In this study, we found that IPA can dock into the Trp binding pocket of M. tuberculosis TrpRS (TrpRSMtb), which was further confirmed by isothermal titration calorimetry (ITC) assay. The biochemical analysis proved that TrpRS can catalyze the reaction between IPA and ATP to generate pyrophosphate (PPi) without Trp as a substrate. Overexpression of wild-type trpS in M. tuberculosis increased the MIC of IPA to 32-fold, and knock-down trpS in Mycolicibacterium smegmatis made it more sensitive to IPA. The supplementation of Trp in the medium abrogated the inhibition of M. tuberculosis by IPA. We demonstrated that IPA can interfere with the function of TrpRS by mimicking Trp, thereby impeding protein synthesis and exerting its anti-TB effect.

Clinical Significance of Tryptophanyl-tRNA Synthetase 1 Gene Expression in Patients With Locally Advanced Gastric Cancer.

BACKGROUND/AIM: The tryptophanyl-tRNA synthetase 1 gene (WARS1), encodes a tryptophan-tRNA synthetase involved in the amino acidification of tryptophan-tRNA and has been reported to be involved in cancer cell growth, metastasis promotion, and drug resistance in a variety of cancers. This study investigated the clinical significance of WARS1 expression as a biomarker in gastric cancer tissues obtained from patients with locally advanced gastric cancer (GC) who underwent radical resection. PATIENTS AND METHODS: WARS1 expression in GC tissues and adjacent normal gastric mucosa of 253 patients with pStage II/III GC who underwent curative resection was determined using quantitative polymerase chain reaction (PCR). Association of WARS1 expression levels, categorized into high and low expression based on the median expression levels, with clinicopathological factors and overall survival (OS) of these patients was assessed. RESULTS: The low-WARS1 expression group had significantly higher serosal invasion, lymph node metastasis, lymphatic invasion, venous invasion, and pathological stage than did the high-WARS1 expression group. OS was significantly worse in the low- than in the high-WARS1 expression group (5-year survival 52.2% vs. 75.9%; p=0.0001). Furthermore, in multivariate analysis, low WARS1 expression was an independent predictor for poor OS (hazard ratio=2.101; 95% confidence interval=1.328-3.322; p=0.002). CONCLUSION: In patients with locally advanced GC, after curative resection, WARS1 expression in GC tissue may be a useful prognostic marker.

Tryptophanyl-Transfer RNA Synthetase Is Involved in a Negative Feedback Loop Mitigating Interferon-γ-Induced Gene Expression.

Aminoacyl-tRNA synthetases (aaRSs) are essential enzymes responsible for linking a transfer RNA (tRNA) with its cognate amino acid present in all the kingdoms of life. Besides their aminoacyl-tRNA synthetase activity, it was described that many of these enzymes can carry out non-canonical functions. They were shown to be involved in important biological processes such as metabolism, immunity, development, angiogenesis and tumorigenesis. In the present work, we provide evidence that tryptophanyl-tRNA synthetase might be involved in a negative feedback loop mitigating the expression of certain interferon-γ-induced genes. Mining the available TCGA and Gtex data, we found that WARS was highly expressed in cutaneous melanoma (SKCM) compared to other cancers and is of good prognosis for this particular cancer type. WARS expression correlates with genes involved in antigen processing and presentation but also transcription factors involved in IFN-γ signaling such as STAT1. In addition, WARS was found in complex with STAT1 in A375 cells treated with IFN-γ. Finally, we showed that knocking down WARS expression during IFN-γ stimulation further increases the expression of GBP2, APOL1, ISG15, HLA-A and IDO1.

Highly secreted tryptophanyl tRNA synthetase 1 as a potential theranostic target for hypercytokinemic severe sepsis.

