Upregulation of p72 enhances malignant migration and invasion of glioma cells by repressing Beclin1 expression

p72 is the member of the DEAD-box RNA helicase family, which can unwind double-stranded RNA and is efficient for microRNA (miRNA, miR) processing. However, its specific role in glioma has not been elucidated. First, the expression of p72 in glioma cell lines and tissues was explored using Western blot. To explore the role of p72 on glioma progression, adenovirus inhibiting p72 was transfected into A172 and T98G cells. Cell autophagy was determined using GFPLC3 dots, and cell apoptosis was determined using flow cytometry. The effect of Beclin1 was explored using GFP-LC3 dots, flow cytometry, and colony formation. The possible miRNAs that target the 3′-untranslated region (3′-UTR) of Beclin1 were predicted using TargetScan. Dual luciferase reporter assay was applied to determine whether these miRNAs bind to the 3′-UTR of Beclin1. The expression of p72 was significantly increased in glioma cell lines and tissues. Autophagy-related protein Beclin1 was found to be significantly enhanced when p72 was inhibited. The accumulation of GFP-LC3 dots was significant in cells transfected with ad-sh-p72 compared with ad-con. Colony formation capacity and cell apoptosis were also found to be significantly decreased with p72 inhibition. Furthermore, upregulation of Beclin1 contributes to A172 cell autophagy, invasion, and apoptosis. Overexpression of p72 induces increased miR-34-5p and miR-5195-3p expression in A172 and T98G cells. Beclin1 was the target gene of miR-34-5p and miR-5195-3p. In conclusion, we found for the first time that overexpression of p72 decreased Beclin1 expression partially by increasing miR-34-5p and miR-5195-3p expression in A172 and T98G cells.     

MiR-27b promotes sheep skeletal muscle satellite cell proliferation by targeting <Emphasis Type="Italic">myostatin</Emphasis> gene

To investigate the role of miR-27b in sheep skeletal muscle development, here we first cloned the sequence of sheep pre-miR-27b, then further investigated its expression pattern in sheep skeletal muscle in vivo, the relationship of miR-27b expression and sheep skeletal muscle satellite cell proliferation and differentiation in vitro, and then finally confirmed its target gene during this development process. MiR-27b sequence, especially its mature sequence, was conservative among different species. MiR-27b highly expressed in sheep skeletal muscle than other tissues. In skeletal muscle of Suffolk and Bashbay sheep, miR-27b was upregulated during foetal period and downregulated during postnatal period significantly (\(P{<}0.01\)), but it still kept a relatively higher expression level in skeletal muscle of postnatal Suffolk sheep than Bashbay. There is a potential target site of miR-27b on \(3^\prime \)-UTR of sheep myostatin (MSTN) mRNA, and the double luciferase reporter assay proved that miR-27b could successfully bind on this site. When sheep satellite cells were in the proliferation status, miR-27b was upregulated and MSTN was downregulated significantly (\(P{<}0.01\)). When miR-27b mimics was transfected into sheep satellite cells, the cell proliferation was promoted and the protein level of MSTN was significantly downregulated (\(P{<}0.01\)). Moreover, miR-27b regulated its target gene MSTN by translation repression at an early step, and followed by inducing mRNA degradation in sheep satellite cells. Based on these results, we confirm that miR-27b could promote sheep skeletal muscle satellite cell proliferation by targeting MSTN and suppressing its expression.     

An integrated approach of bioinformatic prediction and in vitro analysis identified that miR-34a targets <Emphasis Type="Italic">MET</Emphasis> and <Emphasis Type="Italic">AXL</Emphasis> in triple-negative breast cancer

Background

Breast cancer is the most prevalent cancer among women, and AXL and MET are the key genes in the PI3K/AKT/mTOR pathway as critical elements in proliferation and invasion of cancer cells. MicroRNAs (miRNAs) are small non-coding RNAs regulating the expression of genes.

