Stem-loop RT Primer Research Articles

Evaluation of the expression level of microRNA-21, microRNA-15a, microRNA-372 in human follicular fluid stem cells-derived oocyte-like cells (OLCs).

Today, researchers have succeeded in achieving oocyte-like cells through the in vitro differentiation of stem cells. MicroRNAs are key regulators of oocyte development. In this study we decided to evaluate the expression pattern of microRNA-21, microRNA-15a, and microRNA-372 in oocyte-like cells, to determine the maturation stage of oocyte-like cells. Human follicular fluid samples were collected and centrifuged, and their cells were divided into 3 groups; day 7 as control group, days 14 and 21. During this period, the cells were evaluated for their morphological appearance and viability by inverted microscopy. RNA isolation was performed and cDNA was reversely transcribed by specific stem-loop RT primers. Real-time RT-PCR was used to detect microRNA expression. The relative expression of microRNA-21 and microRNA-15a on day 21 was significantly down-regulated compared to the control group (day 7), but microRNA-372 did not show a significant difference. Also, on day 14 compared to the control group (day 7), microRNA-21 did not show a significant difference; but microRNA-15a and microRNA-372 were significantly down-regulated. MicroRNA-21 and microRNA-15a on day 21 compared to day 14 revealed down-regulated levels, but microRNA-372 revealed up-regulated levels. Our results showed significant decreases in the expression of microRNA-21 and microRNA-15a in oocyte-like cells, as well as in oocytes, which may lead to cytoplasmic maturation, germinal vesicle break down and the completion of meiosis І. In addition, down-regulation expression of microRNA-372 maybe a confirmation that mesenchymal stem cells have differentiated into germ cells, and these cells were differentiated into oocyte-like cells.

B-370 Clinical Utility of microRNA Quantitative Analysis Using Double Quencher Probes and Methylation Analysis by Methylation Sensitive Restriction Enzyme Polymerase Chain Reaction for Bladder Cancer

Abstract Background Histone modifications, DNA methylation, and microRNA (miRNA)-mediated gene silence are examples of epigenetic changes that regulate gene expression without causing sequence changes. The early phases of neoplastic transformation are characterized by the occurrence of these epigenetic changes, which are believed to be crucial for the development and progression of cancer. To increase the sensitivity and practicality of miRNA analysis, we developed a measuring technique using a ZEN double quencher into hydrolysis probe in reverse transcription quantitative polymerase chain reaction (RT-qPCR). Additionally, we developed a method for DNA methylation analysis employing methylation-sensitive restriction enzymes (MSRE) and methylation-insensitive restriction enzymes (MIRE) that can analyze a number of samples quickly. We examined the clinical usefulness of using these systems to understand the level of miRNA expression and methylation in bladder cancer. Methods In this study, 64 biopsied tissues from transurethral bladder tumor resection (TURBT) were used. For miRNA extraction, Cica geniusTM RNA Prep Kit (For Tissue) II (KANTO CHEMICAL CO.,INC.) and a solution that improves miRNA extraction efficiency were used. Using stem-loop RT primers, complementary DNA was created from the isolated miRNA solution. Quantitative analysis was performed by RT-qPCR using a ZEN double quencher probe and miR-21,30a, 200c, and U6 were used as target. Genomic DNA (gDNA) was extracted from the TURBT sample using High Pure PCR Template Preparation Kit (Roche). Restriction enzyme digestion was performed using HapII (Takara Bio) as MSRE and MspI (Takara Bio) as MIRE; the latter has the same recognition site as HapII but is not affected by the presence or absence of methylation. Real-time PCR was performed on the LightCycler 96 (Roche) using Universal ProbeLibrary probes (Roche) targeting ESM1, SFMBT2, and SEPTIN9. From the obtained Cp value, each methylation rate was calculated. The Fisher’s exact test was used to statistically analyze the relationship among miRNA, methylation data and other clinicopathological factors. Results For miR-30a, we observed a higher expression of miRNA was linked to more advanced T stage (P = 0.047). Additionally, ESM1 methylation exhibited a significant correlation with greater grade (P = 0.004) and T stage progress (P = 0.018). Data on miRNA abundance and methylation rate were combined in order to uncover a link with clinical data that was not apparent from either set of data separately. Samples with higher values for both miR-21 and ESM1 methylation rates were shown to have high grade (P = 0.007) and progress to the T stage (P = 0.006). Furthermore, samples with higher values for both miR-200c and SEPTIN9 methylation rates did not progress to the T stage (P = 0.013). Conclusion The combined miRNA and methylation data revealed relationships with clinical results that could not be discovered with either data separately, highlighting the clinical usefulness of the current study’s findings.

