5'ValCAC tRNA fragment generated as part of a protective angiogenin response provides prognostic value in amyotrophic lateral sclerosis

Pre-symptomatic Parkinson's disease blood test quantifying repetitive sequence motifs in transfer RNA fragments

Early, efficient Parkinson's disease (PD) tests may facilitate pre-symptomatic diagnosis and disease-modifying therapies. Here we report elevated levels of PD-specific transfer RNA fragments carrying a conserved sequence motif (RGTTCRA-tRFs) in the substantia nigra, cerebrospinal fluid and blood of patients with PD. A whole blood qPCR test detecting elevated RGTTCRA-tRFs and reduced mitochondrial-originated tRFs (MT-tRFs) segregated pre-symptomatic patients with PD from controls (area under the receiver operating characteristic curve (ROC-AUC) of 0.75 versus 0.71 based on traditional clinical scoring). Strengthening PD relevance, patients carrying PD-related mutations presented higher blood RGTTCRA-tRFs/MT-tRFs ratios than mutation-carrying non-symptomatic controls, and RGTTCRA-tRF levels decreased in patients' blood after deep brain stimulation. Furthermore, RGTTCRA-tRFs complementarity to ribosomal RNA and the translation-supporting LeuCAG3-tRF might aggravate PD via translational inhibition, as reflected by disrupted ribosomal association of RGTTCRA-tRFs in depolarized neuroblastoma cells. Our findings show tRF involvement in PD and suggest a potential simple and safe blood test that may aid clinicians in pre-symptomatic PD diagnosis after validation in larger independent cohorts.

The Role of tRNA Fragments on Neurogenesis Alteration by H₂O₂-induced Oxidative Stress

Transfer RNAs (tRNAs) are small non-coding RNA molecules transcribed from tRNA genes. tRNAs cleaved into a diverse population tRNA fragments (tRFs) ranging in length from 18 to 40 nucleotides, they interact with RNA binding proteins and influence the stability and translation. Stress is one of the reasons for tRFs cleavage. In our study, we modeled oxidative stress conditions with hydrogen peroxide (H2O2) exposure and dealt with one of the frequently expressed tRF in the hippocampus region of the brain, which is tRF-Glu-CTC. For this purpose, neural stem cells (NSCs) were exposed to H2O2, and tRF-Glu-CTC levels were increased in various H2O2 concentrations. A decrease was seen in microtubule-associated protein 2 (MAP2) marker expression. To understand the H2O2 oxidative stress condition on the expression of tRNA fragments, 72 hpf zebrafish embryos exposed to different H2O2 concentrations, an increase in the level of tRF-Glu-CTC was observed in all concentrations of H2O2 compared to control. Subsequently, neurogenesis markers were figured out via Calb2a (calbindin 2a) in situ hybridization (ISH) and HuC/D immunofluorescence staining (IF) staining experiments. Under H2O2 exposure, a decline was observed in Calb2a and HuC/D markers. To understand the inhibitory role of tRF-Glu-CTC on neurogenesis, NSCs were transfected via tRF-Glu-CTC inhibitor, and neurogenesis markers (ßIII-tubulin, MAP2, and GFAP) were determined with qRT-PCR and IF staining. tRF-Glu-CTC inhibitor reversed the diminished neuronal markers expression under the exposure of H2O2. Gene Ontology (GO) enrichment analysis showed us that targets of tRF-Glu-CTC are generally related to neuronal function and synaptic processes.

