Transfer RNA-derived fragment tRF-23-Q99P9P9NDD promotes progression of gastric cancer by targeting ACADSB. / 转移RNA衍生片段tRF-23-Q99P9P9NDD通过靶向ACADSB促进胃癌进展.

Gastric cancer (GC) is one of the most common gastrointestinal tumors. As a newly discovered type of non-coding RNAs, transfer RNA (tRNA)|-derived small RNAs (tsRNAs) play a dual biological role in cancer. Our previous studies have demonstrated the potential of tRF-23-Q99P9P9NDD as a diagnostic and prognostic biomarker for GC. In this work, we confirmed for the first time that tRF-23-Q99P9P9NDD can promote the proliferation, migration, and invasion of GC cells in vitro. The dual luciferase reporter gene assay confirmed that tRF-23-Q99P9P9NDD could bind to the 3' untranslated region (UTR) site of acyl-coenzyme A dehydrogenase short/branched chain (ACADSB). In addition, ACADSB could rescue the effect of tRF-23-Q99P9P9NDD on GC cells. Next, we used Gene Ontology (GO), the Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA) to find that downregulated ACADSB in GC may promote lipid accumulation by inhibiting fatty acid catabolism and ferroptosis. Finally, we verified the correlation between ACADSB and 12 ferroptosis genes at the transcriptional level, as well as the changes in reactive oxygen species (ROS) levels by flow cytometry. In summary, this study proposes that tRF-23-Q99P9P9NDD may affect GC lipid metabolism and ferroptosis by targeting ACADSB, thereby promoting GC progression. It provides a theoretical basis for the diagnostic and prognostic monitoring value of GC and opens up new possibilities for treatment.

METTL8 links mt-tRNA m3C modification to the HIF1α/RTK/Akt axis to sustain GBM stemness and tumorigenicity.

Epitranscriptomic RNA modifications are crucial for the maintenance of glioma stem cells (GSCs), the most malignant cells in glioblastoma (GBM). 3-methylcytosine (m3C) is a new epitranscriptomic mark on RNAs and METTL8 represents an m3C writer that is dysregulated in cancer. Although METTL8 has an established function in mitochondrial tRNA (mt-tRNA) m3C modification, alternative splicing of METTL8 can also generate isoforms that localize to the nucleolus where they may regulate R-loop formation. The molecular basis for METTL8 dysregulation in GBM, and which METTL8 isoform(s) may influence GBM cell fate and malignancy remain elusive. Here, we investigated the role of METTL8 in regulating GBM stemness and tumorigenicity. In GSC, METTL8 is exclusively localized to the mitochondrial matrix where it installs m3C on mt-tRNAThr/Ser(UCN) for mitochondrial translation and respiration. High expression of METTL8 in GBM is attributed to histone variant H2AZ-mediated chromatin accessibility of HIF1α and portends inferior glioma patient outcome. METTL8 depletion impairs the ability of GSC to self-renew and differentiate, thus retarding tumor growth in an intracranial GBM xenograft model. Interestingly, METTL8 depletion decreases protein levels of HIF1α, which serves as a transcription factor for several receptor tyrosine kinase (RTK) genes, in GSC. Accordingly, METTL8 loss inactivates the RTK/Akt axis leading to heightened sensitivity to Akt inhibitor treatment. These mechanistic findings, along with the intimate link between METTL8 levels and the HIF1α/RTK/Akt axis in glioma patients, guided us to propose a HIF1α/Akt inhibitor combination which potently compromises GSC proliferation/self-renewal in vitro. Thus, METTL8 represents a new GBM dependency that is therapeutically targetable.

Complete mitochondrial genome of critically endangered catfish Hemibagrus punctatus (Jerdon, 1849) and comparative analysis for insights into the phylogeny of hemibagrids through mitogenomic approach.