Evaluating the Differential Expression of miR-146a, miR-222, and miR-9 in Matched Serum and Follicular Fluid of Polycystic Ovary Syndrome Patients: Profiling and Predictive Value.

Polycystic ovary syndrome (PCOS) is the most prevalent endocrine disorder of women in reproductive age with significant effects on reproductive and metabolic functions. Many molecular players may be involved in PCOS pathology; however, miRNAs possess great ability in gene expression control in normal ovarian function and folliculogenesis. We appraised the relative expression of miR-146a, miR-222, miR-9, and miR-224 in serum and follicular fluid (FF) of PCOS patients compared to control subjects. PCOS (n = 35) and control (n = 30) subjects were recruited in the study during their enrolment in IVF cycles. Serum and FF of human subjects were collected and stored. Total RNA was isolated from samples and cDNA was synthesized using miRNA-specific stem-loop RT primers. Quantitative real-time PCR was used to evaluate the expression of miRNAs relative to U6 expression. The predictive value of miRNAs' expression for discrimination of PCOS patients from control subjects was evaluated by receiver-operating characteristic (ROC) curve analysis. miR-224 was not detected in serum and FF samples. Significantly, higher levels of miR-146a and miR-9 in serum of PCOS group were detected. In contrast, relative expression of miR-146a and miR-9 significantly decreased in FF. In PCOS group, relative expression of all detected miRNAs was elevated in serum in comparison to FF, whereas in control group no change was noticed. Combination of FF miRNAs showed improved predictive value with area under the ROC curve (AUC) of 0.84, 93.8% sensitivity, and 83.3% specificity. Contradicting alternations of miRNAs in serum and FF are indicative of different sources of miRNAs in body fluids. Presumptive target genes of studied miRNAs in signalling pathways may show the potential role of these miRNA in folliculogenesis.

In-particle stem-loop RT-qPCR for specific and multiplex microRNA profiling

Here we report a novel method of microRNA (miRNA) profiling with particle-based multiplex quantitative reverse transcription polymerase chain reaction (RT-qPCR). To achieve target-specific reaction in a particle, the stem-loop RT primer and forward primer for each target miRNA were chemically immobilized to the particle. Target-specific cDNA synthesis proceeds with the stem-loop RT primer and then qPCR subsequently proceeds with the forward primer to rapidly achieve a quantitative result. High-fidelity multiplex assay was also accomplished in a single PCR process by loading multiple particles for each specific miRNA. The method for primer supply in the particles, involving confinement of the target-specific RT and PCR primers in the matrix of particles, led to the reduction of nonspecific reactions and improved the selectivity of the miRNA assay while minimizing labor in a multiple target assay. Specifically, this particle-based assay enabled the differentiation of mature miRNA from precursor with selectivity of 270:1 in terms of amplification speed. This advanced method also showed good discrimination among highly homologous let-7 family members, with cross-reaction rates of less than 5%. We demonstrated a very simple process of five-plex miRNA profiling in total RNA, and the measured changes in expression level were consistent with those from a conventional singleplex method.

Expression of miR-15a, miR-145, and miR-182 in granulosa-lutein cells, follicular fluid, and serum of women with polycystic ovary syndrome (PCOS).

