Specific sequence determinants of miR-15/107 microRNA gene group targets

miR-107 Targets NSG1 to Regulate Hypopharyngeal Squamous Cell Carcinoma Progression through ERK Pathway

Hypopharyngeal squamous cell carcinoma (HSCC) is a kind of malignant tumor with a poor prognosis and low quality of life in the otolaryngology department. It has been found that microRNA (miRNA) plays an important role in the occurrence and development of various tumors. This study found that the expression level of miRNA-107 (miR-107) in HSCC was significantly reduced. Subsequently, we screened out the downstream direct target gene Neuronal Vesicle Trafficking Associated 1 (NSG1) related to miR-107 through bioinformatics analysis and found that the expression of NSG1 was increased in HSCC tissues. Following the overexpression of miR-107 in HSCC cells, it was observed that miR-107 directly suppressed NSG1 expression, leading to increased apoptosis, decreased proliferation, and reduced invasion capabilities of HSCC cells. Subsequent experiments involving the overexpression and knockdown of NSG1 in HSCC cells demonstrated that elevated NSG1 levels enhanced cell proliferation, migration, and invasion, while the opposite effect was observed upon NSG1 knockdown. Further investigations revealed that changes in NSG1 levels in the HSCC cells were accompanied by alterations in ERK signaling pathway proteins, suggesting a potential regulatory role of NSG1 in HSCC cell proliferation, migration, and invasion through the ERK pathway. These findings highlight the significance of miR-107 and NSG1 in hypopharyngeal cancer metastasis, offering promising targets for therapeutic interventions and prognostic evaluations for HSCC.

Analysis of liver miRNA in Hu sheep with different residual feed intake

Feed efficiency (FE), an important economic trait in sheep production, is indirectly assessed by residual feed intake (RFI). However, RFI in sheep is varied, and the molecular processes that regulate RFI are unclear. It is thus vital to investigate the molecular mechanism of RFI to developing a feed-efficient sheep. The miRNA-sequencing (RNA-Seq) was utilized to investigate miRNAs in liver tissue of 6 out of 137 sheep with extreme RFI phenotypic values. In these animals, as a typical metric of FE, RFI was used to distinguish differentially expressed miRNAs (DE_miRNAs) between animals with high (n = 3) and low (n = 3) phenotypic values. A total of 247 miRNAs were discovered in sheep, with four differentially expressed miRNAs (DE_miRNAs) detected. Among these DE_miRNAs, three were found to be upregulated and one was downregulated in animals with low residual feed intake (Low_RFI) compared to those with high residual feed intake (High_RFI). The target genes of DE_miRNAs were primarily associated with metabolic processes and biosynthetic process regulation. Furthermore, they were also considerably enriched in the FE related to glycolysis, protein synthesis and degradation, and amino acid biosynthesis pathways. Six genes were identified by co-expression analysis of DE_miRNAs target with DE_mRNAs. These results provide a theoretical basis for us to understand the sheep liver miRNAs in RFI molecular regulation.

Orchestration of a blood-derived and ADARB1-centred network in Alzheimer's and Parkinson's disease

The peripheral immune system is thought to influence the pathogenesis of the central nervous system in Alzheimer's disease (AD) and Parkinson's disease (PD). This study aimed to investigate the characteristics of peripheral leukocytes in AD and PD by comprehensively analyzing the transcriptomic and metabolic features in the blood (NCONTROL = 15; NAD = 11; NPD = 13). The study found an ADARB1-centered module that was associated with diagnosis, phenethylamine, and glutamate. The module consisted of ADARB1, a vital RNA-editing enzyme, LINC02960, and 109 miRNAs. The study also predicted that the ADARB1 and involved regulators were targeted by miRNAs in the ADARB1 module. The integrated analysis of transcriptome and metabolic panel revealed a central role of ADARB1, miR-199b-5p, miR-26a, miR-450b-5p, miR-34c-5p, glutamate and phenethylamine in the regulatory relationships. The study highlights a set of synergetic non-coding RNA related to ADARB1 in the blood ecosystem of AD and PD with dynamic glutamate and phenethylamine, providing new insights into the pathogenesis of these diseases.

The Expression Levels of MicroRNAs Differentially Expressed in Sudden Sensorineural Hearing Loss Patients' Serum Are Unchanged for up to 12 Months after Hearing Loss Onset

Sudden sensorineural hearing loss (SSNHL) is an acquired idiopathic hearing loss. Serum levels of small, non-coding RNAs and microRNAs (miRNAs) miR-195-5p/-132-3p/-30a-3p/-128-3p/-140-3p/-186-5p/-375-3p/-590-5p are differentially expressed in SSNHL patients within 28 days of hearing loss onset. This study determines if these changes persist by comparing the serum miRNA expression profile of SSNHL patients within 1 month of hearing loss onset with that of patients 3-12 months after hearing loss onset. We collected serum from consenting adult SSNHL patients at presentation or during clinic follow-up. We matched patient samples drawn 3-12 months after hearing loss onset (delayed group, n = 9 patients) by age and sex to samples drawn from patients within 28 days of hearing loss onset (immediate group, n = 14 patients). We compared the real-time PCR-determined expression levels of the target miRNAs between the two groups. We calculated the air conduction pure-tone-averaged (PTA) audiometric thresholds in affected ears at the initial and final follow-up visits. We undertook inter-group comparisons of hearing outcome status and initial and final PTA audiometric thresholds. There was no significant inter-group difference in miRNA expression level, hearing recovery status and initial and final affected ear PTA audiometric thresholds.

Novel MicroRNA-Regulated Transcript Networks Are Associated with Chemotherapy Response in Ovarian Cancer

High-grade serous ovarian cancer (HGSOC) is a highly lethal gynecologic cancer, in part due to resistance to platinum-based chemotherapy reported among 20% of patients. This study aims to generate novel hypotheses of the biological mechanisms underlying chemotherapy resistance, which remain poorly understood. Differential expression analyses of mRNA- and microRNA-sequencing data from HGSOC patients of The Cancer Genome Atlas identified 21 microRNAs associated with angiogenesis and 196 mRNAs enriched for adaptive immunity and translation. Coexpression network analysis identified three microRNA networks associated with chemotherapy response enriched for lipoprotein transport and oncogenic pathways, as well as two mRNA networks enriched for ubiquitination and lipid metabolism. These network modules were replicated in two independent ovarian cancer cohorts. Moreover, integrative analyses of the mRNA/microRNA sequencing and single-nucleotide polymorphisms (SNPs) revealed potential regulation of significant mRNA transcripts by microRNAs and SNPs (expression quantitative trait loci). Thus, we report novel transcriptional networks and biological pathways associated with resistance to platinum-based chemotherapy in HGSOC patients. These results expand our understanding of the effector networks and regulators of chemotherapy response, which will help to improve the management of ovarian cancer.

