The latest progress on miR‐374 and its functional implications in physiological and pathological processes

Non‐coding RNAs (ncRNAs) have been emerging players in cell development, differentiation, proliferation and apoptosis. Based on their differences in length and structure, they are subdivided into several categories including long non‐coding RNAs (lncRNAs >200nt), stable non‐coding RNAs (60‐300nt), microRNAs (miRs or miRNAs, 18‐24nt), circular RNAs, piwi‐interacting RNAs (26‐31nt) and small interfering RNAs (about 21nt). Therein, miRNAs not only directly regulate gene expression through pairing of nucleotide bases between the miRNA sequence and a specific mRNA that leads to the translational repression or degradation of the target mRNA, but also indirectly affect the function of downstream genes through interactions with lncRNAs and circRNAs. The latest studies have highlighted their importance in physiological and pathological processes. MiR‐374 family member are located at the X‐chromosome inactivation center. In recent years, numerous researches have uncovered that miR‐374 family members play an indispensable regulatory role, such as in reproductive disorders, cell growth and differentiation, calcium handling in the kidney, various cancers and epilepsy. In this review, we mainly focus on the role of miR‐374 family members in multiple physiological and pathological processes. More specifically, we also summarize their promising potential as novel prognostic biomarkers and therapeutic targets from bench to bedside.     

Serum miRNAs are potential biomarkers for the detection of disc degeneration,among which miR‐26a‐5p suppresses Smad1 to regulate disc homeostasis

Disc degeneration is a common clinical condition in which damaged discs cause chronic pain; however, a laboratory diagnosis method for its detection is not available. As circulating miRNAs have potential as biomarkers, their application in disc degeneration has not been explored. Here, we prepared serum miRNAs from a mouse disc degeneration model and performed miRNA‐Seq and quantitative PCR to characterize disc degeneration–associated miRNAs. We identified three miRNAs, including miR‐26a‐5p, miR‐122‐5p and miR‐215‐5p, undergoing perturbation during the pathogenesis of disc degeneration. Specifically, the levels of miR‐26a‐5p in the serum demonstrated steady increases in the model of disc degeneration, compared with those in the pre‐injury samples of younger age or compared with normal controls of the same age but without disc degeneration, whereas the miRNAs miR‐122‐5p and miR‐215‐5p exhibited lower expression in post‐injury samples than in their counterparts without the surgery. Moreover, we found that miR‐26a‐5p targets Smad1 expression, and Smad1 negatively regulates Vegfa expression in disc cells, and thus, miR‐26a‐5p promotes disc degeneration. In summary, we established a method that consistently profiles circulating miRNAs and identified multiple miRNAs as promising biomarkers for disc degeneration, among which miR‐26a‐5p enhances VEGF expression during disc degeneration through targeting Smad1 signalling.     

Hepatic miR‐29ab1 expression modulates chronic hepatic injury

MicroRNAs (miRNAs) are small, regulatory non‐coding RNAs that have potent effects on gene expression. Several miRNA are deregulated in cellular processes involved in human liver diseases and regulation of cellular processes. Recent studies have identified the involvement of miR‐29 in hepatic fibrosis and carcinogenesis. Although several targets of miR‐29 have been identified, there is limited information regarding the cell‐type specific roles of miR‐29 in the liver, and we sought to evaluate the role of this miRNA in hepatic pathobiology. We report the generation of a tissue–specific knockout mouse to evaluate the role of miR‐29 in hepatic fibrosis and carcinogenesis in response to injury. We hypothesized that miR‐29 contributes to the hepatocyte driven response to chronic cellular injury that results in fibrosis. In support of this hypothesis, fibrosis and mortality were enhanced in miR29 knockout mice in response to carbon tetrachloride. Genome‐wide gene expression analysis identified an over‐representation of genes associated with fibrosis. The oncofetal RNA H19 was modulated in a miR‐29 dependent manner following exposure to carbon tetrachloride in vivo. The impact of a hepatocyte specific miR‐29 knockout on survival following chronic hepatic injury in vivo implicates this miRNA as a potential target for intervention. These results provide evidence of the involvement of miR‐29 in chronic hepatic injury, and suggest a role for deregulated hepatocyte expression of miR‐29 in the response to hepatic injury, fibrosis and carcinogenesis.     