Polycystic ovary syndrome (PCOS) is one of the most common endocrinopathies that affects women in reproductive age. MicroRNAs (miRNAs) play crucial roles in normal function of female reproductive system and folliculogenesis. Deregulated expression of miRNAs in PCOS condition may be significantly implicated in the pathogenesis of PCOS. We determined relative expression of miR-15a, miR-145, and miR-182 in granulosa-lutein cells (GLCs), follicular fluid (FF), and serum of PCOS patients. Human subjects were divided into PCOS (n=20) and control (n=21) groups. GLCs, FF, and serum were isolated and stored. RNA isolation was performed and cDNA was reversely transcribed using specific stem-loop RT primers. Relative expression of miRNAs was calculated after normalization against U6 expression. Correlation of miRNAs' expression level with basic clinical features and predictive value of miRNAs in FF and serum were appraised. Relative expression of miR-145 and miR-182 in GLCs was significantly decreased in PCOS, but miR-182 in FF of PCOS patients revealed up-regulated levels. Significant correlations between level of miRNAs in FF and serum and hormonal profile of subjects were observed. MiR-182 in FF showed a significant predictive value with AUC of 0.73, 76.4% sensitivity, and 70.5% specificity which was improved after combination of miR-182 and miR-145. A significant dysregulation of miR-145 and miR-182 in GLCs of PCOS may indicate their involvement in pathogenesis of PCOS. Differential up-regulation of miR-182 in FF of PCOS patients with its promising predictive values for discrimination of PCOS reinforced the importance of studying miRNAs' profile in FF.

Clinicopathological features associated to MiRNA-195 expression in patients with breast cancer: Evidence of a potential biomarker.

Background & Objective:MiRNAs are a systematic class of small non-coding RNAs with impending role as tumor biomarkers. Our objective was to identify the level of expression of Mir-195 in patients with breast cancer along with its correlation with clinicopathologic features.Methods:A total of 209 females in which 139 histologically diagnosed breast cancer (BC) cases and 70 healthy controls matched for age, their relative clinical and histopathological findings were recorded from their laboratory reports and hospital record of the patients. Plasma was used for extraction of total RNA and cDNA was prepared by using both miR-195 stem loop RT primers and gene specific antisense primers while U6 IT was used as control. Quantitative real-time PCR (qRT-PCR) for miR-195 expression status was performed and amplification (down regulation) was recorded.Results:Of 139 samples the expression of miR-195 was down regulated in 72.6% cases and the remaining 27.3% cases behaved same as 70 healthy or normal controls. Significant correlation of low miR-195 expression with higher differentiation grade, lymph node metastasis and clinical stage was found.Conclusion:Significant correlation between miR-195 expression and some clinicopathological features were recognized. MiR-195 could be used as potential non-invasive, molecular biomarker for early detection of breast cancer.

Stem-Loop qRT-PCR for the Detection of Plant microRNAs.

Plant microRNAs (miRNAs) play important roles in the posttranscriptional regulation of protein-coding genes, and they are essential for a normal development and survival. Mature miRNAs are cleaved from larger precursor RNAs and are typically 21-22 nt long.The small size, the lack of a common feature like a poly(A) tail, 3' end-modifications, and presence of a precursor-all these factors affect the detection and hinder the quantification of miRNAs. The stem-loop qRT-PCR method described here is designed to detect and quantify mature miRNAs in a fast, specific, accurate, and reliable manner. Firstly, a miRNA-specific stem-loop RT primer is hybridized to miRNA and then reverse transcribed. Next, the RT product is amplified and monitored in real time using a miRNA-specific forward primer and a universal reverse primer. This method enables miRNA expression profiling from as little as 10 pg of total RNA, and it is suitable for a relatively high-throughput analysis of miRNA expression.

MicroRNA-34a induces a senescence-like change via the down-regulation of SIRT1 and up-regulation of p53 protein in human esophageal squamous cancer cells with a wild-type p53 gene background

MiR-34a has been reported as a non-coding RNA universally expressed in normal old cells and a probable suppressor of diverse cancer cells; however, this miRNA's expression and anti-tumor mechanism in esophageal squamous cancer cells (ESCC) remains unclear. We explored these questions in three human ESCC lines, KYSE-450, KYSE-410, and ECa-109, with wild-type p53 and mutant p53 backgrounds. Through a specific stem-loop RT primer for miR-34a, we examined the relevant expression level of miR-34a in these three cell lines using real-time reverse transcription PCR (qRT-PCR). We found that the expression level of miR-34a induced by the DNA damage agent adrmycin (ADR) was both p53- and time-dependent. Following incubation with miR-34a, cellular growth inhibition was exhibited differently in the three cell lines harbored with different p53 backgrounds. Furthermore, the MTT assay demonstrated an miR-34a-related cytotoxic effect in cell growth. Senescence-associated β-galactosidase (SA-β-Gal) staining was used to examine senescence-like phenotypes induced by miR-34a. Mechanistic investigation suggested that the down-regulation of Sirtuin1 (SIRT1) and up-regulation of p53/p21 contributed to the anti-tumor mechanism of miR-34a in wild-type p53 ECa-109 cells, while neither of the apoptosis-related proteins PARP and caspase-3 caused significant changes. In summary, our findings indicated that the intrinsic expression of miR-34a was relatively low and was expressed differently among different p53 backgrounds and ADR treatment times. The anti-tumor effect of miR-34a was primarily dependent on the regulation of SIRT1 and p53/p21 protein, not apoptosis-associated proteins.

