MicroRNA: Mechanisms of Action, Physio-Pathological Implications, and Disease Biomarkers, 2nd Volume

MicroRNAs (miRNAs) are highly conserved endogenous single-stranded non-coding RNA molecules that play a crucial role in regulating gene expression to maintain normal physiological functions in fish. Nevertheless, the specific physiological role of miRNAs in lower vertebrates, particularly in comparison to mammals, remains elusive. Additionally, the mechanisms underlying the control of antiviral responses triggered by viral stimulation in fish are still not fully understood. In this study, we investigated the regulatory impact of miR-1388 on the signaling pathway mediated by IFN regulatory factor 3 (IRF3). Our findings revealed that following stimulation with the viral analog poly(I:C), the expression of miR-1388 was significantly upregulated in primary immune tissues and macrophages. Through a dual luciferase reporter assay, we corroborated a direct targeting relationship between miR-1388 and tumor necrosis factor receptor (TNFR)-associated factor 3 (TRAF3). Furthermore, our study demonstrated a distinct negative post-transcriptional correlation between miR-1388 and TRAF3. We observed a significant negative post-transcriptional regulatory association between miR-1388 and the levels of antiviral genes following poly(I:C) stimulation. Utilizing reporter plasmids, we elucidated the role of miR-1388 in the antiviral signaling pathway activated by TRAF3. By intervening with siRNA-TRAF3, we validated that miR-1388 regulates the expression of antiviral genes and the production of type I interferons (IFN-Is) through its interaction with TRAF3. Collectively, our experiments highlight the regulatory influence of miR-1388 on the IRF3-mediated signaling pathway by targeting TRAF3 post poly(I:C) stimulation. These findings provide compelling evidence for enhancing our understanding of the mechanisms through which fish miRNAs participate in immune responses. Full article

Hypertension is a chronic, multifactorial disease, leading to high cardiovascular morbidity and mortality globally. Despite the advantages of pharmaceutical treatments, natural products have gained scientific interest due to their emerging phytotherapeutic properties. Chios mastic is a natural Greek product, consisting of bioactive compounds which modify microRNAs’ (small, expression-regulating molecules) expression. In this study, we investigated the antihypertensive properties of Chios mastic through the assessment of miR-21 levels. Herein, plasma samples of 57 individuals with hypertension, recruited for the purposes of the HYPER-MASTIC study, were analyzed. This was a clinical trial with Chios mastic supplements in which the patients were divided into groups receiving high and low mastic doses and placebo supplements, respectively. miR-21 was significantly upregulated in patients compared to normotensive individuals. Mean changes in miR-21 levels were statistically significant, after adjusting for sex and age, between the placebo and low-dose group and between the low- and high-dose group. Post-intervention miR-21 levels were positively associated with night-time systolic blood pressure, pulse pressure, and central systolic mean arterial pressure and negatively associated with night-time pulse wave velocity in the low-dose group. Our findings suggest a potential implication of miR-21 in the association of Chios mastic with night-time blood pressure measurements. Full article

Innate immune response is the first line of host defense against pathogenic microorganisms, and its excessive or insufficient activation is detrimental to the organism. Many individual microRNAs (miRNAs) have emerged as crucial post-transcriptional regulators of immune homeostasis in Drosophila melanogaster. However, the synergistical regulation of miRNAs located within a cluster on the Imd-immune pathway remains obscured. In our study, a genetic screening with 52 transgenic UAS-miRNAs was performed to identify ten miRNAs or miRNA clusters, including the miR310~313 cluster, which may function on Imd-dependent immune responses. The miRNA RT-qPCR analysis showed that the expression of miR-310~313 cluster members exhibited an increase at 6–12 h post E. coli infection. Furthermore, the overexpression of the miR-310~313 cluster impaired the Drosophila survival. And the overexpression of miR-310/311/312 reduced Dpt expression, an indication of Imd pathway induced by Gram-negative bacteria. Conversely, the knockdown of miR-310/311/312 led to increases in Dpt expression. The Luciferase reporter expression assays and RT-qPCR analysis confirmed that miR-310~313 cluster members directly co-targeted and inhibited Imd transcription. These findings reveal that the members of the miR-310~313 cluster synergistically inhibit Imd-dependent immune responses by co-targeting the Imd gene in Drosophila. Full article