Despite intensive clinical and scientific efforts, the mortality rate of sepsis remains high due to the lack of precise biomarkers for patient stratification and therapeutic guidance. Secreted human tryptophanyl-tRNA synthetase 1 (WARS1), an endogenous ligand for Toll-like receptor (TLR) 2 and TLR4 against infection, activates the genes that signify the hyperinflammatory sepsis phenotype. High plasma WARS1 levels stratified the early death of critically ill patients with sepsis, along with elevated levels of cytokines, chemokines, and lactate, as well as increased numbers of absolute neutrophils and monocytes, and higher Sequential Organ Failure Assessment (SOFA) scores. These symptoms were recapitulated in severely ill septic mice with hypercytokinemia. Further, injection of WARS1 into mildly septic mice worsened morbidity and mortality. We created an anti-human WARS1-neutralizing antibody that suppresses proinflammatory cytokine expression in marmosets with endotoxemia. Administration of this antibody into severe septic mice attenuated cytokine storm, organ failure, and early mortality. With antibiotics, the antibody almost completely prevented fatalities. These data imply that blood-circulating WARS1-guided anti-WARS1 therapy may provide a novel theranostic strategy for life-threatening systemic hyperinflammatory sepsis.

Tryptophan-Starved Human Cells Overexpressing Tryptophanyl-tRNA Synthetase Enhance High-Affinity Tryptophan Uptake via Enzymatic Production of Tryptophanyl-AMP.

Our previous study demonstrated that L-tryptophan (Trp)-depleted cells display a marked enhancement in Trp uptake facilitated by extracellular tryptophanyl-tRNA synthetase (TrpRS). Here, we show that Trp uptake into TrpRS-overexpressing cells is also markedly elevated upon Trp starvation. These findings indicate that a Trp-deficient condition is critical for Trp uptake, not only into cells to which TrpRS protein has been added but also into TrpRS-overexpressing cells. We also show that overexpression of TrpRS mutants, which cannot synthesize tryptophanyl-AMP, does not promote Trp uptake, and that inhibition of tryptophanyl-AMP synthesis suppresses this uptake. Overall, these data suggest that tryptophanyl-AMP production by TrpRS is critical for high-affinity Trp uptake.

Exploring the role of tryptophanyl-tRNA synthetase and associations with inflammatory markers and clinical outcomes in COVID-19 patients: A case-control study.

Tryptophanyl-tRNA synthetase (WRS) is a critical enzyme involved in protein synthesis, responsible for charging tRNA with the essential amino acid tryptophan. Recent studies have highlighted its novel role in stimulating innate immunity against bacterial and viral infections. However, the significance of WRS in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection remains elusive. In this study, we aimed to investigate the complex interplay between WRS, inflammatory markers, Toll-like receptor-4 (TLR-4), and clinical outcomes in coronavirus disease 19 (COVID-19) patients. A case-control investigation comprised 127 COVID-19 patients, carefully classified as severe or moderate upon admission, and 112 healthy individuals as a comparative group. Blood samples were meticulously collected before treatment initiation, and WRS, interleukin-6 (IL-6), and C-reactive protein (CRP) concentrations were quantified using a well-established commercial ELISA kit. Peripheral blood mononuclear cells (PBMCs) were isolated from the blood samples, and RNA was extracted for cDNA synthesis. Semi-quantitative real-time polymerase chain reaction (PCR) was employed to assess the relative expression of TLR-4. COVID-19 patients exhibited elevated levels of WRS, IL-6, CRP, and TLR-4 expression compared to healthy individuals, with the severe group displaying significantly higher levels than the moderate group. Notably, severe patients demonstrated substantial fluctuations in CRP, IL-6, and WRS levels over time, a pattern not observed in their moderate counterparts. Although no significant distinctions were observed in the dynamic alterations of WRS, IL-6, CRP, and TLR-4 expression between deceased and surviving patients, a trend emerged indicating higher IL-6_1 levels in deceased patients and elevated lactate dehydrogenase (LDH) levels in severe patients who succumbed to the disease. This pioneering research highlights the dynamic alterations of WRS in COVID-19 patients, providing valuable insights into the correlation between WRS, inflammatory markers, and disease severity within this population. Understanding the role of WRS in SARS-CoV-2 infection may open new avenues for therapeutic interventions targeting innate immunity to combat COVID-19.