Small RNA existed in commercial reverse transcriptase: primary evidence of functional small RNAs.

MicroRNAs (miRNAs) are small RNA molecules (approximately 22 nucleotides long) that take part in the post-transcriptional regulation of gene expression (Chen and Rajewsky, 2007). Thousands of these RNAs have been reported since their discovery. These small molecules have been shown to play an important regulatory role in a wide range of biological and pathological processes (Brennecke et al., 2003; Cuellar and McManus, 2005; Lim et al., 2005). Recently, miRNAs have been found in serum, plasma, urine and other bodily fluids (Chen et al., 2008; Weber et al., 2010). Interestingly, the expression profiles of these extracellular miRNAs are correlated with various diseases; they may be used as biomarkers in diagnosing and monitoring human diseases (Lu et al., 2005). Various techniques have emerged to quantify miRNAs. MiRNA expression can be quantified by two-step RT-qPCR, which can provide relative quantification (Chen et al., 2005). MiRNAs can also be hybridized onmicroarrays, slides or chips with probes for hundreds of miRNA targets, and relative miRNA levels can be determined in different samples (Shingara et al., 2005).High-throughput sequencingmethodscanalsobe used to profile miRNAs (Buermans et al., 2010). RT-qPCR is usually performed as a standard for accuracy and sensitivity during the typical procedure to determine the miRNA expressionprofile. For this reason, the quality of theRT-qPCRsystem is closely related to the final determination and result. We were surprised to find that the background of certain miRNAs was very high in the RT-qPCR results, even in notemplate-controls during practice trials. By considering the high specificity of the stem-loop RT primers, we studied the origin of this high background in miRNA RT-qPCR and found that commercial avian myeloblastosis virus (AMV) reverse transcriptase may contain miRNAs. In practice, DEPC-treated water or ultrapure water (Invitrogen) served as no-template-controls for miRNA quantitation. However, certain miRNAs (for example, Let-7a, miR-16, miR-26a, and miR-191 in this study) exhibited high background signals in these no-template-controls when AMV reverse transcriptase was used (Fig. 1A). DNA sequencing showed that the PCR products were correct (data not shown). We tried two other commercial AMV reverse SMALL RNA IN REVERSE TRANSCRIPTASE: TOO SMALL TO BE FOUND

MiRNA-24 and miRNA-466i-5p controls inflammation in rat hepatocytes.

miRNA-24 and miRNA-466i-5p controls inflammation in rat hepatocytes.

A universal TaqMan-based RT-PCR protocol for cost-efficient detection of small noncoding RNA

Several methods for the detection of RNA have been developed over time. For small RNA detection, a stem-loop reverse primer-based protocol relying on TaqMan RT-PCR has been described. This protocol requires an individual specific TaqMan probe for each target RNA and, hence, is highly cost-intensive for experiments with small sample sizes or large numbers of different samples. We describe a universal TaqMan-based probe protocol which can be used to detect any target sequence and demonstrate its applicability for the detection of endogenous as well as artificial eukaryotic and bacterial small RNAs. While the specific and the universal probe-based protocol showed the same sensitivity, the absolute sensitivity of detection was found to be more than 100-fold lower for both than previously reported. In subsequent experiments, we found previously unknown limitations intrinsic to the method affecting its feasibility in determination of mature template RISC incorporation as well as in multiplexing. Both protocols were equally specific in discriminating between correct and incorrect small RNA targets or between mature miRNA and its unprocessed RNA precursor, indicating the stem-loop RT-primer, but not the TaqMan probe, triggers target specificity. The presented universal TaqMan-based RT-PCR protocol represents a cost-efficient method for the detection of small RNAs.

Differential expression of microRNAs induced by trastuzumab emtansine (T-DM1) during megakaryocytopoiesis.