Computational Detection of MicroRNA Targets

MicroRNAs (miRNAs) are small noncoding RNAs that are recognized as posttranscriptional regulators of gene expression. These molecules have been shown to play important roles in several cellular processes. MiRNAs act on their target by guiding the RISC complex and binding to the mRNA molecule. Thus, it is recognized that the function of a miRNA is determined by the function of its target (s). By using high-throughput methodologies, novel miRNAs are being identified, but their functions remain uncharted. Target validation is crucial to properly understand the specific role of a miRNA in a cellular pathway. However, molecular techniques for experimental validation of miRNA-target interaction are expensive, time-consuming, laborious, and can be not accurate in inferring true interactions. Thus, accurate miRNA target predictions are helpful to understand the functions of miRNAs. There are several algorithms proposed for target prediction and databases containing miRNA-target information. However, these available computational tools for prediction still generate a large number of false positives and fail to detect a considerable number of true targets, which indicates the necessity of highly confident approaches to identify bona fide miRNA-target interactions. This chapter focuses on tools and strategies used for miRNA target prediction, by providing practical insights and outlooks.

The microRNA-195 - BDNF pathway and cognitive deficits in schizophrenia patients with minimal antipsychotic medication exposure

Cognitive impairment is a core characteristic of schizophrenia, but its underlying neural mechanisms remain poorly understood. Reduced brain-derived neurotrophic factor (BDNF), a protein critical for neural plasticity and synaptic signaling, is one of the few molecules consistently associated with cognitive deficits in schizophrenia although the etiological pathway leading to BDNF reduction in schizophrenia is unclear. We examined microRNA-195 (miR-195), a known modulator of BDNF protein expression, as a potential mechanistic component. One-hundred and eighteen first-episode patients with schizophrenia either antipsychotic medication-naïve or within two weeks of antipsychotic medication exposure and forty-seven age- and sex-matched healthy controls were enrolled. MiR-195 and BDNF mRNA and BDNF protein levels in peripheral blood were tested. Cognitive function was assessed using the MATRICS Consensus Cognitive Battery (MCCB). MiR-195 was significantly higher (p = 0.01) whereas BDNF mRNA (p < 0.001) and protein (p = 0.016) levels were significantly lower in patients compared with controls. Higher miR-195 expression was significantly correlated to lower BDNF protein levels in patients (partial r = -0.28, p = 0.003) and lower BDNF protein levels were significantly associated with poorer overall cognitive performance by MCCB and also in speed of processing, working memory, and attention/vigilance domains composite score (p = 0.002-0.004). The subgroup of patients with high miR-195 and low BDNF protein showed the lowest level of cognitive functions, and miR-195 showed significant mediation effects on cognitive functions through BDNF protein. Elevated miR-195 may play a role in regulating BDNF protein expression thereby influencing cognitive impairments in schizophrenia, suggesting that development of cognition enhancing treatment for schizophrenia may consider a micro-RNA based strategy.

A narrative review of the roles of the miR-15/107 family in heart disease: lessons and prospects for heart disease

Heart disease is one of the leading causes of morbidity and mortality globally. To reduce morbidity and mortality among patients with heart disease, it is important to identify drug targets and biomarkers for more effective diagnosis, prognosis, and treatment. MicroRNAs (miRNAs) are characterized as a group of endogenous, small non-coding RNAs, which function by directly inhibiting target genes. The miR-15/107 family is a group of evolutionarily conserved miRNAs comprising 10 members that share an identical motif of AGCAGC, which determines overlapping target genes and cooperation in the biological process. Accumulating evidence has demonstrated the predominant dysregulation of the miR-15/107 family in cardiovascular disease, neurodegenerative disease, and cancer. In this review, we summarize the current understanding of the miR-15/107 family, focusing on its role in the regulation in the development of the heart and the progression of heart disease. We also discuss the potential of different members of the miR-15/107 family as biomarkers for diverse heart disease, as well as the current applications and challenges in the use of the miR-15/107 family in clinical trials for various disease. This paper hopes to explore the potential of the miR-15/107 family as therapeutic targets or biomarkers and to provide directions for future research.

Alzheimer Disease Pathology-Associated Polymorphism in a Complex Variable Number of Tandem Repeat Region Within the MUC6 Gene, Near the AP2A2 Gene

We found evidence of late-onset Alzheimer disease (LOAD)-associated genetic polymorphism within an exon of Mucin 6 (MUC6) and immediately downstream from another gene: Adaptor Related Protein Complex 2 Subunit Alpha 2 (AP2A2). PCR analyses on genomic DNA samples confirmed that the size of the MUC6 variable number tandem repeat (VNTR) region was highly polymorphic. In a cohort of autopsied subjects with quantitative digital pathology data (n = 119), the size of the polymorphic region was associated with the severity of pTau pathology in neocortex. In a separate replication cohort of autopsied subjects (n = 173), more pTau pathology was again observed in subjects with longer VNTR regions (p = 0.031). Unlike MUC6, AP2A2 is highly expressed in human brain. AP2A2 expression was lower in a subset analysis of brain samples from persons with longer versus shorter VNTR regions (p = 0.014 normalizing with AP2B1 expression). Double-label immunofluorescence studies showed that AP2A2 protein often colocalized with neurofibrillary tangles in LOAD but was not colocalized with pTau proteinopathy in progressive supranuclear palsy, or with TDP-43 proteinopathy. In summary, polymorphism in a repeat-rich region near AP2A2 was associated with neocortical pTau proteinopathy (because of the unique repeats, prior genome-wide association studies were probably unable to detect this association), and AP2A2 was often colocalized with neurofibrillary tangles in LOAD.

miR-15/107 microRNA Gene Group: Characteristics and Functional Implications in Cancer

The miR-15/107 group of microRNAs (miRNAs) encloses 10 annotated human members and is defined based on the presence of the sequence AGCAGC near the mature miRNAs’ 5′ end. Members of the miR-15/107 group expressed in humans are highly evolutionarily conserved, and seven of these miRNAs are widespread in vertebrate species. Contrary to the majority of miRNAs, which recognize complementary sequences on the 3′UTR region, some members of the miR-15/107 group are peculiarly characterized by the ability to target the coding sequence (CDS) of their target mRNAs, inhibiting translation without strongly affecting their mRNA levels. There is compelling evidence that different members of the miR-15/107 group regulate overlapping lists of mRNA targets but also show target specificity. The ubiquitously expressed miR-15/107 gene group controls several human cellular pathways, such as proliferation, angiogenesis, and lipid metabolism, and might be altered in various diseases, such as neurodegenerative diseases and cancer. Intriguingly, despite sharing the same seed sequence, different members of this family of miRNAs may behave as oncomiRs or as tumor suppressor miRNAs in the context of cancer cells. This review discusses the regulation and functional contribution of the miR-15/107 group to the control of gene expression. Moreover, we particularly focus on the contribution of specific miR-15/107 group members as tumor suppressors in breast cancer, reviewing literature reporting their ability to function as major controllers of a variety of cell pathways and to act as powerful biomarkers in this disease.

