Extracellular microRNAs Research Articles

Circulating microRNAs and physical activity: Impact in diabetes.

The term "ci-miRNAs," or "circulating microRNAs," refers to extracellular microRNAs (miRNAs) that exist outside of cells and can be detected in various bodily fluids, including blood, saliva, urine, and breast milk. These ci-miRNAs play a role in regulating gene expression and are mainly recognized for their functions beyond the cell, serving as signaling molecules in the blood. Researchers have thoroughly investigated the roles of these circulating miRNAs in various diseases. The capacity to detect and quantify ci-miRNAs in bodily fluids suggests their potential as biomarkers for monitoring several health conditions, including cancer, heart disease, brain disorders, and metabolic disorders, where fluctuations in miRNA levels may correlate with different physiological and pathological states. Current methods enable researchers to identify and measure miRNAs in these fluids, facilitating the exploration of their roles in health maintenance and disease resistance. Although research on ci-miRNAs is ongoing, recent studies focus on uncovering their significance, assessing their viability as biomarkers, and clarifying their functions. However, our understanding of how various types, intensities, and durations of exercise influence the levels of these miRNAs in the bloodstream is still limited. This section seeks to provide an overview of the changes in ci-miRNAs in response to exercise.

Serum Extracellular Vesicle-derived microRNA Profiles in Patients with ST-segment Elevation Myocardial Infarction Undergoing Percutaneous Coronary Intervention

Objective: In this study, we sought to determine the potential of extracellular vesicle (EV) microRNAs (miRNAs) to serve as early diagnostic biomarkers for AMI. Method: Peripheral blood samples were collected from three patients with AMI and three healthy individuals, and serum EV total RNA was extracted. The miRNA differential expression profiles of serum EVs were obtained through next-generation sequencing combined with bioinformatics analysis. Results: In patients with AMI, compared with controls without AMI, 15 differentially expressed miRNAs (11 upregulated and 4 downregulated) were identified. GO analysis predicted 842 target genes. Enrichment analysis revealed 639 genes involved in biological processes, 592 genes involved in molecular function, and 692 genes involved in cellular components. KEGG analysis indicated that the protein processing in the endoplasmic reticulum pathway, P53 pathway, and mRNA surveillance signaling pathway significantly correlated with AMI. PPI network analysis indicated that 842 target proteins and 10 hub genes were significantly associated with the miRNAs. Conclusion: We identified 15 significantly differentially expressed miRNAs in AMI, whose target genes significantly correlated with protein processing in the endoplasmic reticulum pathway and the P53 pathway. Our results provide a reference for use of EV miRNAs as early diagnostic biomarkers in patients with AMI.

MicroRNA Profiling of Bone Marrow Plasma Extracellular Vesicles in Multiple Myeloma, Extramedullary Disease, and Plasma Cell Leukemia.

Multiple myeloma is a plasma cell malignancy characterized by an abnormal increase in monoclonal immunoglobulins. Despite significant advances in treatment, some patients progress to more aggressive forms of multiple myeloma, including extramedullary disease or plasma cell leukemia. Although the exact molecular mechanisms are not known, several studies have confirmed the involvement of small extracellular vesicle-enriched microRNAs in multiple myeloma progression. Therefore, we performed expression profiling of these molecules in bone marrow plasma of multiple myeloma, extramedullary disease, and plasma cell leukemia patients using small RNA sequencing to identify novel molecules involved in disease pathogenesis. In total, 42 microRNAs were significantly dysregulated among analyzed subgroups. Independent validation by RT-qPCR confirmed elevated levels of miR-140-3p, miR-584-5p, miR-191-5p, and miR-143-3p in multiple myeloma patients compared to extramedullary disease and plasma cell leukemia patients. Subsequent statistical analysis revealed significant correlations between patient clinical characteristics or flow cytometry parameters and microRNA expression. These results indicate that dysregulation of microRNAs could contribute to multiple myeloma progression.

Diagnostic Value of Glycosylated Extracellular Vesicle microRNAs in Gastric Cancer.