BACKGROUND: Hemibagrus punctatus (Jerdon, 1849) is a critically endangered bagrid catfish endemic to the Western Ghats of India, whose population is declining due to anthropogenic activities. The current study aims to compare the mitogenome of H. punctatus with that of other Bagrid catfishes and provide insights into their evolutionary relationships. METHODS AND RESULTS: Samples were collected from Hemmige Karnataka, India. In the present study, the mitogenome of H. punctatus was successfully assembled, and its phylogenetic relationships with other Bagridae species were studied. The total genomic DNA of samples was extracted following the phenol-chloroform isoamyl alcohol method. Samples were sequenced, and the Illumina paired-end reads were assembled to a contig length of 16,517 bp. The mitochondrial genome was annotated using MitoFish and MitoAnnotator (Iwasaki et al., 2013). A robust phylogenetic analysis employing NJ (Maximum composite likelihood) and ASAP methods supports the classification of H. punctatus within the Bagridae family, which validates the taxonomic status of this species. In conclusion, this research enriches our understanding of H. punctatus mitogenome, shedding light on its evolutionary dynamics within the Bagridae family and contributing to the broader knowledge of mitochondrial genes in the context of evolutionary biology. CONCLUSIONS: The study's findings contribute to a better understanding of the mitogenome of H. punctatus and provide insights into the evolutionary relationships within other Hemibagrids.

Mistranslating the genetic code with leucine in yeast and mammalian cells.

Translation fidelity relies on accurate aminoacylation of transfer RNAs (tRNAs) by aminoacyl-tRNA synthetases (AARSs). AARSs specific for alanine (Ala), leucine (Leu), serine, and pyrrolysine do not recognize the anticodon bases. Single nucleotide anticodon variants in their cognate tRNAs can lead to mistranslation. Human genomes include both rare and more common mistranslating tRNA variants. We investigated three rare human tRNALeu variants that mis-incorporate Leu at phenylalanine or tryptophan codons. Expression of each tRNALeu anticodon variant in neuroblastoma cells caused defects in fluorescent protein production without significantly increased cytotoxicity under normal conditions or in the context of proteasome inhibition. Using tRNA sequencing and mass spectrometry we confirmed that each tRNALeu variant was expressed and generated mistranslation with Leu. To probe the flexibility of the entire genetic code towards Leu mis-incorporation, we created 64 yeast strains to express all possible tRNALeu anticodon variants in a doxycycline-inducible system. While some variants showed mild or no growth defects, many anticodon variants, enriched with G/C at positions 35 and 36, including those replacing Leu for proline, arginine, alanine, or glycine, caused dramatic reductions in growth. Differential phenotypic defects were observed for tRNALeu mutants with synonymous anticodons and for different tRNALeu isoacceptors with the same anticodon. A comparison to tRNAAla anticodon variants demonstrates that Ala mis-incorporation is more tolerable than Leu at nearly every codon. The data show that the nature of the amino acid substitution, the tRNA gene, and the anticodon are each important factors that influence the ability of cells to tolerate mistranslating tRNAs.

From Enigma to Revelation: Unravelling Biological Functions of Ubiquitous Small Ribozymes.

RNA, widely recognized as an information-carrier molecule, is capable of catalyzing essential biological processes through ribozymes. Despite their ubiquity, specific functions in a biological context and phenotypes based on the ribozymes' activity are often unknown. Here, we present the discovery of a subgroup of minimal HDV-like ribozymes, which reside 3' to viral tRNAs and appear to cleave the 3'-trailers of viral premature tRNA transcripts. This proposed tRNA-processing function is unprecedented for any ribozymes, thus, we designate this subgroup as theta ribozymes. Most theta ribozymes were identified in Caudoviricetes bacteriophages, the main constituent (>90%) of the mammalian gut virome. Intriguingly, our findings further suggest the involvement of theta ribozymes in the transition of certain bacteriophages between distinct genetic codes, thus possibly contributing to the phage lysis trigger. Our discovery expands the limited repertoire of biological functions attributed to HDV-like ribozymes and provides insights into the fascinating world of RNA catalysis.

tRNA-derived small RNAs in human cancers: roles, mechanisms, and clinical application.