Mapping Current Studies of tRNA Fragments onto Disease Landscape

Transfer-RNA-derived fragments (tRFs) are a relatively recently discovered class of non-coding RNAs derived from both precursor and mature transfer RNAs (tRNAs). Research on these molecules has been expanding rapidly, revealing their diverse roles in cellular processes, both in normal physiology and in disease states, often via post-transcriptional regulation of target genes. Altered tRFs abundances have been implicated in various conditions, where they may act as either drivers of disease progression or as protective agents. For instance, specific tRFs are associated with increased risk for cancer metastasis, while others may suppress tumor cell proliferation. Despite the growing recognition of tRFs as functional RNAs rather than sequencing noise, this field of study faces numerous challenges. Inconsistent naming conventions and variability in experimental approaches hinder the comparison of findings across studies, limiting our understanding of the common roles and mechanisms of tRFs. This review provides a comprehensive analysis of current literature on the various roles of tRFs in different diseases, particularly focusing on four broad areas: cancer, neurological, cardiovascular, and musculoskeletal disorders. We analyze studies that link specific tRFs to various aspects of human diseases and provide a convenient classification of these studies regarding the depth of the provided evidence. Further, we note gaps in current investigations and consider strategies to address methodological inconsistencies, including validation experiments and unified nomenclature. By consolidating research in this manner, we aim to facilitate comparisons across diverse studies, enhancing our ability to identify functional commonalities and furthering our understanding of the mechanisms by which tRFs act.

Circulating tsRNAs serve as potential biomarkers for predicting postoperative delirium in elderly patients receiving lower extremity orthopedic surgery

Background

Postoperative delirium (POD) is a serious neuropsychiatric complication in elderly surgical patients, yet its pathogenesis remains incompletely understood. Transfer RNA-derived small RNAs (tsRNAs) have emerged as crucial regulators in neurological disorders. We investigated whether specific tsRNAs could serve as predictive biomarkers for POD.

Methods

This study conducted a prospective case-control study of 158 elderly patients (≥60 years) undergoing orthopedic surgery. Plasma samples were collected preoperatively and on postoperative day 3.tsRNA expression profiles were analyzed using RNA sequencing and validated by RT-qPCR. Propensity score matching was performed to balance demographic and clinical variables. The predictive value of candidate tsRNAs was assessed using ROC analysis, and their potential functions were explored through bioinformatic analyses.

Results

Among 128 non-POD and 30 POD patients, two tsRNAs (Other-14: 31-tRNA-Gly-CCC-3 and Other-39: 73-tRNA-Arg-TCG-5) showed significantly elevated preoperative levels in POD patients (p<0.001).ROC analysis revealed strong predictive performance (AUC=0.868 and 0.956, respectively).These differences persisted in the propensity-matched cohort (29 pairs).Bioinformatic analyses indicated enrichment in pathways related to neurotransmission, inflammation, and metabolism.

Conclusion

This study identified novel tsRNA biomarkers that robustly predict POD risk and provide insights into its molecular pathogenesis. These findings may facilitate early risk stratification and preventive interventions.

Exploring the Potential of tsRNA as Biomarkers for Diagnosis and Treatment of Neurogenetic Disorders

tRNA-derived small RNA (tsRNA) is a recently discovered small non-coding RNA (ncRNA) molecule that widely exists in prokaryotic and eukaryotic transcriptomes and is produced by specific cleavage of mature tRNA or precursor tRNA. In recent years, with the development of high-throughput sequencing technology, tsRNA has been found to have a variety of biological functions, including gene expression regulation, stress signal activation, etc. In addition, it has been found that these molecules are abnormally expressed in various diseases and participate in various pathological processes, which play an important role. At present, more and more studies have shown that the expression level of tsRNA changes significantly during the development of neurogenetic diseases. This review provides an overview of the classification and biological functions of tsRNAs, with a particular emphasis on their roles in neurogenetic disorders and their potential as diagnostic biomarkers and therapeutic targets. Despite the nascent stage of tsRNA research, their relevance to the diagnosis and treatment of neurogenetic diseases warrants further investigation.