An asymmetric structure of bacterial TrpRS supports the half-of-the-sites catalytic mechanism and facilitates antimicrobial screening.

Tryptophanyl-tRNA synthetase (TrpRS) links tryptophan to tRNATrp, thereby playing an indispensable role in protein translation. Unlike most class I aminoacyl-tRNA synthetases (AARSs), TrpRS functions as a homodimer. Herein, we captured an 'open-closed' asymmetric structure of Escherichia coli TrpRS (EcTrpRS) with one active site occupied by a copurified intermediate product and the other remaining empty, providing structural evidence for the long-discussed half-of-the-sites reactivity of bacterial TrpRS. In contrast to its human counterpart, bacterial TrpRS may rely on this asymmetric conformation to functionally bind with substrate tRNA. As this asymmetric conformation is probably a dominant form of TrpRS purified from bacterial cells, we performed fragment screening against asymmetric EcTrpRS to support antibacterial discovery. Nineteen fragment hits were identified, and 8 of them were successfully cocrystallized with EcTrpRS. While a fragment named niraparib bound to the L-Trp binding site of the 'open' subunit, the other 7 fragments all bound to an unprecedented pocket at the interface between two TrpRS subunits. Binding of these fragments relies on residues specific to bacterial TrpRS, avoiding undesired interactions with human TrpRS. These findings improve our understanding of the catalytic mechanism of this important enzyme and will also facilitate the discovery of bacterial TrpRS inhibitors with therapeutic potential.

Tryptophan-dependent and -independent secretions of tryptophanyl- tRNA synthetase mediate innate inflammatory responses.

While cytoplasmic tryptophanyl-tRNA synthetase (WARS1) ligates tryptophan (Trp) to its cognate tRNAs for protein synthesis, it also plays a role as an innate immune activator in extracellular space. However, its secretion mechanism remains elusive. Here, we report that in response to stimuli, WARS1 can be secreted via two distinct pathways: via Trp-dependent secretion of naked protein and via Trp-independent plasma-membrane-derived vesicles (PMVs). In the direct pathway, Trp binding to WARS1 induces a "closed" conformation, generating a hydrophobic surface and basic pocket. The Trp-bound WARS1 then binds stable phosphatidylinositol (4,5)-biphosphate and inner plasma membrane leaflet, passing across the membrane. In the PMV-mediated secretion, WARS1 recruits calpain 2, which is activated by calcium. WARS1 released from PMVs induces inflammatory responses in vivo. These results provide insights into the secretion mechanisms of WARS1 and improve our understanding of how WARS1 is involved in the control of local and systemic inflammation upon infection.

Biallelic variants in WARS1 cause a highly variable neurodevelopmental syndrome and implicate a critical exon for normal auditory function.

Aminoacyl-tRNA synthetases (ARSs) are essential enzymes for faithful assignment of amino acids to their cognate tRNA. Variants in ARS genes are frequently associated with clinically heterogeneous phenotypes in humans and follow both autosomal dominant or recessive inheritance patterns in many instances. Variants in tryptophanyl-tRNA synthetase 1 (WARS1) cause autosomal dominantly inherited distal hereditary motor neuropathy and Charcot-Marie-Tooth disease. Presently, only one family with biallelic WARS1 variants has been described. We present three affected individuals from two families with biallelic variants (p.Met1? and p.(Asp419Asn)) in WARS1, showing varying severities of developmental delay and intellectual disability. Hearing impairment and microcephaly, as well as abnormalities of the brain, skeletal system, movement/gait, and behavior were variable features. Phenotyping of knocked down wars-1 in a Caenorhabditis elegans model showed depletion is associated with defects in germ cell development. A wars1 knockout vertebrate model recapitulates the human clinical phenotypes, confirms variant pathogenicity, and uncovers evidence implicating the p.Met1? variant as potentially impacting an exon critical for normal hearing. Together, our findings provide consolidating evidence for biallelic disruption of WARS1 as causal for an autosomal recessive neurodevelopmental syndrome and present a vertebrate model that recapitulates key phenotypes observed in patients.