Transfer RNA (tRNA)-derived small RNAs (tsRNAs) are a new type of non-coding RNAs (ncRNAs) produced by the specific cleavage of precursor or mature tRNAs. tsRNAs are involved in various basic biological processes such as epigenetic, transcriptional, post-transcriptional, and translation regulation, thereby affecting the occurrence and development of various human diseases, including cancers. Recent studies have shown that tsRNAs play an important role in tumorigenesis by regulating biological behaviors such as malignant proliferation, invasion and metastasis, angiogenesis, immune response, tumor resistance, and tumor metabolism reprogramming. These may be new potential targets for tumor treatment. Furthermore, tsRNAs can exist abundantly and stably in various bodily fluids (e.g., blood, serum, and urine) in the form of free or encapsulated extracellular vesicles, thereby affecting intercellular communication in the tumor microenvironment (TME). Meanwhile, their abnormal expression is closely related to the clinicopathological features of tumor patients, such as tumor staging, lymph node metastasis, and poor prognosis of tumor patients; thus, tsRNAs can be served as a novel type of liquid biopsy biomarker. This review summarizes the discovery, production, and expression of tsRNAs and analyzes their molecular mechanisms in tumor development and potential applications in tumor therapy, which may provide new strategies for early diagnosis and targeted therapy of tumors.

Multiplexed gene editing in citrus by using a multi-intron containing Cas9 gene.

Several expression systems have been developed in clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (CRISPR/Cas9) framework allowing for gene editing of disease-associated genes across diverse citrus varieties. In this study, we present a new approach employing a multi-intron containing Cas9 gene plus multiple gRNAs separated with tRNA sequences to target the phytoene desaturase gene in both 'Carrizo' citrange and 'Duncan' grapefruit. Notably, using this unified vector significantly boosted editing efficiency in both citrus varieties, showcasing mutations in all three designated targets. The implementation of this multiplex gene editing system with a multi-intron-containing Cas9 plus a gRNA-tRNA array demonstrates a promising avenue for efficient citrus genome editing, equipping us with potent tools in the ongoing battle against several diseases such as canker and huanglongbing.

Analysis of the Overlength Main Noncoding Region in Metacarcinus magister (Decapoda: Brachyura) and a Phylogenetic Study of the Cancroidea Species.

Complete mitochondrial genomes (mitogenomes) can provide important information regarding the molecular evolution and phylogenetic relationships of marine invertebrates, especially in Brachyura. Only one Cancroidea species of mitogenomes has been sequenced before; in this research, the mitogenomic characteristics of Metacarcinus magister (Cancridae: Cancroidea) are newly studied. The length of the M. magister mitogenome was 48,820 bp, and it contained the typical 13 protein-coding genes, 2 ribosomal RNA genes, and 22 transfer RNA genes. We performed a series of analyses on the characteristics of the mNCR of M. magister. The phylogenetics, life circumstances, and selective pressures were all analyzed to explain the formation of this length, which revealed the length of the M. magister mitogenome to be approximately three times greater than the normal length of Brachyuran mitogenomes. Phylogenetic analyses based on a dataset of 215 Decapodan mitogenomes indicated that all Eriphioidea crabs were clustered together as a group. Moreover, the rearrangement mechanism of the Cancroidea species was predicted to provide stronger evidence for the phylogenetic analysis. In general, the results obtained in this study will contribute to a better understanding of the cause of the unusual length of the M. magister mitogenome and provide new insights into the phylogeny of Brachyura.

Complete Mitochondrial Genome for Lucilia cuprina dorsalis (Diptera: Calliphoridae) from the Northern Territory, Australia.