Early diagnosis is crucial for improving the prognosis of patients with gastric cancer (GC). However, the currently used biomarkers for diagnosing GC have limited sensitivity and specificity. This study aimed to develop a novel diagnostic model based on miRNAs from glycosylated extracellular vesicles and evaluate its effectiveness in diagnosing gastric cancer. GlyExo-capture technology was used to isolate glycosylated extracellular vesicles from serum samples. The signatures were screened in a discovery cohort of GC patients (n=55) and non-disease controls (n=46) using an integrated process, including high-throughput sequencing technology, screening using a complete bioinformatics algorithm, validation using RT-qPCR, and evaluation by constructing a diagnostic model. The diagnostic model was evaluated in an independent validation cohort (n=139). We developed a diagnostic model for GC based on five miRNA pairs. This diagnostic model demonstrated high sensitivity, specificity, and stable performance in distinguishing GC patients from non-cancer controls with AUC of 0.930 in the independent validation cohort, particularly in differentiating early-stage GC from benign patients. The markers also showed excellent performance in indicating perineural invasion status and lymph node metastasis in the testing cohort. The model demonstrated high sensitivity and specificity in diagnosing patients with GC, especially in differentiating early-stage GC from benign patients. The five miRNA pairs could also aid in making treatment decisions. Thus, miRNAs derived from glycosylated exosomes are promising biomarkers for cancer diagnosis.

Circulating large extracellular vesicles as diagnostic biomarkers of indeterminate thyroid nodules: multi-platform omics analysis.

While most thyroid nodules are benign, 7-15% are malignant. Patients with indeterminate thyroid nodules (specifically Bethesda IV/Thy3f) often undergo diagnostic hemithyroidectomy to reach a diagnosis on final histology. The aim of this study was to assess the feasibility of circulating large extracellular vesicles as diagnostic biomarkers in patients presenting with Thy3f thyroid nodules. This was a two-gate diagnostic accuracy study; patients with Thy3f thyroid nodules were age, sex and body mass index matched to healthy individuals. Final histology confirmed benign and malignant diagnoses. Plasma large extracellular vesicle counts were quantified using flow cytometry. Large extracellular vesicle microRNA and protein profiles were identified using next generation sequencing and mass spectrometry, respectively. A total of 42 patients with Thy3f nodules (22 with cancer, 20 with non-cancer diagnosis) and 16 healthy controls were included. Total large extracellular vesicle concentrations and the concentrations of extracellular vesicles expressing epithelial cell adhesion molecule and the cancer markers atypical chemokine receptor type 7, extracellular matrix metalloproteinase inducer and syndecan-4 were significantly higher in patients with Thy3f nodules (cancer and non-cancer) compared with healthy individuals. In patients with cancerous versus non-cancer Thy3f nodules, one microRNA was upregulated: mir-195-3p (P < 0.001). Five were downregulated: mir-3176 (P < 0.001), mir-205-5p (P < 0.001), novel-hsa-mir-208-3p (P < 0.001), mir-3529-3p (P = 0.01) and let-7i-3p (P = 0.02). Furthermore, three large extracellular vesicle proteins (kallikrein-related peptidase11 (KLK11) (P = 0.001), alpha-1-acid glycoprotein 2 (A1AG2) (P <0.001) and small integral membrane protein 1 (SMIM1) (P = 0.04)) were significantly upregulated, while 20 large extracellular vesicle proteins were significantly downregulated (most downregulated: chemokine (C-X-C motif) ligand 7 (CXCL7), tubulin beta chain 1 (TBB1), binding immunoglobulin protein (BIP) and actinin alpha 1 (ACTN1) (P < 0.001)) in cancerous compared with non-cancer Thy3f nodules. Circulating large extracellular vesicle miRNA and protein profiles have a high diagnostic value to discriminate between benign and malignant nodules for patients with Thy3f cytology. Further validation for clinical performance will be needed.

Bibliometrics of trends in global research on the roles of stem cells in myocardial fibrosis therapy.