WARS1 and SARS1: Two tRNA synthetases implicated in autosomal recessive microcephaly.

Aminoacylation of transfer RNA (tRNA) is a key step in protein biosynthesis, carried out by highly specific aminoacyl-tRNA synthetases (ARSs). ARSs have been implicated in autosomal dominant and autosomal recessive human disorders. Autosomal dominant variants in tryptophanyl-tRNA synthetase 1 (WARS1) are known to cause distal hereditary motor neuropathy and Charcot-Marie-Tooth disease, but a recessively inherited phenotype is yet to be clearly defined. Seryl-tRNA synthetase 1 (SARS1) has rarely been implicated in an autosomal recessive developmental disorder. Here, we report five individuals with biallelic missense variants in WARS1 or SARS1, who presented with an overlapping phenotype of microcephaly, developmental delay, intellectual disability, and brain anomalies. Structural mapping showed that the SARS1 variant is located directly within the enzyme's active site, most likely diminishing activity, while the WARS1 variant is located in the N-terminal domain. We further characterize the identified WARS1 variant by showing that it negatively impacts protein abundance and is unable to rescue the phenotype of a CRISPR/Cas9 wars1 knockout zebrafish model. In summary, we describe two overlapping autosomal recessive syndromes caused by variants in WARS1 and SARS1, present functional insights into the pathogenesis of the WARS1-related syndrome and define an emerging disease spectrum: ARS-related developmental disorders with or without microcephaly.

Neuropilin 1 and its inhibitory ligand mini-tryptophanyl-tRNA synthetase inversely regulate VE-cadherin turnover and vascular permeability.

The formation of a functional blood vessel network relies on the ability of endothelial cells (ECs) to dynamically rearrange their adhesive contacts in response to blood flow and guidance cues, such as vascular endothelial growth factor-A (VEGF-A) and class 3 semaphorins (SEMA3s). Neuropilin 1 (NRP1) is essential for blood vessel development, independently of its ligands VEGF-A and SEMA3, through poorly understood mechanisms. Grounding on unbiased proteomic analysis, we report here that NRP1 acts as an endocytic chaperone primarily for adhesion receptors on the surface of unstimulated ECs. NRP1 localizes at adherens junctions (AJs) where, interacting with VE-cadherin, promotes its basal internalization-dependent turnover and favors vascular permeability initiated by histamine in both cultured ECs and mice. We identify a splice variant of tryptophanyl-tRNA synthetase (mini-WARS) as an unconventionally secreted extracellular inhibitory ligand of NRP1 that, by stabilizing it at the AJs, slows down both VE-cadherin turnover and histamine-elicited endothelial leakage. Thus, our work shows a role for NRP1 as a major regulator of AJs plasticity and reveals how mini-WARS acts as a physiological NRP1 inhibitory ligand in the control of VE-cadherin endocytic turnover and vascular permeability.

Tryptophan depletion results in tryptophan-to-phenylalanine substitutants.

Activated T cells secrete interferon-γ, which triggers intracellular tryptophan shortage by upregulating the indoleamine 2,3-dioxygenase 1 (IDO1) enzyme1-4. Here we show that despite tryptophan depletion, in-frame protein synthesis continues across tryptophan codons. We identified tryptophan-to-phenylalanine codon reassignment (W>F) as the major event facilitating this process, and pinpointed tryptophanyl-tRNA synthetase (WARS1) as its source. We call these W>F peptides 'substitutants' to distinguish them from genetically encoded mutants. Using large-scale proteomics analyses, we demonstrate W>F substitutants to be highly abundant in multiple cancer types. W>F substitutants were enriched in tumours relative to matching adjacent normal tissues, and were associated with increased IDO1 expression, oncogenic signalling and the tumour-immune microenvironment. Functionally, W>F substitutants can impair protein activity, but also expand the landscape of antigens presented at the cell surface to activate T cell responses. Thus, substitutants are generated by an alternative decoding mechanism with potential effects on gene function and tumour immunoreactivity.