The Australian sheep blowfly, Lucilia cuprina dorsalis, is a major sheep ectoparasite causing subcutaneous myiasis (flystrike), which can lead to reduced livestock productivity and, in severe instances, death of the affected animals. It is also a primary colonizer of carrion, an efficient pollinator, and used in maggot debridement therapy and forensic investigations. In this study, we report the complete mitochondrial (mt) genome of L. c. dorsalis from the Northern Territory (NT), Australia, where sheep are prohibited animals, unlike the rest of Australia. The mt genome is 15,943 bp in length, comprising 13 protein-coding genes (PCGs), two ribosomal RNAs (rRNAs), 22 transfer RNAs (tRNAs), and a non-coding control region. The gene order of the current mt genome is consistent with the previously published L. cuprina mt genomes. Nucleotide composition revealed an AT bias, accounting for 77.5% of total mt genome nucleotides. Phylogenetic analyses of 56 species/taxa of dipterans indicated that L. c. dorsalis and L. sericata are the closest among all sibling species of the genus Lucilia, which helps to explain species evolution within the family Luciliinae. This study provides the first complete mt genome sequence for L. c. dorsalis derived from the NT, Australia to facilitate species identification and the examination of the evolutionary history of these blowflies.

A High-Quality Assembly and Comparative Analysis of the Mitogenome of Actinidia macrosperma.

The mitochondrial genome (mitogenome) of Actinidia macrosperma, a traditional medicinal plant within the Actinidia genus, remains relatively understudied. This study aimed to sequence the mitogenome of A. macrosperma, determining its assembly, informational content, and developmental expression. The results revealed that the mitogenome of A. macrosperma is circular, spanning 752,501 bp with a GC content of 46.16%. It comprises 63 unique genes, including 39 protein-coding genes (PCGs), 23 tRNA genes, and three rRNA genes. Moreover, the mitogenome was found to contain 63 SSRs, predominantly mono-nucleotides, as well as 25 tandem repeats and 650 pairs of dispersed repeats, each with lengths equal to or greater than 60, mainly comprising forward repeats and palindromic repeats. Moreover, 53 homologous fragments were identified between the mitogenome and chloroplast genome (cp-genome), with the longest segment measuring 4296 bp. This study represents the initial report on the mitogenome of the A. macrosperma, providing crucial genetic materials for phylogenetic research within the Actinidia genus and promoting the exploitation of species genetic resources.

Structural basis of translation inhibition by a valine tRNA-derived fragment.

Translational regulation by non-coding RNAs is a mechanism commonly used by cells to fine-tune gene expression. A fragment derived from an archaeal valine tRNA (Val-tRF) has been previously identified to bind the small subunit of the ribosome and inhibit translation in Haloferax volcanii Here, we present three cryo-electron microscopy structures of Val-tRF bound to the small subunit of Sulfolobus acidocaldarius ribosomes at resolutions between 4.02 and 4.53 Å. Within these complexes, Val-tRF was observed to bind to conserved RNA-interacting sites, including the ribosomal decoding center. The binding of Val-tRF destabilizes helices h24, h44, and h45 and the anti-Shine-Dalgarno sequence of 16S rRNA. The binding position of this molecule partially overlaps with the translation initiation factor aIF1A and occludes the mRNA P-site codon. Moreover, we found that the binding of Val-tRF is associated with steric hindrance of the H69 base of 23S rRNA in the large ribosome subunit, thereby preventing 70S assembly. Our data exemplify how tRNA-derived fragments bind to ribosomes and provide new insights into the mechanisms underlying translation inhibition by Val-tRFs.

Translation velocity determines the efficacy of engineered suppressor tRNAs on pathogenic nonsense mutations.

Nonsense mutations - the underlying cause of approximately 11% of all genetic diseases - prematurely terminate protein synthesis by mutating a sense codon to a premature stop or termination codon (PTC). An emerging therapeutic strategy to suppress nonsense defects is to engineer sense-codon decoding tRNAs to readthrough and restore translation at PTCs. However, the readthrough efficiency of the engineered suppressor tRNAs (sup-tRNAs) largely varies in a tissue- and sequence context-dependent manner and has not yet yielded optimal clinical efficacy for many nonsense mutations. Here, we systematically analyze the suppression efficacy at various pathogenic nonsense mutations. We discover that the translation velocity of the sequence upstream of PTCs modulates the sup-tRNA readthrough efficacy. The PTCs most refractory to suppression are embedded in a sequence context translated with an abrupt reversal of the translation speed leading to ribosomal collisions. Moreover, modeling translation velocity using Ribo-seq data can accurately predict the suppression efficacy at PTCs. These results reveal previously unknown molecular signatures contributing to genotype-phenotype relationships and treatment-response heterogeneity, and provide the framework for the development of personalized tRNA-based gene therapies.