645 Background: Treatment with the HER2-targeted antibody–drug conjugate T-DM1 resulted in significantly longer PFS and OS vs lapatinib + capecitabine in patients previously treated with trastuzumab and a taxane in the phase 3 study EMILIA. Thrombocytopenia (TCP) was the dose-limiting toxicity for patients treated with T-DM1, although platelets do not express HER2. In EMILIA, grade 3/4 TCP was observed in 12.9% of T-DM1-treated patients. We have previously shown that T-DM1 inhibits megakaryocyte (Mk) production and differentiation. Here, we investigated the effect of T-DM1 on microRNAs (miRNAs) associated with megakaryocytopoiesis. Methods: Human stem cells (HSCs; CD133+/CD34+) from 8 donors were differentiated into Mks in the presence of T-DM1, trastuzumab, or vehicle. Total RNA was extracted using the miRNeasy MiniKit. cDNA was prepared using the Taqman miRNA RT Kit, FAM-MGB probes, and stem-loop RT primer pool set. miRNA expression was measured using the 96.96 Dynamic Array Chip on the Biomark HD Reader. Data were analyzed using Fluidigm real-time analysis software Spotfire 5, and SAS 9.2. hsa−let−7g and hsa−miR−671−3p were chosen as reference miRNAs due to their low variation between treatments and time points. Median normalization was also applied. Results: A total of 526 miRNA RT-qPCR assays were used to map miRNA expression during differentiation of HSCs from 8 separate donors to Mks in vitro over 30 days. Several miRNAs demonstrated temporal changes in their expression profiles during maturation, suggesting these miRNAs are potential drivers of Mk differentiation. T-DM1 treatment inhibited Mk production and differentiation. Concomitant modifications in the expression of specific miRNAs were observed. These modifications were not present in trastuzumab- or vehicle-treated cells, suggesting these miRNAs may be involved in the development of T-DM1–induced TCP. Conclusions: These results suggest that the miRNAs have the potential to be used as biomarkers for TCP in patients treated with T-DM1 and possibly other DM1 conjugates. Specific miRNA alterations related to T-DM1 treatment will be discussed following investigations using clinical samples to validate these preliminary data.

MicroRNA-31 Activates the RAS Pathway and Functions as an Oncogenic MicroRNA in Human Colorectal Cancer by Repressing RAS p21 GTPase Activating Protein 1 (RASA1)

MicroRNAs (miRNAs) are known to play a vital role in colorectal cancer. We found a widespread disruption in miRNA expression during colorectal tumorigenesis using microarray and quantitative RT-PCR analysis; of the 161 miRNAs altered in colorectal cancer compared with normal adjacent tissue samples, miR-31 was the most significantly dysregulated. We identified candidate targets of miR-31 using bioinformatics approaches and validated RAS p21 GTPase activating protein 1 (RASA1) as a direct target. First, we found an inverse correlation between miR-31 and RASA1 protein levels in vivo. Second, in vitro evidence demonstrated that RASA1 expression was significantly decreased by treatment with pre-miR-31-LV, whereas anti-miR-31-LV treatment increased RASA1 protein levels. Third, a luciferase reporter assay confirmed that miR-31 directly recognizes a specific location within the 3'-untranslated region of RASA1 transcripts. Furthermore, the biological consequences of miR-31 targeting RASA1 were examined by the cell proliferation assay in vitro and by the immunodeficient mouse xenograft tumor model in vivo. Taken together, our results demonstrate for the first time that miR-31 plays a significant role in activating the RAS signaling pathway through the inhibition of RASA1 translation, thereby improving colorectal cancer cell growth and stimulating tumorigenesis.