Novel BDNF-regulatory microRNAs in neurodegenerative disorders pathogenesis: An in silico study

Brain-derived neurotrophic factor (BDNF) is a neurotrophic factor with various roles in the central nervous system neurogenesis, neuroprotection, and axonal guide. By attaching to Tropomyosin receptor kinase B (TrkB) receptor, this protein triggers downstream signaling pathways which lead to cellular growth, proliferation, survival, and neuroplasticity. Deregulation at mRNA level is involved in various central nervous system disorders including, Huntington, Alzheimer's, Multiple Sclerosis, and Amyotrophic Lateral Sclerosis diseases. Considering the importance of BDNF functions, deciphering the regulatory mechanisms controlling BDNF expression level could pave the way to develop more accurate and efficient treatments for neurological diseases. Among different regulatory systems, microRNAs (miRNAs) play prominent roles by targeting genes 3' untranslated regions. In this study, 127 validated and bioinformatic-predicted miRNAs with potentially regulatory roles in BDNF expression were analyzed. Various aspects of miRNAsö possible functions were assessed by bioinformatic online tools to find their potential regulatory functions in signaling pathways, neurological disorders, expression of transcription factors and miRNAs sponge. Analyzed data led to introduce 5 newly reported miRNAs that could regulate BDNF expression level. Finally, high throughput sequencing data from different brain regions and neurological disorders were analyzed to measure correlation of candidate miRNAs with BDNF level in experimental studies. In this study, a list of novel miRNAs with possible regulatory roles in BDNF expression level involving in different neurological disorders was introduced.

miR-15a/-16 Inhibit Angiogenesis by Targeting the Tie2 Coding Sequence: Therapeutic Potential of a miR-15a/16 Decoy System in Limb Ischemia

MicroRNA-15a (miR-15a) and miR-16, which are transcribed from the miR-15a/miR-16-1 cluster, inhibit post-ischemic angiogenesis. MicroRNA (miRNA) binding to mRNA coding sequences (CDSs) is a newly emerging mechanism of gene expression regulation. We aimed to (1) identify new mediators of the anti-angiogenic action of miR-15a and -16, (2) develop an adenovirus (Ad)-based miR-15a/16 decoy system carrying a luciferase reporter (Luc) to both sense and inhibit miR-15a/16 activity, and (3) investigate Ad.Luc-Decoy-15a/16 therapeutic potential in a mouse limb ischemia (LI) model. LI increased miR-15a and -16 expression in mouse muscular endothelial cells (ECs). The miRNAs also increased in cultured human umbilical vein ECs (HUVECs) exposed to serum starvation, but not hypoxia. Using bioinformatic tools and luciferase activity assays, we characterized miR-15a and -16 binding to Tie2 CDS. In HUVECs, miR-15a or -16 overexpression reduced Tie2 at the protein, but not the mRNA, level. Conversely, miR-15a or -16 inhibition improved angiogenesis in a Tie2-dependent manner. Local Ad.Luc-Decoy-15a/16 delivery increased Tie2 levels in ischemic skeletal muscle and improved post-LI angiogenesis and perfusion recovery, with reduced toe necrosis. Bioluminescent imaging (in vivo imaging system [IVIS]) provided evidence that the Ad.Luc-Decoy-15a/16 system responds to miR-15a/16 increases. In conclusion, we have provided novel mechanistic evidence of the therapeutic potential of local miR-15a/16 inhibition in LI.

Post-transcriptional regulation of miRNA-15a and miRNA-15b on VEGFR gene and deer antler cell proliferation

Background

Deer antler is the only regenerative organ in mammals, the regeneration of antler is not only the regeneration of bone tissue, but also accompanied by the regeneration of nerves, blood vessels and so on. The purpose of the current study was to explore the effect of miRNA-15a and miRNA-15b on the regulation of sika deer vascular endothelial growth factor receptor (VEGFR) during rapid antler growth.

Materials and methods

The VEGFR 3′-UTR was analyzed by bioinformatics software to identify the highly matched miRNAs. After transfected with miRNA mimics, the expression of selected miRNAs were measured by RT-qPCR and the relative expression level of VEGFR protein was detected by Western Blot. Dual-luciferase activity assay was used to determine the target relationship between VEGFR and miRNAs. The cartilage cell proliferation and telomerase activity were measured by MTT kit and TRAP assay, respectively.

Results

The VEGFR 3′-UTR contains a binding site for miRNA-15a and miRNA-15b. Over-expression of miRNA-15a and miRNA-15b, which significantly reduced the expression level of VEGFR protein, inhibited the proliferation of cartilage cells, and decreased the telomerase activity of cartilage cells in vitro.

Conclusion

miRNA-15a and miRNA-15b represent novel regulatory factors of VEGFR expression in deer antler.

Interpreting the MicroRNA-15/107 family: interaction identification by combining network based and experiment supported approach

Background

The highly conservative miR-15/107 family (also named as miR-15/107 gene group) including ten miRNA members is currently recognized strongly implicated in multiple human disorders. Some studies focus on the entire family rather than individual miRNA for a bigger picture, while there is also certain signature dysregulation for some of the individual miRNA implicated even in the same disorder.

Methods

Faced with the exponential growth of experimental evidence, our study tries to analyze their function and target interactions using various bioinformatics tools.

Results

Firstly, the evolutionary conservative “AGCAGC” sequence and possible clustered transcriptional pattern were described. Secondly, both the experimentally validated and bioinformatically predicted miRNA-target gene relationship of the entire family was analyzed to understand the mechanism of underlying collective effects for target regulation from the miR-15/107 family. Moreover, pathway analysis among miR-15/107 family was performed and displayed in detail, while its impact on cell proliferation is experimentally validated. Eventually, the dysregulation of miR-15/107 in diseases was discussed.