Protective role of Angiogenin in muscle regeneration in amyotrophic lateral sclerosis: Diagnostic and therapeutic implications

Amyotrophic lateral sclerosis (ALS) is a fatal neuromuscular disease with no effective treatments, in part caused by variations in progression and the absence of biomarkers. Mice carrying the SOD1G93A transgene with different genetic backgrounds show variable disease rates, reflecting the diversity of patients. While extensive research has been done on the involvement of the central nervous system, the role of skeletal muscle remains underexplored. We examined the impact of angiogenin, including its RNase activity, in skeletal muscles of ALS mouse models and in biopsies from ALS patients. Elevated levels of angiogenin were found in slowly progressing mice but not in rapidly progressing mice, correlating with increased muscle regeneration and vascularisation. In patients, higher levels of angiogenin in skeletal muscles correlated with milder disease. Mechanistically, angiogenin promotes muscle regeneration and vascularisation through satellite cell-endothelial interactions during myogenesis and angiogenesis. Furthermore, specific angiogenin-derived tiRNAs were upregulated in slowly progressing mice, suggesting their role in mediating the effects of angiogenin. These findings highlight angiogenin and its tiRNAs as potential prognostic markers and therapeutic targets for ALS, offering avenues for patient stratification and interventions to mitigate disease progression by promoting muscle regeneration.

tsRNAs: A Prospective, Effective Therapeutic Intervention for Neurodegenerative Diseases

BACKGROUND

Neurological disorders known as neurodegenerative diseases (NDDs) result in the slow loss of neurons in the central nervous system (CNS) or peripheral nervous system (PNS), as well as the collapse of neural networks in terms of structure and function. NDDs are expected to surpass cancer as the second biggest cause of mortality by 2040, according to World Health Organization (WHO) estimations. Neurons cannot effectively regenerate themselves because they are terminally differentiated. Accordingly, it is challenging to find medications that could stop or slow neurodegeneration.

MAIN BODY

The tsRNAs are a type of small non-coding RNAs derived from mature tRNAs or tRNA precursors. tsRNAs control gene expression and have a role in many physiological and pathological processes, including neurological illnesses. Antisense oligonucleotides are effective therapeutic agents for neurological diseases, and they may be the treatment of choice for neurodegenerative diseases in the future. Here, we review the biogenesis of tsRNA, its physiological and pathological functions in the central nervous system and neurological disorders, and its prospective use as a nucleic acid medication to treat NDDs, providing theoretical support and guidance for further exploration of tsRNAs in therapeutic intervention.

CONCLUSION

tsRNAs are emerging as important regulatory molecules in neurodegenerative diseases. Understanding the functions of tsRNAs in neurodegenerative diseases may provide new insights into disease mechanisms and lead to the development of novel treatment strategies.

Distinct fingerprints of tRNA-derived small non-coding RNA in animal models of neurodegeneration

Transfer RNA-derived small RNAs (tsRNAs) - categorized as tRNA-derived fragments (tRFs), tRNA-derived stress-induced RNAs (tiRNAs) and internal tRF (itRF) - are small non-coding RNAs that participate in various cellular processes such as translation inhibition and responses to cellular stress. We here identified tsRNA profiles within susceptible tissues in animal models of amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD) and Parkinson's disease (PD) to pinpoint disease-specific tsRNAs and those shared across neurodegenerative diseases. We performed small RNA sequencing in the SOD1G93A and TDP43A315T mouse models of ALS (spinal cord), the TauP301S model of FTD (hippocampus), and the parkin/POLG model of PD (substantia nigra). Bioinformatic analysis showed higher expression of 5' tiRNAs selectively in the two ALS models, lower expression of 3' tRFs in both the ALS and FTD mouse models, and lower expression of itRF Arg in the PD model. Experimental validation confirmed the expression of tsRNAs. Gene Ontology analysis of targets associated with validated 3' tRFs indicated functions in the regulation of synaptic and neuronal pathways. Our profiling of tsRNAs indicates disease-specific fingerprints in animal models of neurodegeneration, which require validation in human disease.