Myocardial fibrosis, a condition linked to several cardiovascular diseases, is associated with a poor prognosis. Stem cell therapy has emerged as a potential treatment option and the application of stem cell therapy has been studied extensively. However, a comprehensive bibliometric analysis of these studies has yet to be conducted. To map thematic trends, analyze research hotspots, and project future directions of stem cell-based myocardial fibrosis therapy. We conducted a bibliometric and visual analysis of studies in the Web of Science Core Collection using VOSviewer and Microsoft Excel. The dataset included 1510 articles published between 2001 and 2024. Countries, organizations, authors, references, keywords, and co-citation networks were examined to identify evolving research trends. Our findings revealed a steady increase in the number of publications, with a projected increase to over 200 publications annually by 2030. Initial research focused on stem cell-based therapy, particularly for myocardial infarction and heart failure. More recently, there has been a shift toward cell-free therapy, involving extracellular vesicles, exosomes, and microRNAs. Key research topics include angiogenesis, inflammation, apoptosis, autophagy, and oxidative stress. This analysis highlights the evolution of stem cell therapies for myocardial fibrosis, with emerging interest in cell-free approaches. These results are expected to guide future scientific exploration and decision-making.

Extracellular vesicles and micro-RNAs in liver disease.

Progression of liver disease is dependent on intercellular signaling, including those mediated by extracellular vesicles (EVs). Within these EVs, microRNAs (miRNAs) are packaged to selectively silence gene expression in recipient cells for upregulating or downregulating a specific pathway. Injured hepatocytes secrete EV-associated miRNAs which can be taken up by liver sinusoidal endothelial cells (LSECs), immune cells, hepatic stellate cells (HSCs), and other cell types. In addition, these recipient cells will secrete their own EV-associated miRNAs to propagate a response throughout the tissue and the circulation. In this review, we comment on the implications of EV-miRNAs in the progression of alcohol-associated liver disease (ALD), metabolic dysfunction-associated steatohepatitis (MASH), viral and parasitic infections, liver fibrosis, and liver malignancies. We summarize how circulating miRNAs can be used as biomarkers and the potential of utilizing EVs and miRNAs as therapeutic methods to treat liver disease.

Pathologic function and therapeutic potential of extracellular vesicle miRNA in sepsis.

Sepsis is a systemic inflammatory response initiated by an infection, which can lead to multi-organ dysfunction. The pathophysiology of sepsis is complex, and treatment options are limited. Traditional antibiotic therapies have shown limitations, such as promoting the emergence of antibiotic-resistant bacteria and disrupting the natural microbiota. Consequently, there is a pressing need to explore diverse therapeutic approaches for sepsis management. Extracellular vesicles, which play a crucial role in cell-to-cell communication, are released by various cell types throughout the body and possess a membrane structure composed of a lipid bilayer. MicroRNAs may be encapsulated within these structures and can be selectively delivered to target recipient cells through the activation of cell surface receptors or via endocytosis and fusion, thereby modulating the biological functions of target cells. The article examines the pathological alterations that happen as sepsis progresses and the biological control of extracellular vesicles and microRNAs in sepsis. This review focuses on the role of extracellular vesicles and their microRNAs on controlling the inflammatory response, macrophage polarization, programmed cell death, endothelial dysfunction, and microcirculatory changes in sepsis. Furthermore, the obstacles encountered by this novel therapy are also examined.

Adipose Tissue as a Major Launch Spot for Circulating Extracellular Vesicle-Carried MicroRNAs Coordinating Tissue and Systemic Metabolism.

Circulating microRNAs (miRNAs), especially transported by extracellular vesicles (EVs), have recently emerged as major new participants in interorgan communication, playing an important role in the metabolic coordination of our tissues. Among these, adipose tissue displays an extraordinary ability to secrete a vast list of EV-carried miRNAs into the circulation, representing new hormone-like factors. Despite the limitations of current methodologies for the unequivocal identification of the origin and destination of EV-carried miRNAs in vivo, recent investigations clearly support the important regulatory role of adipose-derived circulating miRNAs in shaping the metabolism and function of other tissues including the liver, muscle, endocrine pancreas, cardiovascular system, gastrointestinal tract, and brain. Here, we review the most recent findings regarding miRNAs transported by adipose-derived EVs (AdEVs) targeting other major metabolic organs and the implications of this dialog for physiology and pathology. We also review here the current and potential future diagnostic and therapeutic applications of AdEV-carried miRNAs.