Chronic kidney disease (CKD) represents an increasing health burden. Evidence suggests the importance of miRNA in diagnosing CKD, yet the reports are inconsistent. This study aimed to determine novel miRNA biomarkers and potential therapeutic targets from hypothesis-free miRNA profiling studies in human and murine CKDs. Comprehensive literature searches were conducted on five databases. Subgroup analyses of kidney diseases, sample types, disease stages, and species were conducted. A total of 38 human and 12 murine eligible studies were analyzed using Robust Rank Aggregation (RRA) and vote-counting analyses. Gene set enrichment analyses of miRNA signatures in each kidney disease were conducted using DIANA-miRPath v4.0 and MIENTURNET. As a result, top target genes, Gene Ontology terms, the interaction network between miRNA and target genes, and molecular pathways in each kidney disease were identified. According to vote-counting analysis, 145 miRNAs were dysregulated in human kidney diseases, and 32 were dysregulated in murine CKD models. By RRA, miR-26a-5p was significantly reduced in the kidney tissue of Lupus nephritis (LN), while miR-107 was decreased in LN patients’ blood samples. In both species, epithelial-mesenchymal transition, Notch, mTOR signaling, apoptosis, G2/M checkpoint, and hypoxia were the most enriched pathways. These miRNA signatures and their target genes must be validated in large patient cohort studies. Full article

Herpesvirus entry mediator (HVEM) is a molecular switch that can modulate immune responses against cancer. The significance of HVEM as an immune checkpoint target and a potential prognostic biomarker in malignancies is still controversial. This study aims to determine whether HVEM is an immune checkpoint target with inhibitory effects on anti-tumor CD4⁺ T cell responses in vitro and whether HVEM gene expression is dysregulated in patients with acute lymphocytic leukemia (ALL). HVEM gene expression in tumor cell lines and peripheral blood mononuclear cells (PBMCs) from ALL patients and healthy controls was measured using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Tumor cells were left untreated (control) or were treated with an HVEM blocker before co-culturing with CD4⁺ T cells in vitro in a carboxyfluorescein succinimidyl ester (CFSE)-dependent proliferation assay. HVEM expression was upregulated in the chronic myelogenous leukemia cell line (K562) (FC = 376.3, p = 0.086) compared with normal embryonic kidney cells (Hek293). CD4⁺ T cell proliferation was significantly increased in the HVEM blocker-treated K562 cells (p = 0.0033). Significant HVEM differences were detected in ALL PBMCs compared with the controls, and these were associated with newly diagnosed ALL (p = 0.0011) and relapsed/refractory (p = 0.0051) B cell ALL (p = 0.0039) patients. A significant differentiation between malignant ALL and the controls was observed in a receiver operating characteristic (ROC) curve analysis with AUC = 0.78 ± 0.092 (p = 0.014). These results indicate that HVEM is an inhibitory molecule that may serve as a target for immunotherapy and a potential ALL biomarker. Full article

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that causes joint inflammation and destruction with an unknown origin. Our study aims to elucidate the molecular mechanism behind HIF1α overexpression in RA. Dysregulated miRNA expressions are known to influence gene behavior, thereby enhancing cell proliferation, inflammation, and resistance to apoptosis, contributing to RA development. Our earlier finding indicated that exogenous miRNA similar to miR-4693-5p may modulate RA-related targets. However, the specific role of miR-4693-5p and its targets in RA remain unexplored. In this study, we found that miR-4693-5p was significantly reduced in PBMCs of RA patients, with evidence suggesting it targets the 3′ UTR of HIF1α, thereby potentially contributing to its overexpression in RA. In vitro overexpression of miR-4693-5p leads to the knockdown of HIF1α, resulting in inhibited expression of Survivin to disrupt apoptosis resistance, inflammation suppression, and a reduction in the total cellular ROS response in SW982 and RAFLS cells. The results were validated using the CIA Rat model. In conclusion, this study provides a crucial foundation for understanding the functional role of miR-4693-5p. These findings improve our understanding and provide novel insights into the molecular mechanisms underlying RA pathogenesis. Full article