Immunostimulatory short non-coding RNAs in the circulation of patients with tuberculosis infection

Mycobacterium tuberculosis (Mtb) infection is among the world's deadliest infectious diseases. Developing effective treatments and biomarkers for tuberculosis requires a deeper understanding of its pathobiology and host responses. Here, we report a comprehensive characterization of circulating short non-coding RNAs (sncRNAs) in plasma samples from Mtb-infected patients. We achieved this by pre-treating plasma RNAs with T4 polynucleotide kinase to convert all RNA ends to those compatible with sncRNA sequencing. We discovered a global and drastic upregulation of plasma sncRNAs in Mtb-infected patients, with tRNA-derived sncRNAs representing the most dramatically elevated class. Most of these tRNA-derived sncRNAs originated from a limited subset of tRNAs, specifically from three tRNA isoacceptors, and exhibited skewed patterns to 5'-derived fragments, such as 5' halves, 5' tRNA fragments (tRFs), and internal tRFs (i-tRFs) from the 5' regions. Further, Mtb-infected patients displayed markedly upregulated and distinct profiles of both rRNA- and mRNA-derived sncRNAs. Some of these sncRNAs, which are abundant and specific to Mtb-infected patients, robustly activated human macrophages via Toll-like receptor 7 and induced cytokine production. This drastic accumulation of circulating, immunostimulatory sncRNAs in the plasma of Mtb-infected patients offers insights into the sncRNA-driven aspects of host immune response against infectious diseases and suggests a pool of potential therapeutic targets and biomarkers.

tRNA-derived fragments are altered in diabetes

AIMS

Maternally inherited diabetes and deafness (MIDD) is a rare form of adult-onset diabetes that can be difficult to diagnose due to its variable clinical phenotype. Transfer RNA-derived small fragments are a novel, emerging class of small non-coding RNAs (sncRNAs) that have significant potential as serum biomarkers due to their stress-induced generation, abundance, stability and ease of detection.

METHODS

We investigated the levels of tiRNA 5'ValCAC (alone and in combination with miR-23b-3p) identified from small RNA sequencing studies in serum samples from healthy controls, type 1 diabetes, type 2 diabetes and MIDD subjects.

RESULTS

Serum levels of 5'ValCAC were reduced in MIDD and type 2 diabetes subjects compared to controls. Type 2 diabetes subjects had higher serum levels of miR-23b-3p compared to all other subjects. Receiver Operating Characteristic analysis showed the potential of 5'ValCAC and miR-23b-3p as MIDD biomarkers, with the combination showing excellent separation from type 2 diabetes subjects.

CONCLUSIONS

This is the first report showing altered serum levels of tiRNAs in diabetes subjects. The combined use of 5'ValCAC and miR-23b-3p as serum biomarkers could potentially differentiate between MIDD subjects and type 2 diabetes subjects.

[Abnormal transfer RNA epigenetic modifications and related impact on neurodegenerative diseases]

Neurodegenerative diseases are a heterogeneous group of neurological disorders characterized by progressive loss of neurons in the central or peripheral nervous system. Research on the pathogenesis and drug targets of these diseases still faces many challenges due to the complex etiology. In recent years, the role of epigenetic modifications in transfer RNA (tRNA) in neurodegenerative diseases has attracted widespread attention. The tRNA modifications are crucial for regulating codon recognition, maintaining molecular structural stability, and the generation of tRNA-derived fragments (tRFs). Recent studies have highlighted a close association between abnormal tRNA modifications and the pathogenesis of various neurodegenerative diseases, especially for abnormalities of elongator complex-dependent tRNA modification and methylation modification, which impact the translation process and tRFs levels. These changes regulate protein homeostasis and cellular stress responses, ultimately influencing the survival of neuronal cells. Moreover, significant changes in tRFs levels have been observed in neurodegenerative diseases, and specific tRFs show distinct effects on neurodegenerative diseases. This review aims to provide an overview of the physiological functions of tRNA epigenetic modifications and their regulatory mechanisms in neurodegenerative diseases, covering both classical functions such as codon recognition and non-classical functions such as tRFs biogenesis. Additionally, the potential of targeting tRNA modifications for therapeutic applications is discussed.