Conclusions

In summary, our study proposes that the collective functions and implication of miR-15/107 family in various human diseases are achieved relying on the massive overlapping target genes. While the minor differences within target gene interaction among family members could also explain the signature behavior for some of the individual miRNA in aspects such as its disease-specific dysregulation and various participation in pathways.

Electronic supplementary material

The online version of this article (10.1186/s12881-019-0824-9) contains supplementary material, which is available to authorized users.

MiRNA let-7b promotes the development of hypoxic pulmonary hypertension by targeting ACE2

Angiotensin-converting enzyme 2 (ACE2) protects against hypoxic pulmonary hypertension (HPH) by inhibiting the proliferation and migration of pulmonary artery smooth muscle cells (PASMCs). Under hypoxia, the hypoxia-inducible factor 1α (HIF-1α) inhibits ACE2 indirectly; however, the underlying mechanism is unclear. In the present study, we found that exposure to chronic hypoxia stimulated microRNA (miRNA) let-7b expression in rat lung via a HIF-1α-dependent pathway. Let-7b downregulated ACE2 expression by directly targeting the coding sequence of ACE2. Our in vitro and in vivo results revealed that let-7b contributed to the pathogenesis of HPH by inducing PASMCs proliferation and migration. Let-7b knockout mitigated right ventricle hypertrophy and pulmonary vessel remodeling in HPH by restoring ACE2 expression. Overall, we demonstrated that HIF-1α inhibited ACE2 expression via the HIF-1α-let-7b-ACE2 axis, which contributed to the pathogenesis of HPH by stimulating PASMCs proliferation and migration. Since let-7b knockout alleviated the development of HPH, let-7b may serve as a potential clinical target for the treatment of HPH.

Combining Results from Distinct MicroRNA Target Prediction Tools Enhances the Performance of Analyses

Target prediction is generally the first step toward recognition of bona fide microRNA (miRNA)-target interactions in living cells. Several target prediction tools are now available, which use distinct criteria and stringency to provide the best set of candidate targets for a single miRNA or a subset of miRNAs. However, there are many false-negative predictions, and consensus about the optimum strategy to select and use the output information provided by the target prediction tools is lacking. We compared the performance of four tools cited in literature—TargetScan (TS), miRanda-mirSVR (MR), Pita, and RNA22 (R22), and we determined the most effective approach for analyzing target prediction data (individual, union, or intersection). For this purpose, we calculated the sensitivity, specificity, precision, and correlation of these approaches using 10 miRNAs (miR-1-3p, miR-17-5p, miR-21-5p, miR-24-3p, miR-29a-3p, miR-34a-5p, miR-124-3p, miR-125b-5p, miR-145-5p, and miR-155-5p) and 1,400 genes (700 validated and 700 non-validated) as targets of these miRNAs. The four tools provided a subset of high-quality predictions and returned few false-positive predictions; however, they could not identify several known true targets. We demonstrate that union of TS/MR and TS/MR/R22 enhanced the quality of in silico prediction analysis of miRNA targets. We conclude that the union rather than the intersection of the aforementioned tools is the best strategy for maximizing performance while minimizing the loss of time and resources in subsequent in vivo and in vitro experiments for functional validation of miRNA-target interactions.

Environmental neurotoxicant manganese regulates exosome-mediated extracellular miRNAs in cell culture model of Parkinson's disease: Relevance to α-synuclein misfolding in metal neurotoxicity

Many chronic neurodegenerative disorders share a common pathogenic mechanism involving the aggregation and deposition of misfolded proteins. Recently, it was shown that these aggregated proteins could be transferred from one cell to another via extracellular nanovesicles called exosomes. Initially thought to be a means of cellular waste removal, exosomes have since been discovered to actively participate in cell-to-cell communication. Importantly, various inflammatory and signaling molecules, as well as small RNAs are selectively packaged in these vesicles. Considering the important role of environmental manganese (Mn) in Parkinson's disease (PD)-like neurological disorders, we characterized the effect of Mn on exosome content and release using an MN9D dopaminergic cell model of PD, which was generated to stably express wild-type human α-synuclein (αSyn). Mn exposure (300μM MnCl₂) for 24h induced the release of exosomes into the extracellular media prior to cytotoxicity, as determined by NanoSight particle analysis and electron microscopy. Strikingly, Western blot analysis revealed that Mn treatment in αSyn-expressing cells increases the protein Rab27a, which regulates the release of exosomes from cells. Moreover, next-generation sequencing showed more small RNAs in exosomes isolated from Mn-exposed cells than from control exosomes. Our miRNA profiling analysis led to the discovery of increased expression of certain miRNAs previously shown to regulate key biological pathways, including protein aggregation, autophagy, inflammation and hypoxia. Collectively, our results provide a glimpse of Mn's role in modulating extracellular miRNA content through exosomal release from dopaminergic neuronal cells and thus potentially contributing to progressive neurodegeneration. Further characterization of extracellular miRNAs and their targets will have major impacts on biomarker discovery and translational strategies for environmentally linked neurodegenerative diseases including PD.

Linking deregulation of non-coding RNA to the core pathophysiology of Alzheimer's disease: An integrative review

The human genome encodes a vast repertoire of protein non-coding RNAs (ncRNA), some specific to the brain. MicroRNAs, which interfere with the translation of target mRNAs, are of particular interest since their deregulation has been implicated in neurodegenerative disorders like Alzheimer's disease (AD). However, it remains challenging to link the complex body of observations on miRNAs and AD into a coherent framework. Using extensive graphical support, this article discusses how a diverse panoply of miRNAs convergently and divergently impact (and are impacted by) core pathophysiological processes underlying AD: neuroinflammation and oxidative stress; aberrant generation of β-amyloid-42 (Aβ42); anomalies in the production, cleavage and post-translational marking of Tau; impaired clearance of Aβ42 and Tau; perturbation of axonal organisation; disruption of synaptic plasticity; endoplasmic reticulum stress and the unfolded protein response; mitochondrial dysfunction; aberrant induction of cell cycle re-entry; and apoptotic loss of neurons. Intriguingly, some classes of miRNA provoke these cellular anomalies, whereas others act in a counter-regulatory, protective mode. Moreover, changes in levels of certain species of miRNA are a consequence of the above-mentioned anomalies. In addition to miRNAs, circular RNAs, piRNAs, long non-coding RNAs and other types of ncRNA are being increasingly implicated in AD. Overall, a complex mesh of deregulated and multi-tasking ncRNAs reciprocally interacts with core pathophysiological mechanisms underlying AD. Alterations in ncRNAs can be detected in CSF and the circulation as well as the brain and are showing promise as biomarkers, with the ultimate goal clinical exploitation as targets for novel modes of symptomatic and course-altering therapy.