Exosomes have the ability to transport RNA/miRNAs and possess immune modulatory functions. Heat stress, a significant limiting factor in the poultry industry, can induce oxidative stress and suppress the immune responses of laying hens. In this study, we investigated the expression profiles of serum exosomes and their miRNAs in Roman laying hens who were fed a diet with either 0 or 200 mg/kg curcumin under heat stress conditions. The numbers of exosomes were significantly higher in both the HC (heat stress) and HT (heat stress with 200 mg/kg curcumin) groups compared to the NC (control) group and NT (control with 200 mg/kg curcumin) group (p < 0.05). Additionally, we observed that the most prevalent particle diameters were 68.75 nm, 68.25 nm, 54.25 nm, and 60.25 nm in the NC, NT, HC, and HT groups, respectively. From our sRNA library analysis, we identified a total of 863 unique miRNAs; among them, we screened out for subsequent bioinformatics analysis a total of 328 gga-miRNAs(chicken miRNA from the miRbase database). The KEGG pathways that are associated with target genes which are regulated by differentially expressed miRNAs across all four groups at a p-value < 0.01 included oxidative phosphorylation, protein export, cysteine and methionine metabolism, fatty acid degradation, ubiquitin-mediated proteolysis, and cardiac muscle contraction. The above findings suggest that curcumin could mitigate heat-induced effects on laying hens by altering the miRNA expression profiles of serum exosomes along with related regulatory pathways. Full article

In recent years, rising temperatures have caused heat stress (HS), which has had a significant impact on livestock production and growth, presenting considerable challenges to the agricultural industry. Research has shown that miR-425-5p regulates cellular proliferation in organisms. However, the specific role of miR-425-5p in bovine mammary epithelial cells (BMECs) remains to be determined. The aim of this study was to investigate the potential of miR-425-5p in alleviating the HS-induced proliferation stagnation in BMECs. The results showed that the expression of miR-425-5p significantly decreased when BMEC were exposed to HS. However, the overexpression of miR-425-5p effectively alleviated the inhibitory effect of HS on BMEC proliferation. Furthermore, RNA sequencing analysis revealed 753 differentially expressed genes (DEGs), comprising 361 upregulated and 392 downregulated genes. Some of these genes were associated with proliferation and thermogenesis through enrichment analyses. Further experimentation revealed that TOB2, which acts as a target gene of miR-425-5p, is involved in the regulatory mechanism of BMEC proliferation. In summary, this study suggests that miR-425-5p can promote the proliferation of BMECs by regulating TOB2. The miR-425-5p/TOB2 axis may represent a potential pathway through which miR-425-5p ameliorates the proliferation stagnation of BMECs induced by HS. Full article

