MicroRNA-9 controls a migratory mechanism in human neural progenitor cells

MiR-421 Binds to PINK1 and Enhances Neural Stem Cell Self-Renewal via HDAC3-Dependent FOXO3 Activation

Dysfunctions of neural stem cells (NSCs) often lead to a variety of neurological diseases. Thus, therapies based on NSCs have gained increasing attention recently. It has been documented that microRNA (miR)-421 represses the autophagy and apoptosis of mouse hippocampal neurons and confers a role in the repair of ischemic brain injury (IBI). Herein, we aimed to illustrate the effects of miR-421 on NSC self-renewal. The downstream factors of miR-421 were predicted initially, followed by gain- and loss-of-function assays to examine their effects on NSC self-renewal. Immunoprecipitation and dual luciferase assays were conducted to validate the interaction among miR-421, PTEN-induced putative kinase 1 (PINK1), HDAC3, and forkhead box O3 (FOXO3). A mouse model with IBI was developed to substantiate the impact of the miR-421/PINK1/HDAC3/FOXO3 axis on NSC self-renewal. The expression of miR-421 was downregulated during differentiation of human embryonic NSCs, and miR-421 overexpression accelerated NSC self-renewal. Besides, miR-421 targeted PINK1 and restricted its expression in NSCs and further suppressed HDAC3 phosphorylation and enhanced FOXO3 acetylation. In conclusion, our data elucidated that miR-421 overexpression may facilitate NSC self-renewal through the PINK1/HDAC3/FOXO3 axis, which may provide potential therapeutic targets for the development of novel therapies for IBI.

miR-29a Promotes the Neurite Outgrowth of Rat Neural Stem Cells by Targeting Extracellular Matrix to Repair Brain Injury

Neural stem cells (NSCs) can generate new neurons to repair brain injury and central nervous system disease by promoting neural regeneration. MicroRNAs (miRNAs) involve in neural development, brain damage, and neurological diseases repair. Recent reports show that several miRNAs express in NSCs and are important to neurogenesis. Neurites play a key role in NSC-related neurogenesis. However, the mechanism of NSC neurite generation is rarely studied. We surprisingly noticed that the neurites increased after bone morphogenetic protein (BMP) treatment in rat NSCs. This process was accompanied by the dynamic change of miRNA-29. Then we discovered that miR-29a regulated neural neurites in rat hippocampus NSCs. Overexpression of miR-29a reduced the cell soma area and promoted the neurite outgrowth of NSCs. Cell soma area became small, whereas the number of neurite increased. Moreover, neurite complexity increased dramatically, with more primary and secondary branches after miR-29a overexpression. In addition, miR-29a overexpression still maintained the stemness of NSCs. Besides, we identified that miR-29a can promote the neurite outgrowth by targeting extracellular matrix-related genes like Fibrillin 1 (Fbn1), Follistatin-like 1 (Fstl1), and laminin subunit gamma 2 (Lamc2). These findings may provide a novel role of miR-29a to regulate neurite outgrowth and development of NSCs. We also offered a possible theoretical basis to the migration mechanism of NSCs in brain development and damage repair.

Expression and Regulation Profile of Mature MicroRNA in the Pig: Relevance to Xenotransplantation

The pig is an important source of meat production and provides a valuable model for certain human diseases. MicroRNA (miRNA), which is noncoding RNA and regulates gene expression at the posttranscriptional level, plays a critical role in various biological processes. Studies on identification and function of mature miRNAs in multiple pig tissues are increasing, yet the literature is limited. Therefore, we reviewed current research to determine the miRNAs expressed in specific pig tissues that are involved in carcass values (including muscle and adipocytes), reproduction (including pituitary, testis, and ovary), and development of some solid organs (e.g., brain, lung, kidney, and liver). We also discuss the possible regulating mechanisms of miRNA. Finally, as pig organs are suitable candidates for xenotransplantation, biomarkers of their miRNA in xenotransplantation were evaluated.