Pathomechanistic Networks of Motor System Injury in Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS) is the most common, adult-onset, progressive motor neurodegenerative disorder that results in death within 3 years of the clinical diagnosis. Due to the clinicopathological heterogeneity, any reliable biomarkers for diagnosis or prognosis of ALS have not been identified till date. Moreover, the only three clinically approved treatments are not uniformly effective in slowing the disease progression. Over the last 15 years, there has been a rapid advancement in research on the complex pathomechanistic landscape of ALS that has opened up new avenues for successful clinical translation of targeted therapeutics. Multiple studies suggest that the age-dependent interaction of risk-associated genes with environmental factors and endogenous modifiers is critical to the multi-step process of ALS pathogenesis. In this review, we provide an updated discussion on the dysregulated cross-talk between intracellular homeostasis processes, the unique molecular networks across selectively vulnerable cell types, and the multisystemic nature of ALS pathomechanisms. Importantly, this work highlights the alteration in epigenetic and epitranscriptomic landscape due to gene-environment interactions, which have been largely overlooked in the context of ALS pathology. Finally, we suggest that precision medicine research in ALS will be largely benefitted from the stratification of patient groups based on the clinical phenotype, onset and progression, genome, exposome, and metabolic identities.

Classification, function, and advances in tsRNA in non-neoplastic diseases

tRNA-derived small RNAs (tsRNAs) are non-coding small RNAs produced by specific endonucleases following the processing and splicing of precursor or mature tRNAs upon starvation, oxidative stress, hypoxia, and other adverse conditions. tRNAs are classified into two major categories, tRNA fragments (tRFs) and tRNA-derived stress-induced small RNAs (tiRNAs), based on differences in splice sites. With the development of high-throughput sequencing technologies in recent years, tsRNAs have been found to have important biological functions, including inhibition of apoptosis, epigenetic regulation, cell-cell communication, translation, and regulation of gene expression. Additionally, these molecules have been found to be aberrantly expressed in various diseases and to be involved in several pathological processes. In this article, the classification and nomenclature, biological functions, and potential use of tsRNAs as diagnostic biomarkers and therapeutic targets in non-neoplastic diseases are reviewed. Although tsRNA research is at its infancy, their potential in the treatment of non-tumor diseases warrants further investigation.

Translation dysregulation in neurodegenerative diseases: a focus on ALS

RNA translation is tightly controlled in eukaryotic cells to regulate gene expression and maintain proteome homeostasis. RNA binding proteins, translation factors, and cell signaling pathways all modulate the translation process. Defective translation is involved in multiple neurological diseases including amyotrophic lateral sclerosis (ALS). ALS is a progressive neurodegenerative disorder and poses a major public health challenge worldwide. Over the past few years, tremendous advances have been made in the understanding of the genetics and pathogenesis of ALS. Dysfunction of RNA metabolisms, including RNA translation, has been closely associated with ALS. Here, we first introduce the general mechanisms of translational regulation under physiological and stress conditions and review well-known examples of translation defects in neurodegenerative diseases. We then focus on ALS-linked genes and discuss the recent progress on how translation is affected by various mutant genes and the repeat expansion-mediated non-canonical translation in ALS.

Changes of tRNA-Derived Fragments by Alzheimer's Disease in Cerebrospinal Fluid and Blood Serum

BACKGROUND

Alzheimer's disease (AD) is the most common type of dementia, affecting individuals over 65. AD is also a multifactorial disease, with disease mechanisms incompletely characterized, and disease-modifying therapies are marginally effective. Biomarker signatures may shed light on the diagnosis, disease mechanisms, and the development of therapeutic targets. tRNA-derived RNA fragments (tRFs), a family of recently discovered small non-coding RNAs, have been found to be significantly enhanced in human AD hippocampus tissues. However, whether tRFs change in body fluids is unknown.

OBJECTIVE

To investigate whether tRFs in body fluids are impacted by AD.

METHODS

We first used T4 polynucleotide kinase-RNA-seq, a modified next-generation sequencing technique, to identify detectable tRFs in human cerebrospinal fluid and serum samples. The detectable tRFs were then compared in these fluids from control, AD, and mild cognitive impairment patients using tRF qRT-PCR. The stability of tRFs in serum was also investigated by checking the change in tRFs in response to protein digestion or exosome lysis.

RESULTS

Among various tRFs, tRF5-ProAGG seemed to be impacted by AD in both cerebrospinal fluid and serum. AD-impacted serum tRF5-ProAGG showed a correlation with the AD stage. Putative targets of tRF5-ProAGG in the hippocampus were also predicted by a computational algorithm, with some targets being validated experimentally and one of them being in a negative correlation with tRF5-ProAGG even using a small size of samples.