Extracellular Vesicle miR-122-5p as a Prognostic Biomarker in Pediatric Classical Hodgkin Lymphoma.

Currently, risk stratification for pediatric Hodgkin lymphoma is based on clinical factors such as stage, bulk, and systemic symptoms. Novel minimally invasive biomarkers could enhance both prognosis and treatment strategies. Therefore, the plasma extracellular vesicles' microRNA profile was characterized by small RNA sequencing in 36 classical Hodgkin lymphoma cases and these findings were confirmed in an extended cohort of 86 patients by RT-qPCR. It was found that the levels of miR-122-5p at diagnosis were significantly higher (p-value: 0.0002) in patients who relapsed compared to patients in remission. The 5-year event-free survival of cases with high and low levels of miR-122-5p was 65 ± 7% and 93 ± 4%, respectively. MiR-122-5p levels were significantly associated with clinical events in both univariate (p-value: 0.0009) and multivariate (p-value: 0.0037) analysis (hazard ratio 5.8). Target prediction analysis suggests an involvement in the polarization of immune cells. The phenotypic characterization of peripheral blood mononuclear cells in 12 patients showed significantly increased levels of CD4+ T-cells in cases with high miR-122-5p levels as compared to low levels (p-value: 0.048). Moreover, CCL17 (TARC) and IL-6 plasma levels at diagnosis were significantly higher as compared to healthy donors (p-value: ≤0.0001). MiR-122-5p could complement current prognostic assays to identify patients at high risk of relapse.

Identification of differentially expressed miRNAs involved in vascular aging reveals pathways associated with the endocrine hormone regulation

Vascular aging refers to a series of processes where the elasticity of blood vessels diminishes, leading to stiffening, and deposition of fat components on the vessel walls, causing inflammation. Cardiovascular diseases, such as stroke and hypertension, play significant roles in morbidity and mortality rates among the elderly population. In this study, the Reactive Hyperemia Index (RHI) was measured to assess vascular endothelial function and aging-induced pathogenesis of vascular diseases in Korean subjects. We aimed to identify extracellular vesicle microRNAs (EV-miRNAs) with differential abundance between groups of individuals at the ends of a continuum in vascular aging acceleration, revealing miRNAs regulating genes in endocrine hormone regulation and tumor-related pathways. We also discovered that the principal component characterizing the global miRNA expression profile is significantly associated with clinical traits including cholesterol levels. Together, these data provide a foundation for understanding the role of miRNAs as modulators of longevity and for developing age-specific epigenetic biomarkers.

Effect of inulin on small extracellular vesicles microRNAs in milk from dairy cows with subclinical mastitis.

Milk contains microRNAs (miRNA) that are shielded by small extracellular vesicles (sEVs). Beyond variations among individuals, many factors including nutrition play a role in shaping miRNA expression profiles. This study is to explore milk-derived sEVs-miRNA variations induced by inulin supplementation in subclinical mastitis-suffering cows. Fourteen lactating cows diagnosed with subclinical mastitis were equally assigned to either an inulin or a control group. Apart from total mixed rations, cows in the inulin group were provided with 300g/d inulin during the morning feeding, while the control group did not receive any supplement. Following 1wk of adaptation and 5wk of treatment, sEVs-miRNA were isolated from the milk of each cow. RNA is subjected to high-throughput sequencing and differentially expressed (DE) miRNA (P < 0.05 and ∣ log2FC∣> 1) were detected through bioinformatics analysis. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were conducted to examine the target genes of DE miRNA. A sum of 350 miRNA was discovered, including 332 in the control group and 249 in the inulin group. Among these, 9 miRNA showed differential expression within the 2 groups, including 3 upregulated and 6 downregulated in the inulin group. The DE miRNA participates in regulating organismal systems, cellular processes, and signal transduction, which may affect inflammatory response and milk production. Overall, our study provides insight into the micromolecular-level mechanism of inulin in alleviating subclinical mastitis in dairy cows.

Integrated Profiling of Extracellular Vesicle microRNA Impact on Trabecular Meshwork mRNA Expression: Insights From Microarray Analysis.