Cellular and extracellular miRNAs are blood‐compartment‐specific diagnostic targets in sepsis

Septic shock is a common medical condition with a mortality approaching 50% where early diagnosis and treatment are of particular importance for patient survival. Novel biomarkers that serve as prompt indicators of sepsis are urgently needed. High‐throughput technologies assessing circulating microRNAs represent an important tool for biomarker identification, but the blood‐compartment specificity of these miRNAs has not yet been investigated. We characterized miRNA profiles from serum exosomes, total serum and blood cells (leukocytes, erythrocytes, platelets) of sepsis patients by next‐generation sequencing and RT‐qPCR (n = 3 × 22) and established differences in miRNA expression between blood compartments. In silico analysis was used to identify compartment‐specific signalling functions of differentially regulated miRNAs in sepsis‐relevant pathways. In septic shock, a total of 77 and 103 miRNAs were down‐ and up‐regulated, respectively. A majority of these regulated miRNAs (14 in serum, 32 in exosomes and 73 in blood cells) had not been previously associated with sepsis. We found a distinctly compartment‐specific regulation of miRNAs between sepsis patients and healthy volunteers. Blood cellular miR‐199b‐5p was identified as a potential early indicator for sepsis and septic shock. miR‐125b‐5p and miR‐26b‐5p were uniquely regulated in exosomes and serum, respectively, while one miRNA (miR‐27b‐3p) was present in all three compartments. The expression of sepsis‐associated miRNAs is compartment‐specific. Exosome‐derived miRNAs contribute significant information regarding sepsis diagnosis and survival prediction and could serve as newly identified targets for the development of novel sepsis biomarkers.     

Emerging roles of non‐coding RNAs in scoliosis

Scoliosis, a complex three‐dimensional deformity of the spine with the Cobb angle (a measure of the spinal lateral curvature) >10 degree, encompasses a spectrum of pathologies, including congenital, idiopathic, syndromic and neuromuscular aetiologies. The pathogenesis is multifactorial involving both environmental and genetic factors but the exact cellular and molecular mechanisms of disease development remain largely unknown. Emerging evidence showed that non‐coding RNAs (ncRNAs), namely microRNAs, long ncRNAs and circular RNAs, are deregulated in many orthopaedic diseases, including scoliosis. Importantly, these deregulated ncRNAs functionally participate in the initiation and progression of scoliosis. Here, we review recent progress in ncRNA research on scoliosis.     

Deregulated microRNAs in CD4+ T cells from individuals with latent tuberculosis versus active tuberculosis

The mechanisms of latent tuberculosis (TB) infection remain elusive. Roles of microRNA (miRNA) have been highlighted in pathogen–host interactions recently. To identify miRNAs involved in the immune response to TB, expression profiles of miRNAs in CD4⁺ T cells from patients with latent TB, active TB and healthy controls were investigated by microarray assay and validated by RT‐qPCR. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were used to analyse the significant functions and involvement in signalling pathways of the differentially expressed miRNAs. To identify potential target genes for miR‐29, interferon‐γ (IFN‐γ) mRNA expression was measured by RT‐qPCR. Our results showed that 27 miRNAs were deregulated among the three groups. RT‐qPCR results were generally consistent with the microarray data. We observed an inverse correlation between miR‐29 level and IFN‐γ mRNA expression in CD4⁺ T cells. GO and KEGG pathway analysis showed that the possible target genes of deregulated miRNAs were significantly enriched in mitogen‐activated protein kinase signalling pathway, focal adhesion and extracellular matrix receptor interaction, which might be involved in the transition from latent to active TB. In all, for the first time, our study revealed that some miRNAs in CD4⁺ T cells were altered in latent and active TB. Function and pathway analysis highlighted the possible involvement of miRNA‐deregulated mRNAs in TB. The study might help to improve understanding of the relationship between miRNAs in CD4⁺ T cells and TB, and laid an important foundation for further identification of the underlying mechanisms of latent TB infection and its reactivation.     