A highly conserved tRNA modification contributes to C. albicans filamentation and virulence.

tRNA modifications play important roles in maintaining translation accuracy in all domains of life. Disruptions in the tRNA modification machinery, especially of the anticodon stem loop, can be lethal for many bacteria and lead to a broad range of phenotypes in baker's yeast. Very little is known about the function of tRNA modifications in host-pathogen interactions, where rapidly changing environments and stresses require fast adaptations. We found that two closely related fungal pathogens of humans, the highly pathogenic Candida albicans and its much less pathogenic sister species, Candida dubliniensis, differ in the function of a tRNA-modifying enzyme. This enzyme, Hma1, exhibits species-specific effects on the ability of the two fungi to grow in the hypha morphology, which is central to their virulence potential. We show that Hma1 has tRNA-threonylcarbamoyladenosine dehydratase activity, and its deletion alters ribosome occupancy, especially at 37°C-the body temperature of the human host. A C. albicans HMA1 deletion mutant also shows defects in adhesion to and invasion into human epithelial cells and shows reduced virulence in a fungal infection model. This links tRNA modifications to host-induced filamentation and virulence of one of the most important fungal pathogens of humans.IMPORTANCEFungal infections are on the rise worldwide, and their global burden on human life and health is frequently underestimated. Among them, the human commensal and opportunistic pathogen, Candida albicans, is one of the major causative agents of severe infections. Its virulence is closely linked to its ability to change morphologies from yeasts to hyphae. Here, this ability is linked-to our knowledge for the first time-to modifications of tRNA and translational efficiency. One tRNA-modifying enzyme, Hma1, plays a specific role in C. albicans and its ability to invade the host. This adds a so-far unknown layer of regulation to the fungal virulence program and offers new potential therapeutic targets to fight fungal infections.

MILIP Binding to tRNAs Promotes Protein Synthesis to Drive Triple-Negative Breast Cancer.

Patients with triple-negative breast cancer (TNBC) have a poor prognosis due to the lack of effective molecular targets for therapeutic intervention. Here we found that the long noncoding RNA (lncRNA) MILIP supports TNBC cell survival, proliferation, and tumorigenicity by complexing with transfer RNAs (tRNA) to promote protein production, thus representing a potential therapeutic target in TNBC. MILIP was expressed at high levels in TNBC cells that commonly harbor loss-of-function mutations of the tumor suppressor p53, and MILIP silencing suppressed TNBC cell viability and xenograft growth, indicating that MILIP functions distinctively in TNBC beyond its established role in repressing p53 in other types of cancers. Mechanistic investigations revealed that MILIP interacted with eukaryotic translation elongation factor 1 alpha 1 (eEF1α1) and formed an RNA-RNA duplex with the type II tRNAs tRNALeu and tRNASer through their variable loops, which facilitated the binding of eEF1α1 to these tRNAs. Disrupting the interaction between MILIP and eEF1α1 or tRNAs diminished protein synthesis and cell viability. Targeting MILIP inhibited TNBC growth and cooperated with the clinically available protein synthesis inhibitor omacetaxine mepesuccinate in vivo. Collectively, these results identify MILIP as an RNA translation elongation factor that promotes protein production in TNBC cells and reveal the therapeutic potential of targeting MILIP, alone and in combination with other types of protein synthesis inhibitors, for TNBC treatment. SIGNIFICANCE: LncRNA MILIP plays a key role in supporting protein production in TNBC by forming complexes with tRNAs and eEF1α1, which confers sensitivity to combined MILIP targeting and protein synthesis inhibitors.