Extracellular vesicles (EVs) secreted by non-pigmented ciliary epithelial (NPCE) cells under oxidative stress may contribute to primary open-angle glaucoma (POAG) pathogenesis by altering gene expression in human trabecular meshwork (HTM) cells. This study investigated the impact of microRNAs (miRNAs) carried by NPCE-derived EVs on HTM cell gene expression under oxidative stress conditions. NPCE cells were exposed to oxidative stress, and EVs were isolated from control and stressed cells. HTM cells were treated with these EVs, followed by microarray analysis to identify differentially expressed miRNAs in EVs and messenger RNAs (mRNAs) in HTM cells. Bioinformatics analysis was used to explore miRNA-mRNA interactions, enriched Gene Ontology (GO) terms, and miRNA-mRNA-GO networks. The study identified 54 differentially expressed miRNAs in stressed NPCE EVs. In HTM cells treated with stressed NPCE EVs, 88 genes were upregulated and 58 downregulated. GO analysis of upregulated genes showed enrichment in processes such as extracellular matrix organization, cell proliferation, and adhesion. Downregulated genes were associated with oxidative phosphorylation and adenosine triphosphate (ATP) biosynthesis. Notably, 59 out of 88 upregulated genes are known targets of downregulated miRNAs. Network analysis identified interactions between downregulated miRNAs and upregulated genes involved in key biological processes relevant to POAG pathogenesis. This study provides new insights into the potential role of NPCE-derived EVs and their miRNA cargo in POAG, suggesting novel mechanisms for disease progression and potential therapeutic targets for further investigation.

Human milk extracellular vesicles modulate inflammation and cell survival in intestinal and immune cells.

Human milk contains extracellular vesicles (EVs) that carry bioactive molecules such as microRNA, to the newborn intestine. The downstream effects of EV cargo on signaling and immune modulation may shield neonates against inflammatory diseases, including necrotizing enterocolitis. Premature infants are especially at risk, while human milk-feeding may offer protection. The effect of gestational-age specific term and preterm EVs from transitional human milk was characterized on human intestinal epithelial cells (HIECs and Caco-2), primary macrophages, and THP-1 monocytes. We hypothesized that term and preterm EVs differentially influence immune-related cytokines and cell death. We found that preterm EVs were enriched in CD14 surface marker, while both term and preterm EVs increased epidermal growth factor secretion. Following inflammatory stimuli, only term EVs inhibited secretion of IL-6 in HIECs, and reduced expression of pro-inflammatory cytokine IL-1β in macrophages. Term and preterm EVs inhibited secretion of IL-1β and reduced inflammasome related cell death. We proposed that human milk EVs regulate immune-related signaling via their conserved microRNA cargo, which could promote tolerance and a homeostatic immune response. These findings provide basis for further studies into potential therapeutic supplementation with EVs in vulnerable newborn populations by considering functional, gestational age-specific effects. IMPACT: This study reveals distinct functional differences between term and preterm transitional human milk extracellular vesicles (EVs) highlighting the importance of gestational age in their bioactivity. Term EVs uniquely inhibited IL-6 secretion, IL-1β expression, and apoptosis following inflammatory stimuli. Both term and preterm human milk EVs reduced IL-1β secretion and inflammasome-induced cell death. Conserved human milk extracellular vesicle microRNA cargo could be a mediator of the anti-inflammatory effects, particularly targeting cytokine production, the inflammasome, and programmed cell death. These findings underscore the importance of considering gestational age in future research exploring the therapeutic potential of human milk extracellular vesicles to prevent or treat intestinal inflammatory diseases in neonates.

Plasma Extracellular Vesicle-derived MicroRNA Associated with Human Alpha-1 Antitrypsin Deficiency-mediated Liver Disease.