Malnutrition is prevalent in patients with chronic kidney disease (CKD), especially those on hemodialysis. Recently, our group described that a new oral nutritional supplement (ONS), specifically designed for malnourished (or at risk) hemodialysis patients with a “similar to the Mediterranean diet” pattern, improved caloric-protein intake, nutritional status and biomarkers of inflammation and oxidation. Our aim in this study was to evaluate whether the new ONS, associated with probiotics or not, may produce changes in miRNA’s expression and its target genes in malnourished hemodialysis patients, compared to individualized diet recommendations. We performed a randomized, multicenter, parallel-group trial in malnourished hemodialysis patients with three groups (1: control (C) individualized diet (n = 11); 2: oral nutritional supplement (ONS) + placebo (ONS-PL) (n = 10); and 3: ONS + probiotics (ONS-PR) (n = 10)); the trial was open regarding the intake of ONS or individualized diet recommendations but double-blinded for the intake of probiotics. MiRNAs and gene expression levels were analyzed by RT-qPCR at baseline and after 3 and 6 months. We observed that the expression of miR-29a and miR-29b increased significantly in patients with ONS-PR at 3 months in comparison with baseline, stabilizing at the sixth month. Moreover, we observed differences between studied groups, where miR-29b expression levels were elevated in patients receiving ONS-PR compared to the control group in the third month. Regarding the gene expression levels, we observed a decrease in the ONS-PR group compared to the control group in the third month for RUNX2 and TNFα. TGFB1 expression was decreased in the ONS-PR group compared to baseline in the third month. PTEN gene expression was significantly elevated in the ONS-PR group at 3 months in comparison with baseline. LEPTIN expression was significantly increased in the ONS-PL group at the 3-month intervention compared to baseline. The new oral nutritional supplement associated with probiotics increases the expression levels of miR-29a and miR-29b after 3 months of intervention, modifying the expression of target genes with anti-inflammatory and anti-fibrotic actions. This study highlights the potential benefit of this oral nutritional supplement, especially associated with probiotics, in malnourished patients with chronic renal disease on hemodialysis. Full article

miR-129 plays a crucial role in regulating various cellular processes, including adipogenesis; however, its downstream molecular mechanisms remain unclear. In this study, we demonstrated that miR-129 promotes yak adipogenesis in vitro via the PI3K/AKT pathway. Overexpression and interference of miR-129 in yak intramuscular preadipocytes (YIMAs) enhanced and inhibited cell differentiation, respectively, with corresponding changes in cell proliferation. Further investigation revealed that miR-129 enhances AKT and p-AKT activity in the AKT pathway without affecting cell apoptosis, and a specific inhibitor (LY294002) was used to confirm that miR-129 regulates YIMAs proliferation and differentiation through the PI3K/AKT pathway. Our findings suggest that miR-129 promotes yak adipogenesis by enhancing PI3K/AKT pathway activity. This study provides the foundation to precisely elucidate the molecular mechanism of miR-129 in YIMAs adipogenesis and develop advanced miRNA-based strategies to improve meat nutrition and obesity-related ailments in beef production. Full article

MiRNAs play crucial roles in a broad spectrum of biological processes, both physiological and pathological. Different reports implicate miR-205 in the control of breast stem cell properties. Differential miR-205 expression has been observed in different stages of mammary gland development and maturation. However, a functional role in this process has not been clearly demonstrated. We generated an miR-205 knockout in the FVB/N mouse strain, which is viable and characterized by enhanced mammary gland development. Indeed, mammary glands of miR-205^−/− female mice at different ages (1.5 and 5.5 months) show increased outgrowth and branching. This evidence is consistent with our previously reported data demonstrating the direct miR-205-mediated targeting of HER3, a master regulator of mammary gland development, and the oncosuppressive activity of this microRNA in different types of breast cancer. Full article

Non-alcoholic fatty liver disease (NAFLD) is characterized by excessive lipid accumulation in the liver. Clarifying the molecular mechanism of lipid metabolism is crucial for the treatment of NAFLD. We examined miR-192-5p levels in the livers of mice in which NAFLD was induced via a high-fat diet (HFD), as well as in mouse primary hepatocytes and human HepG2 cells treated with free fatty acids (FFAs). MiR-192-5p inhibitor was administered to NAFLD mice and hepatocytes to verify the specific function of miR-192-5p in NAFLD. We validated the target gene of miR-192-5p and further illustrated the effects of this miRNA on the regulation of triglyceride (TG) metabolism. We found that miR-192-5p was significantly increased in the livers of NAFLD mice and FFA-treated hepatocytes. Inhibition of miR-192-5p increased the accumulation of hepatic TGs and aggravated hepatic steatosis in NAFLD mice. In FFA-treated hepatocytes, miR-192-5p inhibitors markedly increased TG content, whereas overexpression of miR-192-5p reduced TG levels. Yin Yang 1 (Yy1) was identified as the target gene of miR-192-5p, which regulates TG synthesis via the YY1/fatty-acid synthase (FASN) pathway. Our results demonstrated that miR-192-5p should be considered a protective regulator in NAFLD that can inhibit hepatic TG synthesis by targeting Yy1. Full article