Differential expression of basal microRNAs’ patterns in human dental pulp stem cells

MicroRNAs (miRNAs) are small non‐coding RNAs that regulate translation of mRNA into protein and play a crucial role for almost all biological activities. However, the identification of miRNAs from mesenchymal stem cells (MSCs), especially from dental pulp, is poorly understood. In this study, dental pulp stem cells (DPSCs) were characterized in terms of their proliferation and differentiation capacity. Furthermore, 104 known mature miRNAs were profiled by using real‐time PCR. Notably, we observed 19 up‐regulated miRNAs and 29 significantly down‐regulated miRNAs in DPSCs in comparison with bone marrow MSCs (BM‐MSCs). The 19 up‐regulated miRNAs were subjected to ingenuity analysis, which were composed into 25 functional networks. We have chosen top 2 functional networks, which comprised 10 miRNA (hsa‐miR‐516a‐3p, hsa‐miR‐125b‐1‐3p, hsa‐miR‐221‐5p, hsa‐miR‐7, hsa‐miR‐584‐5p, hsa‐miR‐190a, hsa‐miR‐106a‐5p, hsa‐mir‐376a‐5p, hsa‐mir‐377‐5p and hsa‐let‐7f‐2‐3p). Prediction of target mRNAs and associated biological pathways regulated by each of this miRNA was carried out. We paid special attention to hsa‐miR‐516a‐3p and hsa‐miR‐7‐5p as these miRNAs were highly expressed upon validation with qRT‐PCR analysis. We further proceeded with loss‐of‐function analysis with these miRNAs and we observed that hsa‐miR‐516a‐3p knockdown induced a significant increase in the expression of WNT5A. Likewise, the knockdown of hsa‐miR‐7‐5p increased the expression of EGFR. Nevertheless, further validation revealed the role of WNT5A as an indirect target of hsa‐miR‐516a‐3p. These results provide new insights into the dynamic role of miRNA expression in DPSCs. In conclusion, using miRNA signatures in human as a prediction tool will enable us to elucidate the biological processes occurring in DPSCs.     

Strategies and challenges for non-viral delivery of non-coding RNAs to the heart

Non‐coding RNAs (ncRNAs), such as miRNAs and long non‐coding RNAs (lncRNAs) have been reported as regulators of cardiovascular pathophysiology. Their transient effect and diversified mechanisms of action offer a plethora of therapeutic opportunities for cardiovascular diseases (CVDs). However, physicochemical RNA features such as charge, stability, and structural organization hinder efficient on-target cellular delivery. Here, we highlight recent preclinical advances in ncRNA delivery for the cardiovascular system using non‐viral approaches. We identify the unmet needs and advance possible solutions towards clinical translation. Finding the optimal delivery vehicle and administration route is vital to improve therapeutic efficacy and safety; however, given the different types of ncRNAs, this may ultimately not be frameable within a one-size-fits-all approach.     

Exosome biogenesis,secretion and function of exosomal miRNAs in skeletal muscle myogenesis

Exosomes are membrane‐bound extracellular vesicles that are produced in the endosomal compartment of most mammalian cell types and then released. Exosomes are effective carriers for the intercellular material transfer of material that can influence a series of physiological and pathological processes in recipient cells. Among loaded cargoes, non‐coding RNAs (ncRNAs) vary for the exosome‐producing cell and its homeostatic state, and characterization of the biogenesis and secretion of exosomal ncRNAs and the functions of these ncRNAs in skeletal muscle myogenesis remain preliminary. In this review, we will describe what is currently known of exosome biogenesis, release and uptake of exosomal ncRNAs, as well as the varied functions of exosomal miRNAs in skeletal muscle myogenesis.     