A Facile and Specific Assay for Quantifying MicroRNA by an Optimized RT-qPCR Approach

BackgroundThe spatiotemporal expression patterns of microRNAs (miRNAs) are important to the verification of their predicted function. RT-qPCR is the accepted technique for the quantification of miRNA expression; however, stem-loop RT-PCR and poly(T)-adapter assay, the two most frequently used methods, are not very convenient in practice and have poor specificity, respectively.ResultsWe have developed an optimal approach that integrates these two methods and allows specific and rapid detection of tiny amounts of sample RNA and reduces costs relative to other techniques. miRNAs of the same sample are polyuridylated and reverse transcribed into cDNAs using a universal poly(A)-stem-loop RT primer and then used as templates for SYBR® Green real-time PCR. The technique has a dynamic range of eight orders of magnitude with a sensitivity of up to 0.2 fM miRNA or as little as 10 pg of total RNA. Virtually no cross-reaction is observed among the closely-related miRNA family members and with miRNAs that have only a single nucleotide difference in this highly specific assay. The spatial constraint of the stem-loop structure of the modified RT primer allowed detection of miRNAs directly from cell lysates without laborious total RNA isolation, and the poly(U) tail made it possible to use multiplex RT reactions of mRNA and miRNAs in the same run.ConclusionsThe cost-effective RT-qPCR of miRNAs with poly(A)-stem-loop RT primer is simple to perform and highly specific, which is especially important for samples that are precious and/or difficult to obtain.

Altered expression of microRNA miR-146a correlates with the development of chronic renal inflammation

MicroRNAs (miRNAs) are highly conserved small non-coding RNAs that act as post-transcriptional regulators of target mRNA. In this study, we sought to identify the microRNA underlying local inflammation in a murine model of chronic kidney disease (CKD). In microarray analysis of kidneys, the expression of miR-146a/b was elevated in B6.MRLc1 CKD mice that spontaneously develop renal inflammation with age. Primary-microRNA analysis found that elevated miR-146a/b expression in the kidneys of B6.MRLc1 mice was mainly derived from miR-146a rather than miR-146b, and this expression increased with the development of CKD. Histopathological scores for glomerular and interstitial lesions, mRNA expression of inflammatory mediators, and macrophage infiltration were significantly higher in B6.MRLc1 than C57BL/6 mice and were positively correlated with miR-146a expression. In situ hybridization and laser microdissection-RT-PCR showed that miR-146a expression in interstitial lesions containing inflammatory cells was higher than in the glomerulus. The increased expression of the inflammatory-associated genes RELA, IRAK1, IL1B, IL10, and CXCLs was noted in miR-146a/b-silenced human monocytes. The amount of miR-146a was higher in urine sediments of B6.MRLc1 than of C57BL/6 mice. Thus, miR-146a expression in the kidneys and its urinary excretion was specifically associated with the development of interstitial lesions and correlated with inflammatory cell infiltration.

MiR-125b, a Target of CDX2, Regulates Cell Differentiation through Repression of the Core Binding Factor in Hematopoietic Malignancies

MicroRNA-125b (miR-125b), a small noncoding RNA molecule, has been found to be deregulated and functions as an oncogene in many cancers including hematopoietic malignancies. However, the mechanisms accounting for miR-125b dysregulation remain to be elucidated. The present study aims to identify the factors that might contribute to up-regulation of miR-125b in human hematopoietic malignancies and its downstream targets for lineage-specific differentiation. We at first reported that CDX2, a homeobox transcription factor, binds to promoter regions of the miR-125b gene and activates transcriptional regulation of miR-125b in malignant myeloid cells. We further revealed that increasing levels of CDX2 in malignant myeloid cells activate miR-125b expression, which in turn inhibits core binding factor β (CBFβ) translation, thereby counteracting myeloid cell differentiation, at least for granulocytic lineage, and promoting leukemogenesis. Interestingly, we found that this novel pathway including CDX2, miR-125b, and CBFβ was mediated by undergoing all-trans-retinoic acid induction. Once differentiation ensues with all-trans-retinoic acid treatment, CDX2 activity decreases, leading to a reduction in miR-125b transcription and up-regulation of CBFβ in myeloid cells and in patients. The study provides a new mechanism that contributes to hematopoietic malignancies, which could involve deregulation of miR-125b and its up- and downstream factors. As altered expression of miRNAs has been reported in a wide range of malignancies, delineating the underlying molecular mechanisms of aberrant miRNA expression and characterizing the upstream and downstream factors will help to understand important steps in the pathogenesis of these afflictions.