Nuclear and mitochondrial genomes of Polylopha cassiicola: the first assembly in Chlidanotinae (Tortricidae).

Tortricidae is one of the largest families in Lepidoptera, including subfamilies of Tortricinae, Olethreutinae, and Chlidanotinae. Here, we assembled the gap-free genome for the subfamily Chlidanotinae using Illumina, Nanopore, and Hi-C sequencing from Polylopha cassiicola, a pest of camphor trees in southern China. The nuclear genome is 302.03 Mb in size, with 36.82% of repeats and 98.4% of BUCSO completeness. The karyotype is 2n = 44 for males. We identified 15412 protein-coding genes, 1052 tRNAs, and 67 rRNAs. We also determined the mitochondrial genome of this species and annotated 13 protein-coding genes, 22 tRNAs, and one rRNA. These high-quality genomes provide valuable information for studying phylogeny, karyotypic evolution, and adaptive evolution of tortricid moths.

tRNA anticodon cleavage by target-activated CRISPR-Cas13a effector.

Type VI CRISPR-Cas systems are among the few CRISPR varieties that target exclusively RNA. The CRISPR RNA-guided, sequence-specific binding of target RNAs, such as phage transcripts, activates the type VI effector, Cas13. Once activated, Cas13 causes collateral RNA cleavage, which induces bacterial cell dormancy, thus protecting the host population from the phage spread. We show here that the principal form of collateral RNA degradation elicited by Leptotrichia shahii Cas13a expressed in Escherichia coli cells is the cleavage of anticodons in a subset of transfer RNAs (tRNAs) with uridine-rich anticodons. This tRNA cleavage is accompanied by inhibition of protein synthesis, thus providing defense from the phages. In addition, Cas13a-mediated tRNA cleavage indirectly activates the RNases of bacterial toxin-antitoxin modules cleaving messenger RNA, which could provide a backup defense. The mechanism of Cas13a-induced antiphage defense resembles that of bacterial anticodon nucleases, which is compatible with the hypothesis that type VI effectors evolved from an abortive infection module encompassing an anticodon nuclease.

Elucidating the multichromosomal structure within the Brasenia schreberi mitochondrial genome through assembly and analysis.

Brasenia schreberi, a plant species traditionally utilized in Chinese medicine and cuisine, represents an early evolutionary stage among flowering plants (angiosperms). While the plastid genome of this species has been published, its mitochondrial genome (mitogenome) has not been extensively explored, with a notable absence of thorough comparative analyses of its organellar genomes. In our study, we had assembled the entire mitogenome of B. schreberi utilizing the sequencing data derived from both Illumina platform and Oxford Nanopore. The B. schreberi mitogenome mostly exists as six circular DNA molecules, with the largest being 628,257 base pairs (bp) and the smallest 110,220 bp, amounting to 1.49 megabases (Mb). Then we annotated the mitogenome of B. schreberi. The mitogenome encompasses a total of 71 genes: 40 of these are coding proteins genes (PCGs), 28 are genes for transfer RNA (tRNA), and the remaining 3 are genes for ribosomal RNA (rRNA). In the analysis of codon usage, we noted a unique codon preference specific to each amino acid. The most commonly used codons exhibited an average RSCU of 1.36, indicating a noticeable bias in codon selection. In the repeat sequence analysis, a total of 553 simple sequence repeats (SSRs) were identified, 1,822 dispersed repeats (comprising 1,015 forward and 807 palindromic repeats), and 608 long terminal repeats (LTRs). Additionally, in the analysis of homologous sequences between organelle genomes, we detected 38 homologous sequences derived from the plastid genome, each exceeding 500 bp, within the B. schreberi mitochondrial genome. Notably, ten tRNA genes (trnC-GCA, trnM-CAU, trnI-CAU, trnQ-UUG, trnN-GUU, trnT-GGU, trnW-CCA, trnA-UGC, trnI-GAU, and trnV-GAC) appear to have been completely transferred from the chloroplast to the mitogenome. Utilizing the Deepred-mt to predict the RNA editing sites in the mitogenome, we have identified 675 high-quality RNA editing sites in the 40 mitochondrial PCGs. In the final stage of our study, we performed an analysis of colinearity and inferred the phylogenetic relationship of B. schreberi with other angiosperms, utilizing the mitochondrial PCGs as a basis. The results showed that the non-coding regions of the B. schreberi mitogenome are characterized by an abundance of repetitive sequences and exogenous sequences, and B. schreberi is more closely related with Euryale ferox.