Alpha-1 antitrypsin deficiency (AATD) is a genetic disorder associated with liver disease, ranging from fibrosis to hepatocellular carcinoma. The disease remains asymptomatic until its final stages when liver transplantation is the only available therapy. Biomarkers offer an advantage for disease evaluation. The presence of microRNAs (miRNAs) in plasma extracellular vesicles (EVs) presents a noninvasive approach to assess the molecular signatures of the disease. In this study, we aimed to identify miRNA biomarkers to distinguish molecular signatures of the liver disease associated with AATD in AATD individuals. Using small RNA sequencing and qPCR, we examined plasma EV miRNAs in healthy controls (n = 20) and AATD patients (n = 17). We compared the EV miRNAs of AATD individuals with and without liver disease, developing an approach for detecting liver disease. A set of miRNAs identified in the AATD testing cohort was validated in a separate cohort of AATD patients (n = 45). We identified differential expression of 178 EV miRNAs in the plasma of the AATD testing cohort compared to controls. We categorized AATD individuals into those with and without liver disease, identifying 39 differentially expressed miRNAs. Six miRNAs were selected to test their ability to discriminate liver disease in AATD. These were validated for their specificity and sensitivity in an independent cohort of 45 AATD individuals. Our logistic model established composite scores with three- and four-miRNA combinations, achieving areas under the curve of 0.737 and 0.751, respectively, for predicting AATD liver disease. We introduce plasma EV-derived miRNAs as potential biomarkers for evaluating AATD liver disease. Plasma EV-associated miRNAs may represent a molecular signature of AATD liver disease and could serve as valuable tools for its detection and monitoring.

Extracellular Vesicle microRNAs as Possible Liquid Biopsy Markers in HNSCC-A Longitudinal, Monocentric Study.

Biomarkers for HNSCC are still lacking. Biomolecules obtained via liquid biopsy are being investigated for diagnosis, prognosis, and therapy monitoring, including extracellular vesicles (EVs) and EV-cargo, e.g., proteins, RNA, and microRNA. This study aims to understand localization-dependent EV-microRNA expression in blood sera, their dynamics over time (12 months FU), and insights into their potential in diagnostics and therapy monitoring. Via liquid biopsy, blood serum was taken from 50 patients with HNSCC and 16 controls. Extracellular vesicles were isolated from serum by precipitation, and the contained microRNA-21, -1246, -200c, -let-7a, -181a, and -26a were amplified by reverse transcription and determined with real-time PCR. Expression ratios (HNSCC to healthy controls) were collated with the patients' clinical parameters. A second liquid biopsy was carried out avg. 12 months later in the tumor aftercare. A sub-analysis with the Oropharynx subsite was implemented. EV-mir-21, -let-7a, and -181a were 2.5-3-fold higher expressed in HPV/p16+ than in HPV/p16- HNSCC. Different expressions of EV-mir-181a and -26a could be demonstrated depending on the therapy modality. EV-microRNA could be a promising biomarker in the diagnosis and therapy monitoring of HNSCC. A systematic comparison of EV- and tissue microRNA expression in different HNSCC-subsites is needed.

Cell damage shifts the microRNA content of small extracellular vesicles into a Toll-like receptor 7-activating cargo capable to propagate inflammation and immunity

BackgroundThe physiological relevance of cell-to-cell communication mediated by small extracellular vesicle-encapsulated microRNAs (sEV-miRNAs) remains debated because of the limiting representativity of specific miRNAs within the extracellular pool. We hypothesize that sEV-miRNA non-canonical function consisting of the stimulation of Toll-like receptor 7 (TLR7) may rely on a global shift of the sEV cargo rather than on the induction of one or few specific miRNAs. Psoriasis represents an ideal model to test such hypothesis as it is driven by overt activation of TLR7-expressing plasmacytoid dendritic cells (pDCs) following keratinocyte damage.MethodsTo mimic the onset of psoriasis, keratinocytes were treated with a cocktail of psoriatic cytokines or UV-irradiated. SmallRNA sequencing was performed on sEVs released by healthy and UV-treated keratinocytes. sEV-miRNAs were analyzed for nucleotide composition as well as for the presence of putative TLR7-binding triplets. Primary human pDCs where stimulated with sEVs +/- inhibitors of TLR7 (Enpatoran), of sEV release (GW4869 + manumycin) and of TLR7-mediated pDC activation (anti-BDCA-2 antibody). Secretion of type I IFNs and activation of CD8+T cells were used as readouts. qPCR on psoriatic and healthy skin biopsies was conducted to identify induced miRNAs.ResultssEV-miRNAs released by damaged keratinocytes revealed a significantly higher content of TLR7-activating sequences than healthy cells. As expected, differential expression analysis confirmed the presence of miRNAs upregulated in psoriatic skin, including miR203a. More importantly, 76.5% of induced miRNAs possessed TLR7-binding features and among these we could detect several previously demonstrated TLR7 ligands. In accordance with this in silico analysis, sEVs from damaged keratinocytes recapitulated key events of psoriatic pathogenesis by triggering pDCs to release type I interferon and activate cytotoxic CD8+T cells in a TLR7- and sEV-dependent manner.DiscussionOur results demonstrate that miR203a is just one paradigmatic TLR7-activating miRNA among the hundreds released by UV-irradiated keratinocytes, which altogether trigger pDC activation in psoriatic conditions. This represents the first evidence that cell damage shifts the miRNA content of sEVs towards a TLR7-activating cargo capable to propagate inflammation and immunity, offering strong support to the physiological role of systemic miRNA-based cell-to-cell communication.