COVID-19, caused by the SARS-CoV-2 virus, manifests with a wide range of clinical symptoms that vary from mild respiratory issues to severe respiratory distress. To effectively manage and predict the outcomes of the disease, it is important to understand the molecular mechanisms underlying its severity. This study focuses on analyzing and comparing the expression patterns of microRNAs (miRNAs) in serum, urine, and nasopharyngeal samples from patients with mild, moderate, and severe COVID-19. The aim is to identify potential associations with disease progression and discover suitable markers for diagnosis and prognosis. Our findings indicate the consistent upregulation of miR-21, miR-146a, and miR-155 in urine, serum, and nasopharyngeal samples from patients with mild COVID-19. In moderate cases, there were more significant changes in miRNA expression compared to mild cases. Specifically, miR-let-7 demonstrated upregulation, while miR-146b exhibited downregulation. The most notable alterations in miRNA expression profiles were observed in severe COVID-19 cases, with a significant upregulation of miR-223. Moreover, our analysis using Receiver-operating characteristic (ROC) curves demonstrated that miR-155, miR-let-7, and miR-223 exhibited high sensitivity and specificity, suggesting their potential as biomarkers for distinguishing COVID-19 patients from healthy individuals. Overall, this comparative analysis revealed distinct patterns in miRNA expression. The overlapping expression patterns of miRNAs in urine, serum, and nasopharyngeal samples suggest their potential utility in discriminating disease status. Full article

A growing number of studies have shown that aberrant microRNA (miRNA) expression is closely associated with the evolution and development of various complex human diseases. These key biomarkers’ identification and observation are significant for gaining a deeper understanding of disease pathogenesis and therapeutic mechanisms. Consequently, pinpointing potential miRNA–disease associations (MDA) has become a prominent bioinformatics subject, encouraging several new computational methods given the advances in graph neural networks (GNN). Nevertheless, these existing methods commonly fail to exploit the network nodes’ global feature information, leaving the generation of high-quality embedding representations using graph properties as a critical unsolved issue. Addressing these challenges, we introduce the DAEMDA, a computational method designed to optimize the current models’ efficacy. First, we construct similarity and heterogeneous networks involving miRNAs and diseases, relying on experimentally corroborated miRNA–disease association data and analogous information. Then, a newly-fashioned parallel dual-channel feature encoder, designed to better comprehend the global information within the heterogeneous network and generate varying embedding representations, follows this. Ultimately, employing a neural network classifier, we merge the dual-channel embedding representations and undertake association predictions between miRNA and disease nodes. The experimental results of five-fold cross-validation and case studies of major diseases based on the HMDD v3.2 database show that this method can generate high-quality embedded representations and effectively improve the accuracy of MDA prediction. Full article