MiR-326 is a diagnostic biomarker and regulates cell survival and apoptosis by targeting Bcl-2 in osteosarcoma

Osteosarcoma is a malignant bone tumor in which the survival rate is still low. MicroRNA-326 (miR-326) has been proved a potential diagnostic and prognostic marker for several tumors. However, the clinical value of miR-326 is still unknown. In the present study, we detected the expression of miR-326 in the serum of osteosarcoma patients and in osteosarcoma tissues using qRT-PCR. We compared the serum expression of miR-326 with the clinicopathological characteristics and survival of osteosarcoma patients. Finally, we explored the role of miR-326 of the invasion of osteosarcoma tumor cells using cell migration and invasion assays. We found that the expression of miR-326 was significantly decreased in the serum of osteosarcoma patients and osteosarcoma tumor cells compared to healthy controls (P<0.01). Moreover, a receiver operating characteristic (ROC) curve analysis is indicated that serum miR-326 is a potential diagnostic marker of osteosarcoma with an area under the ROC curve of 0.817. Importantly, patients with a lower expression of miR-326 tended to have distant metastasis (P<0.05) and a more advanced clinical stage (P<0.05). In addition, the survival time of patients with depressed miR-326 expression was significantly shorter compared to patients with high miR-326 expression (P<0.05). Further-more, we found that miR-326 could inhibit the proliferation, migration and invasion of osteosarcoma cells. Thus, we demonstrated that miR-326 might be related to the metastasis of osteosarcoma and could be used as a potential diagnostic and prognostic biomarker in osteosarcoma.

Polyamines release the let-7b-mediated suppression of initiation codon recognition during the protein synthesis of EXT2

Proteoglycans (PGs), a family of glycosaminoglycan (GAG)-protein glycoconjugates, contribute to animal physiology through interactions between their glycan chains and growth factors, chemokines and adhesion molecules. However, it remains unclear how GAG structures are changed during the aging process. Here, we found that polyamine levels are correlated with the expression level of heparan sulfate (HS) in human skin. In cultured cell lines, the EXT1 and EXT2 enzymes, initiating HS biosynthesis, were stimulated at the translational level by polyamines. Interestingly, the initiation codon recognition by 43S preinitiation complex during EXT2 translation is suppressed by let-7b, a member of the let-7 microRNA family, through binding at the N-terminal amino acid coding sequence in EXT2 mRNA. Let-7b-mediated suppression of initiation codon depends on the length of 5'-UTR of EXT2 mRNA and its suppression is inhibited in the presence of polyamines. These findings provide new insights into the HS biosynthesis related to miRNA and polyamines.

Dynamic miRNA-mRNA paradigms: New faces of miRNAs

More and more evidences suggested that the flow of genetic information can be spatially and temporally regulated by non-coding RNAs (ncRNAs), such as microRNAs (miRNAs). Although biogenesis and function of miRNAs have been well detailed, elucidation of the dynamic interplays between miRNAs and mRNAs have just begun. Here, we highlighted that the miRNA-mRNA interactions which could take place in different cellular locations. During dynamic interactions, miRNA binding sites included not only 3'UTRs, but also 5'UTRs and CDSs. Under different physiological or pathological conditions, miRNAs could switch from translational inhibition to activation. Dynamic miRNA-mRNA paradigms which suggested a novel tip of the iceberg beneath the gene regulation network will provide clues for function studies of other ncRNAs.

Cooperation meets competition in microRNA-mediated DMPK transcript regulation

The fundamental role of microRNAs (miRNAs) in the regulation of gene expression has been well-established, but many miRNA-driven regulatory mechanisms remain elusive. In the present study, we demonstrate that miRNAs regulate the expression of DMPK, the gene mutated in myotonic dystrophy type 1 (DM1), and we provide insight regarding the concerted effect of the miRNAs on the DMPK target. Specifically, we examined the binding of several miRNAs to the DMPK 3′ UTR using luciferase assays. We validated the interactions between the DMPK transcript and the conserved miR-206 and miR-148a. We suggest a possible cooperativity between these two miRNAs and discuss gene targeting by miRNA pairs that vary in distance between their binding sites and expression profiles. In the same luciferase reporter system, we showed miR-15b/16 binding to the non-conserved CUG repeat tract present in the DMPK transcript and that the CUG-repeat-binding miRNAs might also act cooperatively. Moreover, we detected miR-16 in cytoplasmic foci formed by exogenously expressed RNAs with expanded CUG repeats. Therefore, we propose that the expanded CUGs may serve as a target for concerted regulation by miRNAs and may also act as molecular sponges for natural miRNAs with CAG repeats in their seed regions, thereby affecting their physiological functions.

Post-transcriptional regulation of BRCA1 through its coding sequence by the miR-15/107 group of miRNAs

MicroRNAs (miRNAs) are important post-transcriptional regulators of gene expression that act by degrading their RNA targets or by repressing the translation of messenger RNAs (mRNAs). Initially thought to primarily target the 3' untranslated region (3'UTR) of mRNAs, miRNAs have since been shown to also target the 5'UTR and coding sequence (CDS). In this work, we focus on the post-transcriptional regulation of the BRCA1 gene, a major tumor suppressor and regulator of double-stranded break DNA repair and show that its mRNA is targeted by many members of the miR-15/107 group at a site located within the CDS. Ectopic expression of these miRNAs across a panel of nine cell lines demonstrated widespread suppression of BRCA1 mRNA levels. Additionally, by cloning a putative target site from BRCA1's amino acid CDS into a luciferase reporter plasmid we confirmed the direct interaction of these miRNAs with this BRCA1 target. We also examined the relationship between ectopic expression of these targeting miRNAs and BRCA1 protein levels in immortalized pancreatic epithelium (hTERT-HPNE), colorectal adenocarcinoma (HCT-116) and pancreatic adenocarcinoma (MIA PaCa-2) cell lines and found protein abundance to be variably regulated in a cell-type specific manner that was not necessarily concordant with mRNA transcript availability. Our findings reveal a previously unrecognized aspect of BRCA1's miRNA-mediated post-transcriptional regulation, namely the targeting of its amino acid coding region by the miR-15/107 group of miRNAs. The resulting regulation is apparently complex and cell-specific, an observation that may have implications for BRCA1-mediated DNA repair across tissue types.