First person – Kyoung-Min Choi

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping researchers promote themselves alongside their papers. Kyoung-Min Choi is co-first author on ‘ Mature microRNA-binding protein QKI suppresses extracellular microRNA let-7b release’, published in JCS. Kyoung-Min is an Associate Research Scholar in the lab of Je-Hyun Yoon at the College of Medicine, University of Oklahoma, investigating the functions of noncoding RNAs in metabolic disorders.

Mature microRNA-binding protein QKI suppresses extracellular microRNA let-7b release.

Argonaute (AGO), a component of RNA-induced silencing complexes (RISCs), is a representative RNA-binding protein (RBP) known to bind with mature microRNAs (miRNAs) and is directly involved in post-transcriptional gene silencing. However, despite the biological significance of miRNAs, the roles of other miRNA-binding proteins (miRBPs) remain unclear in the regulation of miRNA loading, dissociation from RISCs and extracellular release. In this study, we performed protein arrays to profile miRBPs and identify 118 RBPs that directly bind to miRNAs. Among those proteins, the RBP quaking (QKI) inhibits extracellular release of the mature microRNA let-7b by controlling the loading of let-7b into extracellular vesicles via additional miRBPs such as AUF1 (also known as hnRNPD) and hnRNPK. The enhanced extracellular release of let-7b after QKI depletion activates Toll-like receptor 7 (TLR7) and promotes the production of proinflammatory cytokines in recipient cells, leading to brain inflammation in the mouse cortex. Thus, this study reveals the contribution of QKI to the inhibition of brain inflammation via regulation of extracellular let-7b release.

Effects of intrauterine extracellular vesicle microRNAs on embryonic gene expression in low-fertility cows.

Embryo survival and pre-implantation development depend on uterine luminal fluid, which is believed to play a role in early embryonic death and infertility in cows. Extracellular vesicles (EVs) in the uterine luminal fluid contain microRNAs (miRNAs), crucial mediators of intercellular communication. miRNAs regulate conceptus-maternal interactions and participate in embryonic development by suppressing gene expression. Therefore, we hypothesized that miRNAs in the intrauterine EVs of low-fertility cows would hinder embryonic survival and development. EVs were collected from the bovine uterine luminal fluid of both normal- and low-fertility cows 7 days post-estrus. Small RNA-sequencing analysis of miRNAs isolated from these EVs identified eight miRNAs that were highly expressed in normal-fertility cows (normal-fertility miRNAs) and eight with elevated expression in low-fertility cows (low-fertility miRNAs). These two sets of miRNAs were transfected into hatched blastocysts via lipofection. RNA-seq following lipofection with low-fertility miRNAs identified 424 differentially expressed genes (DEGs) relative to the control; in contrast, following lipofection with normal-fertility miRNAs, seven DEGs were identified. Pathway analysis of the DEGs identified following lipofection with low-fertility miRNAs revealed substantial enrichment of mitogen-activated protein kinase (MAPK) signaling. Expression of activator protein 1 (AP1) and interferon-tau (IFNT) mRNA was significantly lower in the low-fertility miRNA transfection group than in the control. IFNT is essential for maternal pregnancy recognition. Therefore, miRNAs in intrauterine EVs from low-fertility cows at 7 days post-estrus may inhibit embryo development and suppress IFNT expression by altering MAPK signaling.