Noncoding RNAs as circulating biomarkers in osteosarcoma patients

Noncoding RNAs (ncRNAs) identify a large family of RNAs that do not encode proteins and represent an important group of tumor biomarkers, directly involved in the process of tumor pathogenesis and progression. Many of them have also been identified in biological fluids of patients with cancer, especially blood, suggesting their role as an emerging class of circulating biomarkers. Many ncRNAs, both miRNAs and lncRNAs, are deregulated in sarcoma tissues, with the most consistent data in osteosarcomas. In patients with osteosarcoma, the role of ncRNAs as circulating biomarkers is taking enormous value, above all for their ability to vary expression levels during disease progression and in response to therapy. In this mini-review, we summarize the main studies supporting the role of circulating ncRNAs in monitoring disease status in patients with osteosarcoma.     

LncRNA MIR503HG inhibits cell migration and invasion via miR‐103/OLFM4 axis in triple negative breast cancer

Long non‐coding RNA MIR503 host gene (MIR503HG) is located on chromosome Xq26.3, and has been found to be deregulated in many types of human malignancy and function as tumour suppressor or promoter based on cancer types. The role of MIR503HG in breast cancer was still unknown. In our study, we found MIR503HG expression was significantly decreased in triple‐negative breast cancer tissues and cell lines. Furthermore, we observed low MIR503HG expression was correlated with late clinical stage, lymph node metastasis and distant metastasis. In the survival analysis, we observed that triple‐negative breast cancer patients with low MIR503HG expression had a statistically significant worse prognosis compared with those with high MIR503HG expression, and low MIR503HG expression was a poor independent prognostic factor for overall survival in triple‐negative breast cancer patients. The study in vitro suggested MIR503HG inhibits cell migration and invasion via miR‐103/OLFM4 axis in triple negative breast cancer. In conclusion, MIR503HG functions as a tumour suppressive long non‐coding RNA in triple negative breast cancer.     

Sl‐lncRNA15492 interacts with Sl‐miR482a and affects Solanum lycopersicum immunity against Phytophthora infestans

Long non‐coding RNAs (lncRNAs) are involved in the resistance of plants to infection by pathogens via interactions with microRNAs (miRNAs). Long non‐coding RNAs are cleaved by miRNAs to produce phased small interfering RNAs (phasiRNAs), which, as competing endogenous RNAs (ceRNAs), function as decoys for mature miRNAs, thus inhibiting their expression, and contain pre‐miRNA sequences to produce mature miRNAs. However, whether lncRNAs and miRNAs mediate other molecular mechanisms during plant resistance to pathogens is unknown. In this study, as a positive regulator, Sl‐lncRNA15492 from tomato (Solanum lycopersicum Zaofen No. 2) plants affected tomato resistance to Phytophthora infestans. Gain‐ and loss‐of‐function experiments and RNA ligase‐mediated 5′‐amplification of cDNA ends (RLM‐5′ RACE) also revealed that Sl‐miR482a was negatively involved in tomato resistance by targeting Sl‐NBS‐LRR genes and that silencing of Sl‐NBS‐LRR1 decreased tomato resistance. Sl‐lncRNA15492 inhibited the expression of mature Sl‐miR482a, whose precursor was located within the antisense sequence of Sl‐lncRNA15492. Further degradome analysis and additional RLM‐5′ RACE experiments verified that mature Sl‐miR482a could also cleave Sl‐lncRNA15492. These results provide a mechanism by which lncRNAs might inhibit precursor miRNA expression through antisense strands of lncRNAs, and demonstrate that Sl‐lncRNA15492 and Sl‐miR482a mutually inhibit the maintenance of Sl‐NBS‐LRR1 homeostasis during tomato resistance to P. infestans.