Methods

Bioinformatic approaches were used to find a miRNA that simultaneously targets both AXL and MET 3′-UTRs. The expression of target miRNA was evaluated in triple-negative (MDA-MB-231) and HER2-overexpressing (SK-BR-3) breast cancer cell lines as well as normal breast cells, MCF-10A, using quantitative real-time PCR. Then, the miRNA was overexpressed in normal and cancer cell lines using a lentiviral vector system. Afterwards, effects of overexpressed miRNA on the expression of AXL and MET genes were evaluated using quantitative real-time PCR.

Results

By applying bioinformatic software and programs, miRNAs that target the 3′-UTR of both AXL and MET mRNAs were determined, and according to the scores, miR-34a was selected for further analyses. The expression level of miR-34a in MDA-MB-231 and SK-BR-3 was lower than that of MCF-10A. Furthermore, AXL and MET expression in SK-BR-3 and MDA-MB-231 was lower and higher, respectively, than that of MCF-10A. After miR-34a overexpression, MET and AXL were downregulated in MDA-MB-231. In addition, MET was downregulated in SK-BR-3, while AXL was upregulated in this cell line.

Conclusions

These findings may indicate that miR-34a is an oncogenic miRNA, downregulated in the distinct breast cancer subtypes. It also targets MET and AXL 3′-UTRs in triple-negative breast cancer. Therefore, it can be considered as a therapeutic target in this type of breast cancer.

     

The 5′-untranslated region of the maize alcohol dehydrogenase gene provides efficient translation of mRNA in plants under stress conditions

The reduced level of expression of most cell proteins under stress conditions is determined by the low efficiency of cap-dependent translation of corresponding mRNAs. The maize gene encoding alcohol dehydrogenase, adh1, is a gene whose mRNA is efficiently translated in hypoxia. The reporter gene assay showed that the leader sequence of the adh1 mRNA provided for efficient translation of the reporter gfp gene in Nicotiana benthamiana cells in hypoxia or heat shock. The presence of this sequence in the 5′-UTR of mRNA did not change the level of expression under aerobic conditions, but the levels of gfp expression in hypoxia or heat shock were reduced five-to tenfold in the absence of this leader and remained unaffected when the adh leader sequence was present in the 5′-UTR. The adh1 leader sequence did not change the mRNA stability nor exhibited a promoter activity. Thus, the adh leader sequence acted as a translational enhancer, providing for efficient mRNA translation in plant cells under stress conditions. Introduction of this sequence into standard expression cassettes was proposed for the development of new systems to efficiently express the target proteins in plants under stress conditions.     

A betasatellite-encoded protein regulates key components of gene silencing system in plants

Small circular single-stranded DNA satellites, called betasatellites, have been found in association with some monopartite begomovirus infections. The Cotton leaf curl Multan betasatellite (CLCuMuB) is known to influence symptom induction in cotton leaf curl disease. CLCuMuB contains a single gene, βC1, whose product is a pathogenicity determinant and a suppressor of RNA silencing. Although induction of RNA silencing by RNA and DNA viruses has been well documented in plants, the interactions between betasatellites and the host’s silencing machinery remain poorly understood. In this study, the transgenic expression of βC1 from CLCuMuB in Arabidopsis thaliana plants produced severe developmental abnormalities, which resembled those produced by mutations in the key genes of the gene silencing pathway. Analysis of transgenic plants expressing CLCuMuB βC1 using real-time PCR showed that the expression levels of both AGO1 and DCL1 genes were significantly increased. In contrast, the expression of HEN1 gene in the βC1-expressing leaf tissues was similar to that of wild-type plants. The CLCuMuB βC1 protein was found to physically interact with the AGO1 protein in a yeast two-hybrid system. It is possible that specific targeting of the gene silencing key components by the CLCuMuB βC1 inhibits the RNA silencing-based host defence.     