Analysis of 13 cell types reveals evidence for the expression of numerous novel primate- and tissue-specific microRNAs

Two decades after the discovery of the first animal microRNA (miRNA), the number of miRNAs in animal genomes remains a vexing question. Here, we report findings from analyzing 1,323 short RNA sequencing samples (RNA-seq) from 13 different human tissue types. Using stringent thresholding criteria, we identified 3,707 statistically significant novel mature miRNAs at a false discovery rate of ≤ 0.05 arising from 3,494 novel precursors; 91.5% of these novel miRNAs were identified independently in 10 or more of the processed samples. Analysis of these novel miRNAs revealed tissue-specific dependencies and a commensurate low Jaccard similarity index in intertissue comparisons. Of these novel miRNAs, 1,657 (45%) were identified in 43 datasets that were generated by cross-linking followed by Argonaute immunoprecipitation and sequencing (Ago CLIP-seq) and represented 3 of the 13 tissues, indicating that these miRNAs are active in the RNA interference pathway. Moreover, experimental investigation through stem-loop PCR of a random collection of newly discovered miRNAs in 12 cell lines representing 5 tissues confirmed their presence and tissue dependence. Among the newly identified miRNAs are many novel miRNA clusters, new members of known miRNA clusters, previously unreported products from uncharacterized arms of miRNA precursors, and previously unrecognized paralogues of functionally important miRNA families (e.g., miR-15/107). Examination of the sequence conservation across vertebrate and invertebrate organisms showed 56.7% of the newly discovered miRNAs to be human-specific whereas the majority (94.4%) are primate lineage-specific. Our findings suggest that the repertoire of human miRNAs is far more extensive than currently represented by public repositories and that there is a significant number of lineage- and/or tissue-specific miRNAs that are uncharacterized.

miR-503 represses human cell proliferation and directly targets the oncogene DDHD2 by non-canonical target pairing

Background

The pathways regulating the transition of mammalian cells from quiescence to proliferation are mediated by multiple miRNAs. Despite significant improvements in our understanding of miRNA targeting, the majority of miRNA regulatory networks are still largely unknown and require experimental validation.

Results

Here we identified miR-503, miR-103, and miR-494 as negative regulators of proliferation in primary human cells. We experimentally determined their genome wide target profiles using RNA-induced silencing complex (RISC) immunoprecipitations and gene expression profiling. Analysis of the genome wide target profiles revealed evidence of extensive regulation of gene expression through non-canonical target pairing by miR-503. We identified the proto-oncogene DDHD2 as a target of miR-503 that requires pairing outside of the canonical 5′ seed region of miR-503, representing a novel mode of miRNA-target pairing. Further bioinformatics analysis implicated miR-503 and DDHD2 in breast cancer tumorigenesis.

Conclusions

Our results provide an extensive genome wide set of targets for miR-503, miR-103, and miR-494, and suggest that miR-503 may act as a tumor suppressor in breast cancer by its direct non-canonical targeting of DDHD2.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1279-9) contains supplementary material, which is available to authorized users.

Identifying microRNAs involved in aging of the lateral wall of the cochlear duct

Age-related hearing loss is a progressive sensorineural hearing loss that occurs during aging. Degeneration of the organ of Corti and atrophy of the lateral wall of the cochlear duct (or scala media) in the inner ear are the two primary causes. MicroRNAs (miRNAs), a class of short non-coding RNAs that regulate the expression of mRNA/protein targets, are important regulators of cellular senescence and aging. We examined miRNA gene expression profiles in the lateral wall of two mouse strains, along with exploration of the potential targets of those miRNAs that showed dynamic expression during aging. We show that 95 and 60 miRNAs exhibited differential expression in C57 and CBA mice during aging, respectively. A majority of downregulated miRNAs are known to regulate pathways of cell proliferation and differentiation, while all upregulated miRNAs are known regulators in the pro-apoptotic pathways. By using apoptosis-related gene array and bioinformatic approaches to predict miRNA targets, we identify candidate miRNA-regulated genes that regulate apoptosis pathways in the lateral wall of C57 and CBA mice during aging.

Role of miR-195 in aortic aneurysmal disease

RATIONALE

Abdominal aortic aneurysms constitute a degenerative process in the aortic wall. Both the miR-29 and miR-15 families have been implicated in regulating the vascular extracellular matrix.

OBJECTIVE

Our aim was to assess the effect of the miR-15 family on aortic aneurysm development.

METHODS AND RESULTS

Among the miR-15 family members, miR-195 was differentially expressed in aortas of apolipoprotein E-deficient mice on angiotensin II infusion. Proteomics analysis of the secretome of murine aortic smooth muscle cells, after miR-195 manipulation, revealed that miR-195 targets a cadre of extracellular matrix proteins, including collagens, proteoglycans, elastin, and proteins associated with elastic microfibrils, albeit miR-29b showed a stronger effect, particularly in regulating collagens. Systemic and local administration of cholesterol-conjugated antagomiRs revealed better inhibition of miR-195 compared with miR-29b in the uninjured aorta. However, in apolipoprotein E-deficient mice receiving angiotensin II, silencing of miR-29b, but not miR-195, led to an attenuation of aortic dilation. Higher aortic elastin expression was accompanied by an increase of matrix metalloproteinases 2 and 9 in mice treated with antagomiR-195. In human plasma, an inverse correlation of miR-195 was observed with the presence of abdominal aortic aneurysms and aortic diameter.

CONCLUSIONS

We provide the first evidence that miR-195 may contribute to the pathogenesis of aortic aneurysmal disease. Although inhibition of miR-29b proved more effective in preventing aneurysm formation in a preclinical model, miR-195 represents a potent regulator of the aortic extracellular matrix. Notably, plasma levels of miR-195 were reduced in patients with abdominal aortic aneurysms suggesting that microRNAs might serve as a noninvasive biomarker of abdominal aortic aneurysms.

