Role of miRNAs in development and disease: Lessons learnt from small organisms

microRNAs in Macrobrachium olfersii embryos: Identification, their biogenesis components and potential targets

In embryonic development, microRNAs (miRNAs) regulate the complex gene expression associated with the complexity of embryogenesis. Today, few studies have been conducted on the identification of miRNAs and components of miRNA biogenesis on embryonic development in crustaceans, especially in prawns. In this context, the aim of this study was to identify in silico components of miRNA biogenesis, and miRNAs and potential target genes during embryonic development in the prawn Macrobrachium olfersii through small RNAs and transcriptome analyses. Using the miRDeep2 program, we identified 17 miRNA precursors in M. olfersii, which seven (miR-9, miR-10, miR-92, miR-125, miR-305, miR-1175, and miR-2788) were reported in the miRBase database, indicating high evolutionary conservation of these sequences among animals. The other 10 miRNAs of M. olfersii were novel miRNAs and only similar to Macrobrachium niponnense miRNAs, indicating genus-specific miRNAs. In addition, eight key components of miRNA biogenesis (DROSHA, PASHA/DGCR8, XPO5, RAN, DICER, TRBP2, AGO, and PIWI) were identified in M. olfersii embryos unigenes. In the annotation of miRNA targets, 516 genes were similar to known sequences in the GenBank database. Regarding the conserved miRNAs, we verified that they were differentially expressed during embryonic development in M. olfersii. In conclusion, this is the first study that identifies conserved and novel miRNAs in the prawn M. olfersii with some miRNA target genes involved in embryonic development. Our results will allow further studies on the function of these miRNAs and miRNA biogenesis components during embryonic development in M. olfersii and other prawns of commercial interest.

MiR-154 inhibits the growth of laryngeal squamous cell carcinoma by targeting GALNT7

MicroRNAs are critical regulators of the development and progression of laryngeal squamous cell carcinoma (LSCC). However, the role of microRNA-154 (miR-154) in the development and progression of LSCC has not been clarified. We found that down-regulated miR-154 expression in LSCC tissues was associated with poorer prognosis in LSCC patients. MiR-154 over-expression inhibited the proliferation, clonogenicity, and migration of LSCC cells and induced cell cycle arrest, which were reversed by miR-154 inhibition. MiR-154 targeted GALNT7 expression by reducing GALNT7-regulated luciferase activity in LSCC cells while up-regulating GALNT7 mRNA transcription in LSCC tissues and cells. GALNT7 silencing significantly attenuated the proliferation, clonogenicity, and migration of LSCC cells and induced cell cycle arrest. Finally, intravenous treatment with lentivirus for miR-154, but not scrambled control miRNA, significantly restrained the growth of implanted LSCC Hep-2 tumors and decreased the tumor mass by reducing GALNT7 expression in mice. Therefore, miR-154 may serve as a novel prognostic marker and therapeutic target for LSCC.

MicroRNA-101-3p inhibits proliferation in retinoblastoma cells by targeting EZH2 and HDAC9

Retinoblastoma is the most frequent intraocular malignant tumor type to occur in childhood. MicroRNA (miR)-101-3p has been reported to function as a tumor suppressor in various types of cancer. However, the biological function and underlying mechanisms of miR-101-3p in retinoblastoma are largely unknown. In the present study, it was identified that miR-101-3p was downregulated in retinoblastoma. MTT and flow cytometry assays demonstrated that ectopic overexpression of miR-101-3p significantly inhibited cell viability and cell cycle progression in WERI-Rb-1 and Y79 cells. In vivo mouse experiments further confirmed the anti-proliferative role of miR-101-3p in retinoblastoma. Additionally, predictions with TargetScan software indicated that the 3′-untranslated regions of enhancer of zeste homolog 2 (EZH2) and histone deacetylase (HDAC9) mRNAs are targeted by miR-101-3p. Accordingly, a dual luciferase reporter gene assay demonstrated that miR-101-3p directly targeted EZH2 and HDAC9 to suppress the proliferation of retinoblastoma cells. Meanwhile, the restoration of EZH2 or HDAC9 expression countered the anti-proliferative effect of miR-101-3p on WERI-Rb-1 and Y79 cells. Collectively, these data highlight the role of miR-101-3p in the tumorigenesis of retinoblastoma, and indicate its suitability as a novel therapeutic target.