CONCLUSIONS

tRF5-ProAGG showed the potential as an AD biomarker and may play a role in disease progression.

Absolute quantification of a plasma tRNA-derived fragment for the diagnosis and prognosis of gastric cancer

Background

The transition from a healthy gastric mucosa to gastric cancer is a multi-step process. Early screening can significantly improve the survival rate of gastric cancer patients. A reliable liquid biopsy for gastric cancer prediction is urgently needed and since tRNA-derived fragments (tRFs) are abundant in various body fluids, tRFs are possible new biomarkers for gastric cancer.

Methods

A total of 438 plasma samples from patients with different gastric mucosal lesions as well as healthy individuals were collected. A specific reverse transcription primer, a forward primer, a reverse primer, and a TaqMan probe were designed. A standard curve was constructed and an absolute quantitation method was devised for detection of tRF-33-P4R8YP9LON4VDP in plasma samples of individuals with differing gastric mucosa lesions. Receiver operating characteristic curves were constructed to evaluate the diagnostic values of tRF-33-P4R8YP9LON4VDP for individual with differing gastric mucosa. A Kaplan-Meier curve was established to calculate the prognostic value of tRF-33-P4R8YP9LON4VDP for advanced gastric cancer patients. Finally, a multivariate Cox regression analysis was performed to assess the independent prognostic value of tRF-33-P4R8YP9LON4VDP for advanced gastric cancer patients.

Results

A detection method for plasma tRF-33-P4R8YP9LON4VDP was successfully established. Levels of plasma tRF-33-P4R8YP9LON4VDP were shown to reflect a gradient change from healthy individuals to gastritis patients to early and advanced gastric cancer patients. Significant differences were found among individuals with differing gastric mucosa, with reduced levels of tRF-33-P4R8YP9LON4VDP significantly related to a poor prognosis. tRF-33-P4R8YP9LON4VDP was found to be an independent predictor of an unfavorable survival outcome.

Conclusions

In this study, we developed a quantitative detection method for plasma tRF-33-P4R8YP9LON4VDP that exhibited hypersensitivity, convenience, and specificity. Detection of tRF-33-P4R8YP9LON4VDP was found to be a valuable means by which to monitor different gastric mucosa and to predict patient prognosis.

Quantification of substoichiometric modification reveals global tsRNA hypomodification, preferences for angiogenin-mediated tRNA cleavage, and idiosyncratic epitranscriptomes of human neuronal cell-lines

Modification of tRNA is an integral part of the epitranscriptome with a particularly pronounced potential to generate diversity in RNA expression. Eukaryotic tRNA contains modifications in up to 20% of their nucleotides, but not all sites are always fully modified. Combinations and permutations of partially modified sites in tRNAs can generate a plethora of tRNA isoforms, termed modivariants. Here, we investigate the stoichiometry of incompletely modified sites in tRNAs from human cell lines for their information content. Using a panel of RNA modification mapping methods, we assess the stoichiometry of sites that contain the modifications 5-methylcytidine (m5C), 2'-O-ribose methylation (Nm), 3-methylcytidine (m3C), 7-methylguanosine (m7G), and Dihydrouridine (D). We discovered that up to 75% of sites can be incompletely modified and that the differential modification status of a cellular tRNA population holds information that allows to discriminate e.g. different cell lines. As a further aspect, we investigated potential causal connectivity between tRNA modification and its processing into tRNA fragments (tiRNAs and tRFs). Upon exposure of cultured living cells to cell-penetrating angiogenin, the modification patterns of the corresponding RNA populations was changed. Importantly, we also found that tsRNAs were significantly less modified than their parent tRNAs at numerous sites, suggesting that tsRNAs might derive chiefly from hypomodified tRNAs.