Clinical and genetic analysis of essential hypertension with mitochondrial tRNAMet 4435A>G and YARS2 mutation. / 携带线粒体tRNAMet 4435A>Gå’Œæ ¸åŸºå› YARS2çªå˜çš„åŽŸå‘æ€§é«˜è¡€åŽ‹å®¶ç³»é—ä¼ å­¦åˆ†æž.

OBJECTIVES: To investigate the role of m.4435A>G and YARS2 c.572G>T (p.G191V) mutations in the development of essential hypertension. METHODS: A hypertensive patient with m.4435A>G and YARS2 p.G191V mutations was identified from previously collected mitochondrial genome and exon sequencing data. Clinical data were collected, and a molecular genetic study was conducted in the proband and his family members. Peripheral venous blood was collected, and immortalized lymphocyte lines constructed. The mitochondrial transfer RNA (tRNA), mitochondrial protein, adenosine triphosphate (ATP), mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) in the constructed lymphocyte cell lines were measured. RESULTS: Mitochondrial genome sequencing showed that all maternal members carried a highly conserved m.4435A>G mutation. The m.4435A>G mutation might affect the secondary structure and folding free energy of mitochondrial tRNA and change its stability, which may influence the anticodon ring structure. Compared with the control group, the cell lines carrying m.4435A>G and YARS2 p.G191V mutations had decreased mitochondrial tRNA homeostasis, mitochondrial protein expression, ATP production and MMP levels, as well as increased ROS levels (all P<0.05). CONCLUSIONS: The YARS2 p.G191V mutation aggravates the changes in mitochondrial translation and mitochondrial function caused by m.4435A>G through affecting the steady-state level of mitochondrial tRNA and further leads to cell dysfunction, indicating that YARS2 p.G191V and m.4435A>G mutations have a synergistic effect in this family and jointly participate in the occurrence and development of essential hypertension.

Altered expression of transfer RNAs and their possible roles in brain white matter injury.

Transfer RNAs (tRNAs) can regulate cell behavior and are associated with neurological disorders. Here, we aimed to investigate the expression levels of tRNAs in oligodendrocyte precursor cells (OPCs) and their possible roles in the regulation of brain white matter injury (WMI). Newborn Sprague-Dawley rats (postnatal day 5) were used to establish a model that mimicked neonatal brain WMI. RNA-array analysis was performed to examine the expression of tRNAs in OPCs. psRNAtarget software was used to predict target mRNAs of significantly altered tRNAs. Gene ontology (GO) and KEGG were used to analyze the pathways for target mRNAs. Eighty-nine tRNAs were changed after WMI (fold change absolute ≥1.5, P  < 0.01), with 31 downregulated and 58 upregulated. Among them, three significantly changed tRNAs were identified, with two being significantly increased (chr10.trna1314-ProTGG and chr2.trna2771-ProAGG) and one significantly decreased (chr10.trna11264-GlyTCC). Further, target mRNA prediction and GO/KEGG pathway analysis indicated that the target mRNAs of these tRNAs are mainly involved in G-protein coupled receptor signaling pathways and beta-alanine metabolism, which are both related to myelin formation. In summary, the expression of tRNAs in OPCs was significantly altered after brain WMI, suggesting that tRNAs may play important roles in regulating WMI. This improves the knowledge about WMI pathophysiology and may provide novel treatment targets for WMI.