Polo-Like Kinase 1 (PLK1), a key mediator of cell-cycle progression, is associated with poor prognosis and is a therapeutic target in a number of malignancies. Putative phosphorylation sites for PLK1 have been identified on Drosha, the main catalytic component of the microprocessor responsible for miR biogenesis. Several kinases, including GSK3β, p70 S6 kinase, ABL, PAK5, p38 MAPK, CSNK1A1 and ANKRD52-PPP6C, have been shown to phosphorylate components of the miR biogenesis machinery, altering their activity and/or localisation, and therefore the biogenesis of distinct miR subsets. We hypothesised that PLK1 regulates miR biogenesis through Drosha phosphorylation. In vitro kinase assays confirmed PLK1 phosphorylation of Drosha at S³⁰⁰ and/or S³⁰². PLK1 inhibition reduced serine-phosphorylated levels of Drosha and its RNA-dependent association with DGCR8. In contrast, a “phospho-mimic” Drosha mutant showed increased association with DGCR8. PLK1 phosphorylation of Drosha alters Drosha Microprocessor complex subcellular localisation, since PLK1 inhibition increased cytosolic protein levels of both DGCR8 and Drosha, whilst nuclear levels were decreased. Importantly, the above effects are independent of PLK1’s cell cycle-regulatory role, since altered Drosha:DGCR8 localisation upon PLK1 inhibition occurred prior to significant accumulation of cells in M-phase, and PLK1-regulated miRs were not increased in M-phase-arrested cells. Small RNA sequencing and qPCR validation were used to assess downstream consequences of PLK1 activity on miR biogenesis, identifying a set of ten miRs (miR-1248, miR-1306-5p, miR-2277-5p, miR-29c-5p, miR-93-3p, miR-152-3p, miR-509-3-5p, miR-511-5p, miR-891a-5p and miR-892a) whose expression levels were statistically significantly downregulated by two pharmacological PLK1 kinase domain inhibitors, RO-5203280 and GSK461364. Opposingly, increased levels of these miRs were observed upon transfection of wild-type or constitutively active PLK1. Importantly, pre-miR levels were reduced upon PLK1 inhibition, and pri-miR levels decreased upon PLK1 activation, and hence, PLK1 Drosha phosphorylation regulates MiR biogenesis at the level of pri-miR-to-pre-miR processing. In combination with prior studies, this work identifies Drosha S³⁰⁰ and S³⁰² as major integration points for signalling by several kinases, whose relative activities will determine the relative biogenesis efficiency of different miR subsets. Identified kinase-regulated miRs have potential for use as kinase inhibitor response-predictive biomarkers, in cancer and other diseases. Full article

The retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) play a crucial role as pattern-recognition receptors within the innate immune system. These receptors, present in various cell and tissue types, serve as essential sensors for viral infections, enhancing the immune system’s capacity to combat infections through the induction of type I interferons (IFN-I) and inflammatory cytokines. RLRs are involved in a variety of physiological and pathological processes, including viral infections, autoimmune disorders, and cancer. An increasing body of research has examined the possibility of RLRs or microRNAs as therapeutic targets for antiviral infections and malignancies, despite the fact that few studies have focused on the regulatory function of microRNAs on RLR signaling. Consequently, our main emphasis in this review is on elucidating the role of microRNAs in modulating the signaling pathways of RLRs in the context of cancer and viral infections. The aim is to establish a robust knowledge base that can serve as a basis for future comprehensive investigations into the interplay between microRNAs and RIG-I, while also facilitating the advancement of therapeutic drug development. Full article

A significant clinical association between osteoporosis (OP) and fibromyalgia (FM) has been shown in the literature. Given the need for specific biomarkers to improve OP and FM management, common miRNAs might provide promising tracks for future prevention and treatment. The aim of this review is to identify miRNAs described in OP and FM, and dysregulated in the same direction in both pathologies. The PubMed database was searched until June 2023, with a clear mention of OP, FM, and miRNA expression. Clinical trials, case–control, and cross-sectional studies were included. Gray literature was not searched. Out of the 184 miRNAs found in our research, 23 are shared by OP and FM: 7 common miRNAs are dysregulated in the same direction for both pathologies (3 up-, 4 downregulated). The majority of these common miRNAs are involved in the Wnt pathway and the cholinergic system and a possible link has been highlighted. Further studies are needed to explore this relationship. Moreover, the harmonization of technical methods is necessary to confirm miRNAs shared between OP and FM. Full article