Aberrant expression of miR-9 in benign and malignant breast tumors

PURPOSE

MicroRNAs (miRNAs) are involved in the progression of breast cancer (BC). miR-9 has been reported to be correlated with either favorable or unfavorable events in BC. This study was aimed to evaluate the expression level of miR-9 in human breast tissues, including benign and malignant tumor samples and also healthy tissue.

MATERIALS AND METHODS

The expression level of miR-9 was analyzed in 10 normal breast tissues, 30 malignant, and 30 benign breast tumor tissue samples using RT-PCR and qPCR. In addition, bioinformatics assessment upon miR-9 functionality in BC cells was performed.

RESULTS AND DISCUSSION

The miR-9 expression level was downregulated in tumor tissues, including benign and malignant compared to the healthy tissue was observed (P value, < 0.0001; fold change, -1.37). In addition, miR-9 expression level was reduced in benign tumors compared with malignant tumors (P value, < 0.0001; fold change, -1.35). Moreover, according to the AUCs (area under curve) of receiver operating characteristic (ROC) curves, miR-9 showed significant capability for distinguishing benign from healthy, malignant from healthy, benign from malignant, and tumor from health tissues. Furthermore, pathways in cancer, p53 signaling pathway, and focal adhesion were manifested by computational analysis as miR-9 related signaling pathways which have logical association with experimental observations.

CONCLUSION

In conclusion, downregulation of miR-9 in benign tumors vs healthy tissue and its overexpression in malignant tumors vs benign tumors suggest paradoxical functionality for this miRNA. Our results shed additional information on controversial expression pattern of miR-9 depending on different progression level of BC.

CBX7 and miR-9 are part of an autoregulatory loop controlling p16(INK) (4a)

Polycomb repressive complexes (PRC1 and PRC2) are epigenetic regulators that act in coordination to influence multiple cellular processes including pluripotency, differentiation, cancer and senescence. The role of PRCs in senescence can be mostly explained by their ability to repress the INK4/ARF locus. CBX7 is one of five mammalian orthologues of Drosophila Polycomb that forms part of PRC1. Despite the relevance of CBX7 for regulating senescence and pluripotency, we have a limited understanding of how the expression of CBX7 is regulated. Here we report that the miR‐9 family of microRNAs (miRNAS) downregulates the expression of CBX7. In turn, CBX7 represses miR‐9‐1 and miR‐9‐2 as part of a regulatory negative feedback loop. The miR‐9/CBX7 feedback loop is a regulatory module contributing to induction of the cyclin‐dependent kinase inhibitor (CDKI) p16^INK4a during senescence. The ability of the miR‐9 family to regulate senescence could have implications for understanding the role of miR‐9 in cancer and aging.

Precise gene modification mediated by TALEN and single-stranded oligodeoxynucleotides in human cells

The development of human embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) facilitates in vitro studies of human disease mechanisms, speeds up the process of drug screening, and raises the feasibility of using cell replacement therapy in clinics. However, the study of genotype-phenotype relationships in ESCs or iPSCs is hampered by the low efficiency of site-specific gene editing. Transcription activator-like effector nucleases (TALENs) spurred interest due to the ease of assembly, high efficiency and faithful gene targeting. In this study, we optimized the TALEN design to maximize its genomic cutting efficiency. We showed that using optimized TALENs in conjunction with single-strand oligodeoxynucleotide (ssODN) allowed efficient gene editing in human cells. Gene mutations and gene deletions for up to 7.8 kb can be accomplished at high efficiencies. We established human tumor cell lines and H9 ESC lines with homozygous deletion of the microRNA-21 (miR-21) gene and miR-9-2 gene. These cell lines provide a robust platform to dissect the roles these genes play during cell differentiation and tumorigenesis. We also observed that the endogenous homologous chromosome can serve as a donor template for gene editing. Overall, our studies demonstrate the versatility of using ssODN and TALEN to establish genetically modified cells for research and therapeutic application.