Role of non-coding RNAs in cardiotoxicity of chemotherapy

The long-time paradoxical situation of non-coding RNAs (ncRNAs) has been terminated for they emerge as executive at full spectrum of gene expression and translation. More recently, it has been demonstrated that some ncRNAs apparently are associated with chemotherapy, causing cardiotoxicity, which taint long-term recovery of patients in growing body of evidence. The current review focused on up-to-date knowledge on regulation change and molecular signaling of ncRNAs, at mean time evaluate their potentials as diagnostic biomarkers or therapeutic targets to monitor and protect cardio function.

miR‑339‑5p negatively regulates loureirin A‑induced hair follicle stem cell differentiation by targeting DLX5

Our previous study indicated that loureirin A induces hair follicle stem cell (HFSC) differentiation through Wnt/β-catenin signaling pathway activation. However, if and how microRNAs (miRNAs/miRs) modulate loureirin A-induced differentiation remains to be elucidated. In the present study, HFSCs were separated from the vibrissae of rats and identified by CD34 and keratin, type 1 cytoskeletal (K)15 expression. Microarray-based miRNA profiling analysis revealed that miR-339-5p was downregulated in loureirin A-induced HFSC differentiation. miR-339-5p overexpression by transfection with miR-339-5p mimics markedly inhibited the expression of K10 and involucrin, which are markers of epidermal differentiation, whereas inhibition of miR-339-5p by miR-339-5p inhibitor transfection promoted the expression of K10 and involucrin. These results suggest that miR-339-5p is a negative regulator of HFSC differentiation following induction by loureirin A. These findings were confirmed by a luciferase assay. Homeobox protein DLX-5 (DLX5) was identified as a direct target of miR-339-5p. Furthermore, it was demonstrated that miR-339-5p inhibited DLX5. Overexpression of miR-339-5p by mimic transfection significantly inhibited protein Wnt-3a (Wnt3a) expression, while inhibition of miR-339-5p by inhibitor transfection significantly increased the expression of Wnt3a. Furthermore, small interfering RNA targeting DLX5 was transfected into HFSCs, and western blot analysis revealed that Wnt3a, involucrin and K10 expression was significantly downregulated. Taken together, these results suggest that miR-339-5p negatively regulated loureirin A-induced HFSC differentiation by targeting DLX5, resulting in Wnt/β-catenin signaling pathway inhibition. This may provide a possible therapeutic target for skin repair and regeneration.

MicroRNA Let-7f-5p Promotes Bone Marrow Mesenchymal Stem Cells Survival by Targeting Caspase-3 in Alzheimer Disease Model

Widespread death of transplanted mesenchymal stem cells (MSCs) hampers the development of stem cell therapy for Alzheimer disease (AD). Cell pre-conditioning might help cope with this challenge. We tested whether let-7f-5p-modified MSCs could prolong the survival of MSCs after transplantation. When exposed to Aβ₂₅₋₃₅in vitro, MSCs showed significant early apoptosis with decrease in the let-7f-5p levels and increased caspase-3 expression. Upregulating microRNA let-7f-5p in MSCs alleviated Aβ₂₅₋₃₅-induced apoptosis by decreasing the caspase-3 levels. After computerized analysis and the luciferase reporter assay, we identified that caspases-3 was the target gene of let-7f-5p. In vivo, hematoxylin and eosin staining confirmed the success of MSCs transplantation into the lateral ventricles, and the let-7f-5p upregulation group showed the lowest apoptotic rate of MSCs detected by TUNEL immunohistochemistry analysis and immunofluorescence. Similarly, bioluminescent imaging showed that let-7f-5p upregulation moderately prolonged the retention of MSCs in brain. In summary, we identified the anti-apoptotic role of let-7f-5p in Aβ₂₅₋₃₅-induced cytotoxicity, as well as the protective effect of let-7f-5p on survival of grafted MSCs by targeting caspase-3 in AD models. These findings show a promising approach of microRNA-modified MSCs transplantation as a therapy for neurodegenerative diseases.

miRNA regulation of innate immunity

MicroRNAs (miRNAs) are small noncoding RNA and are pivotal posttranscriptional regulators of both innate and adaptive immunity. They act by regulating the expression of multiple immune genes, thus, are the important elements to the complex immune regulatory network. Deregulated expression of specific miRNAs can lead to potential autoimmunity, immune tolerance, hyper-inflammatory phenotype, and cancer initiation and progression. In this review, we discuss the contributory pathways and mechanisms by which several miRNAs influence the development of innate immunity and fine-tune immune response. Moreover, we discuss the consequence of deregulated miRNAs and their pathogenic implications.