MiR-103a-3p targets the 5' UTR of GPRC5A in pancreatic cells

MicroRNAs (miRNAs) are short noncoding RNAs that regulate the expression of their targets in a sequence-dependent manner. For protein-coding transcripts, miRNAs regulate expression levels through binding sites in either the 3' untranslated region (3' UTR) or the amino acid coding sequence (CDS) of the targeted messenger RNA (mRNA). Currently, for the 5' untranslated region (5' UTR) of mRNAs, very few naturally occurring examples exist whereby the targeting miRNA down-regulates the expression of the corresponding mRNA in a seed-dependent manner. Here we describe and characterize two miR-103a-3p target sites in the 5' UTR of GPRC5A, a gene that acts as a tumor suppressor in some cancer contexts and as an ongocene in other cancer contexts. In particular, we show that the interaction of miR-103a-3p with each of these two 5' UTR targets reduces the expression levels of both GPRC5A mRNA and GPRC5A protein in one normal epithelial and two pancreatic cancer cell lines. By ectopically expressing "sponges" that contain instances of the wild-type 5' UTR targets we also show that we can reduce miR-103a-3p levels and increase GPRC5A mRNA and protein levels. These findings provide some first knowledge on the post-transcriptional regulation of this tumor suppressor/oncogene and present additional evidence for the participation of 5' UTRs in miRNA driven post-transcriptional regulatory control.

The miR-17/92 cluster: a comprehensive update on its genomics, genetics, functions and increasingly important and numerous roles in health and disease

The miR-17/92 cluster is among the best-studied microRNA clusters. Interest in the cluster and its members has been increasing steadily and the number of publications has grown exponentially since its discovery with more than 1000 articles published in 2012 alone. Originally found to be involved in tumorigenesis, research work in recent years has uncovered unexpected roles for its members in a wide variety of settings that include normal development, immune diseases, cardiovascular diseases, neurodegenerative diseases and aging. In light of its ever-increasing importance and ever-widening regulatory roles, we review here the latest body of knowledge on the cluster's involvement in health and disease as well as provide a novel perspective on the full spectrum of protein-coding and non-coding transcripts that are likely regulated by its members.

MicroRNA binding sites in the coding region of mRNAs: extending the repertoire of post-transcriptional gene regulation

It is well established that microRNAs (miRNAs) induce mRNA degradation by binding to 3' untranslated regions (UTRs). The functionality of sites in the coding domain sequence (CDS), on the other hand, remains under discussion. Such sites have limited impact on target mRNA abundance and recent work suggests that miRNAs bind in the CDS to inhibit translation. What then could be the regulatory benefits of translation inhibition through CDS targeting compared to mRNA degradation following 3' UTR binding? We propose that these domain-dependent effects serve to diversify the functional repertoire of post-transcriptional gene expression control. Possible regulatory benefits may include tuning the time-scale and magnitude of post-transcriptional regulation, regulating protein abundance depending on or independently of the cellular state, and regulation of the protein abundance of alternative splice variants. Finally, we review emerging evidence that these ideas may generalize to RNA-binding proteins beyond miRNAs and Argonaute proteins.

Expression of miR-15/107 family microRNAs in human tissues and cultured rat brain cells

The miR-15/107 family comprises a group of 10 paralogous microRNAs (miRNAs), sharing a 5′ AGCAGC sequence. These miRNAs have overlapping targets. In order to characterize the expression of miR-15/107 family miRNAs, we employed customized TaqMan Low-Density micro-fluid PCR-array to investigate the expression of miR-15/107 family members, and other selected miRNAs, in 11 human tissues obtained at autopsy including the cerebral cortex, frontal cortex, primary visual cortex, thalamus, heart, lung, liver, kidney, spleen, stomach and skeletal muscle. miR-103, miR-195 and miR-497 were expressed at similar levels across various tissues, whereas miR-107 is enriched in brain samples. We also examined the expression patterns of evolutionarily conserved miR-15/107 miRNAs in three distinct primary rat brain cell preparations (enriched for cortical neurons, astrocytes and microglia, respectively). In primary cultures of rat brain cells, several members of the miR-15/107 family are enriched in neurons compared to other cell types in the central nervous system (CNS). In addition to mature miRNAs, we also examined the expression of precursors (pri-miRNAs). Our data suggested a generally poor correlation between the expression of mature miRNAs and their precursors. In summary, we provide a detailed study of the tissue and cell type-specific expression profile of this highly expressed and phylogenetically conserved family of miRNA genes.

Composition of seed sequence is a major determinant of microRNA targeting patterns

MOTIVATION

MicroRNAs (miRNAs) are small non-coding RNAs that are extensively involved in gene expression regulation. One major roadblock in functional miRNA studies is the reliable prediction of genes targeted by miRNAs, as rules defining miRNA target recognition have not been well-established to date. Availability of high-throughput experimental data from a recent CLASH (cross linking, ligation and sequencing of hybrids) study has presented an unprecedented opportunity to characterize miRNA target recognition patterns, which may provide guidance for improved miRNA target prediction.

RESULTS

The CLASH data were analysed to identify distinctive sequence features that characterize canonical and non-canonical miRNA target types. Most miRNA targets were of non-canonical type, i.e. without involving perfect pairing to canonical miRNA seed region. Different miRNAs have distinct targeting patterns, and this miRNA-to-miRNA variability was associated with seed sequence composition. Specifically, seed-based canonical target recognition was dependent on the GC content of the miRNA seed. For miRNAs with low GC content of the seed region, non-canonical targeting was the dominant mechanism for target recognition. In contrast to canonical targeting, non-canonical targeting did not lead to significant target downregulation at either the RNA or protein level.

CONTACT

xwang@radonc.wustl.edu.

Mapping the human miRNA interactome by CLASH reveals frequent noncanonical binding

MicroRNAs (miRNAs) play key roles in gene regulation, but reliable bioinformatic or experimental identification of their targets remains difficult. To provide an unbiased view of human miRNA targets, we developed a technique for ligation and sequencing of miRNA-target RNA duplexes associated with human AGO1. Here, we report data sets of more than 18,000 high-confidence miRNA-mRNA interactions. The binding of most miRNAs includes the 5' seed region, but around 60% of seed interactions are noncanonical, containing bulged or mismatched nucleotides. Moreover, seed interactions are generally accompanied by specific, nonseed base pairing. 18% of miRNA-mRNA interactions involve the miRNA 3' end, with little evidence for 5' contacts, and some of these were functionally validated. Analyses of miRNA:mRNA base pairing showed that miRNA species systematically differ in their target RNA interactions, and strongly overrepresented motifs were found in the interaction sites of several miRNAs. We speculate that these affect the response of RISC to miRNA-target binding.

Dynamic recruitment of microRNAs to their mRNA targets in the regenerating liver

Background

Validation of physiologic miRNA targets has been met with significant challenges. We employed HITS-CLIP to identify which miRNAs participate in liver regeneration, and to identify their target mRNAs.