Long-term effects of peripubertal binge EtOH exposure on hippocampal microRNA expression in the rat

Adolescent binge alcohol abuse induces long-term changes in gene expression, which impacts the physiological stress response and memory formation, two functions mediated in part by the ventral (VH) and dorsal (DH) hippocampus. microRNAs (miRs) are small RNAs that play an important role in gene regulation and are potential mediators of long-term changes in gene expression. Two genes important for regulating hippocampal functions include brain-derived neurotrophic factor (BDNF) and sirtuin-1 (SIRT1), which we identified as putative gene targets of miR-10a-5p, miR-26a, miR-103, miR-495. The purpose of this study was to quantify miR-10a-5p, miR-26a, miR-103, miR-495 expression levels in the dorsal and ventral hippocampus of male Wistar rats during normal pubertal development and then assess the effects of repeated binge-EtOH exposure. In addition, we measured the effects of binge EtOH-exposure on hippocampal Drosha and Dicer mRNA levels, as well as the putative miR target genes, BDNF and SIRT1. Overall, mid/peri-pubertal binge EtOH exposure altered the normal expression patterns of all miRs tested in an age- and brain region-dependent manner and this effect persisted for up to 30 days post-EtOH exposure. Moreover, our data revealed that mid/peri-pubertal binge EtOH exposure significantly affected miR biosynthetic processing enzymes, Drosha and Dicer. Finally, EtOH-induced significant changes in the expression of a subset of miRs, which correlated with changes in the expression of their predicted target genes. Taken together, these data demonstrate that EtOH exposure during pubertal development has long-term effects on miRNA expression in the rat hippocampus.

Role of miRNAs and epigenetics in neural stem cell fate determination

The regulation of gene expression that determines stem cell fate determination is tightly controlled by both epigenetic and posttranscriptional mechanisms. Indeed, small non-coding RNAs such as microRNAs (miRNAs) are able to regulate neural stem cell fate by targeting chromatin-remodeling pathways. Here, we aim to summarize the latest findings regarding the feedback network of epigenetics and miRNAs during embryonic and adult neurogenesis.

Pancreatic cancer diagnosis by free and exosomal miRNA

Patients with pancreatic adenocarcinoma (PaCa) have a dismal prognosis. This is in part due to late diagnosis prohibiting surgical intervention, which provides the only curative option as PaCa are mostly chemo- and radiation resistance. Hope is raised on a reliable non-invasive/minimally invasive diagnosis that is still missing. Recently two diagnostic options are discussed, serum MicroRNA (miRNA) and serum exosomes. Serum miRNA can be free or vesicle-, particularly, exosomes-enclosed. This review will provide an overview on the current state of the diagnostic trials on free serum miRNA and proceed with an introduction of exosomes that use as a diagnostic tool in serum and other body fluids has not received sufficient attention, although serum exosome miRNA in combination with protein marker expression likely will increase the diagnostic and prognostic power. By their crosstalk with host cells, which includes binding-initiated signal transduction, as well as reprogramming target cells via the transfer of proteins, mRNA and miRNA exosomes are suggested to become a most powerful therapeutics. I will discuss which hurdles have still to be taken as well as the different modalities, which can be envisaged to make therapeutic use of exosomes. PaCa are known to most intensely crosstalk with the host as apparent by desmoplasia and frequent paraneoplastic syndromes. Thus, there is hope that the therapeutic application of exosomes brings about a major breakthrough.