<Emphasis Type="Italic">CER1</Emphasis>gene variations associated with bone mineral density,bone markers,and early menopause in postmenopausal women

Background

Osteoporosis has a multifactorial pathogenesis characterized by a combination of low bone mass and increased fragility. In our study, we focused on the effects of polymorphisms in CER1 and DKK1 genes, recently reported as important susceptibility genes for osteoporosis, on bone mineral density (BMD) and bone markers in osteoporotic women. Our objective was to evaluate the effect of CER1 and DKK1 variations in 607 postmenopausal women. The entire DKK1 gene sequence and five selected CER1 SNPs were amplified and resequenced to assess whether there is a correlation between these genes and BMD, early menopause, and bone turnover markers in osteoporotic patients.

Results

Osteoporotic women seem to suffer menopause 2 years earlier than the control group. The entire DKK1 gene sequence analysis revealed six variations. There was no correlation between the six DKK1 variations and osteoporosis, in contrast to the five common CER1 variations that were significantly associated with BMD. Additionally, osteoporotic patients with rs3747532 and rs7022304 CER1 variations had significantly higher serum levels of parathyroid hormone and calcitonin and lower serum levels of osteocalcin and IGF-1.

Conclusions

No significant association between the studied DKK1 variations and osteoporosis was found, while CER1 variations seem to play a significant role in the determination of osteoporosis and a potential predictive role, combined with bone markers, in postmenopausal osteoporotic women.

     

MicroRNA-197 induces epithelial–mesenchymal transition and invasion through the downregulation of HIPK2 in lung adenocarcinoma

The major cause of cancer-related deaths in patients with lung adenocarcinoma (LAD) is due to distant metastasis. Many reports have indicated that miRNA plays a key role in tumour metastasis. The expression of miR-197 is correlated with LAD progression, however, the mechanism of miR-197 is still unknown in the processing of LAD. A Boyden chamber migration/invasion assay was used for the metastatic function study in vitro. Real-time PCR and Western blot assays were employed to analyse the EMT hallmark changes in both the mRNA and protein levels. \(3^{\prime }\)-UTR reporter luciferase assay was used to show that HIPK2 is a direct target of miR-197. miR-197 enhances LAD cell migration and invasion miR-197. The downregulation of miR-197 suppresses the EMT and migration ability. HIPK2 is a direct functional target of miR-197 in LAD metastasis. In summary, miR-197 controls EMT and metastasis by directly silencing HIPK2. The findings suggest that interfering with the miR-197-dependent regulation of HIPK2 could be a useful approach for the treatment of patients with late stage metastatic LAD.     

MicroRNA-215 enhances invasion and migration by targeting retinoblastoma tumor suppressor gene 1 in high-grade glioma

Objective

To elucidate the molecular mechanism of microRNA-215 (miR-215) in the migration and invasion of high grade glioma.

Results

42 Patients were analysed for clinicopathological characteristics. qRT-PCR showed that miR-215 was up-regulated in glioma tissues compared with non-neoplastic brain tissues (P < 0.05). The up-regulated miR-215 was closely associated with high grade glioma (P < 0.01) and poor overall survival (P < 0.01). Transwell assay showed that re-expression of miR-215 enhanced migration and invasion of glioma cells. miR-215 also down-regulated retinoblastoma tumor suppressor gene 1 (RB1) expression by targeting its 3′-UTR. Reversely, re-expression of RB1 inhibited partial effect of miR-215 on migration and invasion in vitro.

Conclusions

Re-expression of miR-215 promoted cell migration and invasion of glioma by targeting RB1. miR-215 can thus be used as a biomarker for tumor progression and prognosis in human high grade glioma.

     

<Emphasis Type="Italic">miR-3075</Emphasis> Inhibited the Migration of Schwann Cells by Targeting Cntn2