Relationship of Axonal Voltage-gated Sodium Channel 1.8 (NaV1.8) mRNA Accumulation to Sciatic Nerve Injury-induced Painful Neuropathy in Rats

Painful peripheral neuropathy is a significant clinical problem; however, its pathological mechanism and effective treatments remain elusive. Increased peripheral expression of tetrodotoxin-resistant voltage-gated sodium channel 1.8 (NaV1.8) has been shown to associate with chronic pain symptoms in humans and experimental animals. Sciatic nerve entrapment (SNE) injury was used to develop neuropathic pain symptoms in rats, resulting in increased NaV1.8 mRNA in the injured nerve but not in dorsal root ganglia (DRG). To study the role of NaV1.8 mRNA in the pathogenesis of SNE-induced painful neuropathy, NaV1.8 shRNA vector was delivered by subcutaneous injection of cationized gelatin/plasmid DNA polyplex into the rat hindpaw and its subsequent retrograde transport via sciatic nerve to DRG. This in vivo NaV1.8 shRNA treatment reversibly and repeatedly attenuated the SNE-induced pain symptoms, an effect that became apparent following a distinct lag period of 3-4 days and lasted for 4-6 days before returning to pretreatment levels. Surprisingly, apparent knockdown of NaV1.8 mRNA occurred only in the injured nerve, not in the DRG, during the pain alleviation period. Levels of heteronuclear NaV1.8 RNA were unaffected by SNE or shRNA treatments, suggesting that transcription of the Scn10a gene encoding NaV1.8 was unchanged. Based on these data, we postulate that increased axonal mRNA transport results in accumulation of functional NaV1.8 protein in the injured nerve and the development of painful neuropathy symptoms. Thus, targeted delivery of agents that interfere with axonal NaV1.8 mRNA may represent effective neuropathic pain treatments.

Dye‐Free MicroRNA Quantification by Using Pyrosequencing with a Sequence‐Tagged Stem–loop RT Primer

Dye‐Free MicroRNA Quantification by Using Pyrosequencing with a Sequence‐Tagged Stem–loop RT Primer

A Microarray-based Approach Identifies ADP Ribosylation Factor-like Protein 2 as a Target of microRNA-16

microRNAs (miRNAs) are generally thought to negatively regulate the expression of their target genes by mRNA degradation or by translation repression. Here we show an efficient way to identify miRNA target genes by screening alterations in global mRNA levels following changes in miRNA levels. In this study, we used mRNA microarrays to measure global mRNA expression in three cell lines with increased or decreased levels of miR-16 and performed bioinformatics analysis based on multiple target prediction algorithms. For further investigation among the predicted miR-16 target genes, we selected genes that show an expression pattern opposite to that of miR-16. One of the candidate target genes that may interact with miR-16, ADP-ribosylation factor-like protein 2 (ARL2), was further investigated. First, ARL2 was deduced to be an ideal miR-16 target by computational predictions. Second, ARL2 mRNA and protein levels were significantly abolished by treatment with miR-16 precursors, whereas a miR-16 inhibitor increased ARL2 mRNA and protein levels. Third, a luciferase reporter assay confirmed that miR-16 directly recognizes the 3'-untranslated region (3'-UTR) of ARL2. Finally, we showed that miR-16 could regulate proliferation and induce a significant G0/G1 cell cycle arrest, which was due at least in part, to the down-regulation of ARL2. In summary, the present study suggests that integrating global mRNA profiling and bioinformatics tools may provide the basis for further investigation of the potential targets of a given miRNA. These results also illustrate a novel function of miR-16 targeting ARL2 in modulating proliferation and cell cycle progression.

Prediction and validation of conservative microRNAs of Solanum tuberosum L.

Potato (Solanum tuberosum) is an important crop around the world, and accounts for a significant amount of the food consumed by humans. However, little information is available about potato miRNAs which play important regulatory roles in plant growth and development. In the present study, computational prediction of potential miRNAs from potato revealed 71 miRNAs belonging to 48 families. Amongst these 71 mRNAs, 65 were predicted for the first time. Most potato miRNA families have one to three members, and sequence analysis showed that the candidate pre-miRNA sequences varied from 48 to 224 bp in length. To verify the predicted miRNAs, specific stem-loop RT primers were designed and real-time PCR assays were used to profile the expression levels of seven miRNAs from different tissues of potato. The results showed that all the selected miRNAs were successfully amplified. Most of them had their highest expression levels in leaves, and the lowest levels in the stem, while miR159 and miR164 presented a different expression pattern. The specific expression levels of each miRNAs in the tested tissues may be related to their particular functions in regulating potato vegetative growth and organ development.