Potential of Non-Coding RNA as Biomarkers for Progressive Supranuclear Palsy

Objective markers for the neurodegenerative disorder progressive supranuclear palsy (PSP) are needed to provide a timely diagnosis with greater certainty. Non-coding RNA (ncRNA), including microRNA, piwi-interacting RNA, and transfer RNA, are good candidate markers in other neurodegenerative diseases, but have not been investigated in PSP. Therefore, as proof of principle, we sought to identify whether they were dysregulated in matched serum and cerebrospinal fluid (CSF) samples of patients with PSP. Small RNA-seq was undertaken on serum and CSF samples from healthy controls (n = 20) and patients with PSP (n = 31) in two cohorts, with reverse transcription-quantitative PCR (RT-qPCR) to confirm their dysregulation. Using RT-qPCR, we found in serum significant down-regulation in hsa-miR-92a-3p, hsa-miR-626, hsa-piR-31068, and tRNA-ValCAC. In CSF, both hsa-let-7a-5p and hsa-piR-31068 showed significant up-regulation, consistent with their changes observed in the RNA-seq results. Interestingly, we saw no correlation in the expression of hsa-piR-31068 within our matched serum and CSF samples, suggesting there is no common dysregulatory mechanism between the two biofluids. While these changes were in a small cohort of samples, we have provided novel evidence that ncRNA in biofluids could be possible diagnostic biomarkers for PSP and further work will help to expand this potential.

Function and Therapeutic Implications of tRNA Derived Small RNAs

tRNA derived small RNAs are mainly composed of tRNA fragments (tRFs) and tRNA halves (tiRs). Several functions have been attributed to tRFs and tiRs since their initial characterizations, spanning all aspects of regulation of the Central Dogma: from nascent RNA silencing, to post-transcriptional gene silencing, and finally, to translational regulation. The length distribution, sequence diversity, and multifaceted functions of tRFs and tiRs positions them as attractive new models for small RNA therapeutics. In this review, we will discuss the principles of tRF biogenesis and function in order to highlight their therapeutic potential.

The Therapeutic Potential of tRNA-derived Small RNAs in Neurodegenerative Disorders

Gene expressions and functions at various levels, namely post-transcriptional, transcriptional, and epigenetic, can be regulated by transfer RNA (tRNA)-derived small RNAs (tsRNAs), which are as well-established as tRNA fragments or tRFs. This regulation occurs when tsRNAs are created through the special endonuclease-mediated cleavage of mature or precursor tRNAs. However, tsRNAs are newly discovered entities, and molecular functions associated with tsRNAs are still not clearly understood. There is increasingly robust evidence suggesting that specific tsRNAs perform fundamental tasks in the pathogenesis of neurodevelopmental, neurodegenerative, and neurobehavioral disorders. Indeed, the patterns of tsRNA expression are uncertain and could be altered in patients suffering from Parkinson's disease, pontocerebellar hypoplasia, amyotrophic lateral sclerosis, Alzheimer's disease, and other neurodegenerative disorders. In the present article, a review is conducted of recent domestic and international progress in research on the potential cellular and molecular mechanisms of tsRNA biogenesis. We also describe endogenous tsRNAs during neuronal development and neurodegenerative disorders, thereby providing theoretical support and guidance for further revealing the therapeutic potential of tsRNAs in neurodegenerative disorders.

tRNA-derived fragments: A new class of non-coding RNA with key roles in nervous system function and dysfunction

tRNA-derived small RNAs (tsRNA) are a recently identified family of non-coding RNA that have been associated with a variety of cellular functions including the regulation of protein translation and gene expression. Recent sequencing and bioinformatic studies have identified the broad spectrum of tsRNA in the nervous system and demonstrated that this new class of non-coding RNA is produced from tRNA by specific cleavage events catalysed by ribonucleases such as angiogenin and dicer. Evidence is also accumulating that production of tsRNA is increased during disease processes where they regulate stress responses, proteostasis, and neuronal survival. Mutations to tRNA cleaving and modifying enzymes have been implicated in several neurodegenerative disorders, and tsRNA levels in the blood are advancing as biomarkers for neurological disease. In this review we summarize the physiological importance of tsRNA in the central nervous system and their relevance to neurological disease.