The IFN-γ/miniTrpRS signaling axis: An insight into the pathophysiology of osteoporosis and therapeutic potential.

Osteoporosis results from dysregulated bone remodeling with increased osteoclast-mediated destruction of bones. We have recently shown in vitro the truncated tryptophanyl-tRNA synthetase (mini-TrpRS)-dependent action of interferon-gamma (IFN-γ) to promote myeloid lineage multinucleation, a fundamental step in the osteoclast formation. In particular, we found that IFN-γ readily induced monocyte aggregation leading to multinuclear giant cell formation that paralleled marked upregulation of mini-TrpRS. However, blockade of mini-TrpRS with its cognate amino acid and decoy substrate D-Tryptophan prevented mini-TrpRS signaling, and markedly reduced the aggregation of monocytes and multinucleation in the presence of IFN. The cell signaling mechanism executed by mini-TrpRS appears inevitably in any inflammatory environment that involves IFN-γ with outcomes depending on the cell type involved. Here, we elaborate on these findings and discuss the potential role of the IFN-γ/mini-TrpRS signaling axis in osteoporosis pathophysiology, which may eventually materialize in a novel therapeutic perspective for this disease.

A Robust Platform for Unnatural Amino Acid Mutagenesis in E. coli Using the Bacterial Tryptophanyl-tRNA synthetase/tRNA pair.

We report the development of a robust user-friendly Escherichia coli (E. coli) expression system, derived from the BL21(DE3) strain, for site-specifically incorporating unnatural amino acids (UAAs) into proteins using engineered E. coli tryptophanyl-tRNA synthetase (EcTrpRS)-tRNATrp pairs. This was made possible by functionally replacing the endogenous EcTrpRS-tRNATrp pair in BL21(DE3) E. coli with an orthogonal counterpart from Saccharomyces cerevisiae, and reintroducing it into the resulting altered translational machinery tryptophanyl (ATMW-BL21) E. coli strain as an orthogonal nonsense suppressor. The resulting expression system benefits from the favorable characteristics of BL21(DE3) as an expression host, and is compatible with the broadly used T7-driven recombinant expression system. Furthermore, the vector expressing the nonsense-suppressing engineered EcTrpRS-tRNATrp pair was systematically optimized to significantly enhance the incorporation efficiency of various tryptophan analogs. Together, the improved strain and the optimized suppressor plasmids enable efficient UAA incorporation (up to 65% of wild-type levels) into several different proteins. This robust and user-friendly platform will significantly expand the scope of the genetically encoded tryptophan-derived UAAs.

WARS2 mutations cause dopa-responsive early-onset parkinsonism and progressive myoclonus ataxia.

INTRODUCTION: Sixteen subjects with biallelic WARS2 variants encoding the tryptophanyl mitochondrial aminoacyl-tRNA synthetase, presenting with a neonatal- or infantile-onset mitochondrial disease, have been reported to date. Here we present six novel cases with WARS2-related diseases and expand the spectrum to later onset phenotypes including dopa-responsive early-onset parkinsonism and progressive myoclonus-ataxia. METHODS: Six individuals from four families underwent whole-exome sequencing within research and diagnostic settings. Following the identification of a genetic defect, in-depth phenotyping and protein expression studies were performed. RESULTS: A relatively common (gnomAD MAF = 0.0033) pathogenic p.(Trp13Gly) missense variant in WARS2 was detected in trans in all six affected individuals in combination with different pathogenic alleles (exon 2 deletion in family 1; p.(Leu100del) in family 2; p.(Gly50Asp) in family 3; and p.(Glu208*) in family 4). Two subjects presented with action tremor around age 10-12 years and developed tremor-dominant parkinsonism with prominent neuropsychiatric features later in their 20s. Two subjects presented with a progressive myoclonus-ataxia dominant phenotype. One subject presented with spasticity, choreo-dystonia, myoclonus, and speech problems. One subject presented with speech problems, ataxia, and tremor. Western blotting analyses in patient-derived fibroblasts showed a markedly decreased expression of the full-length WARS2 protein in both subjects carrying p.(Trp13Gly) and an exon-2 deletion in compound heterozygosity. CONCLUSIONS: This study expands the spectrum of the disease to later onset phenotypes of early-onset tremor-dominant parkinsonism and progressive myoclonus-ataxia phenotypes.