Pinellia ternata (Thunb.) Breit (abbreviated as P. ternata) is a plant with an important medicinal value whose yield is restricted by many factors, such as low reproductive efficiency and continuous cropping obstacles. As an essential breeding material for P. ternata growth and production, the bulbils have significant advantages such as a high survival rate and short breeding cycles. However, the location effect, influencing factors, and molecular mechanism of bulbil occurrence and formation have not been fully explored. In this study, exogenously applied phytohormones were used to induce in vitro petiole of P. ternata to produce bulbil structure. Transcriptome sequencing of mRNA and miRNA were performed in the induced petiole (TCp) and the induced bulbil (TCb). Gene Ontology (GO) term enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed for the identification of key genes and pathways involved in bulbil development. A total of 58,019 differentially expressed genes (DEGs) were identified. The GO and KEGG analysis indicated that DEGs were mainly enriched in plant hormone signal transduction and the starch and sucrose metabolism pathway. The expression profiles of miR167a, miR171a, and miR156a during bulbil induction were verified by qRT-PCR, indicating that these three miRNAs and their target genes may be involved in the process of bulbil induction and play an important role. However, further molecular biological experiments are required to confirm the functions of the identified bulbil development-related miRNAs and targets. Full article

MicroRNAs (miRNAs) are important regulators of embryonic stem cell (ESC) biology, and their study has identified key regulatory mechanisms. To find novel pathways regulated by miRNAs in ESCs, we undertook a bioinformatics analysis of gene pathways differently expressed in the absence of miRNAs due to the deletion of Dicer, which encodes an RNase that is essential for the synthesis of miRNAs. One pathway that stood out was Ca²⁺ signaling. Interestingly, we found that Dicer^−/− ESCs had no difference in basal cytoplasmic Ca²⁺ levels but were hyperresponsive when Ca²⁺ import into the endoplasmic reticulum (ER) was blocked by thapsigargin. Remarkably, the increased Ca²⁺ response to thapsigargin in ESCs resulted in almost no increase in apoptosis and no differences in stress response pathways, despite the importance of miRNAs in the stress response of other cell types. The increased Ca²⁺ response in Dicer^−/− ESCs was also observed during purinergic receptor activation, demonstrating a physiological role for the miRNA regulation of Ca²⁺ signaling pathways. In examining the mechanism of increased Ca²⁺ responsiveness to thapsigargin, neither store-operated Ca²⁺ entry nor Ca²⁺ clearance mechanisms from the cytoplasm appeared to be involved. Rather, it appeared to involve an increase in the expression of one isoform of the IP₃ receptors (Itpr2). miRNA regulation of Itpr2 expression primarily appeared to be indirect, with transcriptional regulation playing a major role. Therefore, the miRNA regulation of Itpr2 expression offers a unique mechanism to regulate Ca²⁺ signaling pathways in the physiology of pluripotent stem cells. Full article

Early recurrence in patients with colorectal cancer (CRC) is associated with a poor prognosis. We aimed to identify circulating microRNAs that are biomarkers of early CRC recurrence and elucidate their functions. We identified miR-4442 as a candidate biomarker by microRNA array analysis comparing preoperative and postoperative plasma levels in patients with CRC, with and without recurrence. The association between preoperative plasma miR-4442 levels, clinicopathological features, and recurrence-free survival was analyzed in 108 patients with CRC after curative surgery. Furthermore, cell-function analyses were performed, and the involvement of miR-4442 in regulating epithelial–mesenchymal transition (EMT) was examined. Preoperatively plasma miR-4442 levels were associated with CRC recurrence and exhibited an incremental increase with earlier recurrence dates. Moreover, miR-4442 demonstrated high sensitivity and specificity as a potential biomarker for early CRC recurrence. The expression of miR-4442 in cancer tissues of patients with metastatic liver cancer from CRC was higher than in normal liver, CRC, and normal colorectal tissues. The overexpression of miR-4442 promoted the proliferative, migratory, and invasive activities of CRC cells, decreased levels of RBMS1 and E-cadherin, and increased levels of N-cadherin and Snail1. Plasma miR-4442 is a clinically useful biomarker for predicting the early recurrence of CRC. Furthermore, miR-4442 regulates EMT in CRC by directly targeting the messenger RNA of RBMS1. Full article