Peripheral nerve injury is a complex biological process that involves the expression changes of various coding and non-coding RNAs. Previously, a number of novel miRNAs that were dysregulated in rat sciatic nerve stumps after peripheral nerve injury were identified and functionally annotated by Solexa sequencing. In the current study, we studied one of these identified novel miRNAs, miR-3075, in depth. Results of transwell-based cell migration assay showed that increased expression of miR-3075 suppressed the migration rate of Schwann cells while decreased expression of miR-3075 elevated the migration rate of Schwann cells, demonstrating that miR-3075 inhibited Schwann cell migration. Results of BrdU cell proliferation assay showed that neither miR-3075 mimic nor miR-3075 inhibitor would affect Schwann cell proliferation. We further studied candidate target genes of miR-3075 by using bioinformatic tools and analyzing gene expression patterns and found that miR-3075 might target contactin 2 (Cntn2). Previous study showed that Cntn2 regulated cell migration and myelination. Our current observation suggested that the biological effects of miR-3075 on Schwann cell phenotype might by through the negative regulation of Cntn2. Overall, our study revealed the function of a novel miRNA, miR-3075, and expanded our current understanding of the molecular mechanisms underlying peripheral nerve injury and regeneration.     

Expression and function of microRNA-9 in the mid-hindbrain area of embryonic chick

Background

MiR-9 is a small non-coding RNA that is highly conserved between species and primarily expressed in the central nervous system (CNS). It is known to influence proliferation and neuronal differentiation in the brain and spinal cord of different vertebrates. Different studies have pointed to regional and species-specific differences in the response of neural progenitors to miR-9.

Methods

In ovo and ex ovo electroporation was used to overexpress or reduce miR-9 followed by mRNA in situ hybridisation and immunofluorescent stainings to evaluate miR- expression and the effect of changed miR-9 expression.

Results

We have investigated the expression and function of miR-9 during early development of the mid-hindbrain region (MH) in chick. Our analysis reveals a closer relationship of chick miR-9 to mammalian miR-9 than to fish and a dynamic expression pattern in the chick neural tube. Early in development, miR-9 is diffusely expressed in the entire brain, bar the forebrain, and it becomes more restricted to specific areas of the CNS at later stages. MiR-9 overexpression at HH9–10 results in a reduction of FGF8 expression and premature neuronal differentiation in the mid-hindbrain boundary (MHB). Within the midbrain miR-9 does not cause premature neuronal differentiation it rather reduces proliferation in the midbrain.

Conclusion

Our findings indicate that miR-9 has regional specific effects in the developing mid-hindbrain region with a divergence of response of regional progenitors.

     

Role of microRNA-195 in cardiomyocyte apoptosis induced by myocardial ischaemia–reperfusion injury

This study aims to investigate microRNA-195 (miR-195) expression in myocardial ischaemia–reperfusion (I/R) injury and the roles of miR-195 in cardiomyocyte apoptosis though targeting Bcl-2. A mouse model of I/R injury was established. MiR-195 expression levels were detected by real-time quantitative PCR (qPCR), and the cardiomyocyte apoptosis was detected by TUNEL assay. After cardiomyocytes isolated from neonatal rats and transfected with miR-195 mimic or inhibitor, the hypoxia/reoxygenation (H/R) injury model was established. Cardiomyocyte apoptosis and mitochondrial membrane potential were evaluated using flow cytometry. Bcl-2 and Bax mRNA expressions were detected by RT-PCR. Bcl-2, Bax and cytochrome c (Cyt-c) protein levels were determined by Western blot. Caspase-3 and caspase-9 activities were assessed by luciferase assay. Compared with the sham group, miR-195 expression levels and rate of cardiomyocyte apoptosis increased significantly in I/R group (both P<0.05). Compared to H/R + negative control (NC) group, rate of cardiomyocyte apoptosis increased in H/R + miR-195 mimic group while decreased in H/R + miR-195 inhibitor group (both P<0.05). MiR-195 knockdown alleviated the loss of mitochondrial membrane potential (P<0.05). MiR-195 overexpression decreased Bcl-2 mRNA and protein expression, increased BaxmRNA and protein expression, Cyt-c protein expression and caspase-3 and caspase-9 activities (all P<0.05). While, downregulated MiR-195 increased Bcl-2 mRNA and protein expression, decreased Bax mRNA and protein expression, Cyt-c protein expression and caspase-3 and caspase-9 activities (all P<0.05). Our study identified that miR-195 expression was upregulated in myocardial I/R injury, and miR-195 overexpression may promote cardiomyocyte apoptosis by targeting Bcl-2 and inducing mitochondrial apoptotic pathway.