Identification and characterization of pig embryo microRNAs by Solexa sequencing

MicroRNAs (miRNAs) are a class of small, non-coding RNAs of approximately 22 nucleotides in length that regulate gene expression by binding to the 3'-untranslated regions of target mRNAs. It is now clear that miRNAs are involved in many biological processes, including proliferation, differentiation and regulation of gene expression during early embryonic development. The miRBase 16.0 (2010) shows that there are 175, 673, 408 and 1048 annotated miRNAs for Caenorhabditis elegans, Mus musculus, Rattus norvegicus and Homo sapiens, respectively. However, there are only 211 miRNAs described for Sus scrofa. In particular, the full set of miRNAs and their expression patterns are still poorly understood in the embryo. Therefore, we combined Solexa sequencing with computational techniques to analyse the sequences and relative expression levels of S. scrofa miRNAs at embryonic day 33 (E33). Of the distinct miRNAs identified, 76 previously known miRNAs and 194 candidate miRNAs were identified in head, and 77 known miRNAs and 130 predicted candidate miRNAs were identified in organ region. Furthermore, we performed additional investigation for identifying the potential target mRNAs using PicTar and TargetScan. Concurrent function analysis suggested that highly expressed miRNAs are mostly involved in the development of nerves, cerebrum, muscle and organs. Our results provide useful information for the investigation into embryonic miRNAs of pig and provide a valuable resource for investigators interested in the regulation of embryonic development in pigs and other animals.

New role of microRNA: carcinogenesis and clinical application in cancer

MicroRNA (miRNA) is a cluster of small non-encoding RNA molecules of 21-23 nucleotides in length, which controls the expression of target gene at the post-transcriptional level. Recent researches have indicated that miRNA plays an essential role in carcinogenesis, such as affecting the cell growth, differentiation, apoptosis, and cell cycle. Nowadays, multiple promising roles of miRNA involved in carcinogenesis are emerging, and it is shown that miRNA closely relates to the process of epithelial-mesenchymal transition (EMT), the regulation of cancer stem cells (CSCs), the development of tumor invasion and migration. miRNA also acts as a biomarker stably expressed in serum and provides new target for molecular target therapy of various cancers. The aim of this review is to illustrate the new role of miRNA in carcinogenesis and highlight the new prospects of miRNA in cancer clinical application, such as in serological diagnosis and molecular-targeted therapeutics.

miRNAs stem cell reprogramming for neuronal induction and differentiation

Mimicking the natural brain environment during neurogenesis represents the main challenge for efficient in vitro neuronal differentiation of stem cells. The discovery of miRNAs opens new possibilities in terms of modulation of stem cells lineage commitment and differentiation. Many studies demonstrated that in vitro transient overexpression or inhibition of brain-specific miRNAs in stem cells significantly directed differentiation along neuronal cell lineages. Modulating miRNA expression offers new pathways for post-transcriptional gene regulation and stem cell commitment. Neurotrophins and neuropoietins signaling pathways are the main field of investigation for neuronal commitment, differentiation, and maturation. This review will highlight examples of crosstalk between stem-cell-specific and brain-specific signaling pathways and key miRNA candidates for neuronal commitment. Recent progress on understanding miRNAs genetic networks offers promising prospects for their increasing application in the development of new cellular therapies in humans.

MicroRNA regulation of neural stem cells and neurogenesis

MicroRNAs are a class of small RNA regulators that are involved in numerous cellular processes, including development, proliferation, differentiation, and plasticity. The emerging concept is that microRNAs play a central role in controlling the balance between stem cell self-renewal and fate determination by regulating the expression of stem cell regulators. This review will highlight recent advances in the regulation of neural stem cell self-renewal and neurogenesis by microRNAs. It will cover microRNA functions during the entire process of neurogenesis, from neural stem cell self-renewal and fate determination to neuronal maturation, synaptic formation, and plasticity. The interplay between microRNAs and both cell-intrinsic and -extrinsic stem cell players, including transcription factors, epigenetic regulators, and extrinsic signaling molecules will be discussed. This is a summary of the topics covered in the mini-symposium on microRNA regulation of neural stem cells and neurogenesis in SFN 2010 and is not meant to be a comprehensive review of the subject.