Increased expression of tryptophan and tyrosine tRNAs elevates stop codon readthrough of reporter systems in human cell lines.

Regulation of translation via stop codon readthrough (SC-RT) expands not only tissue-specific but also viral proteomes in humans and, therefore, represents an important subject of study. Understanding this mechanism and all involved players is critical also from a point of view of prospective medical therapies of hereditary diseases caused by a premature termination codon. tRNAs were considered for a long time to be just passive players delivering amino acid residues according to the genetic code to ribosomes without any active regulatory roles. In contrast, our recent yeast work identified several endogenous tRNAs implicated in the regulation of SC-RT. Swiftly emerging studies of human tRNA-ome also advocate that tRNAs have unprecedented regulatory potential. Here, we developed a universal U6 promotor-based system expressing various human endogenous tRNA iso-decoders to study consequences of their increased dosage on SC-RT employing various reporter systems in vivo. This system combined with siRNA-mediated downregulations of selected aminoacyl-tRNA synthetases demonstrated that changing levels of human tryptophan and tyrosine tRNAs do modulate efficiency of SC-RT. Overall, our results suggest that tissue-to-tissue specific levels of selected near-cognate tRNAs may have a vital potential to fine-tune the final landscape of the human proteome, as well as that of its viral pathogens.

Tryptophanyl-tRNA Synthetase as a Potential Therapeutic Target.

Tryptophanyl-tRNA synthetase (WRS) is an essential enzyme that catalyzes the ligation of tryptophan (Trp) to its cognate tRNAtrp during translation via aminoacylation. Interestingly, WRS also plays physiopathological roles in diseases including sepsis, cancer, and autoimmune and brain diseases and has potential as a pharmacological target and therapeutic. However, WRS is still generally regarded simply as an enzyme that produces Trp in polypeptides; therefore, studies of the pharmacological effects, therapeutic targets, and mechanisms of action of WRS are still at an emerging stage. This review summarizes the involvement of WRS in human diseases. We hope that this will encourage further investigation into WRS as a potential target for drug development in various pathological states including infection, tumorigenesis, and autoimmune and brain diseases.

Identification of Prognostic RBPs in Osteosarcoma.

Osteosarcoma often occurs in children and adolescents and causes poor prognosis. The role of RNA-binding proteins (RBPs) in malignant tumors has been elucidated in recent years. Our study aims to identify key RBPs in osteosarcoma that could be prognostic factors and treatment targets. GSE33382 dataset was downloaded from Gene Expression Omnibus (GEO) database. RBPs extraction and differential expression analysis was performed. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were performed to explore the biological function of differential expression RBPs. Moreover, we constructed Protein-protein interaction (PPI) network and obtained key modules. Key RBPs were identified by univariate Cox regression analysis and multiple stepwise Cox regression analysis combined with the clinical information from Therapeutically Applicable Research to Generate Effective Treatments (TARGET) database. Risk score model was generated and validated by GSE16091 dataset. A total of 38 differential expression RBPs was identified. Go and KEGG results indicated these RBPs were significantly involved in ribosome biogenesis and mRNA surveillance pathway. COX regression analysis showed DDX24, DDX21, WARS and IGF2BP2 could be prognostic factors in osteosarcoma. Spearman's correlation analysis suggested that WARS might be important in osteosarcoma immune infiltration. In conclusion, DDX24, DDX21, WARS and IGF2BP2 might play key role in osteosarcoma, which could be therapuetic targets for osteosarcoma treatment.