Identification of Dysregulated microRNA Networks in Schwann Cell-Like Cultures Exposed to Immune Challenge: Potential Crosstalk with the Protective VIP/PACAP Neuropeptide System

Following peripheral nerve injury, dysregulations of certain non-coding microRNAs (miRNAs) occur in Schwann cells. Whether these alterations are the result of local inflammation and/or correlate with perturbations in the expression profile of the protective vasoactive intestinal peptide (VIP)/pituitary adenylate cyclase-activating polypeptide (PACAP) system is currently unknown. To address these issues, we aimed at profiling the expression of selected miRNAs in the rat RT4 Schwann cell line. Cells exposed to lipopolysaccharide (LPS), to mimic the local inflammatory milieu, were appraised by real-time qPCR, Western blot and ELISAs. We found that upon LPS treatment, levels of pro-inflammatory cytokines (IL-1β, -6, -18, -17A, MCP-1 and TNFα) increased in a time-dependent manner. Unexpectedly, the expression levels of VIP and PACAP were also increased. Conversely, levels of VPAC1 and VPAC2 receptors were reduced. Downregulated miRNAs included miR-181b, -145, -27a, -340 and -132 whereas upregulated ones were miR-21, -206, -146a, -34a, -155, -204 and -29a, respectively. Regression analyses revealed that a subset of the identified miRNAs inversely correlated with the expression of VPAC1 and VPAC2 receptors. In conclusion, these findings identified a novel subset of miRNAs that are dysregulated by immune challenge whose activities might elicit a regulatory function on the VIP/PACAP system.

Identification of a novel functional miR-143-5p recognition element in the Cystic Fibrosis Transmembrane Conductance Regulator 3'UTR

MicroRNAs (miRNAs) are small non-coding RNAs involved in regulation of gene expression. They bind in a sequence-specific manner to miRNA recognition elements (MREs) located in the 3' untranslated region (UTR) of target mRNAs and prevent mRNA translation. MiRNA expression is dysregulated in cystic fibrosis (CF), affecting several biological processes including ion conductance in the epithelial cells of the lung. We previously reported that miR-143 is up-regulated in CF bronchial brushings compared to non-CF. Here we identified two predicted binding sites for miR-143-5p (starting at residues 558 and 644) on the CFTR mRNA, and aimed to assess whether CFTR is a true molecular target of miR-143-5p. Expression of miR-143-5p was found to be up-regulated in a panel of CF vs non-CF cell lines (1.7-fold, P = 0.0165), and its levels were increased in vitro after 20 hours treatment with bronchoalveolar lavage fluid from CF patients compared to vehicle-treated cells (3.3-fold, P = 0.0319). Luciferase assays were performed to elucidate direct miRNA::target interactions and showed that miR-143-5p significantly decreased the reporter activity when carrying the wild-type full length sequence of CFTR 3'UTR (minus 15%, P = 0.005). This repression was rescued by the disruption of the first, but not the second, predicted MRE, suggesting that the residue starting at 558 was the actual active binding site. In conclusion, we here showed that miR-143-5p modestly but significantly inhibits CFTR, improving the knowledge on functional MREs within the CFTR 3'UTR. This could lead to the development of novel therapeutic strategies where miRNA-mediated CFTR repression is blocked thereby possibly increasing the efficacy of the currently available CFTR modulators.

Focus on Mesenchymal Stem Cell-Derived Exosomes: Opportunities and Challenges in Cell-Free Therapy

Mesenchymal stem cells have been at the forefront of regenerative medicine for many years. Exosomes, which are nanovesicles involved in intercellular communication and the transportation of genetic material transportation that can be released by mesenchymal stem cells, have been recently reported to play a role in cell-free therapy of many diseases, including myocardial infarction, drug addiction, and status epilepticus. They are also thought to help ameliorate inflammation-induced preterm brain injury, liver injury, and various types of cancer. This review highlights recent advances in the exploration of mesenchymal stem cell-derived exosomes in therapeutic applications. The natural contents, drug delivery potency, modification methods, and drug loading methods of exosomes are also discussed.