Results

miRNA recruitment to the RISC is highly dynamic, changing more than five-fold for several miRNAs. miRNA recruitment to the RISC did not correlate with changes in overall miRNA expression for these dynamically recruited miRNAs, emphasizing the necessity to determine miRNA recruitment to the RISC in order to fully assess the impact of miRNA regulation. We incorporated RNA-seq quantification of total mRNA to identify expression-weighted Ago footprints, and developed a microRNA regulatory element (MRE) prediction algorithm that represents a greater than 20-fold refinement over computational methods alone. These high confidence MREs were used to generate candidate ‘competing endogenous RNA’ (ceRNA) networks.

Conclusion

HITS-CLIP analysis provide novel insights into global miRNA:mRNA relationships in the regenerating liver.

Tumor suppressor miR-375 regulates MYC expression via repression of CIP2A coding sequence through multiple miRNA-mRNA interactions

miR-375 interacts with five conserved target sites in the CIP2A coding region, whereas the CIP2A 3′ UTR is not conserved across mammalian species. Reexpression of the tumor suppressor miR-375 in cancer cells represses the expression of CIP2A, resulting in a decrease in the MYC protein level and leading to reduced cell proliferation, migration, and invasion.

MicroRNAs (miRNAs) are small, noncoding RNAs involved in posttranscriptional regulation of protein-coding genes in various biological processes. In our preliminary miRNA microarray analysis, miR-375 was identified as the most underexpressed in human oral tumor versus controls. The purpose of the present study is to examine the function of miR-375 as a candidate tumor suppressor miRNA in oral cancer. Cancerous inhibitor of PP2A (CIP2A), a guardian of oncoprotein MYC, is identified as a candidate miR-375 target based on bioinformatics. Luciferase assay accompanied by target sequence mutagenesis elucidates five functional miR-375–binding sites clustered in the CIP2A coding sequence close to the C-terminal domain. Overexpression of CIP2A is clearly demonstrated in oral cancers, and inverse correlation between miR-375 and CIP2A is observed in the tumors, as well as in NCI-60 cell lines, indicating the potential generalized involvement of the miR-375–CIP2A relationship in many other cancers. Transient transfection of miR-375 in oral cancer cells reduces the expression of CIP2A, resulting in decrease of MYC protein levels and leading to reduced proliferation, colony formation, migration, and invasion. Therefore this study shows that underexpression of tumor suppressor miR-375 could lead to uncontrolled CIP2A expression and extended stability of MYC, which contributes to promoting cancerous phenotypes.

Proteomics for understanding miRNA biology

MicroRNAs (miRNAs) are small noncoding RNAs that play important roles in posttranscriptional regulation of gene expression. Mature miRNAs associate with the RNA interference silencing complex to repress mRNA translation and/or degrade mRNA transcripts. Mass spectrometry-based proteomics has enabled identification of several core components of the canonical miRNA processing pathway and their posttranslational modifications which are pivotal in miRNA regulatory mechanisms. The use of quantitative proteomic strategies has also emerged as a key technique for experimental identification of miRNA targets by allowing direct determination of proteins whose levels are altered because of translational suppression. This review focuses on the role of proteomics and labeling strategies to understand miRNA biology.

Integrated miRNA, mRNA and protein expression analysis reveals the role of post-transcriptional regulation in controlling CHO cell growth rate

Background

To study the role of microRNA (miRNA) in the regulation of Chinese hamster ovary (CHO) cell growth, qPCR, microarray and quantitative LC-MS/MS analysis were utilised for simultaneous expression profiling of miRNA, mRNA and protein. The sample set under investigation consisted of clones with variable cellular growth rates derived from the same population. In addition to providing a systems level perspective on cell growth, the integration of multiple profiling datasets can facilitate the identification of non-seed miRNA targets, complement computational prediction tools and reduce false positive and false negative rates.

Results

51 miRNAs were associated with increased growth rate (35 miRNAs upregulated and 16 miRNAs downregulated). Gene ontology (GO) analysis of genes (n=432) and proteins (n=285) found to be differentially expressed (DE) identified biological processes driving proliferation including mRNA processing and translation. To investigate the influence of miRNA on these processes we combined the proteomic and transcriptomic data into two groups. The first set contained candidates where evidence of translational repression was observed (n=158). The second group was a mixture of proteins and mRNAs where evidence of translational repression was less clear (n=515). The TargetScan algorithm was utilised to predict potential targets within these two groups for anti-correlated DE miRNAs.

Conclusions

The evidence presented in this study indicates that biological processes such as mRNA processing and protein synthesis are correlated with growth rate in CHO cells. Through the integration of expression data from multiple levels of the biological system a number of proteins central to these processes including several hnRNPs and components of the ribosome were found to be post-transcriptionally regulated. We utilised the expression data in conjunction with in-silico tools to identify potential miRNA-mediated regulation of mRNA/proteins involved in CHO cell growth rate. These data have allowed us to prioritise candidates for cell engineering and/or biomarkers relevant to industrial cell culture. We also expect the knowledge gained from this study to be applicable to other fields investigating the role of miRNAs in mammalian cell growth.

MicroRNAs in Acute Myeloid Leukemia and Other Blood Disorders

Common blood disorders include hematopoietic cell malignancies or leukemias and plasma cell dyscrasia, all of which have associated microRNA abnormalities. In this paper, we discuss several leukemias including acute myeloid leukemia (AML) and chronic lymphocytic leukemia (CLL) and identify altered microRNAs and their targets. Immune disorders with altered blood levels of antibodies include autoimmune disorders, such as systemic lupus erythematosus (SLE) with associated anti-self-autoantibodies and immunoglobulin A nephropathy (IgAN) also have related microRNA abnormalities. The alterations in microRNAs may serve as therapeutic targets in these blood disorders.

miRNAs and estrogen action

MicroRNAs (miRNAs) are short, noncoding RNAs that generally base-pair within the 3' untranslated region of target mRNAs causing translational inhibition and/or mRNA degradation. Estradiol (E(2)) and other estrogen receptor (ER) ligands suppress or stimulate miRNA expression in human breast cancer cells, endometrial cells, rat mammary gland, and mouse uterus, and post-translationally regulate protein expression. Aberrant miRNA expression is implicated in estrogen-related breast and endometrial cancers, and several miRNAs downregulate ERα. The role of estrogen-regulated miRNA expression, the target genes of these miRNAs, and the role of miRNAs in health and disease is a 'hot' area of research that will yield new insight into molecular mechanisms of estrogen action.